Publish interrupted saved-removal checkpoint and remaining verification

.gitattributes

@@ -12,6 +12,12 @@
 *.png binary
 *.jpg binary
 *.zip binary
+harness/scenario-selection-evidence-20260924/** -text whitespace=cr-at-eol
+harness/scenario-group-spacing-evidence-20260924/** -text whitespace=cr-at-eol
+harness/scenario-reorder-interaction-evidence-20260924/** -text whitespace=cr-at-eol
+harness/scenario-group-removal-evidence-20260925/** -text whitespace=cr-at-eol
+harness/scenario-removal-followup-evidence-20260925/** -text whitespace=cr-at-eol
+harness/fixtures/process-removal-removed-v2-20260925.arcadia -text whitespace=-blank-at-eol
 
 # Exact source/recovery oracles and archived ledgers retain their measured bytes.
 # Keep ordinary text diffs; only disable checkout/check-in newline conversion.
@@ -89,3 +95,12 @@ harness/experiments/analysis-source-s2a-windows-20260913/** -text whitespace=-bl
 
 # Preserve the pinned Iced dependency bytes and upstream manifest.
 crates/vendor/iced_widget/** -text whitespace=cr-at-eol
+
+# Preserve exact Process removal review and portable evidence bytes.
+harness/process-group-removal-evidence-20260925/** -text whitespace=cr-at-eol
+
+# Preserve exact saved-view planner review and portable evidence bytes.
+harness/saved-group-removal-evidence-20260925/** -text whitespace=cr-at-eol
+
+# Preserve exact saved-view application check records.
+harness/saved-group-removal-app-evidence-20260925/** -text whitespace=cr-at-eol

crates/oa-core/examples/auto_layout_probe/boundary_fixtures.rs

@@ -1,131 +0,0 @@
-//! Independent structural falsifiers for incoming boundary ordering.
-use super::*;
-
-fn pair(f: &mut Builder, name: &str, x: f32) -> (Id, Id, Id) {
-    let parent = f.function(name, None, x, 40.0);
-    let a = f.function(&format!("{name} A"), Some(parent), x + 60.0, 130.0);
-    let b = f.function(&format!("{name} B"), Some(parent), x + 60.0, 330.0);
-    (parent, a, b)
-}
-
-pub(super) fn fixtures() -> Vec<(&'static str, Builder)> {
-    let mut all = Vec::new();
-    let mut f = Builder::new("boundary_opposing_parents");
-    let (_, la, lb) = pair(&mut f, "Left", 40.0);
-    let (_, ra, rb) = pair(&mut f, "Right", 820.0);
-    for (name, a, b) in [
-        ("Reverse upper", la, rb),
-        ("Reverse lower", lb, ra),
-        ("Return upper", ra, la),
-        ("Return lower", rb, lb),
-    ] {
-        f.exchange(name, a, b);
-    }
-    all.push(("boundary_opposing_parents", f));
-
-    let mut f = Builder::new("boundary_three_parent_chain");
-    let (_, la, lb) = pair(&mut f, "Left", 40.0);
-    let (middle, ma, mb) = pair(&mut f, "Middle", 820.0);
-    let (_, ra, rb) = pair(&mut f, "Right", 1600.0);
-    for (name, a, b) in [
-        ("Left upper", la, mb),
-        ("Left lower", lb, ma),
-        ("Middle upper", mb, ra),
-        ("Middle lower", ma, rb),
-    ] {
-        f.exchange(name, a, b);
-    }
-    let mut translated = f.clone();
-    for element in [middle, ma, mb] {
-        let node = translated.node(element);
-        let position = &mut translated
-            .project
-            .diagrams
-            .get_mut(&translated.diagram)
-            .unwrap()
-            .nodes
-            .get_mut(&node)
-            .unwrap()
-            .position;
-        position.x += 300.0;
-        position.y += 500.0;
-    }
-    let mut permuted = f.clone();
-    let ids: Vec<_> = permuted.project.relations.keys().copied().collect();
-    for (i, id) in ids.iter().enumerate() {
-        reidentify(
-            &mut permuted.project,
-            *id,
-            Id::from_u128(1_000_000 + i as u128),
-        )
-        .unwrap();
-    }
-    for (i, id) in ids.iter().rev().enumerate() {
-        reidentify(
-            &mut permuted.project,
-            Id::from_u128(1_000_000 + i as u128),
-            *id,
-        )
-        .unwrap();
-    }
-    all.push(("boundary_three_parent_chain", f));
-    all.push(("boundary_three_parent_translated", translated));
-    all.push(("boundary_three_parent_edge_ids_reversed", permuted));
-
-    let mut f = Builder::new("boundary_two_local_sccs");
-    let (_, sa, sb) = pair(&mut f, "Source", 40.0);
-    let target = f.function("Target", None, 820.0, 40.0);
-    let x1 = f.function("X1", Some(target), 880.0, 130.0);
-    let x2 = f.function("X2", Some(target), 1200.0, 130.0);
-    let y1 = f.function("Y1", Some(target), 880.0, 330.0);
-    let y2 = f.function("Y2", Some(target), 1200.0, 330.0);
-    let z = f.function("Z", Some(target), 1520.0, 230.0);
-    for (name, a, b) in [
-        ("X forward", x1, x2),
-        ("X back", x2, x1),
-        ("Y forward", y1, y2),
-        ("Y back", y2, y1),
-        ("X result", x2, z),
-        ("Y result", y2, z),
-        ("Upper boundary", sa, y1),
-        ("Lower boundary", sb, x1),
-    ] {
-        f.exchange(name, a, b);
-    }
-    all.push(("boundary_two_local_sccs", f));
-
-    let mut f = super::fixtures()
-        .into_iter()
-        .find(|(name, _)| *name == "two_containers_reversed_children")
-        .unwrap()
-        .1;
-    let relations: Vec<_> = f.project.relations.values().cloned().collect();
-    for relation in relations {
-        if let RelationBody::FunctionalExchange {
-            source_port,
-            target_port,
-            ..
-        } = relation.body
-        {
-            for (port, side, offset) in [
-                (source_port, PortAnchorSide::Right, 0.3),
-                (target_port, PortAnchorSide::Left, 0.7),
-            ] {
-                let owner = f.project.elements[&port].parent.unwrap();
-                let node = f.node(owner);
-                f.project = prepare_command(
-                    &f.project,
-                    &Command::SetPortAnchor {
-                        diagram: f.diagram,
-                        node,
-                        anchor: PortAnchor { port, side, offset },
-                    },
-                )
-                .unwrap()
-                .project;
-            }
-        }
-    }
-    all.push(("boundary_two_containers_anchored", f));
-    all
-}

crates/oa-core/examples/auto_layout_probe/clearance.rs

@@ -1,279 +0,0 @@
-//! Bounded flat-placement experiment. Empty lead diagnostics are necessary only,
-//! never a claim that routes, labels, or drawing quality are acceptable.
-use oa_core::{Id, ModelError, Project, projection, routing};
-use std::collections::BTreeMap;
-
-const ROUNDS: usize = 4;
-const WORK_LIMIT: usize = 10_000_000;
-const MAX_SPAN: f32 = 100_000.0;
-const MARGIN: f32 = 1.0;
-
-fn fail(message: &str) -> ModelError {
-    ModelError(format!("Clearance probe: {message}"))
-}
-
-fn spend(work: &mut usize, amount: usize) -> Result<(), ModelError> {
-    *work = work.saturating_add(amount);
-    if *work > WORK_LIMIT {
-        return Err(fail("work limit exceeded"));
-    }
-    Ok(())
-}
-
-// A boundary constraint means start[to] >= start[from] + extent[from] + gap.
-// Adjacent total-order constraints below separately preserve start ordering.
-type Constraints = BTreeMap<(usize, usize), f32>;
-
-fn solve(
-    baseline: &[f32],
-    extents: &[f32],
-    order: &[usize],
-    constraints: &Constraints,
-    work: &mut usize,
-) -> Result<Vec<f32>, ModelError> {
-    let mut result = baseline.to_vec();
-    let mut previous = None;
-    for &to in order {
-        if let Some(from) = previous {
-            result[to] = result[to].max(result[from]);
-        }
-        for (&(from, target), &gap) in constraints {
-            spend(work, 1)?;
-            if target == to {
-                result[to] = result[to].max(result[from] + extents[from] + gap);
-            }
-        }
-        previous = Some(to);
-    }
-    let minimum = baseline.iter().copied().fold(f32::INFINITY, f32::min);
-    for (i, &value) in result.iter().enumerate() {
-        if !value.is_finite() || value + extents[i] - minimum > MAX_SPAN {
-            return Err(fail("coordinate/span bound exceeded"));
-        }
-    }
-    Ok(result)
-}
-
-/// Input is an already admitted placement candidate. Never modifies its routes,
-/// authored anchors, sizes or semantics. Error drops the private clone.
-pub fn repair(project: &Project, diagram: Id) -> Result<Project, ModelError> {
-    let original = project
-        .diagrams
-        .get(&diagram)
-        .ok_or_else(|| fail("missing diagram"))?;
-    if original.projection.scenario().is_some() {
-        return Err(fail("Scenario unsupported"));
-    }
-    let baseline = projection::project_diagram(project, original);
-    if baseline.nodes.len() > 256 || baseline.edges.len() > 1024 {
-        return Err(fail("graph bound exceeded"));
-    }
-    if baseline.nodes.len() != original.nodes.len()
-        || baseline
-            .nodes
-            .iter()
-            .any(|n| n.collapsed || n.visual_parent.is_some())
-    {
-        return Err(fail("nested, folded or omitted placements unsupported"));
-    }
-    let mut nodes = baseline.nodes.clone();
-    nodes.sort_by_key(|n| n.id);
-    if nodes.iter().any(|n| {
-        !n.position.x.is_finite()
-            || !n.position.y.is_finite()
-            || !n.size.width.is_finite()
-            || !n.size.height.is_finite()
-            || n.size.width <= 0.0
-            || n.size.height <= 0.0
-    }) {
-        return Err(fail("invalid initial geometry"));
-    }
-    let indices: BTreeMap<_, _> = nodes.iter().enumerate().map(|(i, n)| (n.id, i)).collect();
-    let coordinates = [
-        nodes.iter().map(|n| n.position.x).collect::<Vec<_>>(),
-        nodes.iter().map(|n| n.position.y).collect::<Vec<_>>(),
-    ];
-    let extents = [
-        nodes.iter().map(|n| n.size.width).collect::<Vec<_>>(),
-        nodes.iter().map(|n| n.size.height).collect::<Vec<_>>(),
-    ];
-    for axis in 0..2 {
-        let minimum = coordinates[axis]
-            .iter()
-            .copied()
-            .fold(f32::INFINITY, f32::min);
-        if coordinates[axis]
-            .iter()
-            .zip(&extents[axis])
-            .any(|(&start, &extent)| {
-                !(start + extent).is_finite() || start + extent - minimum > MAX_SPAN
-            })
-        {
-            return Err(fail("initial coordinate/span bound exceeded"));
-        }
-    }
-    let mut orders = [Vec::new(), Vec::new()];
-    let mut ranks = [vec![0; nodes.len()], vec![0; nodes.len()]];
-    for axis in 0..2 {
-        orders[axis] = (0..nodes.len()).collect();
-        orders[axis].sort_by(|&a, &b| {
-            coordinates[axis][a]
-                .total_cmp(&coordinates[axis][b])
-                .then(nodes[a].id.cmp(&nodes[b].id))
-        });
-        for (rank, &i) in orders[axis].iter().enumerate() {
-            ranks[axis][i] = rank;
-        }
-    }
-    let mut constraints = [Constraints::new(), Constraints::new()];
-    let mut work = 0;
-    // Preserve one existing disjoint axis per pair, X before Y. No initially
-    // overlapping pair is silently treated as successfully repaired.
-    for a in 0..nodes.len() {
-        for b in a + 1..nodes.len() {
-            spend(&mut work, 1)?;
-            let mut chosen = None;
-            for axis in 0..2 {
-                for (from, to) in [(a, b), (b, a)] {
-                    let gap = coordinates[axis][to] - coordinates[axis][from] - extents[axis][from];
-                    if gap >= 0.0 {
-                        chosen = Some((axis, from, to, gap));
-                        break;
-                    }
-                }
-                if chosen.is_some() {
-                    break;
-                }
-            }
-            let (axis, from, to, gap) =
-                chosen.ok_or_else(|| fail("initial node overlap unsupported"))?;
-            constraints[axis].insert((from, to), gap);
-        }
-    }
-    let mut result = project.clone();
-    for round in 0..=ROUNDS {
-        let current = &result.diagrams[&diagram];
-        let view = projection::project_diagram(&result, current);
-        if view.nodes.len() != nodes.len()
-            || view.nodes.iter().any(|n| {
-                indices.get(&n.id).is_none_or(|&i| {
-                    n.size != nodes[i].size || n.collapsed || n.visual_parent.is_some()
-                })
-            })
-        {
-            return Err(fail("reprojection changed node identity/size/topology"));
-        }
-        // Charge work units proportional to node count and at most sixteen
-        // endpoint pairs. This is not an exact operation count or a bound on
-        // all projection work; graph, round and span limits apply separately.
-        spend(
-            &mut work,
-            view.edges
-                .len()
-                .saturating_mul(nodes.len().saturating_add(1))
-                .saturating_mul(16),
-        )?;
-        let failures = routing::lead_incompatibilities(&result, current, &view);
-        if failures.is_empty() {
-            return Ok(result);
-        }
-        if round == ROUNDS {
-            return Err(fail("unresolved mandatory leads after four adjustments"));
-        }
-        let mut strengthened = false;
-        for failure in failures {
-            if failure.allowed_pair_count != 1
-                || failure.source.len() != 1
-                || failure.target.len() != 1
-            {
-                return Err(fail("ambiguous endpoint choices unsupported"));
-            }
-            for endpoint in failure.source.iter().chain(&failure.target) {
-                let owner = *indices
-                    .get(&endpoint.owner)
-                    .ok_or_else(|| fail("unknown endpoint owner"))?;
-                let dx = endpoint.stub.x - endpoint.tip.x;
-                let dy = endpoint.stub.y - endpoint.tip.y;
-                if endpoint.blockers.is_empty() {
-                    continue;
-                }
-                let (axis, forward) = match (dx, dy) {
-                    (x, 0.0) if x != 0.0 => (0, x > 0.0),
-                    (0.0, y) if y != 0.0 => (1, y > 0.0),
-                    _ => return Err(fail("noncardinal/degenerate blocked lead")),
-                };
-                for blocker in &endpoint.blockers {
-                    spend(&mut work, 1)?;
-                    let other = *indices
-                        .get(&blocker.id)
-                        .ok_or_else(|| fail("unknown blocker"))?;
-                    let (from, to) = if forward {
-                        (owner, other)
-                    } else {
-                        (other, owner)
-                    };
-                    if ranks[axis][from] >= ranks[axis][to] {
-                        return Err(fail("lead constraint opposes frozen spatial order"));
-                    }
-                    let required = routing::PORT_STUB + routing::CLEARANCE + MARGIN;
-                    let old = constraints[axis].entry((from, to)).or_insert(0.0);
-                    if *old < required {
-                        *old = required;
-                        strengthened = true;
-                    }
-                }
-            }
-        }
-        if !strengthened {
-            return Err(fail(
-                "unresolved lead without a stronger monotone constraint",
-            ));
-        }
-        let x = solve(
-            &coordinates[0],
-            &extents[0],
-            &orders[0],
-            &constraints[0],
-            &mut work,
-        )?;
-        let y = solve(
-            &coordinates[1],
-            &extents[1],
-            &orders[1],
-            &constraints[1],
-            &mut work,
-        )?;
-        let target = result.diagrams.get_mut(&diagram).unwrap();
-        for (i, node) in nodes.iter().enumerate() {
-            let placed = target.nodes.get_mut(&node.id).unwrap();
-            placed.position.x = x[i];
-            placed.position.y = y[i];
-        }
-    }
-    unreachable!("bounded loop returns on final round")
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn separation_propagates_to_neighbor_without_moving_predecessor() {
-        let constraints = BTreeMap::from([((0, 1), 31.0), ((1, 2), 10.0)]);
-        let actual = solve(
-            &[-20.0, 100.0, 210.0],
-            &[100.0; 3],
-            &[0, 1, 2],
-            &constraints,
-            &mut 0,
-        )
-        .unwrap();
-        assert_eq!(actual, vec![-20.0, 111.0, 221.0]);
-    }
-
-    #[test]
-    fn extent_bound_rejects_constraint_expansion() {
-        let constraints = BTreeMap::from([((0, 1), MAX_SPAN)]);
-        assert!(solve(&[0.0, 20.0], &[10.0; 2], &[0, 1], &constraints, &mut 0).is_err());
-    }
-}

crates/oa-core/examples/auto_layout_probe/condensed.rs

@@ -1,654 +0,0 @@
-//! Isolated SCC-block placement experiment; no production-layout acceptance.
-use super::{PlacementNode, PlacementPlan, import_placement};
-use oa_core::{Id, ModelError, Position, Project, Size, projection, routing};
-use std::collections::{BTreeMap, BTreeSet};
-
-const LIMIT: usize = 20_000_000;
-const PAD: f32 = 32.0;
-const SPAN: f32 = 100_000.0;
-
-#[path = "condensed/boundary.rs"]
-mod boundary;
-
-fn error(text: &str) -> ModelError {
-    ModelError(format!("SCC placement: {text}"))
-}
-fn charge(work: &mut usize, count: usize) -> Result<(), ModelError> {
-    *work = work.saturating_add(count);
-    if *work > LIMIT {
-        Err(error("work limit exceeded"))
-    } else {
-        Ok(())
-    }
-}
-
-fn components(arcs: &[BTreeSet<usize>], work: &mut usize) -> Result<Vec<Vec<usize>>, ModelError> {
-    let n = arcs.len();
-    let mut reach = vec![vec![false; n]; n];
-    for (start, reachable) in reach.iter_mut().enumerate() {
-        let mut todo = vec![start];
-        reachable[start] = true;
-        while let Some(at) = todo.pop() {
-            for &next in &arcs[at] {
-                charge(work, 1)?;
-                if !reachable[next] {
-                    reachable[next] = true;
-                    todo.push(next);
-                }
-            }
-        }
-    }
-    let mut used = vec![false; n];
-    let mut result = Vec::new();
-    for i in 0..n {
-        if used[i] {
-            continue;
-        }
-        let mut group = Vec::new();
-        for j in i..n {
-            charge(work, 1)?;
-            if !used[j] && reach[i][j] && reach[j][i] {
-                used[j] = true;
-                group.push(j);
-            }
-        }
-        result.push(group);
-    }
-    Ok(result)
-}
-
-fn perimeter_slots(n: usize, rows: usize, cols: usize) -> Vec<(usize, usize)> {
-    let mut slots = Vec::new();
-    if rows == 1 {
-        slots.extend((0..cols).map(|col| (col, 0)));
-    } else if cols == 1 {
-        slots.extend((0..rows).map(|row| (0, row)));
-    } else {
-        slots.extend((0..cols).map(|col| (col, 0)));
-        slots.extend((1..rows).map(|row| (cols - 1, row)));
-        slots.extend((0..cols - 1).rev().map(|col| (col, rows - 1)));
-        slots.extend((1..rows - 1).rev().map(|row| (0, row)));
-    }
-    slots.truncate(n);
-    slots
-}
-
-// Score occupied maximum-member cells, excluding unused perimeter slots.
-// Heterogeneous members may occupy less than this nominal cell envelope.
-fn perimeter(
-    n: usize,
-    cell: Size,
-    gap: Size,
-    work: &mut usize,
-) -> Result<(Vec<Position>, usize, usize), ModelError> {
-    type GridScore = (bool, f32, f32, usize, usize);
-    let mut best: Option<(GridScore, usize, usize)> = None;
-    for rows in 1..=n {
-        for cols in 1..=n {
-            charge(work, 1)?;
-            let capacity = if rows == 1 || cols == 1 {
-                rows * cols
-            } else {
-                2 * rows + 2 * cols - 4
-            };
-            if capacity < n {
-                continue;
-            }
-            charge(work, capacity)?;
-            let slots = perimeter_slots(n, rows, cols);
-            let max_x = slots.iter().map(|p| p.0).max().unwrap();
-            let max_y = slots.iter().map(|p| p.1).max().unwrap();
-            let width = (max_x + 1) as f32 * cell.width + max_x as f32 * gap.width;
-            let height = (max_y + 1) as f32 * cell.height + max_y as f32 * gap.height;
-            let aspect = (width / height).max(height / width);
-            let key = (
-                aspect > 2.0,
-                if aspect <= 2.0 {
-                    width * height
-                } else {
-                    aspect
-                },
-                width * height,
-                rows,
-                cols,
-            );
-            if best.as_ref().is_none_or(|(old, _, _)| key < *old) {
-                best = Some((key, rows, cols));
-            }
-        }
-    }
-    let (_, rows, cols) = best.ok_or_else(|| error("no perimeter grid"))?;
-    let slots = perimeter_slots(n, rows, cols);
-    Ok((
-        slots
-            .into_iter()
-            .take(n)
-            .map(|(x, y)| Position {
-                x: x as f32 * (cell.width + gap.width),
-                y: y as f32 * (cell.height + gap.height),
-            })
-            .collect(),
-        rows,
-        cols,
-    ))
-}
-
-fn lift(
-    id: Id,
-    parent: Option<Id>,
-    parents: &BTreeMap<Id, Option<Id>>,
-    work: &mut usize,
-) -> Result<Option<Id>, ModelError> {
-    let mut at = id;
-    for _ in 0..=parents.len() {
-        charge(work, 1)?;
-        let Some(&up) = parents.get(&at) else {
-            return Err(error("missing visual ancestor"));
-        };
-        if up == parent {
-            return Ok(Some(at));
-        }
-        let Some(next) = up else {
-            return Ok(None);
-        };
-        at = next;
-    }
-    Err(error("cyclic visual ancestry"))
-}
-
-/// Frozen projected geometry is the minimum; folded nodes remain opaque.
-pub fn candidate(project: &Project, diagram: Id) -> Result<Project, ModelError> {
-    candidate_with_diagnostics(project, diagram).map(|(result, _)| result)
-}
-
-pub fn candidate_with_diagnostics(
-    project: &Project,
-    diagram: Id,
-) -> Result<(Project, serde_json::Value), ModelError> {
-    candidate_policy(project, diagram, false)
-}
-
-pub fn boundary_candidate_with_diagnostics(
-    project: &Project,
-    diagram: Id,
-) -> Result<(Project, serde_json::Value), ModelError> {
-    candidate_policy(project, diagram, true)
-}
-
-fn candidate_policy(
-    project: &Project,
-    diagram: Id,
-    order_boundaries: bool,
-) -> Result<(Project, serde_json::Value), ModelError> {
-    let d = project
-        .diagrams
-        .get(&diagram)
-        .ok_or_else(|| error("missing diagram"))?;
-    if d.projection.scenario().is_some() {
-        return Err(error("Scenario unsupported"));
-    }
-    if d.nodes.len() > 256 {
-        return Err(error("stored-node bound exceeded"));
-    }
-    let view = projection::project_diagram(project, d);
-    if view.edges.len() > 1024 {
-        return Err(error("visible-edge bound exceeded"));
-    }
-    if view.nodes.iter().any(|n| {
-        !n.size.width.is_finite()
-            || !n.size.height.is_finite()
-            || n.size.width <= 0.0
-            || n.size.height <= 0.0
-    }) {
-        return Err(error("invalid projected minima"));
-    }
-    let parents: BTreeMap<_, _> = view.nodes.iter().map(|n| (n.id, n.visual_parent)).collect();
-    let names: BTreeMap<_, _> = view
-        .nodes
-        .iter()
-        .map(|n| (n.id, (project.elements[&n.element].alias.clone(), n.id)))
-        .collect();
-    let mut children: BTreeMap<Option<Id>, Vec<Id>> = BTreeMap::new();
-    for n in &view.nodes {
-        children.entry(n.visual_parent).or_default().push(n.id);
-    }
-    for ids in children.values_mut() {
-        ids.sort_by_key(|id| names[id].clone());
-    }
-    let mut work = 0;
-    let mut depth = BTreeMap::new();
-    for n in &view.nodes {
-        let mut at = n.id;
-        let mut count = 0;
-        let mut seen = BTreeSet::new();
-        while let Some(up) = *parents.get(&at).ok_or_else(|| error("missing parent"))? {
-            charge(&mut work, 1)?;
-            if !seen.insert(at) {
-                return Err(error("cyclic hierarchy"));
-            }
-            count += 1;
-            at = up;
-        }
-        depth.insert(n.id, count);
-    }
-    let routed = routing::route_diagram(project, d, &view);
-    let mut sizes: BTreeMap<_, _> = view.nodes.iter().map(|n| (n.id, n.size)).collect();
-    let mut offsets = BTreeMap::new();
-    let mut diagnostics = Vec::new();
-    let mut boundary_groups = Vec::new();
-    let mut groups: Vec<_> = children.keys().copied().collect();
-    groups.sort_by_key(|p| std::cmp::Reverse(p.map_or(0, |id| depth[&id] + 1)));
-    for parent in groups {
-        let ids = &children[&parent];
-        let index: BTreeMap<_, _> = ids.iter().enumerate().map(|(i, id)| (*id, i)).collect();
-        let mut arcs = vec![BTreeSet::new(); ids.len()];
-        let mut links = Vec::new();
-        let mut undirected = BTreeSet::new();
-        for edge in &view.edges {
-            charge(&mut work, 1)?;
-            let (Some(a), Some(b)) = (
-                lift(edge.source, parent, &parents, &mut work)?,
-                lift(edge.target, parent, &parents, &mut work)?,
-            ) else {
-                continue;
-            };
-            if a == b {
-                continue;
-            }
-            let (a, b) = (index[&a], index[&b]);
-            if edge.oriented {
-                arcs[a].insert(b);
-            } else {
-                undirected.insert((ids[a].min(ids[b]), ids[a].max(ids[b])));
-            }
-            let routed_edge = routed
-                .edges
-                .get(&edge.id)
-                .ok_or_else(|| error("missing estimated edge label"))?;
-            let mut label = routed_edge.label.bounds.size;
-            if let Some(relation) = project.relations.get(&edge.id) {
-                for end in routing::association_end_geometry(relation, routed_edge) {
-                    label.width = label.width.max(end.label.bounds.size.width);
-                    label.height = label.height.max(end.label.bounds.size.height);
-                }
-            }
-            if !label.width.is_finite() || !label.height.is_finite() {
-                return Err(error("invalid estimated label"));
-            }
-            links.push((a, b, label));
-        }
-        let comps = components(&arcs, &mut work)?;
-        let mut owner = vec![0; ids.len()];
-        for (c, members) in comps.iter().enumerate() {
-            for &i in members {
-                owner[i] = c;
-            }
-        }
-        let mut dag = vec![BTreeSet::new(); comps.len()];
-        for (a, targets) in arcs.iter().enumerate() {
-            for &b in targets {
-                if owner[a] != owner[b] {
-                    dag[owner[a]].insert(owner[b]);
-                }
-            }
-        }
-        let mut ranks = vec![0usize; comps.len()];
-        let mut done = BTreeSet::new();
-        while done.len() < comps.len() {
-            let next = (0..comps.len())
-                .find(|c| {
-                    !done.contains(c)
-                        && (0..comps.len()).all(|p| !dag[p].contains(c) || done.contains(&p))
-                })
-                .ok_or_else(|| error("condensation is cyclic"))?;
-            charge(&mut work, comps.len() * comps.len())?;
-            for &to in &dag[next] {
-                ranks[to] = ranks[to].max(ranks[next] + 1);
-            }
-            done.insert(next);
-        }
-        let mut blocks = Vec::new();
-        let mut component_diagnostics = Vec::new();
-        let mut member_offsets = BTreeMap::new();
-        for (c, members) in comps.iter().enumerate() {
-            let mut gap = Size {
-                width: PAD,
-                height: PAD,
-            };
-            for &(a, b, label) in &links {
-                if owner[a] == c && owner[b] == c {
-                    gap.width = gap.width.max(label.width + PAD);
-                    gap.height = gap.height.max(label.height + PAD);
-                }
-            }
-            let mut order = Vec::new();
-            let mut seen = BTreeSet::new();
-            for &start in members {
-                let mut stack = vec![start];
-                while let Some(i) = stack.pop() {
-                    charge(&mut work, 1)?;
-                    if !seen.insert(i) {
-                        continue;
-                    }
-                    order.push(i);
-                    for &j in arcs[i].iter().rev() {
-                        if owner[j] == c && !seen.contains(&j) {
-                            stack.push(j);
-                        }
-                    }
-                }
-            }
-            let cell = Size {
-                width: members
-                    .iter()
-                    .map(|&i| sizes[&ids[i]].width)
-                    .fold(0.0, f32::max),
-                height: members
-                    .iter()
-                    .map(|&i| sizes[&ids[i]].height)
-                    .fold(0.0, f32::max),
-            };
-            let (slots, rows, cols) = if members.len() == 1 {
-                (vec![Position { x: 0.0, y: 0.0 }], 1, 1)
-            } else {
-                perimeter(members.len(), cell, gap, &mut work)?
-            };
-            component_diagnostics.push(serde_json::json!({"component":c,"rank":ranks[c],"members":members.iter().map(|&i|ids[i]).collect::<Vec<_>>(),"walk":order.iter().map(|&i|ids[i]).collect::<Vec<_>>(),"grid_rows":rows,"grid_cols":cols,"gap":gap}));
-            let mut size = Size {
-                width: 0.0,
-                height: 0.0,
-            };
-            for (i, pos) in order.into_iter().zip(slots) {
-                size.width = size.width.max(pos.x + sizes[&ids[i]].width);
-                size.height = size.height.max(pos.y + sizes[&ids[i]].height);
-                member_offsets.insert(i, pos);
-            }
-            blocks.push(size);
-        }
-        let max_rank = ranks.iter().copied().max().unwrap_or(0);
-        charge(
-            &mut work,
-            links
-                .len()
-                .saturating_mul(comps.len().saturating_add(1))
-                .saturating_mul(comps.len().saturating_add(1)),
-        )?;
-        let mut block_positions = vec![Position { x: 0.0, y: 0.0 }; comps.len()];
-        let mut x = 0.0;
-        let mut total = Size {
-            width: 0.0,
-            height: 0.0,
-        };
-        let mut prior_order = vec![0usize; comps.len()];
-        let mut bands = Vec::new();
-        for rank in 0..=max_rank {
-            let mut layer: Vec<_> = (0..comps.len()).filter(|&c| ranks[c] == rank).collect();
-            // Fixed one-pass proximity order, including undirected links, without
-            // inventing direction or changing condensation ranks.
-            layer.sort_by_key(|&c| {
-                let neighbors: Vec<_> = links
-                    .iter()
-                    .filter_map(|&(a, b, _)| {
-                        let (a, b) = (owner[a], owner[b]);
-                        if a == c && ranks[b] < rank {
-                            Some(prior_order[b])
-                        } else if b == c && ranks[a] < rank {
-                            Some(prior_order[a])
-                        } else {
-                            None
-                        }
-                    })
-                    .collect();
-                (
-                    if neighbors.is_empty() {
-                        c
-                    } else {
-                        neighbors.iter().sum::<usize>() / neighbors.len()
-                    },
-                    c,
-                )
-            });
-            // Keep same-rank undirected neighbours contiguous in one canonical
-            // breadth-first walk; these links never become directed rank arcs.
-            let mut proximity = Vec::new();
-            let mut remaining: BTreeSet<_> = layer.iter().copied().collect();
-            for &start in &layer {
-                if !remaining.remove(&start) {
-                    continue;
-                }
-                let mut queue = std::collections::VecDeque::from([start]);
-                while let Some(c) = queue.pop_front() {
-                    proximity.push(c);
-                    for &next in &layer {
-                        charge(&mut work, links.len() + 1)?;
-                        if remaining.contains(&next)
-                            && links.iter().any(|&(a, b, _)| {
-                                (owner[a] == c && owner[b] == next)
-                                    || (owner[b] == c && owner[a] == next)
-                            })
-                        {
-                            remaining.remove(&next);
-                            queue.push_back(next);
-                        }
-                    }
-                }
-            }
-            layer = proximity;
-            let mut cut = Size {
-                width: PAD,
-                height: PAD,
-            };
-            for &(a, b, label) in &links {
-                if owner[a] != owner[b] && (ranks[owner[a]] == rank || ranks[owner[b]] == rank) {
-                    cut.width = cut.width.max(label.width + PAD);
-                    cut.height = cut.height.max(label.height + PAD);
-                }
-            }
-            let mut y = 0.0;
-            let mut width = 0.0_f32;
-            if order_boundaries && parent.is_some() {
-                bands.push(boundary::Band {
-                    components: layer.clone(),
-                    gap: cut.height,
-                });
-            }
-            for (i, c) in layer.into_iter().enumerate() {
-                prior_order[c] = i;
-                block_positions[c] = Position { x, y };
-                y += blocks[c].height + cut.height;
-                width = width.max(blocks[c].width);
-            }
-            total.width = total.width.max(x + width);
-            total.height = total.height.max((y - cut.height).max(0.0));
-            x += width + cut.width;
-        }
-        let header = if let Some(id) = parent {
-            let n = view.nodes.iter().find(|n| n.id == id).unwrap();
-            if n.collapsed {
-                return Err(error("folded node has projected children"));
-            }
-            if d.projection.state_machine().is_some() {
-                projection::state_header_height(project, n.element)
-            } else {
-                64.0
-            }
-        } else {
-            0.0
-        };
-        for (i, id) in ids.iter().enumerate() {
-            let b = block_positions[owner[i]];
-            let m = member_offsets[&i];
-            offsets.insert(
-                *id,
-                Position {
-                    x: b.x + m.x + if parent.is_some() { PAD } else { 0.0 },
-                    y: b.y + m.y + if parent.is_some() { header + PAD } else { 0.0 },
-                },
-            );
-        }
-        if let Some(id) = parent {
-            let size = sizes.get_mut(&id).unwrap();
-            size.width = size.width.max(total.width + 2.0 * PAD);
-            size.height = size.height.max(total.height + header + 2.0 * PAD);
-            if order_boundaries {
-                boundary_groups.push(boundary::Group {
-                    parent: id,
-                    blocks: comps
-                        .iter()
-                        .enumerate()
-                        .map(|(c, members)| boundary::Block {
-                            members: members.iter().map(|&i| ids[i]).collect(),
-                            size: blocks[c],
-                            position: block_positions[c],
-                        })
-                        .collect(),
-                    bands,
-                    undirected: undirected
-                        .iter()
-                        .map(|(a, b)| (owner[index[a]], owner[index[b]]))
-                        .collect(),
-                });
-            }
-        }
-        let lifted: Vec<_> = arcs
-            .iter()
-            .enumerate()
-            .flat_map(|(a, targets)| targets.iter().map(move |&b| (ids[a], ids[b])))
-            .collect();
-        diagnostics.push(serde_json::json!({"visible_parent":parent,"components":component_diagnostics,"directed_lifted_edges":lifted,"undirected_lifted_pairs":undirected,"block_positions":block_positions,"bounds":total,"policy":"SCCs of sibling-subtree quotient, not global semantic SCCs. Undirected edges affect local gap and deterministic proximity only; no rank direction invented."}));
-    }
-    let boundary_report = if order_boundaries {
-        let report = boundary::reorder(
-            &mut boundary_groups,
-            &parents,
-            &mut offsets,
-            &sizes,
-            &view.edges,
-            &mut work,
-        )?;
-        for group in &boundary_groups {
-            let diagnostic = diagnostics
-                .iter_mut()
-                .find(|entry| entry["visible_parent"] == serde_json::json!(group.parent))
-                .unwrap();
-            diagnostic["block_positions"] =
-                serde_json::json!(group.blocks.iter().map(|b| b.position).collect::<Vec<_>>());
-        }
-        Some(report)
-    } else {
-        None
-    };
-    let mut plans = Vec::new();
-    for n in &view.nodes {
-        let mut position = offsets[&n.id];
-        let mut parent = n.visual_parent;
-        while let Some(id) = parent {
-            charge(&mut work, 1)?;
-            let p = offsets[&id];
-            position.x += p.x;
-            position.y += p.y;
-            parent = parents[&id];
-        }
-        position.x += 40.0;
-        position.y += 40.0;
-        let size = sizes[&n.id];
-        if !position.x.is_finite()
-            || !position.y.is_finite()
-            || position.x + size.width > SPAN
-            || position.y + size.height > SPAN
-        {
-            return Err(error("extent bound exceeded"));
-        }
-        plans.push(PlacementNode {
-            id: n.id,
-            position,
-            size,
-        });
-    }
-    let result = import_placement(
-        project,
-        diagram,
-        PlacementPlan {
-            schema: 1,
-            nodes: plans,
-        },
-    )?;
-    let final_view = projection::project_view(&result, diagram);
-    charge(
-        &mut work,
-        final_view.edges.len() * (final_view.nodes.len() + 1) * 16,
-    )?;
-    if !routing::lead_incompatibilities(&result, &result.diagrams[&diagram], &final_view).is_empty()
-    {
-        return Err(error(
-            "final mandatory port lead incompatible; no repair attempted",
-        ));
-    }
-    let mut report = serde_json::json!({"groups":diagnostics,"work_charged":work,"work_limit":LIMIT,"scope":"Projected-forest quotient heuristic; actual final reprojection and necessary lead guard checked. No full-route or readability acceptance."});
-    if let Some(boundary_report) = boundary_report {
-        report["boundary_order"] = boundary_report;
-    }
-    Ok((result, report))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    #[test]
-    fn directed_cycles_remain_separate_across_one_way_bridge() {
-        let arcs = vec![
-            BTreeSet::from([1]),
-            BTreeSet::from([0, 2]),
-            BTreeSet::from([3]),
-            BTreeSet::from([2]),
-        ];
-        assert_eq!(
-            components(&arcs, &mut 0).unwrap(),
-            vec![vec![0, 1], vec![2, 3]]
-        );
-    }
-    #[test]
-    fn perimeter_places_ten_unique_cells_without_overlap() {
-        let (positions, _, _) = perimeter(
-            10,
-            Size {
-                width: 224.0,
-                height: 132.0,
-            },
-            Size {
-                width: 32.0,
-                height: 32.0,
-            },
-            &mut 0,
-        )
-        .unwrap();
-        assert_eq!(positions.len(), 10);
-        for (i, a) in positions.iter().enumerate() {
-            for b in &positions[i + 1..] {
-                assert!((a.x - b.x).abs() >= 256.0 || (a.y - b.y).abs() >= 164.0);
-            }
-        }
-    }
-
-    #[test]
-    fn two_node_perimeter_scores_occupied_cells_instead_of_an_unused_row() {
-        let (positions, rows, cols) = perimeter(
-            2,
-            Size {
-                width: 224.0,
-                height: 160.0,
-            },
-            Size {
-                width: 250.0,
-                height: 56.0,
-            },
-            &mut 0,
-        )
-        .unwrap();
-        assert_eq!((rows, cols), (2, 1));
-        assert_eq!(
-            positions,
-            vec![Position { x: 0.0, y: 0.0 }, Position { x: 0.0, y: 216.0 }]
-        );
-    }
-}

crates/oa-core/examples/auto_layout_probe/condensed/boundary.rs

@@ -1,686 +0,0 @@
-//! One deterministic boundary-order pass; dependency cycles use frozen scores.
-use super::{charge, components, error, lift};
-use oa_core::{Id, ModelError, Position, Size, projection::ProjectedEdge};
-use std::collections::{BTreeMap, BTreeSet};
-
-pub(super) struct Block {
-    pub members: Vec<Id>,
-    pub size: Size,
-    pub position: Position,
-}
-pub(super) struct Band {
-    pub components: Vec<usize>,
-    pub gap: f32,
-}
-pub(super) struct Group {
-    pub parent: Id,
-    pub blocks: Vec<Block>,
-    pub bands: Vec<Band>,
-    pub undirected: BTreeSet<(usize, usize)>,
-}
-
-#[derive(Clone)]
-struct Unit {
-    blocks: Vec<usize>,
-    sources: BTreeSet<Id>,
-    hints: Vec<(Id, Id, Id)>,
-}
-
-fn center(
-    id: Id,
-    parents: &BTreeMap<Id, Option<Id>>,
-    offsets: &BTreeMap<Id, Position>,
-    sizes: &BTreeMap<Id, Size>,
-    work: &mut usize,
-) -> Result<f64, ModelError> {
-    let mut at = Some(id);
-    let mut seen = BTreeSet::new();
-    let mut y = 0.0_f32;
-    while let Some(node) = at {
-        charge(work, 1)?;
-        if !seen.insert(node) {
-            return Err(error("boundary cyclic ancestry"));
-        }
-        let pos = offsets
-            .get(&node)
-            .ok_or_else(|| error("boundary missing offset"))?;
-        if !pos.x.is_finite() || !pos.y.is_finite() {
-            return Err(error("boundary nonfinite offset"));
-        }
-        if seen.len() == 1 {
-            y = pos.y;
-        } else {
-            y += pos.y;
-        }
-        if !y.is_finite() {
-            return Err(error("boundary composed position overflow"));
-        }
-        at = *parents
-            .get(&node)
-            .ok_or_else(|| error("boundary missing parent"))?;
-    }
-    let size = sizes
-        .get(&id)
-        .ok_or_else(|| error("boundary missing source size"))?;
-    y += 40.0;
-    let center = f64::from(y) + f64::from(size.height) / 2.0;
-    if !center.is_finite() {
-        return Err(error("boundary nonfinite center"));
-    }
-    Ok(center)
-}
-
-fn translate(value: f32, old_origin: f32, new_origin: f32) -> Result<f32, ModelError> {
-    // Bound the complete displacement, including origin subtraction. A rounded
-    // f32 delta can hide lost relative precision even when its addition is exact.
-    let intended = f64::from(value) + (f64::from(new_origin) - f64::from(old_origin));
-    let next = intended as f32;
-    if !next.is_finite() || (f64::from(next) - intended).abs() > 0.001 {
-        return Err(error("boundary member translation precision exceeded"));
-    }
-    Ok(next)
-}
-
-fn score(
-    unit: &Unit,
-    parents: &BTreeMap<Id, Option<Id>>,
-    offsets: &BTreeMap<Id, Position>,
-    sizes: &BTreeMap<Id, Size>,
-    work: &mut usize,
-) -> Result<Option<f64>, ModelError> {
-    if unit.sources.is_empty() {
-        return Ok(None);
-    }
-    let mut total = 0.0;
-    for &source in &unit.sources {
-        total += center(source, parents, offsets, sizes, work)?;
-    }
-    let value = total / unit.sources.len() as f64;
-    if !value.is_finite() {
-        return Err(error("boundary nonfinite mean"));
-    }
-    Ok(Some(value))
-}
-
-fn ordered_units(scores: &[Option<f64>]) -> Vec<usize> {
-    let mut anchored: Vec<_> = (0..scores.len()).filter(|&i| scores[i].is_some()).collect();
-    anchored.sort_by(|&a, &b| {
-        scores[a]
-            .unwrap()
-            .total_cmp(&scores[b].unwrap())
-            .then(a.cmp(&b))
-    });
-    let mut next = anchored.into_iter();
-    (0..scores.len())
-        .map(|i| {
-            if scores[i].is_some() {
-                next.next().unwrap()
-            } else {
-                i
-            }
-        })
-        .collect()
-}
-
-fn packing(
-    blocks: &[Block],
-    before: &[usize],
-    after: &[usize],
-    gap: f32,
-) -> Result<Vec<f32>, ModelError> {
-    const EPS: f64 = 0.001;
-    let origin = f64::from(blocks[before[0]].position.y);
-    let mut canonical = origin;
-    for &c in before {
-        if (f64::from(blocks[c].position.y) - canonical).abs() > EPS {
-            return Err(error("boundary non-prefix canonical band"));
-        }
-        canonical += f64::from(blocks[c].size.height) + f64::from(gap);
-    }
-    let mut next = origin;
-    let mut ys = Vec::new();
-    for &c in after {
-        let y = next as f32;
-        if !y.is_finite() || (f64::from(y) - next).abs() > EPS {
-            return Err(error("boundary prefix precision bound exceeded"));
-        }
-        ys.push(y);
-        next += f64::from(blocks[c].size.height) + f64::from(gap);
-    }
-    if (next - canonical).abs() > EPS {
-        return Err(error("boundary envelope changed"));
-    }
-    if before == after {
-        Ok(before.iter().map(|&c| blocks[c].position.y).collect())
-    } else {
-        Ok(ys)
-    }
-}
-
-pub(super) fn reorder(
-    groups: &mut [Group],
-    parents: &BTreeMap<Id, Option<Id>>,
-    offsets: &mut BTreeMap<Id, Position>,
-    sizes: &BTreeMap<Id, Size>,
-    edges: &[ProjectedEdge],
-    work: &mut usize,
-) -> Result<serde_json::Value, ModelError> {
-    let mut group_order: Vec<_> = (0..groups.len()).collect();
-    group_order.sort_by_key(|&i| groups[i].parent);
-    let mut offset_owner = BTreeMap::new();
-    let mut parent_seen = BTreeSet::new();
-    let mut units: Vec<Vec<Vec<Unit>>> = vec![Vec::new(); groups.len()];
-    let mut active = BTreeSet::new();
-    for &g in &group_order {
-        let group = &groups[g];
-        if !parent_seen.insert(group.parent) || !parents.contains_key(&group.parent) {
-            return Err(error("boundary duplicate/missing group parent"));
-        }
-        let mut child_block = BTreeMap::new();
-        for (c, block) in group.blocks.iter().enumerate() {
-            if !block.size.width.is_finite()
-                || !block.size.height.is_finite()
-                || block.size.width <= 0.0
-                || block.size.height <= 0.0
-                || !block.position.x.is_finite()
-                || !block.position.y.is_finite()
-            {
-                return Err(error("boundary invalid block geometry"));
-            }
-            for &id in &block.members {
-                if parents.get(&id) != Some(&Some(group.parent))
-                    || !offsets.contains_key(&id)
-                    || child_block.insert(id, c).is_some()
-                    || offset_owner.insert(id, g).is_some()
-                {
-                    return Err(error("boundary invalid child membership"));
-                }
-            }
-        }
-        let mut covered = BTreeSet::new();
-        for band in &group.bands {
-            if !band.gap.is_finite() || band.gap < 0.0 || band.components.is_empty() {
-                return Err(error("boundary invalid band"));
-            }
-            let local: BTreeMap<_, _> = band
-                .components
-                .iter()
-                .enumerate()
-                .map(|(i, &c)| (c, i))
-                .collect();
-            for &c in &band.components {
-                if c >= group.blocks.len() || !covered.insert(c) {
-                    return Err(error("boundary duplicate/unknown band block"));
-                }
-            }
-            let mut arcs = vec![BTreeSet::new(); band.components.len()];
-            for &(a, b) in &group.undirected {
-                charge(work, 1)?;
-                if let (Some(&a), Some(&b)) = (local.get(&a), local.get(&b)) {
-                    arcs[a].insert(b);
-                    arcs[b].insert(a);
-                }
-            }
-            let bundles = components(&arcs, work)?;
-            let mut band_units = Vec::new();
-            for bundle in bundles {
-                if bundle.windows(2).any(|v| v[1] != v[0] + 1) {
-                    return Err(error("boundary undirected bundle not contiguous"));
-                }
-                let blocks: Vec<_> = bundle.iter().map(|&i| band.components[i]).collect();
-                let mut unit = Unit {
-                    blocks,
-                    sources: BTreeSet::new(),
-                    hints: Vec::new(),
-                };
-                for edge in edges {
-                    charge(work, 1)?;
-                    if !edge.oriented {
-                        continue;
-                    }
-                    let target = lift(edge.target, Some(group.parent), parents, work)?;
-                    let Some(target) = target else {
-                        continue;
-                    };
-                    if !unit.blocks.contains(
-                        child_block
-                            .get(&target)
-                            .ok_or_else(|| error("boundary missing lifted target"))?,
-                    ) {
-                        continue;
-                    }
-                    if lift(edge.source, Some(group.parent), parents, work)?.is_none() {
-                        unit.sources.insert(edge.source);
-                        unit.hints.push((edge.id, edge.source, edge.target));
-                    }
-                }
-                unit.hints.sort();
-                band_units.push(unit);
-            }
-            if band_units.iter().filter(|u| !u.sources.is_empty()).count() >= 2 {
-                active.insert(g);
-            }
-            units[g].push(band_units);
-        }
-        if covered.len() != group.blocks.len() {
-            return Err(error("boundary incomplete band inventory"));
-        }
-    }
-    let active_order: Vec<_> = group_order
-        .into_iter()
-        .filter(|g| active.contains(g))
-        .collect();
-    let active_index: BTreeMap<_, _> = active_order
-        .iter()
-        .enumerate()
-        .map(|(i, &g)| (g, i))
-        .collect();
-    let mut dependencies = vec![BTreeSet::new(); active_order.len()];
-    let mut dependency_evidence = BTreeSet::new();
-    for (&g, &gi) in &active_index {
-        for unit in units[g].iter().flatten() {
-            for &source in &unit.sources {
-                let mut at = Some(source);
-                let mut seen = BTreeSet::new();
-                while let Some(node) = at {
-                    charge(work, 1)?;
-                    if !seen.insert(node) {
-                        return Err(error("boundary dependency ancestry cycle"));
-                    }
-                    if let Some(&owner) = offset_owner.get(&node)
-                        && let Some(&oi) = active_index.get(&owner)
-                    {
-                        dependencies[oi].insert(gi);
-                        dependency_evidence.insert((
-                            groups[owner].parent,
-                            groups[g].parent,
-                            source,
-                            node,
-                        ));
-                    }
-                    at = *parents
-                        .get(&node)
-                        .ok_or_else(|| error("boundary missing dependency ancestor"))?;
-                }
-            }
-        }
-    }
-    let sccs = components(&dependencies, work)?;
-    let mut scc_owner = vec![0; active_order.len()];
-    for (s, members) in sccs.iter().enumerate() {
-        for &i in members {
-            scc_owner[i] = s;
-        }
-    }
-    let mut dag = vec![BTreeSet::new(); sccs.len()];
-    for (a, targets) in dependencies.iter().enumerate() {
-        for &b in targets {
-            if scc_owner[a] != scc_owner[b] {
-                dag[scc_owner[a]].insert(scc_owner[b]);
-            }
-        }
-    }
-    let mut done = BTreeSet::new();
-    let mut records = Vec::new();
-    let mut processed = Vec::new();
-    while done.len() < sccs.len() {
-        charge(work, sccs.len() * sccs.len())?;
-        let s = (0..sccs.len())
-            .find(|s| {
-                !done.contains(s)
-                    && (0..sccs.len()).all(|p| !dag[p].contains(s) || done.contains(&p))
-            })
-            .ok_or_else(|| error("boundary condensation cycle"))?;
-        // Score the entire dependency SCC before modifying any offsets.
-        let mut snapshots = Vec::new();
-        for &i in &sccs[s] {
-            let g = active_order[i];
-            for (b, band_units) in units[g].iter().enumerate() {
-                let scores = band_units
-                    .iter()
-                    .map(|u| score(u, parents, offsets, sizes, work))
-                    .collect::<Result<Vec<_>, _>>()?;
-                snapshots.push((g, b, scores));
-            }
-        }
-        for (g, b, scores) in snapshots {
-            let band_units = &units[g][b];
-            let order = ordered_units(&scores);
-            let before = groups[g].bands[b].components.clone();
-            let gap = groups[g].bands[b].gap;
-            let after: Vec<_> = order
-                .iter()
-                .flat_map(|&u| band_units[u].blocks.iter().copied())
-                .collect();
-            let ys = packing(&groups[g].blocks, &before, &after, gap)?;
-            let mut changed = Vec::new();
-            for (&c, y) in after.iter().zip(ys) {
-                charge(work, groups[g].blocks[c].members.len() + 1)?;
-                let old = groups[g].blocks[c].position.y;
-                if !y.is_finite() {
-                    return Err(error("boundary packing overflow"));
-                }
-                if y != old {
-                    changed.push(c);
-                }
-                for id in &groups[g].blocks[c].members {
-                    let p = offsets
-                        .get_mut(id)
-                        .ok_or_else(|| error("boundary lost member offset"))?;
-                    p.y = translate(p.y, old, y)?;
-                }
-                groups[g].blocks[c].position.y = y;
-            }
-            groups[g].bands[b].components = after.clone();
-            let changed_units: Vec<_> = band_units
-                .iter()
-                .enumerate()
-                .filter(|(_, u)| u.blocks.iter().any(|c| changed.contains(c)))
-                .map(|(i, _)| i)
-                .collect();
-            records.push(serde_json::json!({"parent":groups[g].parent,"band":b,"before_blocks":before,"after_blocks":after,"unit_order":order,"scores":scores,"changed_blocks":changed,"changed_units":changed_units,"envelope_epsilon":0.001,"units":band_units.iter().map(|u|serde_json::json!({"blocks":u.blocks,"source_owners":u.sources,"edge_hints":u.hints})).collect::<Vec<_>>()}));
-        }
-        processed.push(serde_json::json!({"parents":sccs[s].iter().map(|&i|groups[active_order[i]].parent).collect::<Vec<_>>(),"cyclic":sccs[s].len()>1||sccs[s].iter().any(|&i|dependencies[i].contains(&i)),"policy":"all scores snapshotted before one simultaneous group-permutation pass"}));
-        done.insert(s);
-    }
-    Ok(
-        serde_json::json!({"active_parents":active_order.iter().map(|&g|groups[g].parent).collect::<Vec<_>>(),"dependencies":dependency_evidence,"dependency_components":processed,"bands":records,"limitation":"One pass; cyclic dependencies use a common snapshot, not a fixed-point solution. Root unchanged; no quality or repeat-stability acceptance."}),
-    )
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    fn id(n: u128) -> Id {
-        Id::from_u128(n)
-    }
-    fn block(n: u128, y: f32, height: f32) -> Block {
-        Block {
-            members: vec![id(n)],
-            size: Size {
-                width: 10.0,
-                height,
-            },
-            position: Position { x: 0.0, y },
-        }
-    }
-    fn edge(n: u128, source: u128, target: u128) -> ProjectedEdge {
-        ProjectedEdge {
-            id: id(n),
-            source: id(source),
-            target: id(target),
-            trace: false,
-            oriented: true,
-            source_port: None,
-            target_port: None,
-        }
-    }
-    #[test]
-    fn anchored_sort_preserves_unanchored_ordinal_slot() {
-        assert_eq!(
-            ordered_units(&[Some(90.0), None, Some(10.0), Some(10.0)]),
-            vec![2, 1, 3, 0]
-        );
-    }
-    #[test]
-    fn heterogeneous_blocks_use_new_prefix_not_old_slots() {
-        let blocks = vec![
-            Block {
-                members: vec![],
-                size: Size {
-                    width: 10.0,
-                    height: 100.0,
-                },
-                position: Position { x: 0.0, y: 0.0 },
-            },
-            Block {
-                members: vec![],
-                size: Size {
-                    width: 10.0,
-                    height: 20.0,
-                },
-                position: Position { x: 0.0, y: 132.0 },
-            },
-        ];
-        assert_eq!(
-            packing(&blocks, &[0, 1], &[1, 0], 32.0).unwrap(),
-            vec![0.0, 52.0]
-        );
-    }
-    #[test]
-    fn center_includes_grandparent_offset_change() {
-        let (a, b, c) = (Id::from_u128(1), Id::from_u128(2), Id::from_u128(3));
-        let parents = BTreeMap::from([(a, None), (b, Some(a)), (c, Some(b))]);
-        let mut offsets = BTreeMap::from([
-            (a, Position { x: 0.0, y: 100.0 }),
-            (b, Position { x: 0.0, y: 20.0 }),
-            (c, Position { x: 0.0, y: 5.0 }),
-        ]);
-        let sizes = BTreeMap::from([(
-            c,
-            Size {
-                width: 10.0,
-                height: 10.0,
-            },
-        )]);
-        assert_eq!(
-            center(c, &parents, &offsets, &sizes, &mut 0).unwrap(),
-            170.0
-        );
-        offsets.get_mut(&a).unwrap().y += 300.0;
-        assert_eq!(
-            center(c, &parents, &offsets, &sizes, &mut 0).unwrap(),
-            470.0
-        );
-    }
-    #[test]
-    fn ancestor_dependency_updates_downstream_scores_before_its_permutation() {
-        // Downstream parent1 sorts before upstream20, so an absent ancestor
-        // dependency would leave downstream order unchanged and fail this test.
-        let mut groups = vec![
-            Group {
-                parent: id(1),
-                blocks: vec![block(2, 0.0, 100.0), block(3, 132.0, 100.0)],
-                bands: vec![Band {
-                    components: vec![0, 1],
-                    gap: 32.0,
-                }],
-                undirected: BTreeSet::new(),
-            },
-            Group {
-                parent: id(20),
-                blocks: vec![block(21, 0.0, 100.0), block(22, 132.0, 100.0)],
-                bands: vec![Band {
-                    components: vec![0, 1],
-                    gap: 32.0,
-                }],
-                undirected: BTreeSet::new(),
-            },
-        ];
-        let parents = BTreeMap::from([
-            (id(1), None),
-            (id(2), Some(id(1))),
-            (id(3), Some(id(1))),
-            (id(20), None),
-            (id(21), Some(id(20))),
-            (id(22), Some(id(20))),
-            (id(23), Some(id(21))),
-            (id(30), None),
-            (id(31), None),
-            (id(32), None),
-        ]);
-        let mut offsets: BTreeMap<_, _> = [
-            (1, 0.0),
-            (2, 0.0),
-            (3, 132.0),
-            (20, 0.0),
-            (21, 0.0),
-            (22, 132.0),
-            (23, 10.0),
-            (30, 300.0),
-            (31, 0.0),
-            (32, 50.0),
-        ]
-        .into_iter()
-        .map(|(n, y)| (id(n), Position { x: 0.0, y }))
-        .collect();
-        let sizes = parents
-            .keys()
-            .map(|&n| {
-                (
-                    n,
-                    Size {
-                        width: 10.0,
-                        height: 10.0,
-                    },
-                )
-            })
-            .collect();
-        let edges = vec![
-            edge(101, 30, 21),
-            edge(102, 31, 22),
-            edge(103, 23, 2),
-            edge(104, 32, 3),
-        ];
-        let report = reorder(&mut groups, &parents, &mut offsets, &sizes, &edges, &mut 0).unwrap();
-        assert_eq!(groups[1].bands[0].components, vec![1, 0]);
-        assert_eq!(groups[0].bands[0].components, vec![1, 0]);
-        assert_eq!(offsets[&id(21)].y, 132.0);
-        assert_eq!(offsets[&id(23)].y, 10.0); // descendant is not directly moved
-        assert_eq!(
-            center(id(23), &parents, &offsets, &sizes, &mut 0).unwrap(),
-            187.0
-        );
-        assert_eq!(
-            report["dependency_components"][0]["parents"][0],
-            serde_json::json!(id(20))
-        );
-    }
-    #[test]
-    fn undirected_bundle_stays_whole_around_unanchored_unit() {
-        let mut groups = vec![Group {
-            parent: id(100),
-            blocks: vec![
-                block(101, 0.0, 20.0),
-                block(102, 30.0, 30.0),
-                block(103, 70.0, 40.0),
-                block(104, 120.0, 10.0),
-            ],
-            bands: vec![Band {
-                components: vec![0, 1, 2, 3],
-                gap: 10.0,
-            }],
-            undirected: BTreeSet::from([(0, 1)]),
-        }];
-        let parents = BTreeMap::from([
-            (id(100), None),
-            (id(101), Some(id(100))),
-            (id(102), Some(id(100))),
-            (id(103), Some(id(100))),
-            (id(104), Some(id(100))),
-            (id(110), None),
-            (id(111), None),
-        ]);
-        let mut offsets: BTreeMap<_, _> = [
-            (100, 0.0),
-            (101, 0.0),
-            (102, 30.0),
-            (103, 70.0),
-            (104, 120.0),
-            (110, 300.0),
-            (111, 0.0),
-        ]
-        .into_iter()
-        .map(|(n, y)| (id(n), Position { x: 0.0, y }))
-        .collect();
-        let sizes = parents
-            .keys()
-            .map(|&n| {
-                (
-                    n,
-                    Size {
-                        width: 10.0,
-                        height: 10.0,
-                    },
-                )
-            })
-            .collect();
-        let report = reorder(
-            &mut groups,
-            &parents,
-            &mut offsets,
-            &sizes,
-            &[
-                edge(201, 110, 101),
-                edge(202, 110, 102),
-                edge(203, 111, 104),
-            ],
-            &mut 0,
-        )
-        .unwrap();
-        assert_eq!(groups[0].bands[0].components, vec![3, 2, 0, 1]);
-        assert_eq!(
-            [
-                offsets[&id(104)].y,
-                offsets[&id(103)].y,
-                offsets[&id(101)].y,
-                offsets[&id(102)].y
-            ],
-            [0.0, 20.0, 70.0, 100.0]
-        );
-        assert_eq!(
-            report["bands"][0]["units"][0]["source_owners"]
-                .as_array()
-                .unwrap()
-                .len(),
-            1
-        );
-    }
-    #[test]
-    fn center_uses_final_plan_f32_composition_and_translation_has_error_bound() {
-        let parents = BTreeMap::from([(id(1), None), (id(2), Some(id(1))), (id(3), Some(id(2)))]);
-        let offsets = BTreeMap::from([
-            (
-                id(1),
-                Position {
-                    x: 0.0,
-                    y: -100000.0,
-                },
-            ),
-            (
-                id(2),
-                Position {
-                    x: 0.0,
-                    y: 100000.0,
-                },
-            ),
-            (id(3), Position { x: 0.0, y: 0.1 }),
-        ]);
-        let sizes = BTreeMap::from([(
-            id(3),
-            Size {
-                width: 10.0,
-                height: 10.0,
-            },
-        )]);
-        assert_eq!(
-            center(id(3), &parents, &offsets, &sizes, &mut 0).unwrap(),
-            45.1015625
-        );
-        assert_eq!(translate(10.125, 0.0, 0.375).unwrap(), 10.5);
-        assert!(translate(32768.0, 0.0, 0.002).is_err());
-    }
-
-    #[test]
-    fn member_offset_survives_large_origin_subtraction() {
-        let blocks = vec![
-            block(1, 0.0, 65404.0),
-            block(2, 65436.0, 68.0),
-            block(3, 65536.0, 100.0),
-            block(4, 65668.0, 68.002),
-        ];
-        let ys = packing(&blocks, &[0, 1, 2, 3], &[3, 2, 1, 0], 32.0).unwrap();
-        let member = translate(65568.0, 65536.0, ys[1]).unwrap();
-        assert!((f64::from(member) - f64::from(ys[1]) - 32.0).abs() <= 0.001);
-    }
-}

crates/oa-core/examples/auto_layout_probe/layered.rs

@@ -1,380 +0,0 @@
-//! Isolated #32 experiment, not a production layout engine.
-//! Uses existing Layout sizing, three deterministic ordering passes, and one
-//! core-estimated-label spacing pass. Automatic elbows remain derived. Folded/omitted
-//! node topology is explicitly unsupported; filtered edges retain their metadata.
-use oa_core::{Command, Id, ModelError, Position, Project, Size, projection, routing};
-use std::collections::{BTreeMap, BTreeSet};
-
-const WORK_LIMIT: usize = 200_000;
-const NODE_LIMIT: usize = 256;
-const EDGE_LIMIT: usize = 1024;
-
-fn spend(work: &mut usize) -> Result<(), ModelError> {
-    *work += 1;
-    if *work > WORK_LIMIT {
-        return Err(ModelError("Layered probe work limit exceeded.".into()));
-    }
-    Ok(())
-}
-
-/// Return a new Project; caller owns comparison, history and serialization.
-pub fn candidate(project: &Project, diagram: Id) -> Result<Project, ModelError> {
-    let original = project
-        .diagrams
-        .get(&diagram)
-        .ok_or_else(|| ModelError("Missing probe diagram.".into()))?;
-    let view = projection::project_diagram(project, original);
-    if view.nodes.len() > NODE_LIMIT || view.edges.len() > EDGE_LIMIT {
-        return Err(ModelError("Layered probe graph limit exceeded.".into()));
-    }
-    if view.nodes.len() != original.nodes.len() || view.nodes.iter().any(|n| n.collapsed) {
-        return Err(ModelError(
-            "Layered probe does not support folded/omitted node topology.".into(),
-        ));
-    }
-    let routed = routing::route_diagram(project, original, &view);
-    let eligible: BTreeSet<_> = view
-        .edges
-        .iter()
-        .filter(|edge| {
-            projection::edge_endpoint_placements(project, original, edge.id)
-                == Some((edge.source, edge.target))
-                && routed
-                    .edges
-                    .get(&edge.id)
-                    .is_some_and(|route| !route.custom_suspended)
-        })
-        .map(|edge| edge.id)
-        .collect();
-    let mut result = oa_core::prepare_command(project, &Command::Layout(diagram))?.project;
-    // Discard baseline route translation: final routes are reconstructed directly
-    // from original geometry, avoiding two translations and preserving list order.
-    result.diagrams.get_mut(&diagram).unwrap().routes = original.routes.clone();
-    for route in &mut result.diagrams.get_mut(&diagram).unwrap().routes {
-        if eligible.contains(&route.edge) {
-            route.waypoints.clear();
-            route.label = None;
-        }
-    }
-    let baseline = projection::project_view(&result, diagram);
-    let labels = routing::route_diagram(&result, &result.diagrams[&diagram], &baseline);
-    let mut gap_x = 64.0_f32;
-    let mut gap_y = 32.0_f32;
-    for edge in labels.edges.values() {
-        gap_x = gap_x.max(edge.label.bounds.size.width + 24.0);
-        gap_y = gap_y.max(edge.label.bounds.size.height + 24.0);
-        if let Some(relation) = result.relations.get(&edge.id) {
-            for end in routing::association_end_geometry(relation, edge) {
-                gap_x = gap_x.max(end.label.bounds.size.width + 24.0);
-                gap_y = gap_y.max(end.label.bounds.size.height + 24.0);
-            }
-        }
-    }
-    if !gap_x.is_finite() || !gap_y.is_finite() {
-        return Err(ModelError("Nonfinite estimated label bound.".into()));
-    }
-    let parents: BTreeMap<_, _> = baseline
-        .nodes
-        .iter()
-        .map(|n| (n.id, n.visual_parent))
-        .collect();
-    let mut children: BTreeMap<Option<Id>, Vec<Id>> = BTreeMap::new();
-    for node in &baseline.nodes {
-        children
-            .entry(node.visual_parent)
-            .or_default()
-            .push(node.id);
-    }
-    let names: BTreeMap<_, _> = baseline
-        .nodes
-        .iter()
-        .map(|n| (n.id, (result.elements[&n.element].alias.clone(), n.id)))
-        .collect();
-    for siblings in children.values_mut() {
-        siblings.sort_by_key(|id| names[id].clone());
-    }
-    let minima: BTreeMap<_, _> = baseline.nodes.iter().map(|n| (n.id, n.size)).collect();
-    let headers: BTreeMap<_, _> = baseline
-        .nodes
-        .iter()
-        .map(|n| {
-            (
-                n.id,
-                if original.projection.state_machine().is_some() {
-                    projection::state_header_height(&result, n.element)
-                } else {
-                    64.0
-                },
-            )
-        })
-        .collect();
-    let mut positions: BTreeMap<_, _> = baseline.nodes.iter().map(|n| (n.id, n.position)).collect();
-    let mut sizes = minima.clone();
-    let mut work = 0;
-    let mut group_order: Vec<_> = children.keys().copied().collect();
-    group_order.sort_by_key(|parent| {
-        parent.map_or(0, |id| {
-            baseline.nodes.iter().find(|n| n.id == id).unwrap().depth + 1
-        })
-    });
-    let mut groups = BTreeMap::new();
-    for pass in 0..3 {
-        for parent in &group_order {
-            let siblings = &children[parent];
-            let mut arcs = BTreeSet::new();
-            for edge in &baseline.edges {
-                spend(&mut work)?;
-                let a = child_under(edge.source, *parent, &parents, &mut work)?;
-                let b = child_under(edge.target, *parent, &parents, &mut work)?;
-                if edge.oriented
-                    && let (Some(a), Some(b)) = (a, b)
-                    && a != b
-                {
-                    arcs.insert((a, b));
-                }
-            }
-            let ranks = ranks(siblings, &arcs, &mut work)?;
-            let mut layers: BTreeMap<usize, Vec<Id>> = BTreeMap::new();
-            for id in siblings {
-                layers.entry(ranks[id]).or_default().push(*id);
-            }
-            // Boundary neighbours participate even though they are not siblings.
-            // Incoming preference anchors the downstream order to its upstream
-            // counterpart instead of swapping both sides simultaneously.
-            let mut scores = BTreeMap::new();
-            for id in siblings {
-                let mut incoming = Vec::new();
-                for edge in &baseline.edges {
-                    spend(&mut work)?;
-                    let a = child_under(edge.source, *parent, &parents, &mut work)?;
-                    let b = child_under(edge.target, *parent, &parents, &mut work)?;
-                    if edge.oriented && b == Some(*id) && a != Some(*id) {
-                        incoming.push(positions[&edge.source].y + sizes[&edge.source].height / 2.0);
-                    }
-                }
-                // Do not also chase outgoing boundary neighbours: simultaneous
-                // swaps in two connected containers can preserve the crossing.
-                let values = &incoming;
-                let score = if values.is_empty() {
-                    positions[id].y
-                } else {
-                    values.iter().sum::<f32>() / values.len() as f32
-                };
-                scores.insert(*id, score);
-            }
-            for layer in layers.values_mut() {
-                // First pass starts from canonical alias order; subsequent passes
-                // retain a deterministic alias tie break, never hash iteration.
-                if pass > 0 {
-                    layer.sort_by(|a, b| {
-                        scores[a]
-                            .total_cmp(&scores[b])
-                            .then_with(|| names[a].cmp(&names[b]))
-                    });
-                }
-            }
-            groups.insert(*parent, layers.into_values().collect::<Vec<_>>());
-        }
-        // Recompute from frozen minima, never add spacing to last pass's size.
-        sizes = minima.clone();
-        measure(None, &groups, &headers, &mut sizes, gap_x, gap_y, &mut work)?;
-        place(
-            None,
-            Position { x: 40.0, y: 40.0 },
-            &groups,
-            &headers,
-            &sizes,
-            &mut positions,
-            gap_x,
-            gap_y,
-            &mut work,
-        )?;
-    }
-    let d = result.diagrams.get_mut(&diagram).unwrap();
-    for (id, node) in &mut d.nodes {
-        node.position = positions[id];
-        node.size = sizes[id];
-    }
-    let deltas: BTreeMap<_, _> = original
-        .nodes
-        .iter()
-        .map(|(id, node)| {
-            (
-                *id,
-                Position {
-                    x: positions[id].x - node.position.x,
-                    y: positions[id].y - node.position.y,
-                },
-            )
-        })
-        .collect();
-    let translated: BTreeMap<_, _> = projection::translated_routes(project, original, &deltas)
-        .into_iter()
-        .map(|r| (r.edge, r))
-        .collect();
-    d.routes = original
-        .routes
-        .iter()
-        .map(|route| {
-            let mut route = translated.get(&route.edge).unwrap_or(route).clone();
-            if eligible.contains(&route.edge) {
-                route.waypoints.clear();
-                route.label = None;
-            }
-            route
-        })
-        .collect();
-    if d.nodes.values().any(|n| {
-        !n.position.x.is_finite()
-            || !n.position.y.is_finite()
-            || !n.size.width.is_finite()
-            || !n.size.height.is_finite()
-            || n.size.width <= 0.0
-            || n.size.height <= 0.0
-    }) {
-        return Err(ModelError("Invalid layered probe geometry.".into()));
-    }
-    oa_core::validate_candidate(&result)?;
-    Ok(result)
-}
-
-fn child_under(
-    mut id: Id,
-    parent: Option<Id>,
-    parents: &BTreeMap<Id, Option<Id>>,
-    work: &mut usize,
-) -> Result<Option<Id>, ModelError> {
-    for _ in 0..=parents.len() {
-        spend(work)?;
-        let Some(actual) = parents.get(&id) else {
-            return Ok(None);
-        };
-        if *actual == parent {
-            return Ok(Some(id));
-        }
-        let Some(next) = actual else { return Ok(None) };
-        id = *next;
-    }
-    Err(ModelError("Layered probe containment cycle.".into()))
-}
-
-fn ranks(
-    ids: &[Id],
-    arcs: &BTreeSet<(Id, Id)>,
-    work: &mut usize,
-) -> Result<BTreeMap<Id, usize>, ModelError> {
-    let mut remaining: BTreeSet<_> = ids.iter().copied().collect();
-    let mut ranks: BTreeMap<_, usize> = BTreeMap::new();
-    while !remaining.is_empty() {
-        let mut ready = None;
-        for id in ids.iter().filter(|id| remaining.contains(*id)) {
-            let mut blocked = false;
-            for (a, b) in arcs {
-                spend(work)?;
-                blocked |= b == id && remaining.contains(a);
-            }
-            if !blocked {
-                ready = Some(*id);
-                break;
-            }
-        }
-        // Explicit cycle fallback: break the first canonical remaining vertex's
-        // incoming ranking constraints. Actual relation direction is unchanged.
-        let id = ready.unwrap_or_else(|| *ids.iter().find(|id| remaining.contains(*id)).unwrap());
-        let mut rank = 0;
-        for (a, b) in arcs {
-            spend(work)?;
-            if *b == id
-                && let Some(previous) = ranks.get(a)
-            {
-                rank = rank.max(previous + 1);
-            }
-        }
-        ranks.insert(id, rank);
-        remaining.remove(&id);
-    }
-    Ok(ranks)
-}
-
-type Groups = BTreeMap<Option<Id>, Vec<Vec<Id>>>;
-
-fn measure(
-    parent: Option<Id>,
-    groups: &Groups,
-    headers: &BTreeMap<Id, f32>,
-    sizes: &mut BTreeMap<Id, Size>,
-    gx: f32,
-    gy: f32,
-    work: &mut usize,
-) -> Result<Size, ModelError> {
-    let Some(layers) = groups.get(&parent) else {
-        return Ok(Size {
-            width: 0.0,
-            height: 0.0,
-        });
-    };
-    let mut width = 0.0;
-    let mut height = 0.0_f32;
-    for (i, layer) in layers.iter().enumerate() {
-        let mut lw = 0.0_f32;
-        let mut lh = 0.0;
-        for (j, id) in layer.iter().enumerate() {
-            spend(work)?;
-            let content = measure(Some(*id), groups, headers, sizes, gx, gy, work)?;
-            let size = sizes.get_mut(id).unwrap();
-            if groups.contains_key(&Some(*id)) {
-                size.width = size.width.max(content.width + 48.0);
-                size.height = size.height.max(content.height + headers[id] + 24.0);
-            }
-            lw = lw.max(size.width);
-            lh += size.height + if j == 0 { 0.0 } else { gy };
-        }
-        width += lw + if i == 0 { 0.0 } else { gx };
-        height = height.max(lh);
-    }
-    Ok(Size { width, height })
-}
-
-#[allow(clippy::too_many_arguments)]
-fn place(
-    parent: Option<Id>,
-    origin: Position,
-    groups: &Groups,
-    headers: &BTreeMap<Id, f32>,
-    sizes: &BTreeMap<Id, Size>,
-    positions: &mut BTreeMap<Id, Position>,
-    gx: f32,
-    gy: f32,
-    work: &mut usize,
-) -> Result<(), ModelError> {
-    let Some(layers) = groups.get(&parent) else {
-        return Ok(());
-    };
-    let mut x = origin.x;
-    for layer in layers {
-        let mut y = origin.y;
-        let mut width = 0.0_f32;
-        for id in layer {
-            spend(work)?;
-            positions.insert(*id, Position { x, y });
-            place(
-                Some(*id),
-                Position {
-                    x: x + 24.0,
-                    y: y + headers[id],
-                },
-                groups,
-                headers,
-                sizes,
-                positions,
-                gx,
-                gy,
-                work,
-            )?;
-            y += sizes[id].height + gy;
-            width = width.max(sizes[id].width);
-        }
-        x += width + gx;
-    }
-    Ok(())
-}

crates/oa-core/examples/routing_cost_probe.rs

@@ -1,192 +0,0 @@
-//! Frozen-corpus route-only timing. Protocol: harness/experiments/routing-independent-20260925/timing-protocol.md.
-use oa_core::{Id, Project, projection, routing, validate_candidate};
-use serde::Deserialize;
-use serde_json::json;
-use std::hint::black_box;
-use std::path::{Component, Path, PathBuf};
-use std::time::{Duration, Instant};
-
-const ROUNDS: usize = 7;
-const SLOW_CALL: Duration = Duration::from_secs(5);
-
-#[derive(Deserialize)]
-struct Manifest {
-    schema: u32,
-    cases: Vec<Case>,
-    #[serde(flatten)]
-    metadata: std::collections::BTreeMap<String, serde_json::Value>,
-}
-
-#[derive(Deserialize)]
-struct Case {
-    name: String,
-    project_file: PathBuf,
-    diagram: Id,
-    description: String,
-    #[serde(flatten)]
-    metadata: std::collections::BTreeMap<String, serde_json::Value>,
-}
-
-fn timed_route(
-    project: &Project,
-    diagram: &oa_core::Diagram,
-    view: &projection::ProjectedView,
-) -> (routing::RoutedView, Duration) {
-    // Input black_box is outside the clock. Result consumption is inside it;
-    // allocation is part of routing, result destruction is outside the clock.
-    let project = black_box(project);
-    let diagram = black_box(diagram);
-    let view = black_box(view);
-    let started = Instant::now();
-    let result = black_box(routing::route_diagram(project, diagram, view));
-    let elapsed = started.elapsed();
-    (result, elapsed)
-}
-
-fn point_digest(route: &routing::RoutedView) -> String {
-    // Stable FNV-1a64 over ID bytes, point count and IEEE754 coordinate bits,
-    // little endian. Diagnostic only, not a cryptographic integrity guarantee.
-    let mut hash = 0xcbf29ce484222325_u64;
-    let mut feed = |bytes: &[u8]| {
-        for byte in bytes {
-            hash ^= u64::from(*byte);
-            hash = hash.wrapping_mul(0x100000001b3);
-        }
-    };
-    for (id, edge) in &route.edges {
-        feed(id.as_bytes());
-        feed(&(edge.points.len() as u64).to_le_bytes());
-        for point in &edge.points {
-            feed(&point.x.to_bits().to_le_bytes());
-            feed(&point.y.to_bits().to_le_bytes());
-        }
-    }
-    format!("{hash:016x}")
-}
-
-fn relative_project(root: &Path, file: &Path) -> Result<PathBuf, Box<dyn std::error::Error>> {
-    if file.as_os_str().is_empty()
-        || !file
-            .components()
-            .all(|part| matches!(part, Component::Normal(_)))
-    {
-        return Err(
-            "project_file must be a nonempty relative path without parent traversal".into(),
-        );
-    }
-    let path = root.join(file).canonicalize()?;
-    if !path.starts_with(root) {
-        return Err("project_file resolves outside the manifest directory".into());
-    }
-    Ok(path)
-}
-
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut args = std::env::args_os().skip(1);
-    let manifest_path = PathBuf::from(
-        args.next()
-            .ok_or("usage: routing_cost_probe MANIFEST.json")?,
-    )
-    .canonicalize()?;
-    if args.next().is_some() {
-        return Err(
-            "protocol is fixed: one warmup and seven measured calls; no extra arguments".into(),
-        );
-    }
-    let manifest: Manifest = serde_json::from_slice(&std::fs::read(&manifest_path)?)?;
-    if manifest.schema != 1 || manifest.cases.is_empty() {
-        return Err("expected schema1 with at least one case".into());
-    }
-    let root = manifest_path
-        .parent()
-        .ok_or("manifest has no parent directory")?;
-    println!(
-        "{}",
-        json!({
-            "protocol": "routing_cost_probe_v1", "manifest_schema": manifest.schema,
-            "warmup_calls": 1, "measured_calls": ROUNDS,
-            "slow_call_limit_ns": SLOW_CALL.as_nanos(),
-            "debug_assertions": cfg!(debug_assertions),
-            "os": std::env::consts::OS, "arch": std::env::consts::ARCH,
-            "case_count": manifest.cases.len(),
-            "corpus_metadata": manifest.metadata,
-            "clock_scope": "route_diagram plus result black_box; excludes projection, JSON, equality, digest, output and result destruction",
-            "digest": "FNV-1a64 IDs/counts/f32 point bits; diagnostic, not cryptographic",
-            "acceptance": "none; external receipts must bind source, optimized build, binary and corpus"
-        })
-    );
-    let mut names = std::collections::BTreeSet::new();
-    for case in manifest.cases {
-        if !names.insert(case.name.clone()) {
-            return Err("duplicate case name".into());
-        }
-        let bytes = std::fs::read(relative_project(root, &case.project_file)?)?;
-        let project: Project = serde_json::from_slice(&bytes)?;
-        validate_candidate(&project)?;
-        let original = project.clone();
-        let diagram = project
-            .diagrams
-            .get(&case.diagram)
-            .ok_or("case diagram is absent")?;
-        let view = projection::project_diagram(&project, diagram);
-        let (first, warmup) = timed_route(&project, diagram, &view);
-        let mut samples = Vec::with_capacity(ROUNDS);
-        let mut equality = Vec::with_capacity(ROUNDS);
-        let mut endpoints = Vec::with_capacity(ROUNDS);
-        let mut censored = warmup > SLOW_CALL;
-        if !censored {
-            for _ in 0..ROUNDS {
-                let (route, elapsed) = timed_route(&project, diagram, &view);
-                samples.push(elapsed.as_nanos());
-                equality.push(route == first);
-                endpoints.push(
-                    route.edges.len() == first.edges.len()
-                        && route.edges.iter().all(|(id, edge)| {
-                            first.edges.get(id).is_some_and(|other| {
-                                edge.points.first() == other.points.first()
-                                    && edge.points.last() == other.points.last()
-                            })
-                        }),
-                );
-                if elapsed > SLOW_CALL {
-                    censored = true;
-                    break;
-                }
-            }
-        }
-        let mut ordered = samples.clone();
-        ordered.sort_unstable();
-        let complete = !censored && samples.len() == ROUNDS;
-        let median = complete.then(|| ordered[ROUNDS / 2]);
-        let warnings: usize = first.edges.values().map(|edge| edge.warnings.len()).sum();
-        let project_unchanged = project == original;
-        let stable = equality.iter().all(|same| *same);
-        println!(
-            "{}",
-            json!({
-                "case": case.name, "description": case.description,
-                "corpus_case_metadata": case.metadata,
-                "project_file": case.project_file, "diagram": case.diagram,
-                "project_bytes": bytes.len(), "nodes": view.nodes.len(),
-                "edges": view.edges.len(), "ports": view.ports.len(),
-                "routed_edges": first.edges.len(), "warnings": warnings,
-                "route_points": first.edges.values().map(|edge| edge.points.len()).sum::<usize>(),
-                "route_point_digest": point_digest(&first),
-                "warmup_ns": warmup.as_nanos(), "samples_ns": samples,
-                "median_ns": median, "max_observed_measured_ns": ordered.last(),
-                "complete": complete, "censored": censored,
-                "censor_reason": if censored { Some("single call exceeded five seconds; remaining repeats skipped") } else { None },
-                "repeat_full_routed_view_equal_warmup": equality,
-                "repeat_endpoints_equal_warmup": endpoints,
-                "stability_observed": !samples.is_empty(),
-                "project_unchanged": project_unchanged
-            })
-        );
-        if !stable || !project_unchanged {
-            return Err(
-                "routing stability or Project preservation failed; receipt above retained".into(),
-            );
-        }
-    }
-    Ok(())
-}

crates/oa-core/examples/routing_eval_corpus.rs

@@ -1,555 +0,0 @@
-//! Source-first inputs for independent routing experiments. Never invokes layout/routing.
-use oa_core::*;
-use serde_json::{Value, json};
-use std::{collections::BTreeMap, error::Error, fs, path::PathBuf};
-
-struct Case {
-    name: &'static str,
-    description: &'static str,
-    project: Project,
-    diagram: Id,
-    trace_edges: Vec<Id>,
-    metadata: Value,
-}
-
-struct Builder {
-    project: Project,
-    diagram: Id,
-    base: u128,
-    next: u128,
-    edges: Vec<Id>,
-}
-
-impl Builder {
-    fn new(name: &str, base: u128) -> Self {
-        let mut project = Project::empty();
-        project.id = Id::from_u128(base);
-        project.alias = name.into();
-        project.name = name.into();
-        let old = project.ensure_diagram(Layer::Sa);
-        let diagram = Id::from_u128(base + 1);
-        reidentify(&mut project, old, diagram).unwrap();
-        let d = project.diagrams.get_mut(&diagram).unwrap();
-        d.alias = format!("{name}_main");
-        d.name = format!("{name} main view");
-        d.projection = ProjectionKind::FunctionalDataflow;
-        Self {
-            project,
-            diagram,
-            base,
-            next: base + 100,
-            edges: Vec::new(),
-        }
-    }
-
-    fn stable(&mut self, old: Id) -> Id {
-        let id = Id::from_u128(self.next);
-        self.next += 1;
-        reidentify(&mut self.project, old, id).unwrap();
-        id
-    }
-
-    fn function(&mut self, name: &str, x: f32, y: f32) -> Id {
-        let old = self
-            .project
-            .add_element(Kind::Function, Layer::Sa, name, None)
-            .unwrap();
-        let id = self.stable(old);
-        let old = self.project.place(self.diagram, id, Position { x, y });
-        self.stable(old);
-        id
-    }
-
-    fn exchange(
-        &mut self,
-        name: &str,
-        source: Id,
-        target: Id,
-        source_port: PortChoice,
-        target_port: PortChoice,
-    ) -> Id {
-        let id = Id::from_u128(self.base + 10_000 + self.edges.len() as u128);
-        let request = FunctionalExchangeRequest {
-            id,
-            alias: format!("flow_{:02}", self.edges.len()),
-            name: name.into(),
-            description: String::new(),
-            source,
-            target,
-            source_port,
-            target_port,
-            items: vec![],
-        };
-        let commands = ports::plan_functional_exchange(&self.project, &request).unwrap();
-        self.project = execute_batch(&self.project, &commands).unwrap();
-        self.edges.push(id);
-        id
-    }
-
-    fn port_pair(&self, edge: Id) -> (Id, Id) {
-        let RelationBody::FunctionalExchange {
-            source_port,
-            target_port,
-            ..
-        } = self.project.relations[&edge].body
-        else {
-            unreachable!()
-        };
-        (source_port, target_port)
-    }
-
-    fn anchor(&mut self, owner: Id, port: Id, side: PortAnchorSide, offset: f32) {
-        let node = self.project.diagrams[&self.diagram]
-            .nodes
-            .values()
-            .find(|n| n.element == owner)
-            .unwrap()
-            .id;
-        self.project = prepare_command(
-            &self.project,
-            &Command::SetPortAnchor {
-                diagram: self.diagram,
-                node,
-                anchor: PortAnchor { port, side, offset },
-            },
-        )
-        .unwrap()
-        .project;
-    }
-}
-
-fn sentinel(edge: Id, x: f32, y: f32) -> EdgeRoute {
-    EdgeRoute {
-        edge,
-        source_attachment: None,
-        target_attachment: None,
-        waypoints: vec![Position { x, y }],
-        label: Some(EdgeLabel {
-            fraction: 0.4,
-            offset: Position { x: -30., y: -70. },
-        }),
-    }
-}
-
-fn workshop() -> Vec<Case> {
-    let original =
-        persistence::decode(include_bytes!("../../../examples/routing-workshop.json")).unwrap();
-    let diagram = original
-        .diagrams
-        .values()
-        .find(|d| d.alias == "sa_system_boundary_and_functions")
-        .unwrap()
-        .id;
-    assert_eq!(
-        original.diagrams[&diagram].projection,
-        ProjectionKind::Allocation
-    );
-    assert_eq!(original.diagrams[&diagram].nodes.len(), 12);
-    let container = original
-        .elements
-        .values()
-        .find(|e| e.alias == "rescue_coordination_system")
-        .unwrap()
-        .id;
-    let placement = original.diagrams[&diagram]
-        .nodes
-        .values()
-        .find(|n| n.element == container)
-        .unwrap()
-        .id;
-    let traces: Vec<_> = [
-        "sa_report_to_relay",
-        "sa_direct_advice",
-        "sa_incident_decision",
-    ]
-    .iter()
-    .map(|alias| {
-        original
-            .relations
-            .values()
-            .find(|r| r.alias == *alias)
-            .unwrap()
-            .id
-    })
-    .collect();
-    let mut folded = original.clone();
-    assert!(!folded.diagrams[&diagram].nodes[&placement].collapsed);
-    folded
-        .diagrams
-        .get_mut(&diagram)
-        .unwrap()
-        .nodes
-        .get_mut(&placement)
-        .unwrap()
-        .collapsed = true;
-    let mut restored = folded.clone();
-    restored
-        .diagrams
-        .get_mut(&diagram)
-        .unwrap()
-        .nodes
-        .get_mut(&placement)
-        .unwrap()
-        .collapsed = false;
-    assert_eq!(restored, original);
-    vec![
-        Case {
-            name: "workshop_sa_original",
-            description: "Saved coastal rescue Allocation view, all source records retained.",
-            project: original,
-            diagram,
-            trace_edges: traces.clone(),
-            metadata: json!({"source":"examples/routing-workshop.json","view_alias":"sa_system_boundary_and_functions"}),
-        },
-        Case {
-            name: "workshop_sa_folded",
-            description: "Same saved Project with only rescue_coordination_system placement folded.",
-            project: folded,
-            diagram,
-            trace_edges: traces,
-            metadata: json!({"source":"examples/routing-workshop.json","folded_placement":placement,
-                "folded_element":container,"unfold_restores_original_exact":true}),
-        },
-    ]
-}
-
-fn mixed() -> Vec<Case> {
-    let mut b = Builder::new("mixed_dispatch", 100_000);
-    let nodes: Vec<_> = [
-        ("Sensor A", 40., 90.),
-        ("Sensor B", 40., 510.),
-        ("Ingest", 380., 250.),
-        ("Validate", 720., 80.),
-        ("Archive", 720., 510.),
-        ("Correlate", 1060., 270.),
-        ("Plan", 1400., 80.),
-        ("Dispatch", 1740., 270.),
-        ("Actuator", 1400., 680.),
-        ("Operator", 1740., 680.),
-    ]
-    .into_iter()
-    .map(|(name, x, y)| b.function(name, x, y))
-    .collect();
-    let e0 = b.exchange(
-        "Sensor A observations",
-        nodes[0],
-        nodes[2],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    let ingest_input = b.port_pair(e0).1;
-    let e1 = b.exchange(
-        "Sensor B observations",
-        nodes[1],
-        nodes[2],
-        PortChoice::Create,
-        PortChoice::Reuse(ingest_input),
-    );
-    let e2 = b.exchange(
-        "Validate incoming observations",
-        nodes[2],
-        nodes[3],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    let ingest_output = b.port_pair(e2).0;
-    let e3 = b.exchange(
-        "Archive incoming observations",
-        nodes[2],
-        nodes[4],
-        PortChoice::Reuse(ingest_output),
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Validated observations",
-        nodes[3],
-        nodes[5],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Archived context",
-        nodes[4],
-        nodes[5],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Correlated situation",
-        nodes[5],
-        nodes[6],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Planned actions",
-        nodes[6],
-        nodes[7],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    let e8 = b.exchange(
-        "Actuator dispatch",
-        nodes[7],
-        nodes[8],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    let dispatch_output = b.port_pair(e8).0;
-    let e9 = b.exchange(
-        "Operator dispatch copy",
-        nodes[7],
-        nodes[9],
-        PortChoice::Reuse(dispatch_output),
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Operator acknowledgement",
-        nodes[9],
-        nodes[8],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Archived actuator policy",
-        nodes[4],
-        nodes[8],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    b.exchange(
-        "Sensor B archive stream",
-        nodes[1],
-        nodes[4],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    let feedback = b.exchange(
-        "Sensor A sampling feedback",
-        nodes[6],
-        nodes[0],
-        PortChoice::Create,
-        PortChoice::Create,
-    );
-    let (feedback_output, feedback_input) = b.port_pair(feedback);
-    b.anchor(nodes[0], b.port_pair(e0).0, PortAnchorSide::Right, 0.25);
-    b.anchor(nodes[2], ingest_input, PortAnchorSide::Left, 0.3);
-    b.anchor(nodes[2], ingest_output, PortAnchorSide::Bottom, 0.6);
-    b.anchor(nodes[6], feedback_output, PortAnchorSide::Top, 0.5);
-    b.anchor(nodes[0], feedback_input, PortAnchorSide::Left, 0.6);
-    b.anchor(nodes[7], dispatch_output, PortAnchorSide::Right, 0.5);
-    b.project
-        .diagrams
-        .get_mut(&b.diagram)
-        .unwrap()
-        .routes
-        .push(sentinel(feedback, 300., -100.));
-    let secondary = Id::from_u128(b.base + 2);
-    let mut other = b.project.diagrams[&b.diagram].clone();
-    other.id = secondary;
-    other.alias = "mixed_dispatch_secondary".into();
-    other.name = "Feedback review sentinel".into();
-    other.description = "Unaffected other-view preservation sentinel".into();
-    other.nodes.clear();
-    other.routes = vec![sentinel(feedback, 460., 480.)];
-    b.project.diagrams.insert(secondary, other);
-    for (i, element) in [nodes[0], nodes[2], nodes[6]].into_iter().enumerate() {
-        let old = b.project.place(
-            secondary,
-            element,
-            Position {
-                x: 100. + i as f32 * 340.,
-                y: 100.,
-            },
-        );
-        let stable = b.stable(old);
-        b.project
-            .diagrams
-            .get_mut(&secondary)
-            .unwrap()
-            .nodes
-            .get_mut(&stable)
-            .unwrap()
-            .alias = format!("feedback_review_{i}");
-    }
-    assert_eq!(b.edges.len(), 14);
-    assert_eq!(b.project.diagrams[&b.diagram].nodes.len(), 10);
-    let originals = b.edges.clone();
-    let replacements: Vec<_> = originals.iter().rev().copied().collect();
-    let mut permuted = b.project.clone();
-    for (i, id) in originals.iter().enumerate() {
-        reidentify(&mut permuted, *id, Id::from_u128(1_000_000 + i as u128)).unwrap();
-    }
-    for (i, id) in replacements.iter().enumerate() {
-        reidentify(&mut permuted, Id::from_u128(1_000_000 + i as u128), *id).unwrap();
-    }
-    let mut restored = permuted.clone();
-    for (i, id) in replacements.iter().enumerate() {
-        reidentify(&mut restored, *id, Id::from_u128(1_000_000 + i as u128)).unwrap();
-    }
-    for (i, id) in originals.iter().enumerate() {
-        reidentify(&mut restored, Id::from_u128(1_000_000 + i as u128), *id).unwrap();
-    }
-    assert_eq!(restored, b.project);
-    let correspondence: BTreeMap<_, _> = originals.iter().copied().zip(replacements).collect();
-    let traces = vec![e1, e3, e9, feedback];
-    let permuted_traces = traces.iter().map(|id| correspondence[id]).collect();
-    let metadata = json!({"shared_input":ingest_input,"shared_outputs":[ingest_output,dispatch_output],
-        "sentinel_edge":feedback,"secondary_diagram":secondary,"fixed_anchor_records":6,
-        "authored_waypoint_count_main":1,"authored_label_count_main":1,
-        "declared_feedback_cycle":[nodes[0],nodes[2],nodes[3],nodes[5],nodes[6],nodes[0]]});
-    vec![
-        Case {
-            name: "mixed_dispatch",
-            description: "Ten-function sensing/decision/dispatch network, explicit port sharing and fixed anchors.",
-            project: b.project,
-            diagram: b.diagram,
-            trace_edges: traces,
-            metadata,
-        },
-        Case {
-            name: "mixed_dispatch_edge_ids_reversed",
-            description: "Same mixed Project with fixed reversed relation-ID permutation, remapped references.",
-            project: permuted,
-            diagram: b.diagram,
-            trace_edges: permuted_traces,
-            metadata: json!({"paired_case":"mixed_dispatch","edge_id_correspondence":correspondence,
-                "inverse_recovers_original_exact":true,"secondary_diagram":secondary}),
-        },
-    ]
-}
-
-fn sparse() -> Case {
-    let mut b = Builder::new("subsystems_40_sparse", 200_000);
-    let names = [
-        "Sensing",
-        "Communications",
-        "Assessment",
-        "Planning",
-        "Delivery",
-    ];
-    let stages = [
-        "Acquire",
-        "Decode",
-        "Validate",
-        "Enrich",
-        "Aggregate",
-        "Decide",
-        "Package",
-        "Publish",
-    ];
-    let mut nodes = Vec::new();
-    for (group, name) in names.iter().enumerate() {
-        let row: Vec<_> = stages
-            .iter()
-            .enumerate()
-            .map(|(stage, label)| {
-                b.function(
-                    &format!("{name} {label}"),
-                    80. + stage as f32 * 300.,
-                    80. + group as f32 * 240.,
-                )
-            })
-            .collect();
-        nodes.push(row);
-    }
-    for group in 0..5 {
-        for stage in 0..7 {
-            b.exchange(
-                &format!(
-                    "{} {} to {}",
-                    names[group],
-                    stages[stage],
-                    stages[stage + 1]
-                ),
-                nodes[group][stage],
-                nodes[group][stage + 1],
-                PortChoice::Create,
-                PortChoice::Create,
-            );
-        }
-    }
-    let mut trace_edges = Vec::new();
-    for group in 0..5 {
-        for stage in [1, 3, 5, 7] {
-            let next = (group + 1) % 5;
-            let id = b.exchange(
-                &format!(
-                    "{} {} handoff to {} {}",
-                    names[group],
-                    stages[stage],
-                    names[next],
-                    stages[stage - 1]
-                ),
-                nodes[group][stage],
-                nodes[next][stage - 1],
-                PortChoice::Create,
-                PortChoice::Create,
-            );
-            if (group == 0 && stage == 1) || (group == 4 && stage == 7) {
-                trace_edges.push(id);
-            }
-        }
-    }
-    assert_eq!(b.edges.len(), 55);
-    assert_eq!(b.project.diagrams[&b.diagram].nodes.len(), 40);
-    Case {
-        name: "subsystems_40_sparse",
-        description: "Five eight-stage subsystem chains with twenty directed cross-subsystem handoffs; all ports distinct.",
-        project: b.project,
-        diagram: b.diagram,
-        trace_edges,
-        metadata: json!({"groups":names,"stages":stages,"chain_edges":35,"cross_edges":20,
-            "all_exchange_ports_distinct":true,"grid_columns":8,"grid_rows":5}),
-    }
-}
-
-fn main() -> Result<(), Box<dyn Error>> {
-    let mut args = std::env::args_os().skip(1);
-    let output = PathBuf::from(
-        args.next()
-            .ok_or("Usage: routing_eval_corpus NEW_DIRECTORY")?,
-    );
-    if args.next().is_some() {
-        return Err("Expected exactly one new output directory".into());
-    }
-    if output.exists() {
-        return Err("Output directory already exists; refusing overwrite".into());
-    }
-    let mut cases = workshop();
-    cases.extend(mixed());
-    cases.push(sparse());
-    let mut files = Vec::new();
-    let mut entries = Vec::new();
-    for case in cases {
-        validate_candidate(&case.project)?;
-        let file = format!("{}.json", case.name);
-        let traces: Vec<_> = case
-            .trace_edges
-            .iter()
-            .map(|id| {
-                let relation = &case.project.relations[id];
-                json!({"edge":id,"alias":relation.alias,"name":relation.name,
-                "source":relation.source(),"target":relation.target()})
-            })
-            .collect();
-        entries.push(json!({"name":case.name,"project_file":file,"diagram":case.diagram,
-            "description":case.description,"metadata":case.metadata,"trace_tasks":traces,
-            "source_counts":{"elements":case.project.elements.len(),"relations":case.project.relations.len(),
-                "views":case.project.diagrams.len(),"selected_view_placements":case.project.diagrams[&case.diagram].nodes.len(),
-                "selected_view_authored_routes":case.project.diagrams[&case.diagram].routes.len()}}));
-        files.push((file, serde_json::to_vec_pretty(&case.project)?));
-    }
-    let manifest = json!({"schema":1,"cases":entries,"definition_baseline":"f72aa2ca",
-        "construction":"Source-authored positions/topology, no Layout/projection/routing calls; validate all before writing.",
-        "invariants":"Routing is read-only. Preserve all semantic records, port identities, fixed anchors, authored routes/labels, fold flags, and other views. ID permutation correspondence is explicit. No quality or automatic endpoint-side expectation.",
-        "generation_in_routing_timing":false});
-    let manifest_bytes = serde_json::to_vec_pretty(&manifest)?;
-    fs::create_dir(&output)?;
-    for (name, bytes) in files {
-        fs::write(output.join(name), bytes)?;
-    }
-    fs::write(output.join("manifest.json"), manifest_bytes)?;
-    println!("{}", output.join("manifest.json").display());
-    Ok(())
-}

crates/oa-core/src/routing.rs

@@ -6,9 +6,7 @@ use crate::{
     RelationBody, RelationKind, Size,
 };
 mod attachments;
-mod leads;
 pub use attachments::{attachment_from_point, attachment_point, semantic_port_endpoint};
-pub use leads::{LeadBlocker, LeadEndpoint, LeadIncompatibility, lead_incompatibilities};
 use std::cmp::Ordering;
 use std::collections::{BTreeMap, BTreeSet, BinaryHeap};
 use std::fmt;
@@ -422,73 +420,6 @@ fn endpoints(
     .collect()
 }
 
-fn effective_route<'a>(
-    project: &Project,
-    diagram: &Diagram,
-    edge: &ProjectedEdge,
-    stored: Option<&'a crate::EdgeRoute>,
-) -> (
-    bool,
-    Option<&'a crate::EdgeRoute>,
-    [Option<EdgeAttachment>; 2],
-) {
-    let promoted = projection::edge_endpoint_placements(project, diagram, edge.id)
-        .is_some_and(|(source, target)| source != edge.source || target != edge.target);
-    let route = if promoted { None } else { stored };
-    let attachments = [EdgeEnd::Source, EdgeEnd::Target].map(|end| {
-        semantic_port_endpoint(project, edge.id, end)
-            .is_none()
-            .then(|| route.and_then(|r| r.attachment(end)))
-            .flatten()
-    });
-    (promoted, route, attachments)
-}
-#[allow(clippy::too_many_arguments)]
-fn edge_endpoints(
-    project: &Project,
-    diagram: &Diagram,
-    edge: &ProjectedEdge,
-    source: &ProjectedNode,
-    target: &ProjectedNode,
-    view: &ProjectedView,
-    attachments: [Option<EdgeAttachment>; 2],
-) -> [Vec<Endpoint>; 2] {
-    [
-        endpoints(
-            project,
-            diagram,
-            source,
-            semantic_port_endpoint(project, edge.id, EdgeEnd::Source).or(edge.source_port),
-            view,
-            attachments[0],
-        ),
-        endpoints(
-            project,
-            diagram,
-            target,
-            semantic_port_endpoint(project, edge.id, EdgeEnd::Target).or(edge.target_port),
-            view,
-            attachments[1],
-        ),
-    ]
-}
-fn allowed_endpoint_pair(edge: &ProjectedEdge, a: Endpoint, b: Endpoint, coincident: bool) -> bool {
-    !(edge.source == edge.target
-        && edge.source_port.is_none()
-        && edge.target_port.is_none()
-        && a.point == b.point
-        && a.stub == b.stub
-        && !coincident)
-}
-fn lead_pair_clear(edge: &ProjectedEdge, a: Endpoint, b: Endpoint, obstacles: &[Rect]) -> bool {
-    !obstacles
-        .iter()
-        .any(|r| r.id != edge.source && r.crosses(a.point, a.stub))
-        && !obstacles
-            .iter()
-            .any(|r| r.id != edge.target && r.crosses(b.point, b.stub))
-}
-
 fn ancestors(id: Id, nodes: &BTreeMap<Id, &ProjectedNode>, out: &mut BTreeSet<Id>) {
     let mut current = nodes.get(&id).and_then(|n| n.visual_parent);
     let mut seen = BTreeSet::new();
@@ -581,8 +512,16 @@ fn route_diagram_impl(
             continue;
         };
         let stored = authored.get(&edge.id).copied();
-        let (custom_suspended, route, attachments) =
-            effective_route(project, diagram, edge, stored);
+        let promoted = projection::edge_endpoint_placements(project, diagram, edge.id)
+            .is_some_and(|(source, target)| source != edge.source || target != edge.target);
+        let custom_suspended = promoted;
+        let route = if promoted { None } else { stored };
+        let attachments = [EdgeEnd::Source, EdgeEnd::Target].map(|end| {
+            semantic_port_endpoint(project, edge.id, end)
+                .is_none()
+                .then(|| route.and_then(|r| r.attachment(end)))
+                .flatten()
+        });
         let pins = route.map_or_else(Vec::new, |r| r.waypoints.clone());
         let obstacles = edge_obstacles(edge, &nodes, &rectangles, &headers);
 
@@ -620,11 +559,24 @@ fn route_diagram_impl(
                 });
             }
         }
-        let ends = edge_endpoints(project, diagram, edge, source, target, view, attachments);
         let (points, pin_lengths, failure) = route_edge(
             edge,
-            &ends[0],
-            &ends[1],
+            &endpoints(
+                project,
+                diagram,
+                source,
+                semantic_port_endpoint(project, edge.id, EdgeEnd::Source).or(edge.source_port),
+                view,
+                attachments[0],
+            ),
+            &endpoints(
+                project,
+                diagram,
+                target,
+                semantic_port_endpoint(project, edge.id, EdgeEnd::Target).or(edge.target_port),
+                view,
+                attachments[1],
+            ),
             &pins,
             &obstacles,
             &previous,
@@ -841,7 +793,13 @@ fn route_edge(
         for &b in target_ends {
             // A real self-relation must leave and return at distinct anchors.
             // Reusing one anchor makes the cheapest path a degenerate stub.
-            if !allowed_endpoint_pair(edge, a, b, coincident) {
+            if edge.source == edge.target
+                && edge.source_port.is_none()
+                && edge.target_port.is_none()
+                && a.point == b.point
+                && a.stub == b.stub
+                && !coincident
+            {
                 continue;
             }
             let estimate = manhattan(a.stub, pins.first().copied().unwrap_or(b.stub))
@@ -865,7 +823,13 @@ fn route_edge(
             }) {
                 continue;
             }
-            if !lead_pair_clear(edge, a, b, obstacles) {
+            if obstacles
+                .iter()
+                .any(|r| r.id != edge.source && r.crosses(a.point, a.stub))
+                || obstacles
+                    .iter()
+                    .any(|r| r.id != edge.target && r.crosses(b.point, b.stub))
+            {
                 continue;
             }
             let mut points = vec![a.point, a.stub];

crates/oa-core/src/routing/leads.rs

@@ -1,173 +0,0 @@
-//! Necessary terminal-lead checks shared with experimental placement consumers.
-use super::*;
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct LeadBlocker {
-    pub id: Id,
-    /// The actual routing obstacle: clearance inflated, ancestor body excluded.
-    pub bounds: RoutingBounds,
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct LeadEndpoint {
-    pub owner: Id,
-    pub tip: Position,
-    pub stub: Position,
-    pub blockers: Vec<LeadBlocker>,
-    /// Separate information only; not part of the router's early lead guard.
-    pub stub_containers: Vec<LeadBlocker>,
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub struct LeadIncompatibility {
-    pub edge: Id,
-    pub source: Vec<LeadEndpoint>,
-    pub target: Vec<LeadEndpoint>,
-    pub allowed_pair_count: usize,
-    pub lead_clear_pair_count: usize,
-}
-
-fn blocker(r: &Rect) -> LeadBlocker {
-    LeadBlocker {
-        id: r.id,
-        bounds: RoutingBounds {
-            position: pos(r.left, r.top),
-            size: Size {
-                width: r.right - r.left,
-                height: r.bottom - r.top,
-            },
-        },
-    }
-}
-
-fn describe(owner: Id, endpoint: Endpoint, obstacles: &[Rect]) -> LeadEndpoint {
-    LeadEndpoint {
-        owner,
-        tip: endpoint.point,
-        stub: endpoint.stub,
-        blockers: obstacles
-            .iter()
-            .filter(|r| r.id != owner && r.crosses(endpoint.point, endpoint.stub))
-            .map(blocker)
-            .collect(),
-        stub_containers: obstacles
-            .iter()
-            .filter(|r| r.contains(endpoint.stub))
-            .map(blocker)
-            .collect(),
-    }
-}
-
-/// Return only edges for which every allowed endpoint pair fails the router's
-/// existing mandatory-lead guard. Empty output is NECESSARY ONLY: it does not
-/// establish a clear route, clear pins, successful search, or label clearance.
-/// Uses the supplied final projection; does not modify the Project or choose
-/// different ports/attachments. Stub containment is reported separately and
-/// does not change the lead guard or its historical pinned/degenerate behavior.
-pub fn lead_incompatibilities(
-    project: &Project,
-    diagram: &Diagram,
-    view: &ProjectedView,
-) -> Vec<LeadIncompatibility> {
-    let nodes: BTreeMap<_, _> = view.nodes.iter().map(|n| (n.id, n)).collect();
-    let rectangles: Vec<_> = nodes.values().map(|n| Rect::node(n)).collect();
-    let authored: BTreeMap<_, _> = diagram.routes.iter().map(|r| (r.edge, r)).collect();
-    let headers: BTreeMap<_, _> = nodes
-        .values()
-        .map(|node| {
-            (
-                node.id,
-                if diagram.projection.state_machine().is_some() && !node.collapsed {
-                    projection::state_header_height(project, node.element)
-                } else {
-                    HEADER
-                },
-            )
-        })
-        .collect();
-    let mut ordered: Vec<_> = view.edges.iter().collect();
-    ordered.sort_by_key(|e| e.id);
-    let mut result = Vec::new();
-    for edge in ordered {
-        let (Some(source), Some(target)) = (nodes.get(&edge.source), nodes.get(&edge.target))
-        else {
-            continue;
-        };
-        let (_, _, attachments) =
-            effective_route(project, diagram, edge, authored.get(&edge.id).copied());
-        let ends = edge_endpoints(project, diagram, edge, source, target, view, attachments);
-        let obstacles = edge_obstacles(edge, &nodes, &rectangles, &headers);
-        let coincident = edge.source == edge.target
-            && ends[0].len() == 1
-            && ends[1].len() == 1
-            && ends[0][0].point == ends[1][0].point
-            && ends[0][0].stub == ends[1][0].stub;
-        let mut allowed_pair_count = 0;
-        let mut lead_clear_pair_count = 0;
-        for &a in &ends[0] {
-            for &b in &ends[1] {
-                if !allowed_endpoint_pair(edge, a, b, coincident) {
-                    continue;
-                }
-                allowed_pair_count += 1;
-                if lead_pair_clear(edge, a, b, &obstacles) {
-                    lead_clear_pair_count += 1;
-                }
-            }
-        }
-        if lead_clear_pair_count == 0 {
-            result.push(LeadIncompatibility {
-                edge: edge.id,
-                source: ends[0]
-                    .iter()
-                    .map(|&e| describe(edge.source, e, &obstacles))
-                    .collect(),
-                target: ends[1]
-                    .iter()
-                    .map(|&e| describe(edge.target, e, &obstacles))
-                    .collect(),
-                allowed_pair_count,
-                lead_clear_pair_count,
-            });
-        }
-    }
-    result
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn coincident_selfloop_exception_and_stub_containment_remain_separate() {
-        let owner = Id::from_u128(1);
-        let edge = ProjectedEdge {
-            id: Id::from_u128(2),
-            source: owner,
-            target: owner,
-            source_port: None,
-            target_port: None,
-            trace: false,
-            oriented: true,
-        };
-        let endpoint = Endpoint {
-            point: pos(0., 0.),
-            stub: pos(18., 0.),
-        };
-        assert!(!allowed_endpoint_pair(&edge, endpoint, endpoint, false));
-        assert!(allowed_endpoint_pair(&edge, endpoint, endpoint, true));
-        let obstacles = [Rect {
-            id: owner,
-            left: -1.,
-            right: 20.,
-            top: -1.,
-            bottom: 1.,
-        }];
-        assert!(lead_pair_clear(&edge, endpoint, endpoint, &obstacles));
-        let diagnostic = describe(owner, endpoint, &obstacles);
-        assert!(diagnostic.blockers.is_empty());
-        assert_eq!(diagnostic.stub_containers.len(), 1);
-        // This diagnostic must not be folded into the historical early guard.
-        assert_eq!(diagnostic.stub_containers[0].id, owner);
-    }
-}

crates/oa-core/tests/lead_feasibility.rs

@@ -1,238 +0,0 @@
-use oa_core::{projection, routing, *};
-
-struct Fixture {
-    p: Project,
-    d: Id,
-    edge: Id,
-    source: Id,
-    target: Id,
-    blocker: Id,
-}
-fn fixture(ports: bool, gap: f32) -> Fixture {
-    let mut p = Project::empty();
-    let kind = if ports {
-        Kind::Function
-    } else {
-        Kind::DataType
-    };
-    let a = p.add_element(kind, Layer::Sa, "Source", None).unwrap();
-    let b = p.add_element(kind, Layer::Sa, "Target", None).unwrap();
-    let c = p.add_element(kind, Layer::Sa, "Blocker", None).unwrap();
-    for element in p.elements.values_mut() {
-        if let Some(SharedBody::DataType { definition, .. }) = element.shared_mut() {
-            *definition = DataTypeDefinition::Record { supertype: None };
-        }
-    }
-    let edge = p.relate(
-        if ports {
-            RelationKind::FunctionalExchange
-        } else {
-            RelationKind::DataAssociation
-        },
-        "Flow",
-        a,
-        b,
-    );
-    let d = p.ensure_diagram(Layer::Sa);
-    let source = p.place(d, a, Position { x: 0., y: 0. });
-    let target = p.place(
-        d,
-        b,
-        Position {
-            x: 500.,
-            y: 180. + gap,
-        },
-    );
-    let blocker = p.place(d, c, Position { x: 500., y: 20. });
-    for n in p.diagrams.get_mut(&d).unwrap().nodes.values_mut() {
-        n.size = Size {
-            width: 224.,
-            height: 160.,
-        };
-    }
-    if ports {
-        for (owner, end, side) in [
-            (source, EdgeEnd::Source, PortAnchorSide::Right),
-            (target, EdgeEnd::Target, PortAnchorSide::Top),
-        ] {
-            let port = routing::semantic_port_endpoint(&p, edge, end).unwrap();
-            p.diagrams
-                .get_mut(&d)
-                .unwrap()
-                .nodes
-                .get_mut(&owner)
-                .unwrap()
-                .port_anchors
-                .push(PortAnchor {
-                    port,
-                    side,
-                    offset: 0.5,
-                });
-        }
-    }
-    validate_candidate(&p).unwrap();
-    Fixture {
-        p,
-        d,
-        edge,
-        source,
-        target,
-        blocker,
-    }
-}
-fn report(f: &Fixture) -> Vec<routing::LeadIncompatibility> {
-    routing::lead_incompatibilities(
-        &f.p,
-        &f.p.diagrams[&f.d],
-        &projection::project_view(&f.p, f.d),
-    )
-}
-fn attachment_route(edge: Id) -> EdgeRoute {
-    EdgeRoute {
-        edge,
-        source_attachment: Some(EdgeAttachment {
-            side: PortAnchorSide::Top,
-            offset: 0.25,
-        }),
-        target_attachment: Some(EdgeAttachment {
-            side: PortAnchorSide::Bottom,
-            offset: 0.75,
-        }),
-        waypoints: vec![Position { x: 300., y: 400. }],
-        label: None,
-    }
-}
-
-#[test]
-fn exact_twenty_gap_is_blocked_thirty_plus_clears_without_mutation() {
-    let f = fixture(true, 20.);
-    let original = f.p.clone();
-    let r = report(&f);
-    assert_eq!(r.len(), 1);
-    assert_eq!(
-        (
-            r[0].edge,
-            r[0].allowed_pair_count,
-            r[0].lead_clear_pair_count
-        ),
-        (f.edge, 1, 0)
-    );
-    assert_eq!(r[0].source[0].owner, f.source);
-    let end = &r[0].target[0];
-    assert_eq!(end.owner, f.target);
-    assert_eq!(end.tip, Position { x: 612., y: 200. });
-    assert_eq!(end.stub, Position { x: 612., y: 182. });
-    assert_eq!(end.blockers.len(), 1);
-    assert_eq!(end.blockers[0].id, f.blocker);
-    assert_eq!(
-        end.blockers[0].bounds,
-        routing::RoutingBounds {
-            position: Position { x: 488., y: 8. },
-            size: Size {
-                width: 248.,
-                height: 184.
-            },
-        }
-    );
-    assert_eq!(end.stub_containers, end.blockers);
-    assert_eq!(f.p, original);
-    assert!(report(&fixture(true, 30.)).is_empty());
-    assert!(report(&fixture(true, 31.)).is_empty());
-}
-
-#[test]
-fn semantic_manual_ports_override_dormant_route_attachments_and_pins() {
-    let mut f = fixture(true, 20.);
-    let expected = report(&f);
-    f.p.diagrams
-        .get_mut(&f.d)
-        .unwrap()
-        .routes
-        .push(attachment_route(f.edge));
-    assert_eq!(report(&f), expected);
-    let view = projection::project_view(&f.p, f.d);
-    let routed = routing::route_diagram(&f.p, &f.p.diagrams[&f.d], &view);
-    assert_eq!(
-        routed.edges[&f.edge].points.last(),
-        Some(&expected[0].target[0].tip)
-    );
-    assert!(
-        routed.edges[&f.edge]
-            .warnings
-            .contains(&routing::RouteWarning::NoClearPath)
-    );
-}
-
-#[test]
-fn unconstrained_nonport_alternative_is_not_hard_blocked() {
-    let mut f = fixture(false, 20.);
-    assert!(report(&f).is_empty());
-    let mut route = attachment_route(f.edge);
-    route.source_attachment = Some(EdgeAttachment {
-        side: PortAnchorSide::Right,
-        offset: 0.5,
-    });
-    route.target_attachment = Some(EdgeAttachment {
-        side: PortAnchorSide::Top,
-        offset: 0.5,
-    });
-    f.p.diagrams.get_mut(&f.d).unwrap().routes.push(route);
-    let r = report(&f);
-    assert_eq!(r.len(), 1);
-    assert_eq!(r[0].allowed_pair_count, 1);
-    assert_eq!(r[0].target[0].blockers[0].id, f.blocker);
-}
-
-#[test]
-fn nested_endpoint_body_is_traversable_and_promoted_attachments_are_suspended() {
-    let mut f = fixture(false, 20.);
-    // DataType containment is not required for this routing-only view witness:
-    // construct the supplied projected forest explicitly, retaining real owners.
-    let mut view = projection::project_view(&f.p, f.d);
-    let parent = Id::new_v4();
-    let source = view.nodes.iter_mut().find(|n| n.id == f.source).unwrap();
-    source.visual_parent = Some(parent);
-    source.position = Position { x: 40., y: 100. };
-    let element = source.element;
-    view.nodes.push(projection::ProjectedNode {
-        id: parent,
-        element,
-        position: Position { x: 0., y: 0. },
-        size: Size {
-            width: 300.,
-            height: 300.,
-        },
-        visual_parent: None,
-        depth: 0,
-        collapsed: false,
-        allocation_summary: false,
-    });
-    let mut route = attachment_route(f.edge);
-    route.source_attachment = Some(EdgeAttachment {
-        side: PortAnchorSide::Right,
-        offset: 0.5,
-    });
-    route.target_attachment = Some(EdgeAttachment {
-        side: PortAnchorSide::Top,
-        offset: 0.5,
-    });
-    f.p.diagrams.get_mut(&f.d).unwrap().routes.push(route);
-    let r = routing::lead_incompatibilities(&f.p, &f.p.diagrams[&f.d], &view);
-    assert_eq!(r.len(), 1);
-    assert!(
-        r[0].source[0].blockers.is_empty(),
-        "Ancestor body must not block source lead"
-    );
-    // Promotion changes actual projected owner: custom attachments no longer apply.
-    view.edges
-        .iter_mut()
-        .find(|e| e.id == f.edge)
-        .unwrap()
-        .source = parent;
-    let with_dormant = routing::lead_incompatibilities(&f.p, &f.p.diagrams[&f.d], &view);
-    f.p.diagrams.get_mut(&f.d).unwrap().routes.clear();
-    assert_eq!(
-        with_dormant,
-        routing::lead_incompatibilities(&f.p, &f.p.diagrams[&f.d], &view)
-    );
-}

crates/oa-desktop/src/allocation_input.rs

@@ -60,6 +60,7 @@ impl Root<'_> {
             return false;
         }
         let canvas = DiagramCanvas {
+            removal_input: &self.app.saved_removal_input,
             selection: self.app.diagram_selection.as_ref(),
             allocation: Some(self.app.allocation_capability()),
             project: self.app.project(),

crates/oa-desktop/src/app.rs

@@ -19,12 +19,18 @@ mod hosted;
 pub(crate) mod multiselect;
 #[cfg(test)]
 mod multiselect_tests;
+pub(crate) mod process_removal;
 mod reference_authoring;
+mod removal_review;
 #[cfg(test)]
 mod review_navigation_tests;
+pub(crate) mod saved_removal;
 #[cfg(test)]
 mod scenario_details_tests;
 mod scenario_diagram;
+mod scenario_multiselect;
+pub(crate) mod scenario_removal;
+pub(crate) mod scenario_reorder;
 mod scenario_spacing;
 #[cfg(test)]
 mod source_indentation_tests;
@@ -215,11 +221,14 @@ mod direct_scenario_tests {
         let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Select(
             context, f.sender,
         )));
-        assert_eq!(
-            app.scenario_context(),
-            Some(context),
-            "same-owner selection retains gesture context"
+        let fresh = app.scenario_context().unwrap();
+        assert_eq!(fresh.visit, context.visit);
+        assert_eq!(fresh.representation, context.representation);
+        assert_ne!(
+            fresh.epoch, context.epoch,
+            "selection retires older gestures"
         );
+        let context = fresh;
         let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Reorder {
             context,
             occurrence: created,
@@ -437,6 +446,10 @@ pub enum Message {
     BehaviorDiagram(Choice),
     StateDiagram(crate::behavior::state_edit::Event),
     ScenarioCanvas(crate::behavior::scenario::CanvasEvent),
+    ScenarioReorder(Box<scenario_reorder::Event>),
+    ScenarioRemoval(Box<scenario_removal::Event>),
+    ProcessRemoval(Box<process_removal::Event>),
+    SavedRemoval(Box<saved_removal::Event>),
     TopologyCanvas(crate::behavior::topology::CanvasEvent),
     PlaceSelected,
     HideSelected,
@@ -523,12 +536,14 @@ pub struct App {
     pub guide: crate::guide::State,
     pub traceability: crate::views::traceability::State,
     pub behavior: crate::behavior::State,
+    pub(crate) scenario_reorder: scenario_reorder::State,
     pub data_state: crate::data_view::State,
     pub inspector_tab: crate::navigation::InspectorTab,
     pub layer: Layer,
     pub selected: Id,
     pub selected_node: Option<Id>,
     pub diagram_selection: Option<crate::diagram_selection::Selection>,
+    pub(crate) saved_removal_input: crate::removal_input::Lifetime,
     pub draft: Option<Draft>,
     pub active_diagram: Option<Id>,
     pub search: String,
@@ -645,12 +660,14 @@ impl App {
             guide: crate::guide::State::default(),
             traceability: Default::default(),
             behavior: Default::default(),
+            scenario_reorder: Default::default(),
             data_state: Default::default(),
             inspector_tab: Default::default(),
             layer,
             selected,
             selected_node: None,
             diagram_selection: None,
+            saved_removal_input: Default::default(),
             draft,
             active_diagram,
             search: String::new(),
@@ -1348,8 +1365,128 @@ impl App {
         ])
     }
     pub fn update(&mut self, message: Message) -> Task<Message> {
+        // Group dialogs only accept their stamped Cancel button. A delayed
+        // singleton dialog packet cannot close a later aggregate review.
+        if matches!(message, Message::CancelDelete)
+            && self.delete_target.as_ref().is_some_and(|target| {
+                target.scenario.is_some() || target.process.is_some() || target.saved.is_some()
+            })
+        {
+            return Task::none();
+        }
+        if let Message::SavedRemoval(event) = message {
+            return self.saved_removal_event(*event);
+        }
+        if let Message::StateDiagram(behavior::state_edit::Event::ModelRemoval(event)) = message {
+            return self.saved_removal_event(*event);
+        }
+        if let Message::ProcessRemoval(event) = message {
+            return self.process_removal_event(*event);
+        }
+        // Process review Escape is captured with its token by the root widget.
+        if matches!(message, Message::Escape)
+            && self
+                .delete_target
+                .as_ref()
+                .is_some_and(|target| target.process.is_some() || target.saved.is_some())
+        {
+            return Task::none();
+        }
+        if let Message::ScenarioRemoval(event) = message {
+            return self.scenario_removal_event(*event);
+        }
+        if let Message::ConfirmDelete(token) = &message {
+            if self
+                .delete_target
+                .as_ref()
+                .is_none_or(|target| target.snapshot.token != *token)
+            {
+                return Task::none();
+            }
+            if self
+                .delete_target
+                .as_ref()
+                .is_some_and(|target| target.saved.is_some())
+            {
+                self.confirm_saved_removal(*token);
+                return Task::none();
+            }
+            if self
+                .delete_target
+                .as_ref()
+                .is_some_and(|target| target.scenario.is_some())
+            {
+                self.confirm_scenario_removal(*token);
+                return Task::none();
+            }
+            if self
+                .delete_target
+                .as_ref()
+                .is_some_and(|target| target.process.is_some())
+            {
+                self.confirm_process_removal(*token);
+                return Task::none();
+            }
+        }
+        // Captured reorder packets must be admitted before shared navigation,
+        // camera or source boundaries can disturb a newer operation.
+        if let Message::ScenarioReorder(event) = message {
+            return self.scenario_reorder_event(*event);
+        }
+        if let Message::ScenarioCanvas(behavior::scenario::CanvasEvent::Selection(event)) = message
+        {
+            return self.scenario_selection_event(*event);
+        }
+        // A delayed Scenario menu cannot retire the current reveal/gesture even
+        // when it uses the same semantic owner after a representation round trip.
+        if let Message::Menu(crate::model_menu::Event::Open(request)) = &message
+            && (request.scenario.is_some() || request.process.is_some() || request.canvas.is_some())
+            && crate::model_menu::Opened::new(self, request.clone(), self.menu_sequence).is_none()
+        {
+            return Task::none();
+        }
+        if let Message::Menu(crate::model_menu::Event::Invoke(token, _)) = &message
+            && let Some(menu) = &self.model_menu
+            && (menu.request.scenario.is_some()
+                || menu.request.process.is_some()
+                || menu.request.canvas.is_some())
+            && (menu.token != *token || !menu.valid(self))
+        {
+            // Consume an expired menu's own packet without touching a newer
+            // menu or crossing source/selection boundaries.
+            if menu.token == *token {
+                self.model_menu = None;
+            }
+            return Task::none();
+        }
+        if self.scenario_group_selected()
+            && matches!(
+                &message,
+                Message::Command(Command::MoveStep(..)) | Message::Delete
+            )
+        {
+            self.status =
+                "Use Reorder or Remove above the canvas to act on the complete Scenario selection."
+                    .into();
+            return Task::none();
+        }
+        if self.topology_context().is_some()
+            && self
+                .multiselect_snapshot()
+                .is_some_and(|s| s.targets().len() > 1)
+            && matches!(&message, Message::Delete)
+        {
+            self.status =
+                "Use Remove selected above the canvas to review the complete Process selection."
+                    .into();
+            return Task::none();
+        }
         let preview_read_only = self.process_preview_primary().is_some();
         let selection_boundary = self.multiselect_boundary();
+        let scenario_selection_before = self.scenario_context().and_then(|context| {
+            self.multiselect_snapshot()
+                .map(|selection| (context, selection))
+        });
         // Reject delayed gestures before they can retire newer input ownership.
         if let Message::Connection(
             crate::connection_edit::Event::Endpoint(captured, _)
@@ -1518,6 +1655,16 @@ impl App {
             }) {
                 return Task::none();
             }
+            if self.scenario_group_selected()
+                && matches!(
+                    event,
+                    behavior::scenario::CanvasEvent::Select(..)
+                        | behavior::scenario::CanvasEvent::Remove(..)
+                        | behavior::scenario::CanvasEvent::Reorder { .. }
+                )
+            {
+                return Task::none();
+            }
             // Passive layout/form reports retain their existing epoch rules;
             // camera input uses its separate lifetime below. All other actions
             // must match the exact context before shared reveal reconciliation.
@@ -1605,9 +1752,20 @@ impl App {
         {
             self.reconcile_multiselect();
         }
+        if let Some((context, selection)) = scenario_selection_before
+            && self.scenario_context() == Some(context)
+            && self.multiselect_snapshot().as_ref() != Some(&selection)
+        {
+            // Legacy singleton selection retires old spacing packets. If the
+            // action already advanced its context, its new navigation/reveal
+            // owns that context and must not be retired by reconciliation.
+            self.behavior.scenario.cancel_spacing();
+            self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        }
         if preview_read_only && self.process_preview_primary().is_none() && self.draft.is_none() {
             self.refresh_draft();
         }
+        self.scenario_reorder_reconcile();
         task
     }
     fn behavior_control(&mut self, intent: behavior::canvas_workspace::Intent) -> Task<Message> {
@@ -2158,6 +2316,10 @@ impl App {
             }
             Message::CheckpointLoaded(result) => return self.checkpoint_loaded(result),
             Message::Hosted(event) => return self.hosted_event(event),
+            Message::ScenarioReorder(event) => return self.scenario_reorder_event(*event),
+            Message::ScenarioRemoval(event) => return self.scenario_removal_event(*event),
+            Message::ProcessRemoval(event) => return self.process_removal_event(*event),
+            Message::SavedRemoval(event) => return self.saved_removal_event(*event),
             Message::ScenarioCanvas(event) => {
                 use crate::behavior::scenario::{self, CanvasEvent};
                 let context = event.context();
@@ -2666,6 +2828,9 @@ impl App {
                 if request.process.is_some() {
                     request.process = self.topology_context().map(Box::new);
                 }
+                if request.scenario.is_some() {
+                    request.scenario = self.scenario_context().map(Box::new);
+                }
                 self.model_menu = crate::model_menu::Opened::new(self, request, self.menu_sequence);
             }
             Message::Menu(crate::model_menu::Event::Close) => {
@@ -2695,9 +2860,21 @@ impl App {
                         "Apply or revert pending edits before using modeling actions.".into();
                     return Task::none();
                 }
-                if matches!(*action, Message::DiagramSelection(_))
-                    || (menu.request.process.is_some()
-                        && matches!(*action, Message::TopologyCanvas(_)))
+                if matches!(
+                    *action,
+                    Message::DiagramSelection(_) | Message::SavedRemoval(_)
+                ) || (menu.request.process.is_some()
+                    && matches!(
+                        *action,
+                        Message::TopologyCanvas(_) | Message::ProcessRemoval(_)
+                    ))
+                    || (menu.request.scenario.is_some()
+                        && matches!(
+                            *action,
+                            Message::ScenarioCanvas(_)
+                                | Message::ScenarioReorder(_)
+                                | Message::ScenarioRemoval(_)
+                        ))
                 {
                     return self.update(*action);
                 }
@@ -2740,6 +2917,10 @@ impl App {
                 return self.update(Message::Add(child));
             }
             Message::Escape => {
+                if self.scenario_reorder.session.is_some() {
+                    self.scenario_reorder_cancel();
+                    return Task::none();
+                }
                 let restore_source_focus = self.source_navigation_available()
                     && (self.source_navigation.open || self.text_workspace.drawer().is_some());
                 let dismiss_find_only = restore_source_focus && self.source_navigation.open;
@@ -3608,9 +3789,9 @@ impl App {
                     .is_some_and(|s| s.targets().len() > 1)
                 {
                     self.status = if self.topology_context().is_some() {
-                        "Group removal needs an aggregate review. Select one contribution to remove it individually."
+                        "Use Remove selected above the canvas to review the complete Process selection."
                     } else {
-                        "Group model-deletion review is not available yet. Select one element or use Hide selected."
+                        "Use Delete from model above the canvas to review the complete selection, or Hide selected to remove placements."
                     }.into();
                     return Task::none();
                 }

crates/oa-desktop/src/app/allocation_drag_tests.rs

@@ -63,6 +63,7 @@ fn fixture(layer: Layer) -> Fixture {
 }
 fn canvas(app: &App) -> DiagramCanvas<'_> {
     DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: app.diagram_selection.as_ref(),
         allocation: Some(app.allocation_capability()),
         project: app.project(),

crates/oa-desktop/src/app/architecture_authoring/tests.rs

@@ -67,6 +67,7 @@ fn architecture_f2_routes_selected_node_to_inline_rename_and_exact_undo() {
     let camera = (app.zoom, app.pan);
     let bounds = iced::Rectangle::new(iced::Point::ORIGIN, iced::Size::new(600., 380.));
     let canvas = crate::diagram::DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: None,
         project: app.project(),
         view_index: None,

crates/oa-desktop/src/app/architecture_authoring_tests.rs

@@ -221,6 +221,7 @@ fn architecture_canvas_left_click_uses_world_coordinate_once_at_zoom_and_pan() {
         y: (local.y - app.pan.y) / app.zoom,
     };
     let canvas = crate::diagram::DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: None,
         project: app.project(),
         view_index: None,
@@ -299,6 +300,7 @@ fn architecture_f2_rename_preserves_identity_placement_and_atomic_history() {
     let diagrams = app.project().diagrams.clone();
     let camera = (app.zoom, app.pan);
     let canvas = crate::diagram::DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: None,
         project: app.project(),
         view_index: None,

crates/oa-desktop/src/app/behavior_removal_tests.rs

@@ -179,7 +179,7 @@ async fn mounted_scenario_use_delete_keeps_definition_and_second_use_and_rejects
     let token = delete(&mut mounted, &mut app, true).await;
     send(&mut mounted, &mut app, Message::ConfirmDelete(stale)).await;
     assert!(app.delete_pending, "old token does not cancel new dialog");
-    // Keep selection and epoch deliberately unchanged: owner is an independent witness.
+    // Keep selection and epoch unchanged while moving to another Scenario owner.
     let captured = app.scenario_context().unwrap();
     assert_eq!(captured.scenario, owners[0]);
     assert_eq!(
@@ -197,9 +197,28 @@ async fn mounted_scenario_use_delete_keeps_definition_and_second_use_and_rejects
     assert_eq!(other.epoch, captured.epoch);
     assert_eq!(app.selected, uses[0]);
     assert!(
-        app.delete_target.as_ref().unwrap().snapshot.valid(&app),
-        "the independent owner guard must reject an otherwise current token"
+        !app.delete_target.as_ref().unwrap().snapshot.valid(&app),
+        "the real captured snapshot rejects the changed Scenario destination"
     );
+    // Isolate the independent behavior-owner predicate: a current, unqualified
+    // object request has no old Scenario envelope or destination to reject it.
+    // This test-only replacement does not refresh the captured behavior owner.
+    let otherwise_current = crate::model_menu::Opened::new(
+        &app,
+        crate::model_menu::Request::object(uses[0], Point::ORIGIN),
+        token,
+    )
+    .unwrap();
+    assert!(otherwise_current.valid(&app));
+    let target = app.delete_target.as_ref().unwrap();
+    assert_eq!(target.selection, app.selected);
+    assert_eq!(target.placement, None);
+    assert_eq!(app.selected_node, None);
+    assert_eq!(target.behavior_owner, Some(owners[0]));
+    assert_eq!(diagram_removal::behavior_owner(&app), Some(owners[1]));
+    assert!(app.delete_pending);
+    assert!(!app.behavior.has_pending() && !app.source_dirty() && !app.draft_dirty());
+    app.delete_target.as_mut().unwrap().snapshot = otherwise_current;
     send(&mut mounted, &mut app, Message::ConfirmDelete(token)).await;
     assert_eq!(app.document.bundle(), &original);
     assert!(!app.delete_pending && app.delete_target.is_none());

crates/oa-desktop/src/app/diagram_removal.rs

@@ -15,6 +15,9 @@ pub struct Confirmation {
     pub selection: Id,
     pub placement: Option<Id>,
     pub behavior_owner: Option<Id>,
+    pub(crate) scenario: Option<super::scenario_removal::Review>,
+    pub(crate) process: Option<super::process_removal::Review>,
+    pub(crate) saved: Option<super::saved_removal::Review>,
 }
 
 pub fn enabled(app: &App) -> bool {
@@ -209,6 +212,9 @@ impl App {
                     selection: self.selected,
                     placement: placement(self),
                     behavior_owner: behavior_owner(self),
+                    scenario: None,
+                    process: None,
+                    saved: None,
                 }
             });
         self.delete_pending = self.delete_target.is_some();

crates/oa-desktop/src/app/escape.rs

@@ -1,4 +1,4 @@
-//! Keep overlay Escape ahead of modal cancellation in the ordinary widget tree.
+//! Keep overlay ownership ahead of cancellation and captured reorder Apply.
 //!
 //! Iced skips root.update when an overlay captures an event. Keeping this
 //! wrapper present even when inactive preserves the child's widget state. A
@@ -24,9 +24,34 @@ pub(crate) fn root<'a, R: renderer::Renderer + 'a>(
                 && app.architecture.is_none()));
     Element::new(Bridge {
         content,
+        removal_cancel: app
+            .delete_target
+            .as_ref()
+            .filter(|target| {
+                app.delete_pending && (target.process.is_some() || target.saved.is_some())
+            })
+            .map(|target| {
+                if target.saved.is_some() {
+                    return Message::SavedRemoval(Box::new(super::saved_removal::Event::Cancel {
+                        token: target.snapshot.token,
+                    }));
+                }
+                Message::ProcessRemoval(Box::new(super::process_removal::Event::Cancel {
+                    token: target.snapshot.token,
+                }))
+            }),
+        reorder_active: app.scenario_reorder_enabled() && app.scenario_reorder.session.is_some(),
+        reorder_apply: crate::behavior::scenario::reorder_view::apply_message(app),
         messages: [
             architecture_authoring::captured_escape_message(app),
-            modal.then_some(Message::Escape),
+            modal.then_some(Message::Escape).or_else(|| {
+                app.scenario_reorder.session.as_ref().map(|session| {
+                    crate::behavior::scenario::reorder_view::message(
+                        session,
+                        super::scenario_reorder::Intent::Cancel,
+                    )
+                })
+            }),
         ],
     })
 }
@@ -34,6 +59,9 @@ pub(crate) fn root<'a, R: renderer::Renderer + 'a>(
 struct Bridge<'a, R> {
     content: Element<'a, Message, Theme, R>,
     messages: [Option<Message>; 2],
+    removal_cancel: Option<Message>,
+    reorder_active: bool,
+    reorder_apply: Option<Message>,
 }
 
 impl<R: renderer::Renderer> Widget<Message, Theme, R> for Bridge<'_, R> {
@@ -87,6 +115,43 @@ impl<R: renderer::Renderer> Widget<Message, Theme, R> for Bridge<'_, R> {
         shell: &mut Shell<'_, Message>,
         viewport: &Rectangle,
     ) {
+        if self.reorder_active
+            && matches!(event,
+            Event::Keyboard(keyboard::Event::KeyPressed { key: keyboard::Key::Named(keyboard::key::Named::Enter), modifiers, .. })
+                if modifiers.control() && !modifiers.alt() && !modifiers.shift() && !modifiers.logo())
+        {
+            // A picker may have opened earlier in this same input batch, before
+            // App state can invalidate the captured reorder action.
+            if let Some(element) = self.content.as_widget_mut().overlay(
+                &mut tree.children[0],
+                layout,
+                renderer,
+                viewport,
+                Vector::ZERO,
+            ) {
+                let mut current = overlay::Nested::new(element);
+                let node = current.layout(renderer, viewport.size());
+                current.update(
+                    event,
+                    Layout::new(&node),
+                    cursor,
+                    renderer,
+                    clipboard,
+                    shell,
+                );
+                shell.capture_event();
+                return;
+            }
+            if matches!(
+                event,
+                Event::Keyboard(keyboard::Event::KeyPressed { repeat: false, .. })
+            ) && let Some(message) = &self.reorder_apply
+            {
+                shell.publish(message.clone());
+            }
+            shell.capture_event();
+            return;
+        }
         let escape = matches!(
             event,
             Event::Keyboard(keyboard::Event::KeyPressed {
@@ -99,6 +164,11 @@ impl<R: renderer::Renderer> Widget<Message, Theme, R> for Bridge<'_, R> {
         // Escape would otherwise reach focused fields underneath it. Offer only
         // Escape to the current overlay before updating the ordinary tree.
         if escape {
+            if let Some(cancel) = &self.removal_cancel {
+                shell.publish(cancel.clone());
+                shell.capture_event();
+                return;
+            }
             if let Some(element) = self.content.as_widget_mut().overlay(
                 &mut tree.children[0],
                 layout,
@@ -120,6 +190,13 @@ impl<R: renderer::Renderer> Widget<Message, Theme, R> for Bridge<'_, R> {
             if shell.is_event_captured() {
                 return;
             }
+            if self.reorder_active
+                && let Some(cancel) = &self.messages[1]
+            {
+                shell.publish(cancel.clone());
+                shell.capture_event();
+                return;
+            }
         }
         self.content.as_widget_mut().update(
             &mut tree.children[0],

crates/oa-desktop/src/app/multiselect.rs

@@ -100,6 +100,7 @@ impl App {
             (self.page == Page::Behavior).then_some(self.behavior.diagram.placement),
             self.topology_context(),
             self.behavior.topology.selection_address(),
+            self.scenario_context(),
         )
     }
     pub(crate) fn multiselect_context(&self) -> Option<Context> {
@@ -109,6 +110,9 @@ impl App {
                 if let Some(current) = self.topology_context() {
                     return Some(process_context(current));
                 }
+                if let Some(current) = self.scenario_context() {
+                    return Some(crate::behavior::scenario::selection::context(current));
+                }
                 let current = self.state_context()?;
                 crate::behavior::state_edit::validate_context(self.project(), current, current)
                     .ok()?;
@@ -119,6 +123,14 @@ impl App {
     }
 
     pub(crate) fn multiselect_target_visible(&self, target: &Target) -> bool {
+        if let Some(context) = self.scenario_context() {
+            return crate::behavior::scenario::selection::visible(
+                self.project(),
+                context,
+                self.selected,
+            )
+            .contains(target);
+        }
         if let Some(context) = self.topology_context() {
             return self
                 .behavior
@@ -152,6 +164,10 @@ impl App {
     }
 
     pub(crate) fn multiselect_envelope(&self, event: &Event) -> bool {
+        // Scenario input additionally needs its representation and visit.
+        if self.scenario_context().is_some() {
+            return false;
+        }
         let Some(current) = self.multiselect_context() else {
             return false;
         };
@@ -219,6 +235,10 @@ impl App {
     }
 
     pub(crate) fn reconcile_multiselect(&mut self) {
+        if self.scenario_context().is_some() {
+            self.reconcile_scenario_multiselect();
+            return;
+        }
         if self.topology_context().is_some() {
             self.reconcile_process_multiselect();
             return;
@@ -284,6 +304,10 @@ impl App {
     }
 
     pub(super) fn inspect_multiselect_primary(&mut self) {
+        if self.scenario_context().is_some() {
+            self.inspect_scenario_multiselect_primary();
+            return;
+        }
         if self.topology_context().is_some() {
             self.inspect_process_multiselect_primary();
             return;

crates/oa-desktop/src/app/process_removal.rs

@@ -0,0 +1,230 @@
+//! One captured Process selection, one impact review, one document transaction.
+use super::multiselect::process_context;
+use super::*;
+use crate::behavior::topology::{self, group_removal};
+use crate::diagram_selection::Snapshot;
+use crate::diagram_usage::Target;
+use crate::model_menu;
+
+#[cfg(test)]
+mod tests;
+pub(crate) mod view;
+
+#[derive(Debug, Clone)]
+pub(crate) enum Event {
+    Begin {
+        input_generation: u64,
+        context: topology::Context,
+        snapshot: Box<Snapshot>,
+    },
+    Query {
+        token: u64,
+        query: String,
+    },
+    Page {
+        token: u64,
+        page: usize,
+    },
+    Cancel {
+        token: u64,
+    },
+}
+
+pub(crate) struct Review {
+    input_generation: u64,
+    pub(crate) context: topology::Context,
+    pub(crate) snapshot: Snapshot,
+    pub(crate) plan: group_removal::Plan,
+    pub(crate) query: String,
+    pub(crate) page: usize,
+}
+
+pub(crate) fn begin(app: &App) -> Option<Message> {
+    let input_generation = app.behavior.topology.removal_generation()?;
+    let context = app.topology_context()?;
+    let snapshot = app.multiselect_snapshot()?;
+    (snapshot.targets().len() > 1).then_some(Message::ProcessRemoval(Box::new(Event::Begin {
+        input_generation,
+        context,
+        snapshot: Box::new(snapshot),
+    })))
+}
+
+impl App {
+    pub(crate) fn process_removal_enabled(&self) -> bool {
+        diagram_removal::enabled(self)
+            && !self.source_rename.open()
+            && self.behavior.topology.selecting()
+            && self.behavior.topology.removal_generation().is_some()
+            && self.topology_context().is_some()
+    }
+
+    fn process_removal_matches(&self, context: topology::Context, snapshot: &Snapshot) -> bool {
+        if self.topology_context() != Some(context)
+            || !self
+                .diagram_selection
+                .as_ref()
+                .is_some_and(|selected| selected.matches(snapshot, process_context(context)))
+        {
+            return false;
+        }
+        let visible = self
+            .behavior
+            .topology
+            .selection_targets(self.project(), context.owner);
+        snapshot
+            .targets()
+            .iter()
+            .all(|target| visible.contains(target))
+    }
+
+    pub(super) fn process_removal_event(&mut self, event: Event) -> Task<Message> {
+        match event {
+            Event::Begin {
+                input_generation,
+                context,
+                snapshot,
+            } => {
+                // Admission precedes every shared input/selection boundary. A
+                // stale packet must not prune the set or retire a newer editor.
+                if self.behavior.topology.removal_generation() != Some(input_generation)
+                    || !self.process_removal_matches(context, &snapshot)
+                    || !self.process_removal_enabled()
+                    || snapshot.targets().len() < 2
+                {
+                    return Task::none();
+                }
+                let plan =
+                    match group_removal::prepare(self.project(), context.owner, snapshot.targets())
+                    {
+                        Ok(plan) => plan,
+                        Err(reason) => {
+                            self.status = reason;
+                            return Task::none();
+                        }
+                    };
+                let Some(primary_target) = snapshot.primary().cloned() else {
+                    return Task::none();
+                };
+                let primary = match &primary_target {
+                    Target::ProcessOccurrence(endpoint) => endpoint.occurrence,
+                    Target::ProcessLink(id) => *id,
+                    _ => return Task::none(),
+                };
+                self.source_interaction();
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                let context = self.topology_context().expect("admitted Process");
+                let snapshot = self.multiselect_snapshot().expect("admitted selection");
+                let mut request = model_menu::Request::object(primary, iced::Point::ORIGIN);
+                request.process = Some(Box::new(context));
+                request.selection_target = Some(Box::new(primary_target));
+                self.menu_sequence = self.menu_sequence.wrapping_add(1);
+                self.delete_target = model_menu::Opened::new(self, request, self.menu_sequence)
+                    .map(|opened| diagram_removal::Confirmation {
+                        snapshot: opened,
+                        selection: self.selected,
+                        placement: None,
+                        behavior_owner: Some(context.owner),
+                        scenario: None,
+                        saved: None,
+                        process: Some(Review {
+                            input_generation,
+                            context,
+                            snapshot,
+                            plan,
+                            query: String::new(),
+                            page: 0,
+                        }),
+                    });
+                self.delete_pending = self.delete_target.is_some();
+            }
+            Event::Query { token, query } => {
+                if let Some(target) = self
+                    .delete_target
+                    .as_mut()
+                    .filter(|target| target.snapshot.token == token)
+                    && let Some(review) = target.process.as_mut()
+                {
+                    review.query = query;
+                    review.page = 0;
+                }
+            }
+            Event::Page { token, page } => {
+                if let Some(target) = self
+                    .delete_target
+                    .as_mut()
+                    .filter(|target| target.snapshot.token == token)
+                    && let Some(review) = target.process.as_mut()
+                {
+                    review.page = page;
+                }
+            }
+            Event::Cancel { token } => {
+                if self.delete_target.as_ref().is_some_and(|target| {
+                    target.snapshot.token == token && target.process.is_some()
+                }) {
+                    self.delete_target = None;
+                    self.delete_pending = false;
+                    self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                    self.status = "Removal cancelled. Model and selection unchanged.".into();
+                }
+            }
+        }
+        Task::none()
+    }
+
+    pub(crate) fn process_removal_review_valid(
+        &self,
+        target: &diagram_removal::Confirmation,
+    ) -> bool {
+        let Some(review) = &target.process else {
+            return false;
+        };
+        self.delete_pending
+            && !self.busy
+            && target.snapshot.valid(self)
+            && self.behavior.topology.removal_generation() == Some(review.input_generation)
+            && self.process_removal_matches(review.context, &review.snapshot)
+            && self.selected == target.selection
+            && !self.source_dirty()
+            && !self.draft_dirty()
+            && !self.behavior.has_pending()
+            && !self.source_rename.open()
+            && self.behavior.topology.selecting()
+    }
+
+    pub(super) fn confirm_process_removal(&mut self, token: u64) {
+        let Some(target) = self
+            .delete_target
+            .as_ref()
+            .filter(|target| target.snapshot.token == token && target.process.is_some())
+        else {
+            return;
+        };
+        let valid = self.process_removal_review_valid(target);
+        let target = self.delete_target.take().expect("captured review");
+        self.delete_pending = false;
+        self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        if !valid {
+            self.status =
+                "Removal review expired. Nothing was removed; review the current selection again."
+                    .into();
+            return;
+        }
+        let review = target.process.expect("Process review");
+        match self.document.execute(review.plan.command) {
+            Ok(_) => {
+                self.selected = review.context.owner;
+                self.selected_node = None;
+                self.behavior.active_owner = Some(review.context.owner);
+                self.sync();
+                self.reconcile_multiselect();
+                self.status = format!(
+                    "Removed {} selected Process contributions or links in one change. Referenced definitions preserved. Undo restores the model.",
+                    review.snapshot.targets().len()
+                );
+            }
+            Err(error) => self.status = format!("Nothing removed: {error}"),
+        }
+    }
+}

crates/oa-desktop/src/app/process_removal/tests.rs

@@ -0,0 +1,646 @@
+use super::*;
+use crate::behavior::topology::{CanvasEvent, CanvasTool, direct_tests};
+use oa_core::source_project::SourceBundle;
+
+fn local(id: Id) -> Target {
+    Target::ProcessOccurrence(OccurrenceEndpoint {
+        references: vec![],
+        occurrence: id,
+    })
+}
+fn choose(app: &mut App, target: Target, choice: multiselect::Choice) {
+    let context = app.multiselect_context().unwrap();
+    let _ = app.update(Message::DiagramSelection(multiselect::Event::Choose(
+        context, target, choice,
+    )));
+}
+fn open_project(project: Project, owner: Id) -> App {
+    let mut app = App::with_project(project);
+    let _ = app.update(Message::Select(owner));
+    let _ = app.update(Message::Page(Page::Behavior));
+    app.reconcile_multiselect();
+    app.window_size = iced::Size::new(1600., 1000.);
+    app
+}
+fn fixture(layer: Layer) -> (App, direct_tests::Fixture) {
+    let f = direct_tests::fixture(layer);
+    let mut app = open_project(f.p.clone(), f.owner);
+    choose(
+        &mut app,
+        Target::ProcessLink(f.link),
+        multiselect::Choice::Replace,
+    );
+    choose(&mut app, local(f.nodes[0]), multiselect::Choice::Add);
+    assert!(app.process_removal_enabled());
+    assert_eq!(app.multiselect_snapshot().unwrap().targets().len(), 2);
+    (app, f)
+}
+fn send(app: &mut App, event: Event) {
+    let _ = app.update(Message::ProcessRemoval(Box::new(event)));
+}
+fn open(app: &mut App) -> u64 {
+    let message = begin(app).unwrap();
+    let _ = app.update(message);
+    let target = app.delete_target.as_ref().expect("aggregate review");
+    assert!(app.process_removal_review_valid(target));
+    target.snapshot.token
+}
+fn native_bundle(source: &str) -> SourceBundle {
+    SourceBundle {
+        entry: "project.arcadia".into(),
+        files: [("project.arcadia".into(), source.into())]
+            .into_iter()
+            .collect(),
+    }
+}
+const BASELINE: &str = include_str!(concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    "/../../harness/fixtures/process-removal-baseline-20260925.arcadia"
+));
+const REMOVED: &str = include_str!(concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    // V1 assumed canonical whitespace. V2 independently retains removed-token
+    // trivia and existing reference spelling under language section 7's rules.
+    "/../../harness/fixtures/process-removal-removed-v2-20260925.arcadia"
+));
+fn native() -> App {
+    let document = Document::from_bundle(native_bundle(BASELINE), Default::default()).unwrap();
+    let owner = alias(document.project(), "assessment");
+    let mut app = open_project(document.project().clone(), owner);
+    app.document = document;
+    // Replace the generated split workspace just as open_source_project does.
+    // sync preserves discovered files and is not a new-document initializer.
+    app.source_workspace = Workspace::new(app.document.bundle(), true);
+    app.sync();
+    app.reconcile_multiselect();
+    assert_eq!(app.source_workspace.bundle(), native_bundle(BASELINE));
+    app
+}
+fn alias(project: &Project, name: &str) -> Id {
+    project
+        .identities()
+        .into_iter()
+        .find(|(_, alias)| *alias == name)
+        .unwrap()
+        .0
+}
+
+#[test]
+fn process_group_removal_literal_native_model_and_source_oracle_undoes_once() {
+    let mut app = native();
+    for (index, name) in ["a", "c", "approved"].iter().enumerate() {
+        let id = alias(app.project(), name);
+        let target = if *name == "approved" {
+            Target::ProcessLink(id)
+        } else {
+            local(id)
+        };
+        choose(
+            &mut app,
+            target,
+            if index == 0 {
+                multiselect::Choice::Replace
+            } else {
+                multiselect::Choice::Add
+            },
+        );
+    }
+    let before = app.document.snapshot();
+    let selected = app.multiselect_snapshot().unwrap();
+    let camera = app.behavior.topology.camera_boundary();
+    let token = open(&mut app);
+    let review = app
+        .delete_target
+        .as_ref()
+        .unwrap()
+        .process
+        .as_ref()
+        .unwrap();
+    assert_eq!(review.snapshot.targets(), selected.targets());
+    assert_eq!(review.snapshot.primary(), selected.primary());
+    let rows = view::matching_rows(app.project(), review);
+    assert!(
+        rows.iter().any(|row| row.label.contains("@caller")
+            && row.disposition.contains("Uses changed definition"))
+    );
+    assert!(
+        rows.iter().any(|row| row.label.contains("@outer")
+            && row.disposition.contains("Uses changed definition"))
+    );
+    assert!(rows.iter().any(|row| {
+        row.label
+            .contains("Implicit listed order; 1 adjacent ordered pairs")
+            && row.disposition.starts_with("After")
+    }));
+    assert_eq!(app.document.bundle(), &before.bundle);
+    let expected = Document::from_bundle(native_bundle(REMOVED), Default::default()).unwrap();
+    let _ = app.update(Message::ConfirmDelete(token));
+    assert_eq!(app.project(), expected.project());
+    assert_eq!(
+        app.document.bundle(),
+        expected.bundle(),
+        "literal independently authored source oracle"
+    );
+    assert_eq!(app.source_workspace.bundle(), *expected.bundle());
+    assert_eq!(app.selected, alias(app.project(), "assessment"));
+    assert!(app.multiselect_snapshot().unwrap().targets().is_empty());
+    assert!(app.behavior.topology.camera_boundary() == camera);
+    let removed = app.document.bundle().clone();
+    let _ = app.update(Message::Undo);
+    assert_eq!(app.project(), &before.decoded.project);
+    assert_eq!(app.document.bundle(), &before.bundle);
+    assert!(!app.document.can_undo());
+    let _ = app.update(Message::Redo);
+    assert_eq!(app.document.bundle(), &removed);
+}
+
+#[test]
+fn process_group_removal_mixed_card_link_is_one_exact_transaction_in_both_layers() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (mut app, f) = fixture(layer);
+        let before = app.document.snapshot();
+        let token = open(&mut app);
+        let review = app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .process
+            .as_ref()
+            .unwrap();
+        assert_eq!(
+            review.plan.removed,
+            [f.nodes[0], f.link].into_iter().collect()
+        );
+        let _ = app.update(Message::ConfirmDelete(token));
+        let mut expected = f.p.clone();
+        expected.elements.remove(&f.nodes[0]);
+        expected.relations.remove(&f.link);
+        *expected
+            .elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap() = vec![f.nodes[1], f.nodes[2]];
+        assert_eq!(app.project(), &expected);
+        for id in f.work.into_iter().chain([f.exchange]) {
+            assert!(app.project().contains(id));
+        }
+        let removed = app.document.bundle().clone();
+        assert_eq!(
+            Document::from_bundle(removed.clone(), Default::default())
+                .unwrap()
+                .project(),
+            &expected
+        );
+        let _ = app.update(Message::Undo);
+        assert_eq!(app.project(), &before.decoded.project);
+        assert_eq!(app.document.bundle(), &before.bundle);
+        assert!(!app.document.can_undo());
+        let _ = app.update(Message::Redo);
+        assert_eq!(app.document.bundle(), &removed);
+    }
+}
+
+#[test]
+fn process_group_removal_cancel_stale_packets_and_failed_commit_preserve_redo_source_and_selection()
+{
+    for failure in [false, true] {
+        let (mut app, f) = fixture(Layer::Oa);
+        app.document
+            .execute(Command::Rename(f.nodes[2], "Future name".into()))
+            .unwrap();
+        let future = app.document.bundle().clone();
+        assert!(app.document.undo());
+        app.sync();
+        app.reconcile_multiselect();
+        let baseline = app.document.snapshot();
+        let source = app.source_editor.text();
+        let selected = app.multiselect_snapshot().unwrap();
+        let camera = app.behavior.topology.camera_boundary();
+        let old_begin = begin(&app).unwrap();
+        let first = open(&mut app);
+        send(&mut app, Event::Cancel { token: first });
+        let second = open(&mut app);
+        let epoch = app.canvas_epoch;
+        for message in [
+            old_begin,
+            Message::ConfirmDelete(first),
+            Message::CancelDelete,
+            Message::Escape,
+            Message::ProcessRemoval(Box::new(Event::Cancel { token: first })),
+            Message::ProcessRemoval(Box::new(Event::Query {
+                token: first,
+                query: "stale".into(),
+            })),
+            Message::ProcessRemoval(Box::new(Event::Page {
+                token: first,
+                page: 90,
+            })),
+        ] {
+            let _ = app.update(message);
+            assert_eq!(app.delete_target.as_ref().unwrap().snapshot.token, second);
+            assert_eq!(app.canvas_epoch, epoch);
+        }
+        if failure {
+            // Force a genuine atomic engine failure after the admitted deletion.
+            // Neither the successful first candidate command nor history leaks.
+            let review = app
+                .delete_target
+                .as_mut()
+                .unwrap()
+                .process
+                .as_mut()
+                .unwrap();
+            review.plan.command = Command::Batch(vec![
+                Command::Delete(f.nodes[0]),
+                Command::Delete(Id::new_v4()),
+            ]);
+            let _ = app.update(Message::ConfirmDelete(second));
+            assert!(app.status.starts_with("Nothing removed:"));
+        } else {
+            send(&mut app, Event::Cancel { token: second });
+        }
+        assert!(std::sync::Arc::ptr_eq(&baseline, &app.document.snapshot()));
+        assert_eq!(app.project(), &baseline.decoded.project);
+        assert_eq!(app.document.bundle(), &baseline.bundle);
+        assert_eq!(app.source_editor.text(), source);
+        assert_eq!(app.source_workspace.bundle(), baseline.bundle);
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().targets(),
+            selected.targets()
+        );
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().primary(),
+            selected.primary()
+        );
+        assert!(app.behavior.topology.camera_boundary() == camera);
+        assert!(app.document.can_redo() && !app.document.can_undo());
+        let _ = app.update(Message::Redo);
+        assert_eq!(app.document.bundle(), &future);
+    }
+}
+
+#[test]
+fn process_group_removal_stale_secondary_and_context_are_rejected_before_any_boundary() {
+    for change in 0..4 {
+        let (mut app, f) = fixture(Layer::Sa);
+        let message = begin(&app).unwrap();
+        match change {
+            0 => {
+                app.diagram_selection
+                    .as_mut()
+                    .unwrap()
+                    .remove(&Target::ProcessLink(f.link));
+            }
+            1 => {
+                app.canvas_document = Id::new_v4();
+            }
+            2 => {
+                app.canvas_epoch = app.canvas_epoch.wrapping_add(1);
+            }
+            _ => {
+                app.document
+                    .execute(Command::Rename(f.nodes[2], "New revision".into()))
+                    .unwrap();
+            }
+        }
+        let source = app.document.bundle().clone();
+        let selected = app.multiselect_snapshot();
+        let epoch = app.canvas_epoch;
+        let _ = app.update(message);
+        assert!(app.delete_target.is_none());
+        assert_eq!(app.canvas_epoch, epoch);
+        assert_eq!(app.multiselect_snapshot(), selected);
+        assert_eq!(app.document.bundle(), &source);
+    }
+    let (mut app, f) = fixture(Layer::Oa);
+    let token = open(&mut app);
+    app.diagram_selection
+        .as_mut()
+        .unwrap()
+        .remove(&Target::ProcessLink(f.link));
+    let current = app.document.snapshot();
+    let _ = app.update(Message::ConfirmDelete(token));
+    assert!(app.status.contains("expired"));
+    assert!(std::sync::Arc::ptr_eq(&current, &app.document.snapshot()));
+}
+
+#[test]
+fn process_group_removal_pending_inputs_and_legacy_singleton_messages_preserve_all_members() {
+    for pending in ["clean", "properties", "source", "tool", "busy", "form"] {
+        let (mut app, f) = fixture(Layer::Oa);
+        match pending {
+            "properties" => {
+                let _ = app.update(Message::Field("/name".into(), "Unapplied".into()));
+            }
+            "source" => {
+                let text = format!("{}\n// pending", app.source_workspace.text());
+                let _ = app.update(Message::SourceEdit(text_editor::Action::SelectAll));
+                let _ = app.update(Message::SourceEdit(text_editor::Action::Edit(
+                    text_editor::Edit::Paste(std::sync::Arc::new(text)),
+                )));
+            }
+            "tool" => app.behavior.topology.choose(CanvasTool::Connect),
+            "busy" => app.busy = true,
+            "form" => {
+                let context = app.topology_context().unwrap();
+                let _ = app.update(Message::TopologyCanvas(CanvasEvent::Begin {
+                    context,
+                    tool: topology::Tool::Work,
+                    control: ControlKind::Choice,
+                    insertion: topology::Insertion::default(),
+                }));
+                assert!(app.behavior.has_pending());
+            }
+            _ => {}
+        }
+        let baseline = app.document.snapshot();
+        let selected = app.multiselect_snapshot().unwrap();
+        let epoch = app.canvas_epoch;
+        let source = app.source_workspace.bundle();
+        if pending != "clean" {
+            let message = begin(&app).unwrap();
+            let _ = app.update(message);
+        }
+        let _ = app.update(Message::Delete);
+        let context = app.topology_context().unwrap();
+        let _ = app.update(Message::TopologyCanvas(CanvasEvent::Remove(
+            context, f.nodes[0],
+        )));
+        assert!(app.delete_target.is_none());
+        assert_eq!(app.canvas_epoch, epoch);
+        assert_eq!(app.multiselect_snapshot().unwrap(), selected);
+        assert_eq!(app.document.bundle(), &baseline.bundle);
+        assert_eq!(app.source_workspace.bundle(), source);
+        assert!(!app.document.can_undo());
+    }
+}
+
+#[test]
+fn process_group_removal_qualified_member_refuses_whole_set_without_path_stripping() {
+    let mut app = native();
+    let owner = alias(app.project(), "caller");
+    let root = alias(app.project(), "r1");
+    let other = alias(app.project(), "r2");
+    let leaf = alias(app.project(), "a");
+    let _ = app.update(Message::Select(owner));
+    let context = app.topology_context().unwrap();
+    let _ = app.update(Message::TopologyCanvas(CanvasEvent::Expand(context, root)));
+    let qualified = Target::ProcessOccurrence(OccurrenceEndpoint {
+        references: vec![root],
+        occurrence: leaf,
+    });
+    choose(&mut app, qualified.clone(), multiselect::Choice::Replace);
+    choose(&mut app, local(other), multiselect::Choice::Add);
+    let selected = app.multiselect_snapshot().unwrap();
+    assert_eq!(selected.targets(), &[qualified, local(other)]);
+    let before = app.document.snapshot();
+    let epoch = app.canvas_epoch;
+    let message = begin(&app).unwrap();
+    let _ = app.update(message);
+    assert!(app.delete_target.is_none());
+    assert_eq!(app.canvas_epoch, epoch);
+    assert_eq!(app.multiselect_snapshot().unwrap(), selected);
+    assert!(std::sync::Arc::ptr_eq(&before, &app.document.snapshot()));
+    assert!(!app.document.can_undo());
+}
+
+#[test]
+fn process_group_removal_unselected_context_subject_does_not_replace_the_group() {
+    for unselected in [false, true] {
+        let (mut app, f) = fixture(Layer::Oa);
+        let selection = app.multiselect_snapshot().unwrap();
+        let clicked = if unselected { f.nodes[2] } else { f.nodes[0] };
+        let mut request = model_menu::Request::object(clicked, iced::Point::ORIGIN);
+        request.process = app.topology_context().map(Box::new);
+        request.selection_target = Some(Box::new(local(clicked)));
+        let _ = app.update(Message::Menu(model_menu::Event::Open(request)));
+        let token = app.model_menu.as_ref().unwrap().token;
+        let message = begin(&app).unwrap();
+        let _ = app.update(Message::Menu(model_menu::Event::Invoke(
+            token,
+            Box::new(message),
+        )));
+        let review = app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .process
+            .as_ref()
+            .unwrap();
+        assert_eq!(review.snapshot.targets(), selection.targets());
+        assert_eq!(review.snapshot.primary(), selection.primary());
+        assert!(!review.plan.removed.contains(&f.nodes[2]));
+    }
+}
+
+#[test]
+fn process_review_lists_transitive_callers_even_when_all_modes_stay_explicit() {
+    let mut app = native();
+    let a = alias(app.project(), "a");
+    let link = alias(app.project(), "approved");
+    choose(&mut app, local(a), multiselect::Choice::Replace);
+    choose(
+        &mut app,
+        Target::ProcessLink(link),
+        multiselect::Choice::Add,
+    );
+    let token = open(&mut app);
+    let review = app
+        .delete_target
+        .as_ref()
+        .unwrap()
+        .process
+        .as_ref()
+        .unwrap();
+    assert!(
+        review.plan.interpretation.is_empty(),
+        "remaining Control keeps the definition explicit"
+    );
+    let rows = view::matching_rows(app.project(), review);
+    for alias in ["@caller", "@outer"] {
+        assert!(
+            rows.iter().any(|row| row.label.contains(alias)
+                && row.disposition.contains("Uses changed definition"))
+        );
+    }
+    send(
+        &mut app,
+        Event::Query {
+            token,
+            query: "@outer".into(),
+        },
+    );
+    let review = app
+        .delete_target
+        .as_ref()
+        .unwrap()
+        .process
+        .as_ref()
+        .unwrap();
+    let rows = view::matching_rows(app.project(), review);
+    assert_eq!(rows.len(), 1);
+    assert!(rows[0].label.contains("@assessment"));
+    assert!(rows[0].label.contains("03 Mission using Response"));
+}
+
+#[tokio::test]
+async fn mounted_process_group_delete_and_shift_delete_capture_group_escape_is_stamped() {
+    use crate::behavior::canvas_workspace::tests::{Mounted, key};
+    use iced::{
+        keyboard::{self, key::Named},
+        mouse,
+    };
+    for shift in [false, true] {
+        let (mut app, _) = fixture(Layer::Oa);
+        let selected = app.multiselect_snapshot().unwrap();
+        let source = app.document.bundle().clone();
+        let mut mounted = Mounted::new(&mut app).await;
+        mounted
+            .batch(&mut app, &[key(Named::F6)], mouse::Cursor::Unavailable)
+            .await;
+        let mut remove = key(Named::Delete);
+        if let iced::Event::Keyboard(keyboard::Event::KeyPressed { modifiers, .. }) = &mut remove {
+            *modifiers = if shift {
+                keyboard::Modifiers::SHIFT
+            } else {
+                keyboard::Modifiers::default()
+            };
+        }
+        let output = mounted
+            .batch(&mut app, &[remove.clone()], mouse::Cursor::Unavailable)
+            .await;
+        assert!(output.iter().any(|message| matches!(message, Message::ProcessRemoval(event) if matches!(&**event, Event::Begin { snapshot, .. } if snapshot.targets() == selected.targets()))), "{output:?}");
+        let token = app.delete_target.as_ref().unwrap().snapshot.token;
+        if let iced::Event::Keyboard(keyboard::Event::KeyPressed { repeat, .. }) = &mut remove {
+            *repeat = true;
+        }
+        let output = mounted
+            .batch(&mut app, &[remove], mouse::Cursor::Unavailable)
+            .await;
+        assert!(
+            !output
+                .iter()
+                .any(|message| matches!(message, Message::ConfirmDelete(_)))
+        );
+        assert_eq!(app.delete_target.as_ref().unwrap().snapshot.token, token);
+        let output = mounted
+            .batch(&mut app, &[key(Named::Escape)], mouse::Cursor::Unavailable)
+            .await;
+        assert!(output.iter().any(|message| matches!(message, Message::ProcessRemoval(event) if matches!(&**event, Event::Cancel { token: captured } if *captured == token))), "{output:?}");
+        assert!(app.delete_target.is_none());
+        assert_eq!(app.document.bundle(), &source);
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().targets(),
+            selected.targets()
+        );
+        assert!(!app.document.can_undo());
+    }
+}
+
+#[tokio::test]
+async fn mounted_process_group_removal_queued_delete_is_revoked_by_later_press_in_same_batch() {
+    use crate::behavior::canvas_workspace::tests::{Mounted, key};
+    use iced::{Event as Input, keyboard::key::Named, mouse};
+    let (mut app, f) = fixture(Layer::Oa);
+    let mut mounted = Mounted::new(&mut app).await;
+    mounted
+        .batch(&mut app, &[key(Named::F6)], mouse::Cursor::Unavailable)
+        .await;
+    let bounds = mounted.geometry(&app).bounds("process-viewport");
+    let local = app
+        .behavior
+        .topology
+        .removal_test_point(&app, f.owner, f.nodes[0], None);
+    let at = bounds.position() + iced::Vector::new(local.x, local.y);
+    let before = app.document.snapshot();
+    let selected = app.multiselect_snapshot().unwrap();
+    let epoch = app.canvas_epoch;
+    let messages = mounted
+        .batch(
+            &mut app,
+            &[
+                key(Named::Delete),
+                Input::Mouse(mouse::Event::CursorMoved { position: at }),
+                Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+            ],
+            mouse::Cursor::Available(at),
+        )
+        .await;
+    assert!(messages.iter().any(|message| matches!(message, Message::ProcessRemoval(event) if matches!(&**event, Event::Begin { .. }))), "the first event queues a real review packet: {messages:?}");
+    assert!(
+        app.delete_target.is_none(),
+        "later press must revoke that packet before App consumes it"
+    );
+    assert_eq!(
+        app.canvas_epoch, epoch,
+        "refusal does not retire the active gesture"
+    );
+    assert_eq!(app.multiselect_snapshot().unwrap(), selected);
+    assert!(std::sync::Arc::ptr_eq(&before, &app.document.snapshot()));
+    assert!(!app.process_removal_enabled());
+    assert!(
+        begin(&app).is_none(),
+        "active gesture cannot capture another review"
+    );
+    mounted
+        .batch(
+            &mut app,
+            &[key(Named::Escape)],
+            mouse::Cursor::Available(at),
+        )
+        .await;
+    // Escape leaves viewport focus; F6 restores keyboard ownership and sends
+    // the canvas cancellation boundary before a fresh Delete.
+    mounted
+        .batch(&mut app, &[key(Named::F6)], mouse::Cursor::Unavailable)
+        .await;
+    assert!(app.process_removal_enabled());
+    // Cancelling the pointer gesture retains the group and permits a fresh review.
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        selected.targets()
+    );
+    mounted
+        .batch(&mut app, &[key(Named::Delete)], mouse::Cursor::Unavailable)
+        .await;
+    assert!(app.delete_target.is_some());
+    assert!(std::sync::Arc::ptr_eq(&before, &app.document.snapshot()));
+}
+
+#[tokio::test]
+async fn mounted_process_group_removal_queued_delete_is_revoked_by_camera_pan_start() {
+    use crate::behavior::canvas_workspace::tests::{Mounted, key};
+    use iced::{Event as Input, keyboard::key::Named, mouse};
+    for button in [mouse::Button::Middle, mouse::Button::Left] {
+        let (mut app, _) = fixture(Layer::Sa);
+        let mut mounted = Mounted::new(&mut app).await;
+        mounted
+            .batch(&mut app, &[key(Named::F6)], mouse::Cursor::Unavailable)
+            .await;
+        let bounds = mounted.geometry(&app).bounds("process-viewport");
+        let at = iced::Point::new(
+            bounds.x + bounds.width - 12.,
+            bounds.y + bounds.height - 12.,
+        );
+        let before = app.document.snapshot();
+        let messages = mounted
+            .batch(
+                &mut app,
+                &[
+                    key(Named::Delete),
+                    Input::Mouse(mouse::Event::CursorMoved { position: at }),
+                    Input::Mouse(mouse::Event::ButtonPressed(button)),
+                ],
+                mouse::Cursor::Available(at),
+            )
+            .await;
+        assert!(messages.iter().any(|message| matches!(message, Message::ProcessRemoval(event) if matches!(&**event, Event::Begin { .. }))), "real Delete is queued: {messages:?}");
+        assert!(
+            app.delete_target.is_none(),
+            "camera input retires earlier review packet"
+        );
+        assert!(std::sync::Arc::ptr_eq(&before, &app.document.snapshot()));
+        assert!(!app.document.can_undo());
+    }
+}

crates/oa-desktop/src/app/process_removal/view.rs

@@ -0,0 +1,156 @@
+//! Review the complete captured removal impact before one explicit confirmation.
+use super::{Event, Review};
+use crate::app::{App, Message, diagram_removal};
+use crate::diagram_usage::Target;
+use crate::style;
+use iced::widget::{button, column, container, row, scrollable, text, text_input};
+use iced::{Element, Length::Fill};
+use oa_core::Project;
+use std::collections::BTreeSet;
+
+const PAGE_SIZE: usize = 6;
+
+pub(super) fn matching_rows(
+    project: &Project,
+    review: &Review,
+) -> Vec<super::super::removal_review::ImpactRow> {
+    let selected = review
+        .snapshot
+        .targets()
+        .iter()
+        .filter_map(|target| match target {
+            Target::ProcessOccurrence(endpoint) if endpoint.references.is_empty() => {
+                Some(endpoint.occurrence)
+            }
+            Target::ProcessLink(id) => Some(*id),
+            _ => None,
+        })
+        .collect();
+    super::super::removal_review::matching_rows(
+        project,
+        &review.plan.removed,
+        &review.plan.changed,
+        &selected,
+        &review.plan.interpretation,
+        &review.plan.affected_uses,
+        &review.query,
+    )
+}
+
+pub(crate) fn view<'a>(
+    app: &'a App,
+    target: &'a diagram_removal::Confirmation,
+) -> Element<'a, Message> {
+    let Some(review) = target.process.as_ref() else {
+        return text("Process removal review is unavailable.").into();
+    };
+    let token = target.snapshot.token;
+    let valid = app.process_removal_review_valid(target);
+    let rows = matching_rows(app.project(), review);
+    let callers: BTreeSet<_> = review
+        .plan
+        .affected_uses
+        .values()
+        .flatten()
+        .chain(
+            review
+                .plan
+                .interpretation
+                .iter()
+                .flat_map(|impact| impact.callers.iter()),
+        )
+        .copied()
+        .collect();
+    let semantic_summary = if review.plan.interpretation.is_empty() && callers.is_empty() {
+        "No listed-order or analysis-mode changes; no affected caller definitions.".to_owned()
+    } else {
+        format!(
+            "Order / analysis changes in {} definitions · {} caller definitions affected. Review their effects below.",
+            review.plan.interpretation.len(),
+            callers.len()
+        )
+    };
+    let pages = rows.len().div_ceil(PAGE_SIZE).max(1);
+    let page = review.page.min(pages - 1);
+    let mut impacts = column![].spacing(12).width(Fill);
+    for impact in rows.iter().skip(page * PAGE_SIZE).take(PAGE_SIZE) {
+        impacts = impacts.push(
+            column![
+                text(impact.disposition.clone())
+                    .size(12)
+                    .color(style::MUTED),
+                text(impact.label.clone())
+                    .size(13)
+                    .width(Fill)
+                    .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            ]
+            .spacing(3)
+            .width(Fill),
+        );
+    }
+    if rows.is_empty() {
+        impacts = impacts.push(text("No matching effects. Try a name, alias or effect.").size(13));
+    }
+    let previous = button("Previous").on_press_maybe((page > 0).then(|| {
+        Message::ProcessRemoval(Box::new(Event::Page {
+            token,
+            page: page - 1,
+        }))
+    }));
+    let next = button("Next").on_press_maybe((page + 1 < pages).then(|| {
+        Message::ProcessRemoval(Box::new(Event::Page {
+            token,
+            page: page + 1,
+        }))
+    }));
+    let mut footer = column![].spacing(8).width(Fill);
+    if !valid {
+        footer = footer.push(
+            text("This review expired. Cancel and review the current selection again.")
+                .size(13)
+                .width(Fill)
+                .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        );
+    }
+    footer = footer.push(
+        row![
+            container(
+                button("Cancel")
+                    .padding(10)
+                    .on_press(Message::ProcessRemoval(Box::new(Event::Cancel { token })))
+            )
+            .id("delete-cancel"),
+            container(
+                button("Remove selected contributions / links")
+                    .style(button::danger)
+                    .padding(10)
+                    .on_press_maybe(valid.then_some(Message::ConfirmDelete(token)))
+            )
+            .id("delete-confirm"),
+        ]
+        .spacing(10),
+    );
+    column![
+        text(format!("Remove {} selected contributions / links?", review.snapshot.targets().len())).size(21),
+        text(format!("{} records removed · {} records updated", review.plan.removed.len(), review.plan.changed.len())).size(14),
+        text(semantic_summary).size(13).width(Fill).wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        text_input("Search affected names, aliases or effects", &review.query)
+            .id("process-removal-query")
+            .on_input(move |query| Message::ProcessRemoval(Box::new(Event::Query { token, query })))
+            .size(13),
+        row![previous, text(format!("Page {} of {} · {} matches", page + 1, pages, rows.len())).size(12), next]
+            .spacing(10).align_y(iced::Alignment::Center),
+        scrollable(column![
+            text("Removes selected local contributions or maintained links and the additional records listed below. Referenced definitions, work and exchanges are preserved. Reused topology, entry/exit connections and diagnostics may change. Review every listed order and affected caller definition; this review does not compute complete caller graphs. One Undo restores the entire change.")
+                .size(13).width(Fill).wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            impacts,
+        ].spacing(14).width(Fill))
+            .width(Fill).height(Fill).spacing(8).id("process-removal-impact"),
+        footer,
+    ]
+    .spacing(12)
+    .width(Fill)
+    // Keep confirmation and search outside the flexible, scrollable impact body.
+    .height((app.window_size.height - 160.).clamp(260., 570.))
+    .into()
+}

crates/oa-desktop/src/app/removal_review.rs

@@ -0,0 +1,148 @@
+//! Shared stored-record and derived Process effect descriptions.
+use oa_core::{Id, Project};
+use std::collections::{BTreeMap, BTreeSet};
+
+pub(crate) struct ImpactRow {
+    pub(crate) label: String,
+    pub(crate) disposition: String,
+}
+
+pub(crate) fn matching_rows(
+    project: &Project,
+    removed: &BTreeSet<Id>,
+    changed: &BTreeSet<Id>,
+    selected: &BTreeSet<Id>,
+    interpretation: &[crate::removal_effects::InterpretationChange],
+    affected_uses: &BTreeMap<Id, BTreeSet<Id>>,
+    query: &str,
+) -> Vec<ImpactRow> {
+    let aliases: BTreeMap<Id, &str> = project.identities().into_iter().collect();
+    let label = |id: Id| {
+        let name = project.named(id);
+        let identity = aliases
+            .get(&id)
+            .map_or_else(|| id.to_string(), |alias| format!("@{alias}"));
+        if name == "Missing object" || name.is_empty() {
+            identity
+        } else {
+            format!("{name} ({identity})")
+        }
+    };
+    let mut rows = vec![];
+    for id in removed {
+        rows.push(ImpactRow {
+            label: label(*id),
+            disposition: if selected.contains(id) {
+                "Removed · selected"
+            } else {
+                "Additional removed"
+            }
+            .into(),
+        });
+    }
+    for id in changed {
+        rows.push(ImpactRow {
+            label: label(*id),
+            disposition: "Updated · preserved".into(),
+        });
+    }
+    // Interpretation is separate from stored record deltas: callers may keep
+    // identical records while their reused definition or analysis changes.
+    for impact in interpretation {
+        let owner = label(impact.owner);
+        let shared_order = impact.before.local_order == impact.before.expanded_order
+            && impact.after.local_order == impact.after.expanded_order;
+        for (dimension, before, after, shown) in [
+            (
+                if shared_order {
+                    "Listed and reused order"
+                } else {
+                    "Local listed order"
+                },
+                &impact.before.local_order,
+                &impact.after.local_order,
+                true,
+            ),
+            (
+                "Order inside reused definitions",
+                &impact.before.expanded_order,
+                &impact.after.expanded_order,
+                !shared_order,
+            ),
+        ] {
+            if !shown || before == after {
+                continue;
+            }
+            for (when, order) in [("Before", before), ("After", after)] {
+                let summary = match order {
+                    None => "Explicit topology; no implicit listed order".to_owned(),
+                    Some(ids) if ids.is_empty() => {
+                        "Empty order; no ordered pair; contextual flow may be incomplete".to_owned()
+                    }
+                    Some(ids) if ids.len() == 1 => {
+                        "One item in this order; no ordered pair".to_owned()
+                    }
+                    Some(ids) => format!(
+                        "Implicit listed order; {} adjacent ordered pairs",
+                        ids.len() - 1
+                    ),
+                };
+                rows.push(ImpactRow {
+                    label: format!("{owner}: {summary}"),
+                    disposition: format!("{when} · {dimension}"),
+                });
+                if let Some(ids) = order {
+                    for (index, id) in ids.iter().enumerate() {
+                        rows.push(ImpactRow {
+                            label: format!("{owner}: #{} {}", index + 1, label(*id)),
+                            disposition: format!("{when} · {dimension} · listed position"),
+                        });
+                    }
+                }
+            }
+        }
+        if impact.before.contextual_analysis != impact.after.contextual_analysis {
+            rows.push(ImpactRow {
+                label: format!(
+                    "{owner}: contextual analysis {} → {}",
+                    if impact.before.contextual_analysis {
+                        "enabled"
+                    } else {
+                        "disabled"
+                    },
+                    if impact.after.contextual_analysis {
+                        "enabled"
+                    } else {
+                        "disabled"
+                    }
+                ),
+                disposition:
+                    "Analysis mode changes; this is not a claim of complete graph connectivity"
+                        .into(),
+            });
+        }
+    }
+    let mut affected = affected_uses.clone();
+    for impact in interpretation {
+        affected
+            .entry(impact.owner)
+            .or_default()
+            .extend(impact.callers.iter().copied());
+    }
+    for (definition, callers) in affected {
+        for caller in callers {
+            rows.push(ImpactRow {
+                label: format!("{} uses {}", label(caller), label(definition)),
+                disposition: "Uses changed definition · affected caller definition".into(),
+            });
+        }
+    }
+    let query = query.trim().to_lowercase();
+    rows.into_iter()
+        .filter(|row| {
+            query.is_empty()
+                || row.label.to_lowercase().contains(&query)
+                || row.disposition.to_lowercase().contains(&query)
+        })
+        .collect()
+}

crates/oa-desktop/src/app/saved_removal.rs

@@ -0,0 +1,296 @@
+//! Explicit saved-view model deletion: one captured group and one transaction.
+use super::*;
+use crate::diagram::group_removal;
+use crate::diagram_selection::Snapshot;
+use crate::diagram_usage::Target;
+use crate::{model_menu, route_edit::Context};
+
+#[cfg(test)]
+mod tests;
+pub(crate) mod view;
+
+#[derive(Debug, Clone)]
+pub(crate) enum Event {
+    Begin {
+        input_generation: u64,
+        context: Context,
+        snapshot: Box<Snapshot>,
+    },
+    Query {
+        token: u64,
+        query: String,
+    },
+    Page {
+        token: u64,
+        page: usize,
+    },
+    Cancel {
+        token: u64,
+    },
+}
+
+pub(crate) struct Review {
+    input_generation: u64,
+    pub(crate) context: Context,
+    pub(crate) snapshot: Snapshot,
+    pub(crate) plan: group_removal::Plan,
+    pub(crate) query: String,
+    pub(crate) page: usize,
+}
+
+fn context(app: &App) -> Option<Context> {
+    let current = match app.page {
+        Page::Diagram => app.route_context()?,
+        Page::Behavior if app.topology_context().is_none() && app.scenario_context().is_none() => {
+            app.state_context()?
+        }
+        _ => return None,
+    };
+    let saved = app.project().diagrams.get(&current.diagram)?;
+    (saved.projection.is_architecture() || saved.projection.state_machine().is_some())
+        .then_some(current)
+}
+
+pub(crate) fn begin(app: &App) -> Option<Message> {
+    let input_generation = app.saved_removal_input.idle()?;
+    let context = context(app)?;
+    let snapshot = app.multiselect_snapshot()?;
+    (snapshot.targets().len() > 1).then_some(Message::SavedRemoval(Box::new(Event::Begin {
+        input_generation,
+        context,
+        snapshot: Box::new(snapshot),
+    })))
+}
+
+impl App {
+    fn saved_removal_selecting(&self) -> bool {
+        self.connection.is_none()
+            && self.selected_bend.is_none()
+            && match self.page {
+                Page::Diagram => self
+                    .architecture
+                    .as_ref()
+                    .is_none_or(|state| !state.inline() && !state.saved.placing),
+                Page::Behavior => {
+                    self.behavior.diagram.tool == crate::behavior::state_edit::Tool::Select
+                }
+                _ => false,
+            }
+    }
+
+    pub(crate) fn saved_removal_enabled(&self) -> bool {
+        diagram_removal::enabled(self)
+            && !self.source_rename.open()
+            && self.saved_removal_selecting()
+            && self.saved_removal_input.idle().is_some()
+            && context(self).is_some()
+    }
+
+    fn saved_removal_matches(&self, captured: Context, snapshot: &Snapshot) -> bool {
+        context(self) == Some(captured)
+            && self.diagram_selection.as_ref().is_some_and(|selection| {
+                selection.matches(snapshot, multiselect::context(captured))
+            })
+            && snapshot
+                .targets()
+                .iter()
+                .all(|target| self.multiselect_target_visible(target))
+    }
+
+    pub(super) fn saved_removal_event(&mut self, event: Event) -> Task<Message> {
+        match event {
+            Event::Begin {
+                input_generation,
+                context: captured,
+                snapshot,
+            } => {
+                // Refuse before source/editor/selection boundaries can disturb a
+                // newer interaction, including a later press in the same batch.
+                if self.saved_removal_input.idle() != Some(input_generation)
+                    || !self.saved_removal_matches(captured, &snapshot)
+                    || !self.saved_removal_enabled()
+                    || snapshot.targets().len() < 2
+                {
+                    return Task::none();
+                }
+                let plan = match group_removal::prepare(
+                    self.project(),
+                    captured.diagram,
+                    snapshot.targets(),
+                ) {
+                    Ok(plan) => plan,
+                    Err(reason) => {
+                        self.status = reason;
+                        return Task::none();
+                    }
+                };
+                let Some(primary_target) = snapshot.primary().cloned() else {
+                    return Task::none();
+                };
+                let (primary, placement) = match &primary_target {
+                    Target::Placement(id) => (
+                        self.project().diagrams[&captured.diagram].nodes[id].element,
+                        Some(*id),
+                    ),
+                    Target::Port { port, .. } => (*port, None),
+                    Target::Edge(id) => (*id, None),
+                    Target::StateRow { relation, .. } => (*relation, None),
+                    _ => return Task::none(),
+                };
+                let Some(token) = self.menu_sequence.checked_add(1) else {
+                    return Task::none();
+                };
+                self.source_interaction();
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                let context = context(self).expect("admitted saved view");
+                let snapshot = self.multiselect_snapshot().expect("admitted selection");
+                let mut request = model_menu::Request::object(primary, iced::Point::ORIGIN);
+                request.canvas = Some(context);
+                request.placement = placement;
+                request.selection_target = Some(Box::new(primary_target));
+                self.menu_sequence = token;
+                self.delete_target = model_menu::Opened::new(self, request, token).map(|opened| {
+                    diagram_removal::Confirmation {
+                        snapshot: opened,
+                        selection: self.selected,
+                        placement,
+                        behavior_owner: None,
+                        scenario: None,
+                        process: None,
+                        saved: Some(Review {
+                            input_generation,
+                            context,
+                            snapshot,
+                            plan,
+                            query: String::new(),
+                            page: 0,
+                        }),
+                    }
+                });
+                self.delete_pending = self.delete_target.is_some();
+            }
+            Event::Query { token, query } => {
+                if let Some(review) = self
+                    .delete_target
+                    .as_mut()
+                    .filter(|target| target.snapshot.token == token)
+                    .and_then(|target| target.saved.as_mut())
+                {
+                    review.query = query;
+                    review.page = 0;
+                }
+            }
+            Event::Page { token, page } => {
+                if let Some(review) = self
+                    .delete_target
+                    .as_mut()
+                    .filter(|target| target.snapshot.token == token)
+                    .and_then(|target| target.saved.as_mut())
+                {
+                    review.page = page;
+                }
+            }
+            Event::Cancel { token } => {
+                if self
+                    .delete_target
+                    .as_ref()
+                    .is_some_and(|target| target.snapshot.token == token && target.saved.is_some())
+                {
+                    self.delete_target = None;
+                    self.delete_pending = false;
+                    self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                    self.status = "Model deletion cancelled. Model and selection unchanged.".into();
+                }
+            }
+        }
+        Task::none()
+    }
+
+    pub(crate) fn saved_removal_review_valid(
+        &self,
+        target: &diagram_removal::Confirmation,
+    ) -> bool {
+        let Some(review) = &target.saved else {
+            return false;
+        };
+        self.delete_pending
+            && !self.busy
+            && target.snapshot.valid(self)
+            && self.saved_removal_input.idle() == Some(review.input_generation)
+            && self.saved_removal_matches(review.context, &review.snapshot)
+            && self.selected == target.selection
+            && !self.source_dirty()
+            && !self.draft_dirty()
+            && !self.behavior.has_pending()
+            && !self.source_rename.open()
+            && self.saved_removal_selecting()
+    }
+
+    pub(super) fn confirm_saved_removal(&mut self, token: u64) {
+        let Some(target) = self
+            .delete_target
+            .as_ref()
+            .filter(|target| target.snapshot.token == token && target.saved.is_some())
+        else {
+            return;
+        };
+        let valid = self.saved_removal_review_valid(target);
+        let target = self.delete_target.take().expect("captured saved review");
+        self.delete_pending = false;
+        self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        if !valid {
+            self.status = "Model deletion review expired. Nothing was deleted; review the current selection again.".into();
+            return;
+        }
+        let review = target.saved.expect("saved review");
+        let machine = self.project().diagrams[&review.context.diagram]
+            .projection
+            .state_machine();
+        match self.document.execute(review.plan.command) {
+            Ok(_) => {
+                self.selected_node = None;
+                self.behavior.diagram.placement = None;
+                // A selected machine can own the current saved view. Retire
+                // those UI references only after its transaction succeeds.
+                if self
+                    .behavior
+                    .active_owner
+                    .is_some_and(|id| !self.project().contains(id))
+                {
+                    self.behavior.active_owner = None;
+                }
+                if self
+                    .behavior
+                    .diagram
+                    .diagram
+                    .is_some_and(|id| !self.project().diagrams.contains_key(&id))
+                {
+                    self.behavior.diagram = Default::default();
+                }
+                if self.page == Page::Behavior
+                    && let Some(machine) = machine.filter(|id| self.project().contains(*id))
+                {
+                    self.selected = machine;
+                    self.behavior.active_owner = Some(machine);
+                } else {
+                    self.selected = if self
+                        .project()
+                        .diagrams
+                        .contains_key(&review.context.diagram)
+                    {
+                        review.context.diagram
+                    } else {
+                        self.project().id
+                    };
+                }
+                self.sync();
+                self.reconcile_multiselect();
+                self.status = format!(
+                    "Deleted {} selected model subjects in one change across all views. Undo restores the model.",
+                    review.plan.selected.len()
+                );
+            }
+            Err(error) => self.status = format!("Nothing deleted: {error}"),
+        }
+    }
+}

crates/oa-desktop/src/app/saved_removal/tests.rs

@@ -0,0 +1,940 @@
+//! Saved semantic removal through App, with independently edited complete models.
+use super::*;
+use crate::diagram_usage::Target;
+use oa_core::*;
+
+fn point(x: f32, y: f32) -> Position {
+    Position { x, y }
+}
+
+fn saved(project: &mut Project, layer: Layer, projection: ProjectionKind) -> Id {
+    let id = Id::new_v4();
+    project.diagrams.insert(
+        id,
+        Diagram {
+            id,
+            alias: format!("saved_{}", id.simple()),
+            name: "Saved view".into(),
+            description: "Authored view metadata must survive".into(),
+            layer,
+            projection,
+            nodes: Default::default(),
+            routes: vec![],
+            layout: None,
+            view_options: Default::default(),
+        },
+    );
+    id
+}
+
+fn architecture(project: Project, diagram: Id) -> App {
+    validate_candidate(&project).unwrap();
+    let layer = project.diagrams[&diagram].layer;
+    let mut app = App::with_project(project);
+    app.page = Page::Diagram;
+    app.layer = layer;
+    app.active_diagram = Some(diagram);
+    app.selected = diagram;
+    app.selected_node = None;
+    app.refresh_draft();
+    app.reconcile_multiselect();
+    app.window_size = iced::Size::new(1600., 1000.);
+    app
+}
+
+fn choose(app: &mut App, targets: &[Target]) {
+    for (index, target) in targets.iter().enumerate() {
+        let context = app.multiselect_context().unwrap();
+        let _ = app.update(Message::DiagramSelection(multiselect::Event::Choose(
+            context,
+            target.clone(),
+            if index == 0 {
+                multiselect::Choice::Replace
+            } else {
+                multiselect::Choice::Add
+            },
+        )));
+    }
+    assert_eq!(app.multiselect_snapshot().unwrap().targets(), targets);
+}
+
+fn send(app: &mut App, event: Event) {
+    let _ = app.update(Message::SavedRemoval(Box::new(event)));
+}
+
+fn open(app: &mut App) -> u64 {
+    assert!(app.saved_removal_enabled());
+    let message = begin(app).expect("captured saved group");
+    let _ = app.update(message);
+    let confirmation = app.delete_target.as_ref().expect("saved group review");
+    assert!(app.saved_removal_review_valid(confirmation));
+    assert!(confirmation.saved.is_some());
+    confirmation.snapshot.token
+}
+
+fn source_matches(app: &App) {
+    let compiled = source_project::compile_bundle(app.document.bundle(), LIMITS).unwrap();
+    assert_eq!(&compiled.decoded.project, app.project());
+    assert_eq!(&compiled.bundle, app.document.bundle());
+    assert_eq!(
+        source_workspace::reachable(&app.source_workspace.bundle()).unwrap(),
+        *app.document.bundle()
+    );
+}
+
+fn mounted_fixture(state_view: bool) -> App {
+    if state_view {
+        let mut f = state_fixture(Layer::Sa);
+        choose(
+            &mut f.app,
+            &[Target::Placement(f.na), Target::Placement(f.nb)],
+        );
+        f.app
+    } else {
+        architecture_fixture(Layer::Sa).app
+    }
+}
+
+fn focus_canvas(mounted: &mut crate::behavior::canvas_workspace::tests::Mounted, app: &App) {
+    use iced::advanced::widget::{self, operation::Focusable};
+    struct Focus;
+    impl widget::Operation for Focus {
+        fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn widget::Operation)) {
+            visit(self);
+        }
+        fn focusable(
+            &mut self,
+            id: Option<&widget::Id>,
+            _: iced::Rectangle,
+            state: &mut dyn Focusable,
+        ) {
+            if id == Some(&widget::Id::from("diagram-keyboard-owner")) {
+                state.focus();
+            } else {
+                state.unfocus();
+            }
+        }
+    }
+    mounted.operate(app, &mut Focus);
+}
+
+fn shift_delete() -> iced::Event {
+    let mut event =
+        crate::behavior::canvas_workspace::tests::key(iced::keyboard::key::Named::Delete);
+    if let iced::Event::Keyboard(iced::keyboard::Event::KeyPressed { modifiers, .. }) = &mut event {
+        *modifiers = iced::keyboard::Modifiers::SHIFT;
+    }
+    event
+}
+
+#[tokio::test]
+async fn saved_removal_mounted_shift_delete_review_query_and_stamped_escape_preserve_source() {
+    use crate::behavior::canvas_workspace::tests::{Mounted, key};
+    use iced::{keyboard::key::Named, mouse};
+    for state_view in [false, true] {
+        let mut app = mounted_fixture(state_view);
+        let mut mounted = Mounted::new(&mut app).await;
+        focus_canvas(&mut mounted, &app);
+        let selected = app.multiselect_snapshot().unwrap();
+        let before = app.document.snapshot();
+        let messages = mounted
+            .batch(&mut app, &[shift_delete()], mouse::Cursor::Unavailable)
+            .await;
+        assert!(messages.iter().any(|message| matches!(message, Message::SavedRemoval(event) if matches!(&**event, Event::Begin { snapshot, .. } if snapshot.targets() == selected.targets()))), "{state_view}: {messages:?}");
+        let confirmation = app.delete_target.as_ref().unwrap();
+        assert!(app.saved_removal_review_valid(confirmation));
+        let token = confirmation.snapshot.token;
+        send(
+            &mut app,
+            Event::Query {
+                token,
+                query: "no matching record".into(),
+            },
+        );
+        mounted.settle(&mut app).await;
+        assert!(app.saved_removal_review_valid(app.delete_target.as_ref().unwrap()));
+        let messages = mounted
+            .batch(&mut app, &[key(Named::Escape)], mouse::Cursor::Unavailable)
+            .await;
+        assert!(messages.iter().any(|message| matches!(message, Message::SavedRemoval(event) if matches!(&**event, Event::Cancel { token: t } if *t == token))), "{messages:?}");
+        assert!(app.delete_target.is_none());
+        assert!(Arc::ptr_eq(&before, &app.document.snapshot()));
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().targets(),
+            selected.targets()
+        );
+    }
+}
+
+#[tokio::test]
+async fn saved_removal_mounted_later_press_or_tab_revokes_queued_review_before_app() {
+    use crate::behavior::canvas_workspace::tests::{Mounted, key};
+    use iced::{Event as Input, keyboard::key::Named, mouse};
+    for state_view in [false, true] {
+        for tab in [false, true] {
+            let mut app = mounted_fixture(state_view);
+            let mut mounted = Mounted::new(&mut app).await;
+            focus_canvas(&mut mounted, &app);
+            let geometry = mounted.geometry(&app);
+            let bounds = geometry
+                .focused
+                .iter()
+                .find(|(id, _, _)| {
+                    id.as_ref() == Some(&iced::advanced::widget::Id::from("diagram-keyboard-owner"))
+                })
+                .unwrap()
+                .1;
+            let at = iced::Point::new(
+                bounds.x + bounds.width - 12.,
+                bounds.y + bounds.height - 12.,
+            );
+            let before = app.document.snapshot();
+            let boundary = if tab {
+                key(Named::Tab)
+            } else {
+                Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle))
+            };
+            let messages = mounted
+                .batch(
+                    &mut app,
+                    &[
+                        shift_delete(),
+                        Input::Mouse(mouse::Event::CursorMoved { position: at }),
+                        boundary,
+                    ],
+                    mouse::Cursor::Available(at),
+                )
+                .await;
+            assert!(messages.iter().any(|message| matches!(message, Message::SavedRemoval(event) if matches!(&**event, Event::Begin { .. }))), "{state_view}/{tab}: {messages:?}");
+            assert!(
+                app.delete_target.is_none(),
+                "later input must retire the queued request"
+            );
+            assert!(Arc::ptr_eq(&before, &app.document.snapshot()));
+            if !tab {
+                assert!(begin(&app).is_none(), "active pan owns an input lease");
+                mounted
+                    .batch(
+                        &mut app,
+                        &[Input::Window(iced::window::Event::Unfocused)],
+                        mouse::Cursor::Unavailable,
+                    )
+                    .await;
+                assert!(
+                    app.saved_removal_input.idle().is_some(),
+                    "abandoned gesture releases its lease"
+                );
+            }
+        }
+    }
+}
+
+struct Architecture {
+    app: App,
+    diagram: Id,
+    parent: Id,
+    child: Id,
+    survivor: Id,
+    parent_node: Id,
+    child_node: Id,
+    survivor_node: Id,
+    edge: Id,
+    port: Option<Id>,
+    expected: Project,
+}
+
+fn architecture_fixture(layer: Layer) -> Architecture {
+    let mut project = Project::empty();
+    let kind = if layer == Layer::Oa {
+        Kind::Activity
+    } else {
+        Kind::Function
+    };
+    let parent = project.add_element(kind, layer, "Parent", None).unwrap();
+    let child = project
+        .add_element(kind, layer, "Child", Some(parent))
+        .unwrap();
+    let survivor = project.add_element(kind, layer, "Survivor", None).unwrap();
+    project.elements.get_mut(&survivor).unwrap().description =
+        "Unrelated authored description".into();
+    let edge = project.relate(
+        if layer == Layer::Oa {
+            RelationKind::Interaction
+        } else {
+            RelationKind::FunctionalExchange
+        },
+        "Incident",
+        child,
+        survivor,
+    );
+    let port = match project.relations[&edge].body {
+        RelationBody::FunctionalExchange { source_port, .. } => Some(source_port),
+        _ => None,
+    };
+    let diagram = saved(&mut project, layer, ProjectionKind::Overview);
+    let parent_node = project.place(diagram, parent, point(0., 0.));
+    let child_node = project.place(diagram, child, point(40., 100.));
+    let survivor_node = project.place(diagram, survivor, point(800., 50.));
+    project
+        .diagrams
+        .get_mut(&diagram)
+        .unwrap()
+        .routes
+        .push(EdgeRoute {
+            edge,
+            source_attachment: None,
+            target_attachment: None,
+            waypoints: vec![point(450.25, 90.5)],
+            label: None,
+        });
+    let other = saved(&mut project, layer, ProjectionKind::Overview);
+    let other_child = project.place(other, child, point(-40., 100.));
+    project.place(other, survivor, point(700., 100.));
+    project
+        .diagrams
+        .get_mut(&other)
+        .unwrap()
+        .view_options
+        .hidden_edges
+        .push(edge);
+    let mut expected = project.clone();
+    expected.elements.remove(&parent);
+    expected.elements.remove(&child);
+    if let Some(port) = port {
+        expected.elements.remove(&port);
+    }
+    expected.relations.remove(&edge);
+    let view = expected.diagrams.get_mut(&diagram).unwrap();
+    view.nodes.remove(&parent_node);
+    view.nodes.remove(&child_node);
+    view.routes.clear();
+    let view = expected.diagrams.get_mut(&other).unwrap();
+    view.nodes.remove(&other_child);
+    view.view_options.hidden_edges.clear();
+    validate_candidate(&expected).unwrap();
+    let mut app = architecture(project, diagram);
+    let mut targets = vec![
+        Target::Placement(parent_node),
+        Target::Placement(child_node),
+        Target::Edge(edge),
+    ];
+    if let Some(port) = port {
+        targets.push(Target::Port {
+            port,
+            placement: child_node,
+        });
+    }
+    choose(&mut app, &targets);
+    Architecture {
+        app,
+        diagram,
+        parent,
+        child,
+        survivor,
+        parent_node,
+        child_node,
+        survivor_node,
+        edge,
+        port,
+        expected,
+    }
+}
+
+#[test]
+fn saved_architecture_mixed_semantics_are_one_exact_model_source_transaction_in_oa_and_sa() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut f = architecture_fixture(layer);
+        let before = f.app.document.snapshot();
+        let selection = f.app.multiselect_snapshot().unwrap();
+        let camera = (f.app.zoom, f.app.pan);
+        let token = open(&mut f.app);
+        let review = f
+            .app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .saved
+            .as_ref()
+            .unwrap();
+        let mut subjects: BTreeSet<_> = [f.parent, f.child, f.edge].into_iter().collect();
+        subjects.extend(f.port);
+        assert_eq!(review.plan.selected, subjects);
+        assert_eq!(review.snapshot.targets(), selection.targets());
+        assert_eq!(review.snapshot.primary(), selection.primary());
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        let _ = f.app.update(Message::ConfirmDelete(token));
+        assert_eq!(f.app.project(), &f.expected);
+        assert_eq!(f.app.selected, f.diagram);
+        assert!(f.app.multiselect_snapshot().unwrap().targets().is_empty());
+        assert_eq!((f.app.zoom, f.app.pan), camera);
+        source_matches(&f.app);
+        let after = f.app.document.bundle().clone();
+        let _ = f.app.update(Message::Undo);
+        assert_eq!(f.app.project(), &before.decoded.project);
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        assert!(!f.app.document.can_undo());
+        let _ = f.app.update(Message::Redo);
+        assert_eq!(f.app.project(), &f.expected);
+        assert_eq!(f.app.document.bundle(), &after);
+        source_matches(&f.app);
+    }
+}
+
+struct States {
+    app: App,
+    diagram: Id,
+    other: Id,
+    machine: Id,
+    region: Id,
+    a: Id,
+    b: Id,
+    na: Id,
+    nb: Id,
+    work: Id,
+    action: Id,
+    row: Id,
+    edge: Id,
+}
+
+fn state_fixture(layer: Layer) -> States {
+    let mut project = Project::empty();
+    let owner = project
+        .add_element(
+            if layer == Layer::Oa {
+                Kind::Entity
+            } else {
+                Kind::System
+            },
+            layer,
+            "Owner",
+            None,
+        )
+        .unwrap();
+    let machine = project
+        .add_element(Kind::StateMachine, layer, "Modes", Some(owner))
+        .unwrap();
+    let region = project
+        .add_element(Kind::Region, layer, "Region", Some(machine))
+        .unwrap();
+    let a = project
+        .add_element(Kind::State, layer, "Operating", Some(region))
+        .unwrap();
+    let b = project
+        .add_element(Kind::State, layer, "Standby", Some(region))
+        .unwrap();
+    let work = project
+        .add_element(
+            if layer == Layer::Oa {
+                Kind::Activity
+            } else {
+                Kind::Function
+            },
+            layer,
+            "Reusable work",
+            None,
+        )
+        .unwrap();
+    let action = project.relate(RelationKind::StateAction, "Entry work", a, work);
+    let row = project.relate(RelationKind::StateTransition, "Internal check", a, a);
+    if let RelationBody::StateTransition {
+        transition_kind, ..
+    } = &mut project.relations.get_mut(&row).unwrap().body
+    {
+        *transition_kind = TransitionKind::Internal;
+    }
+    let edge = project.relate(RelationKind::StateTransition, "Change mode", a, b);
+    let diagram = saved(
+        &mut project,
+        layer,
+        ProjectionKind::StateMachine { machine },
+    );
+    let na = project.place(diagram, a, point(10., 20.));
+    let nb = project.place(diagram, b, point(600., 20.));
+    let other = saved(
+        &mut project,
+        layer,
+        ProjectionKind::StateMachine { machine },
+    );
+    project.place(other, a, point(70., 80.));
+    project.place(other, b, point(670., 80.));
+    let architecture_view = saved(&mut project, layer, ProjectionKind::Overview);
+    project.place(architecture_view, owner, point(0., 0.));
+    validate_candidate(&project).unwrap();
+    let mut app = architecture(project, architecture_view);
+    app.page = Page::Behavior;
+    app.behavior.active_owner = Some(machine);
+    app.behavior.diagram = crate::behavior::state_view::State {
+        diagram: Some(diagram),
+        ..Default::default()
+    };
+    app.selected = diagram;
+    app.refresh_draft();
+    app.reconcile_multiselect();
+    States {
+        app,
+        diagram,
+        other,
+        machine,
+        region,
+        a,
+        b,
+        na,
+        nb,
+        work,
+        action,
+        row,
+        edge,
+    }
+}
+
+#[test]
+fn saved_state_rows_delete_relations_not_referenced_work_and_state_overlap_is_exact() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        for include_owner in [false, true] {
+            let mut f = state_fixture(layer);
+            let mut targets = vec![
+                Target::StateRow {
+                    placement: f.na,
+                    relation: f.action,
+                },
+                Target::StateRow {
+                    placement: f.na,
+                    relation: f.row,
+                },
+            ];
+            if include_owner {
+                targets.push(Target::Placement(f.na));
+            } else {
+                targets.push(Target::Placement(f.nb));
+            }
+            choose(&mut f.app, &targets);
+            let before = f.app.document.snapshot();
+            let camera = (f.app.behavior.diagram.zoom, f.app.behavior.diagram.pan);
+            let mut expected = f.app.project().clone();
+            expected.relations.remove(&f.action);
+            expected.relations.remove(&f.row);
+            expected.relations.remove(&f.edge);
+            let removed_state = if include_owner { f.a } else { f.b };
+            expected.elements.remove(&removed_state);
+            for view in expected.diagrams.values_mut() {
+                view.nodes.retain(|_, node| node.element != removed_state);
+            }
+            validate_candidate(&expected).unwrap();
+            let token = open(&mut f.app);
+            let review = f
+                .app
+                .delete_target
+                .as_ref()
+                .unwrap()
+                .saved
+                .as_ref()
+                .unwrap();
+            assert_eq!(
+                review.context.diagram, f.diagram,
+                "must not resolve stale Architecture field"
+            );
+            assert_eq!(
+                review.plan.selected,
+                [f.action, f.row, removed_state].into_iter().collect()
+            );
+            assert!(!review.plan.removed.contains(&f.work));
+            let _ = f.app.update(Message::ConfirmDelete(token));
+            assert_eq!(f.app.project(), &expected);
+            assert!(f.app.project().contains(f.work));
+            assert_eq!(
+                (f.app.behavior.diagram.zoom, f.app.behavior.diagram.pan),
+                camera
+            );
+            assert!(f.app.project().contains(f.app.selected));
+            source_matches(&f.app);
+            let after = f.app.document.bundle().clone();
+            let _ = f.app.update(Message::Undo);
+            assert_eq!(f.app.project(), &before.decoded.project);
+            assert_eq!(f.app.document.bundle(), &before.bundle);
+            assert!(!f.app.document.can_undo());
+            let _ = f.app.update(Message::Redo);
+            assert_eq!(f.app.project(), &expected);
+            assert_eq!(f.app.document.bundle(), &after);
+        }
+    }
+}
+
+#[test]
+fn saved_cancel_and_stale_modal_packets_preserve_exact_redo_source_selection_and_camera() {
+    let mut f = architecture_fixture(Layer::Sa);
+    f.app
+        .document
+        .execute(Command::Rename(f.survivor, "Future name".into()))
+        .unwrap();
+    let future = f.app.document.snapshot();
+    assert!(f.app.document.undo());
+    f.app.sync();
+    f.app.reconcile_multiselect();
+    let before = f.app.document.snapshot();
+    let editor = f.app.source_editor.text();
+    let selected = f.app.multiselect_snapshot().unwrap();
+    let camera = (f.app.zoom, f.app.pan);
+    let old_begin = begin(&f.app).unwrap();
+    let first = open(&mut f.app);
+    send(&mut f.app, Event::Cancel { token: first });
+    let second = open(&mut f.app);
+    let epoch = f.app.canvas_epoch;
+    for message in [
+        old_begin,
+        Message::ConfirmDelete(first),
+        Message::CancelDelete,
+        Message::Escape,
+        Message::SavedRemoval(Box::new(Event::Cancel { token: first })),
+        Message::SavedRemoval(Box::new(Event::Query {
+            token: first,
+            query: "stale".into(),
+        })),
+        Message::SavedRemoval(Box::new(Event::Page {
+            token: first,
+            page: 999,
+        })),
+    ] {
+        let _ = f.app.update(message);
+        assert_eq!(f.app.delete_target.as_ref().unwrap().snapshot.token, second);
+        assert_eq!(f.app.canvas_epoch, epoch);
+        let review = f
+            .app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .saved
+            .as_ref()
+            .unwrap();
+        assert!(review.query.is_empty());
+        assert_eq!(review.page, 0);
+    }
+    send(&mut f.app, Event::Cancel { token: second });
+    assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+    assert_eq!(f.app.source_editor.text(), editor);
+    assert_eq!(f.app.source_workspace.bundle(), before.bundle);
+    assert_eq!(
+        f.app.multiselect_snapshot().unwrap().targets(),
+        selected.targets()
+    );
+    assert_eq!(
+        f.app.multiselect_snapshot().unwrap().primary(),
+        selected.primary()
+    );
+    assert_eq!((f.app.zoom, f.app.pan), camera);
+    assert!(f.app.document.can_redo() && !f.app.document.can_undo());
+    let _ = f.app.update(Message::Redo);
+    assert_eq!(f.app.project(), &future.decoded.project);
+    assert_eq!(f.app.document.bundle(), &future.bundle);
+}
+
+#[test]
+fn saved_begin_and_confirm_reject_selection_membership_and_primary_aba() {
+    for after_open in [false, true] {
+        for primary_only in [false, true] {
+            let mut f = architecture_fixture(Layer::Oa);
+            let delayed = begin(&f.app).unwrap();
+            let token = after_open.then(|| open(&mut f.app));
+            let before = f.app.document.snapshot();
+            let captured = f.app.multiselect_snapshot().unwrap();
+            let selected = f.app.diagram_selection.as_mut().unwrap();
+            let primary = captured.primary().unwrap();
+            if primary_only {
+                assert!(selected.set_primary(&Target::Placement(f.parent_node)));
+                assert!(selected.set_primary(primary));
+            } else {
+                assert!(selected.remove(primary));
+                assert!(selected.add(primary.clone(), |_| true));
+            }
+            let restored = f.app.multiselect_snapshot().unwrap();
+            assert_eq!(restored.targets(), captured.targets());
+            assert_eq!(restored.primary(), captured.primary());
+            assert_ne!(restored.generation(), captured.generation());
+            let epoch = f.app.canvas_epoch;
+            let _ = f
+                .app
+                .update(token.map(Message::ConfirmDelete).unwrap_or(delayed));
+            assert!(f.app.delete_target.is_none());
+            assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+            assert_eq!(
+                f.app.multiselect_snapshot().unwrap().targets(),
+                restored.targets()
+            );
+            if !after_open {
+                assert_eq!(f.app.canvas_epoch, epoch);
+            }
+        }
+    }
+}
+
+#[test]
+fn saved_stale_context_packets_do_not_retire_current_selection_or_history() {
+    for change in 0..4 {
+        let mut f = architecture_fixture(Layer::Sa);
+        let delayed = begin(&f.app).unwrap();
+        match change {
+            0 => {
+                f.app.canvas_document = Id::new_v4();
+            }
+            1 => {
+                f.app.canvas_epoch = f.app.canvas_epoch.wrapping_add(1);
+            }
+            2 => {
+                f.app
+                    .document
+                    .execute(Command::Rename(f.survivor, "New revision".into()))
+                    .unwrap();
+            }
+            _ => {
+                f.app.active_diagram = f
+                    .app
+                    .project()
+                    .diagrams
+                    .keys()
+                    .copied()
+                    .find(|id| *id != f.diagram);
+            }
+        }
+        let current = f.app.document.snapshot();
+        let selection = f.app.multiselect_snapshot();
+        let epoch = f.app.canvas_epoch;
+        let _ = f.app.update(delayed);
+        assert!(f.app.delete_target.is_none());
+        assert!(Arc::ptr_eq(&current, &f.app.document.snapshot()));
+        assert_eq!(f.app.multiselect_snapshot(), selection);
+        assert_eq!(f.app.canvas_epoch, epoch);
+    }
+}
+
+#[test]
+fn saved_admission_preserves_property_source_and_state_editor_drafts_and_nonselect_tool() {
+    for pending in ["properties", "source", "form", "tool", "busy"] {
+        let mut f = state_fixture(Layer::Sa);
+        choose(
+            &mut f.app,
+            &[Target::Placement(f.na), Target::Placement(f.nb)],
+        );
+        let delayed = begin(&f.app).unwrap();
+        match pending {
+            "properties" => {
+                let _ = f
+                    .app
+                    .update(Message::Field("/name".into(), "Unapplied".into()));
+            }
+            "source" => {
+                let text = format!("{}\n// pending", f.app.source_workspace.text());
+                let _ = f
+                    .app
+                    .update(Message::SourceEdit(text_editor::Action::SelectAll));
+                let _ = f.app.update(Message::SourceEdit(text_editor::Action::Edit(
+                    text_editor::Edit::Paste(Arc::new(text)),
+                )));
+            }
+            "form" => {
+                let _ = f.app.update(Message::Behavior(behavior::Event::States(
+                    behavior::states::Event::Edit(f.edge),
+                )));
+                let _ = f.app.update(Message::Behavior(behavior::Event::States(
+                    behavior::states::Event::Guard("Retained guard".into()),
+                )));
+            }
+            "tool" => {
+                f.app.behavior.diagram.tool = behavior::state_edit::Tool::Transition;
+            }
+            _ => f.app.busy = true,
+        }
+        let before = f.app.document.snapshot();
+        let source = f.app.source_workspace.bundle();
+        let selection = f.app.multiselect_snapshot();
+        let draft = f
+            .app
+            .draft
+            .as_ref()
+            .map(|d| serde_json::to_value(d.recovery_snapshot()).unwrap());
+        let form = f.app.behavior.recovery_snapshot();
+        let epoch = f.app.canvas_epoch;
+        let _ = f.app.update(delayed);
+        assert!(f.app.delete_target.is_none(), "{pending}");
+        assert!(
+            Arc::ptr_eq(&before, &f.app.document.snapshot()),
+            "{pending}"
+        );
+        assert_eq!(f.app.source_workspace.bundle(), source);
+        assert_eq!(f.app.multiselect_snapshot(), selection);
+        assert_eq!(
+            f.app
+                .draft
+                .as_ref()
+                .map(|d| serde_json::to_value(d.recovery_snapshot()).unwrap()),
+            draft
+        );
+        assert_eq!(f.app.behavior.recovery_snapshot(), form);
+        assert_eq!(f.app.canvas_epoch, epoch);
+    }
+}
+
+#[test]
+fn saved_input_lease_and_finished_gesture_reject_old_packets_at_begin_and_confirm() {
+    for after_open in [false, true] {
+        for finished in [false, true] {
+            let mut f = architecture_fixture(Layer::Oa);
+            let delayed = begin(&f.app).unwrap();
+            let token = after_open.then(|| open(&mut f.app));
+            let before = f.app.document.snapshot();
+            let selected = f.app.multiselect_snapshot().unwrap();
+            let lease = f.app.saved_removal_input.acquire().unwrap();
+            let mut lease = Some(lease);
+            if finished {
+                drop(lease.take());
+            }
+            let _ = f
+                .app
+                .update(token.map(Message::ConfirmDelete).unwrap_or(delayed));
+            assert!(f.app.delete_target.is_none());
+            assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+            assert_eq!(
+                f.app.multiselect_snapshot().unwrap().targets(),
+                selected.targets()
+            );
+            assert_eq!(
+                f.app.multiselect_snapshot().unwrap().primary(),
+                selected.primary()
+            );
+            drop(lease);
+        }
+    }
+}
+
+#[test]
+fn saved_context_menu_keeps_the_whole_group_even_when_unselected_object_was_clicked() {
+    for unselected in [false, true] {
+        let mut f = architecture_fixture(Layer::Sa);
+        let selected = f.app.multiselect_snapshot().unwrap();
+        let (object, placement) = if unselected {
+            (f.survivor, f.survivor_node)
+        } else {
+            (f.child, f.child_node)
+        };
+        let mut request = model_menu::Request::object(object, iced::Point::ORIGIN);
+        request.canvas = f.app.route_context();
+        request.placement = Some(placement);
+        request.selection_target = Some(Box::new(Target::Placement(placement)));
+        let _ = f
+            .app
+            .update(Message::Menu(model_menu::Event::Open(request)));
+        let entries = model_menu::popup(&f.app).unwrap().entries;
+        let invoke = entries
+            .into_iter()
+            .find_map(|entry| match entry {
+                crate::context_menu::Entry::Action { label, message, .. }
+                    if label == "Delete selected from model…" =>
+                {
+                    message
+                }
+                _ => None,
+            })
+            .expect("explicit semantic group menu action");
+        let _ = f.app.update(invoke);
+        let review = f
+            .app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .saved
+            .as_ref()
+            .unwrap();
+        assert_eq!(review.snapshot.targets(), selected.targets());
+        assert!(!review.plan.selected.contains(&f.survivor));
+    }
+}
+
+#[test]
+fn saved_hide_and_plain_delete_never_promote_mixed_targets_to_model_removal() {
+    for message_kind in ["delete", "hide"] {
+        let mut f = architecture_fixture(Layer::Sa);
+        let before = f.app.document.snapshot();
+        let selected = f.app.multiselect_snapshot().unwrap();
+        let _ = f.app.update(if message_kind == "delete" {
+            Message::Delete
+        } else {
+            Message::HideSelected
+        });
+        assert!(Arc::ptr_eq(&before, &f.app.document.snapshot()));
+        assert_eq!(
+            f.app.multiselect_snapshot().unwrap().targets(),
+            selected.targets()
+        );
+        assert!(f.app.delete_target.is_none());
+        let token = open(&mut f.app);
+        let _ = f.app.update(Message::ConfirmDelete(token));
+        assert_eq!(f.app.project(), &f.expected);
+    }
+    let mut f = architecture_fixture(Layer::Oa);
+    choose(
+        &mut f.app,
+        &[
+            Target::Placement(f.parent_node),
+            Target::Placement(f.survivor_node),
+        ],
+    );
+    let mut expected = f.app.project().clone();
+    let view = expected.diagrams.get_mut(&f.diagram).unwrap();
+    view.nodes.remove(&f.parent_node);
+    view.nodes.remove(&f.survivor_node);
+    let _ = f.app.update(Message::HideSelected);
+    assert_eq!(f.app.project(), &expected);
+    assert!(f.app.project().contains(f.parent) && f.app.project().contains(f.survivor));
+    source_matches(&f.app);
+}
+
+#[test]
+fn saved_state_owner_deletion_removes_owned_views_and_chooses_surviving_inspection_context() {
+    let mut f = state_fixture(Layer::Sa);
+    let mut project = f.app.project().clone();
+    let owner_node = project.place(f.diagram, f.machine, point(-400., -200.));
+    f.app.document = Document::from_project(project.clone(), LIMITS).unwrap();
+    f.app.source_workspace = Workspace::new(f.app.document.bundle(), true);
+    f.app.sync();
+    f.app.reconcile_multiselect();
+    choose(
+        &mut f.app,
+        &[Target::Placement(owner_node), Target::Placement(f.na)],
+    );
+    let before = f.app.document.snapshot();
+    let mut expected = project;
+    for id in [f.machine, f.region, f.a, f.b] {
+        expected.elements.remove(&id);
+    }
+    for id in [f.action, f.row, f.edge] {
+        expected.relations.remove(&id);
+    }
+    expected.diagrams.remove(&f.diagram);
+    expected.diagrams.remove(&f.other);
+    validate_candidate(&expected).unwrap();
+    let token = open(&mut f.app);
+    let _ = f.app.update(Message::ConfirmDelete(token));
+    assert_eq!(f.app.project(), &expected);
+    assert!(f.app.project().contains(f.app.selected));
+    assert!(
+        f.app
+            .behavior
+            .active_owner
+            .is_none_or(|id| f.app.project().contains(id))
+    );
+    assert!(
+        f.app
+            .behavior
+            .diagram
+            .diagram
+            .is_none_or(|id| f.app.project().diagrams.contains_key(&id))
+    );
+    assert!(
+        f.app
+            .multiselect_snapshot()
+            .is_none_or(|s| s.targets().is_empty())
+    );
+    source_matches(&f.app);
+    let _ = f.app.update(Message::Undo);
+    assert_eq!(f.app.project(), &before.decoded.project);
+    assert_eq!(f.app.document.bundle(), &before.bundle);
+    assert!(!f.app.document.can_undo());
+}

crates/oa-desktop/src/app/saved_removal/view.rs

@@ -0,0 +1,145 @@
+//! Review the complete captured removal impact before one explicit confirmation.
+use super::{Event, Review};
+use crate::app::{App, Message, diagram_removal};
+use crate::style;
+use iced::widget::{button, column, container, row, scrollable, text, text_input};
+use iced::{Element, Length::Fill};
+use oa_core::Project;
+use std::collections::BTreeSet;
+
+const PAGE_SIZE: usize = 6;
+
+pub(super) fn matching_rows(
+    project: &Project,
+    review: &Review,
+) -> Vec<super::super::removal_review::ImpactRow> {
+    super::super::removal_review::matching_rows(
+        project,
+        &review.plan.removed,
+        &review.plan.changed,
+        &review.plan.selected,
+        &review.plan.interpretation,
+        &review.plan.affected_uses,
+        &review.query,
+    )
+}
+
+pub(crate) fn view<'a>(
+    app: &'a App,
+    target: &'a diagram_removal::Confirmation,
+) -> Element<'a, Message> {
+    let Some(review) = target.saved.as_ref() else {
+        return text("Model deletion review is unavailable.").into();
+    };
+    let token = target.snapshot.token;
+    let valid = app.saved_removal_review_valid(target);
+    let rows = matching_rows(app.project(), review);
+    let callers: BTreeSet<_> = review
+        .plan
+        .affected_uses
+        .values()
+        .flatten()
+        .chain(
+            review
+                .plan
+                .interpretation
+                .iter()
+                .flat_map(|impact| impact.callers.iter()),
+        )
+        .copied()
+        .collect();
+    let semantic_summary = if review.plan.interpretation.is_empty() && callers.is_empty() {
+        "No detected Process order/analysis changes or affected Process caller definitions."
+            .to_owned()
+    } else {
+        format!(
+            "Order / analysis changes in {} definitions · {} caller definitions affected. Review their effects below.",
+            review.plan.interpretation.len(),
+            callers.len()
+        )
+    };
+    let pages = rows.len().div_ceil(PAGE_SIZE).max(1);
+    let page = review.page.min(pages - 1);
+    let mut impacts = column![].spacing(12).width(Fill);
+    for impact in rows.iter().skip(page * PAGE_SIZE).take(PAGE_SIZE) {
+        impacts = impacts.push(
+            column![
+                text(impact.disposition.clone())
+                    .size(12)
+                    .color(style::MUTED),
+                text(impact.label.clone())
+                    .size(13)
+                    .width(Fill)
+                    .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            ]
+            .spacing(3)
+            .width(Fill),
+        );
+    }
+    if rows.is_empty() {
+        impacts = impacts.push(text("No matching effects. Try a name, alias or effect.").size(13));
+    }
+    let previous = button("Previous").on_press_maybe((page > 0).then(|| {
+        Message::SavedRemoval(Box::new(Event::Page {
+            token,
+            page: page - 1,
+        }))
+    }));
+    let next = button("Next").on_press_maybe((page + 1 < pages).then(|| {
+        Message::SavedRemoval(Box::new(Event::Page {
+            token,
+            page: page + 1,
+        }))
+    }));
+    let mut footer = column![].spacing(8).width(Fill);
+    if !valid {
+        footer = footer.push(
+            text("This review expired. Cancel and review the current selection again.")
+                .size(13)
+                .width(Fill)
+                .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        );
+    }
+    footer = footer.push(
+        row![
+            container(
+                button("Cancel")
+                    .padding(10)
+                    .on_press(Message::SavedRemoval(Box::new(Event::Cancel { token })))
+            )
+            .id("delete-cancel"),
+            container(
+                button("Delete selected from model")
+                    .style(button::danger)
+                    .padding(10)
+                    .on_press_maybe(valid.then_some(Message::ConfirmDelete(token)))
+            )
+            .id("delete-confirm"),
+        ]
+        .spacing(10),
+    );
+    column![
+        text(format!("Delete {} model subjects?", review.plan.selected.len())).size(21),
+        text(format!("{} selected diagram objects · {} unique model subjects", review.snapshot.targets().len(), review.plan.selected.len())).size(13),
+        text(format!("{} records removed · {} records updated", review.plan.removed.len(), review.plan.changed.len())).size(14),
+        text(semantic_summary).size(13).width(Fill).wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        text_input("Search affected names, aliases or effects", &review.query)
+            .id("saved-removal-query")
+            .on_input(move |query| Message::SavedRemoval(Box::new(Event::Query { token, query })))
+            .size(13),
+        row![previous, text(format!("Page {} of {} · {} matches", page + 1, pages, rows.len())).size(12), next]
+            .spacing(10).align_y(iced::Alignment::Center),
+        scrollable(column![
+            text("Deletes the selected model subjects and their listed dependent records across all views. This is different from hiding placements. Removing a State row preserves its referenced work; deleting a trace preserves its endpoints unless separately selected or owned by another deleted subject. Reused Process definitions may change; review their listed effects and callers. One Undo restores the entire model and source change.")
+                .size(13).width(Fill).wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            impacts,
+        ].spacing(14).width(Fill))
+            .width(Fill).height(Fill).spacing(8).id("saved-removal-impact"),
+        footer,
+    ]
+    .spacing(12)
+    .width(Fill)
+    // Keep confirmation and search outside the flexible, scrollable impact body.
+    .height((app.window_size.height - 160.).clamp(260., 570.))
+    .into()
+}

crates/oa-desktop/src/app/scenario_multiselect.rs

@@ -0,0 +1,135 @@
+//! Exact rendered Scenario selection, independent of semantic movement permission.
+use super::*;
+use crate::behavior::scenario::{self, selection};
+use crate::diagram_selection::Selection;
+use crate::diagram_usage::Target;
+
+#[cfg(test)]
+mod tests;
+
+impl App {
+    pub(crate) fn scenario_selection_envelope(&self, event: &selection::Event) -> bool {
+        self.scenario_context() == Some(event.context)
+            && self.diagram_selection.as_ref().is_some_and(|selected| {
+                selected.matches(&event.snapshot, selection::context(event.context))
+            })
+    }
+
+    pub(super) fn reconcile_scenario_multiselect(&mut self) {
+        let Some(context) = self.scenario_context() else {
+            return;
+        };
+        let scope = selection::context(context).scope;
+        let visible = selection::visible(self.project(), context, self.selected);
+        let old = self
+            .diagram_selection
+            .as_ref()
+            .filter(|s| s.scope() == scope)
+            .and_then(Selection::primary)
+            .cloned();
+        let legacy = Target::ScenarioObject(self.selected);
+        let held = old.as_ref() == Some(&legacy);
+        let lost = old.as_ref().is_some_and(|target| !visible.contains(target));
+        let selected = self
+            .diagram_selection
+            .get_or_insert_with(|| Selection::new(scope));
+        selected.reconcile(scope, |target| visible.contains(target));
+        if held || lost {
+            if selected.primary() != old.as_ref() {
+                self.inspect_scenario_multiselect_primary();
+            }
+        } else if selected.primary() != Some(&legacy) {
+            if visible.contains(&legacy) {
+                selected.replace(legacy, |target| visible.contains(target));
+            } else {
+                selected.clear();
+            }
+        }
+    }
+
+    pub(super) fn inspect_scenario_multiselect_primary(&mut self) {
+        let Some(context) = self.scenario_context() else {
+            return;
+        };
+        self.selected = match self.diagram_selection.as_ref().and_then(Selection::primary) {
+            Some(Target::ScenarioObject(id)) => *id,
+            _ => context.scenario,
+        };
+        self.selected_node = None;
+        self.selected_bend = None;
+        self.selected_attachment = None;
+        self.behavior.diagram.placement = None;
+        self.diagram_navigation_focus = None;
+        self.refresh_draft();
+    }
+
+    /// This is dispatched before shared navigation/gesture retirement. Invalid
+    /// captures and unchanged selection must not disturb a newer input owner.
+    pub(super) fn scenario_selection_event(&mut self, event: selection::Event) -> Task<Message> {
+        use multiselect::Choice;
+        use selection::Intent;
+        if !self.scenario_selection_envelope(&event) {
+            return Task::none();
+        }
+        let visible = selection::visible(self.project(), event.context, self.selected);
+        if !event.snapshot.targets().iter().all(|t| visible.contains(t)) {
+            return Task::none();
+        }
+        if !diagram_removal::enabled(self)
+            || self.source_rename.open()
+            || self.behavior.scenario.canvas_tool(event.context.scenario)
+                != scenario::CanvasTool::Select
+        {
+            self.status =
+                "Finish or cancel the active edit before changing the Scenario selection.".into();
+            return Task::none();
+        }
+        let selected = self.diagram_selection.as_mut().expect("admitted selection");
+        let valid = |target: &Target| visible.contains(target);
+        let changed = match &event.intent {
+            Intent::Choose(target, choice) => {
+                if !valid(target) {
+                    return Task::none();
+                }
+                match choice {
+                    Choice::Replace => selected.replace(target.clone(), valid),
+                    Choice::Add => selected.add(target.clone(), valid),
+                    Choice::Remove => selected.remove(target),
+                    Choice::Toggle => selected.toggle(target.clone(), valid),
+                    Choice::Inspect => selected.set_primary(target),
+                }
+            }
+            Intent::Collapse(target) => {
+                if !selected.contains(target) || !valid(target) {
+                    return Task::none();
+                }
+                selected.replace(target.clone(), valid)
+            }
+            Intent::Clear => selected.clear(),
+            Intent::Refuse(reason) => {
+                self.status = reason.clone();
+                return Task::none();
+            }
+        };
+        if changed {
+            self.scenario_reorder_cancel();
+            self.source_interaction();
+            self.reconcile_pending_diagram_reveal(&Message::ScenarioCanvas(
+                scenario::CanvasEvent::Selection(Box::new(event)),
+            ));
+            self.behavior.scenario.cancel_spacing();
+            // Every generation change, including a secondary membership ABA,
+            // retires old singleton spacing packets as well as group captures.
+            self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+            self.inspect_scenario_multiselect_primary();
+        }
+        Task::none()
+    }
+
+    pub(super) fn scenario_group_selected(&self) -> bool {
+        self.scenario_context().is_some()
+            && self
+                .multiselect_snapshot()
+                .is_some_and(|s| s.targets().len() > 1)
+    }
+}

crates/oa-desktop/src/app/scenario_multiselect/tests.rs

@@ -0,0 +1,379 @@
+use super::*;
+use crate::behavior::scenario::{CanvasEvent, selection::Intent, spacing};
+use crate::behavior::scenario_layout::Representation;
+use crate::diagram_usage::Surface;
+use iced::{Size, Vector};
+
+fn setup(saved: bool) -> (App, Id, Id, Id, Id) {
+    let (document, owner, diagram, lane, message) = spacing::controller::tests::fixture();
+    let mut app = App::with_project(document.project().clone());
+    let _ = app.update(Message::Select(owner));
+    if saved {
+        let _ = app.update(Message::Diagram(super::super::Choice {
+            id: diagram,
+            label: "Saved".into(),
+        }));
+    } else {
+        let _ = app.update(Message::Page(Page::Behavior));
+    }
+    let context = app.scenario_context().unwrap();
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Viewport(
+        context,
+        Size::new(900., 600.),
+    )));
+    assert!(app.multiselect_snapshot().unwrap().targets().is_empty());
+    (app, owner, diagram, lane, message)
+}
+
+fn capture(app: &App, intent: Intent) -> selection::Event {
+    selection::Event {
+        context: app.scenario_context().unwrap(),
+        snapshot: app.multiselect_snapshot().unwrap(),
+        intent,
+    }
+}
+fn send(app: &mut App, event: selection::Event) {
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+        event,
+    ))));
+}
+fn choose(app: &mut App, id: Id, choice: multiselect::Choice) {
+    send(
+        app,
+        capture(app, Intent::Choose(Target::ScenarioObject(id), choice)),
+    );
+}
+fn inert(app: &mut App, messages: Vec<Message>, preserve_status: bool) {
+    let model = app.project().clone();
+    let bundle = app.document.bundle().clone();
+    let source = app.source_workspace.bundle();
+    let revision = app.document.revision();
+    let history = (app.document.can_undo(), app.document.can_redo());
+    let selected = app.multiselect_snapshot();
+    let primary = app.selected;
+    let context = app.scenario_context();
+    let camera = app.camera_boundary();
+    let status = app.status.clone();
+    let spacing = (
+        app.behavior.scenario.spacing_stamp(),
+        app.behavior.scenario.spacing_token(),
+    );
+    for message in messages {
+        let _ = app.update(message);
+        assert_eq!(app.project(), &model);
+        assert_eq!(app.document.bundle(), &bundle);
+        assert_eq!(app.source_workspace.bundle(), source);
+        assert_eq!(app.document.revision(), revision);
+        assert_eq!((app.document.can_undo(), app.document.can_redo()), history);
+        assert_eq!(app.multiselect_snapshot(), selected);
+        assert_eq!(app.selected, primary);
+        assert_eq!(app.scenario_context(), context);
+        assert!(app.camera_boundary() == camera);
+        assert_eq!(
+            (
+                app.behavior.scenario.spacing_stamp(),
+                app.behavior.scenario.spacing_token()
+            ),
+            spacing
+        );
+        if preserve_status {
+            assert_eq!(app.status, status);
+        }
+    }
+}
+fn packet(event: selection::Event) -> Message {
+    Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(event)))
+}
+
+#[test]
+fn exact_scenario_membership_primary_and_noops_preserve_model_source_and_history() {
+    for saved in [false, true] {
+        let (mut app, owner, diagram, lane, message) = setup(saved);
+        let model = app.project().clone();
+        let bundle = app.document.bundle().clone();
+        let revision = app.document.revision();
+        choose(&mut app, message, multiselect::Choice::Add);
+        choose(&mut app, lane, multiselect::Choice::Add);
+        choose(&mut app, message, multiselect::Choice::Inspect);
+        let snapshot = app.multiselect_snapshot().unwrap();
+        assert_eq!(
+            snapshot.targets(),
+            &[
+                Target::ScenarioObject(message),
+                Target::ScenarioObject(lane)
+            ]
+        );
+        assert_eq!(snapshot.primary(), Some(&Target::ScenarioObject(message)));
+        assert_eq!(
+            snapshot.context().scope.surface,
+            if saved {
+                Surface::Saved(diagram)
+            } else {
+                Surface::Scenario(owner)
+            }
+        );
+        assert_eq!(app.selected, message);
+        let repeated = capture(
+            &app,
+            Intent::Choose(Target::ScenarioObject(message), multiselect::Choice::Add),
+        );
+        inert(&mut app, vec![packet(repeated)], true);
+        let stale_collapse = capture(&app, Intent::Collapse(Target::ScenarioObject(lane)));
+        choose(&mut app, lane, multiselect::Choice::Remove);
+        choose(&mut app, lane, multiselect::Choice::Add);
+        choose(&mut app, message, multiselect::Choice::Inspect);
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().targets(),
+            snapshot.targets()
+        );
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().primary(),
+            snapshot.primary()
+        );
+        inert(&mut app, vec![packet(stale_collapse)], true);
+        assert_eq!(app.project(), &model);
+        assert_eq!(app.document.bundle(), &bundle);
+        assert_eq!(app.document.revision(), revision);
+        assert!(!app.document.can_undo() && !app.document.can_redo());
+    }
+}
+
+#[test]
+fn same_owner_representation_round_trip_clears_group_and_rejects_old_packets() {
+    let (mut app, owner, diagram, lane, message) = setup(true);
+    choose(&mut app, message, multiselect::Choice::Add);
+    choose(&mut app, lane, multiselect::Choice::Add);
+    let old = capture(&app, Intent::Clear);
+    let snapshot = app.multiselect_snapshot().unwrap();
+    let mut second = app.project().diagrams[&diagram].clone();
+    let other = Id::new_v4();
+    second.id = other;
+    second.alias = "other_saved".into();
+    second.name = "Other saved".into();
+    // Navigation itself is tested against a model with both saved identities.
+    let mut project = app.project().clone();
+    project.diagrams.insert(other, second);
+    let mut app = App::with_project(project);
+    let _ = app.update(Message::Select(owner));
+    let _ = app.update(Message::Diagram(super::super::Choice {
+        id: diagram,
+        label: "A".into(),
+    }));
+    choose(&mut app, message, multiselect::Choice::Add);
+    choose(&mut app, lane, multiselect::Choice::Add);
+    let first = capture(&app, Intent::Clear);
+    let first_visit = first.context.visit;
+    for representation in [
+        Representation::Saved { diagram: other },
+        Representation::Derived { owner },
+        Representation::Saved { diagram },
+    ] {
+        let context = app.scenario_context().unwrap();
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Representation(
+            context,
+            representation,
+        )));
+        assert!(app.multiselect_snapshot().unwrap().targets().len() <= 1);
+    }
+    assert_ne!(app.scenario_context().unwrap().visit, first_visit);
+    choose(&mut app, message, multiselect::Choice::Replace);
+    choose(&mut app, lane, multiselect::Choice::Add);
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        snapshot.targets()
+    );
+    inert(&mut app, vec![packet(first), packet(old)], true);
+}
+
+#[test]
+fn unsupported_targets_and_bare_generic_packets_are_inert_before_side_effects() {
+    let (mut app, _, _, lane, message) = setup(true);
+    choose(&mut app, message, multiselect::Choice::Add);
+    choose(&mut app, lane, multiselect::Choice::Add);
+    let current = app.multiselect_context().unwrap();
+    let events = [
+        Target::Whole,
+        Target::Placement(message),
+        Target::ScenarioObject(Id::new_v4()),
+    ]
+    .into_iter()
+    .map(|target| {
+        packet(capture(
+            &app,
+            Intent::Choose(target, multiselect::Choice::Replace),
+        ))
+    })
+    .chain([
+        Message::DiagramSelection(multiselect::Event::Clear(current)),
+        Message::DiagramSelection(multiselect::Event::Choose(
+            current,
+            Target::ScenarioObject(message),
+            multiselect::Choice::Replace,
+        )),
+    ])
+    .collect();
+    inert(&mut app, events, true);
+}
+
+#[test]
+fn group_rejects_legacy_singleton_remove_reorder_and_index_arrows() {
+    let (mut app, owner, _, lane, message) = setup(true);
+    choose(&mut app, message, multiselect::Choice::Add);
+    choose(&mut app, lane, multiselect::Choice::Add);
+    let context = app.scenario_context().unwrap();
+    inert(
+        &mut app,
+        vec![
+            Message::ScenarioCanvas(CanvasEvent::Select(context, message)),
+            Message::ScenarioCanvas(CanvasEvent::Remove(context, lane)),
+            Message::ScenarioCanvas(CanvasEvent::Reorder {
+                context,
+                occurrence: message,
+                slot: scenario::Slot {
+                    parent: owner,
+                    before: None,
+                },
+            }),
+            Message::Command(Command::MoveStep(owner, 0, 1)),
+            Message::Delete,
+        ],
+        false,
+    );
+    assert!(!app.delete_pending);
+}
+
+#[test]
+fn secondary_selection_aba_retires_old_spacing_without_canceling_a_new_gesture() {
+    let (mut app, _, _, lane, message) = setup(true);
+    choose(&mut app, message, multiselect::Choice::Add);
+    let old = super::super::scenario_spacing::tests::packet_for_app(
+        &app,
+        spacing::Target::Message(message),
+    );
+    choose(&mut app, lane, multiselect::Choice::Add);
+    let group_begin = super::super::scenario_spacing::tests::packet_for_app(
+        &app,
+        spacing::Target::Message(message),
+    );
+    let original = app.document.snapshot();
+    let selected = app.multiselect_snapshot().unwrap();
+    let epoch = app.canvas_epoch;
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(group_begin)));
+    assert_eq!(app.project(), &original.decoded.project);
+    assert_eq!(app.document.bundle(), &original.bundle);
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        selected.targets()
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().primary(),
+        selected.primary()
+    );
+    assert_eq!(
+        app.canvas_epoch, epoch,
+        "pending click retains its admitted lifetime"
+    );
+    assert_eq!(
+        app.behavior.scenario.spacing_token(),
+        Some(group_begin.token())
+    );
+    choose(&mut app, lane, multiselect::Choice::Remove);
+    assert!(app.behavior.scenario.spacing_token().is_none());
+    inert(
+        &mut app,
+        vec![Message::ScenarioCanvas(CanvasEvent::Spacing(old))],
+        true,
+    );
+    let current = super::super::scenario_spacing::tests::packet_for_app(
+        &app,
+        spacing::Target::Message(message),
+    );
+    let spacing::Event::Begin { press_screen, .. } = current else {
+        unreachable!()
+    };
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(current)));
+    assert_eq!(app.behavior.scenario.spacing_token(), Some(current.token()));
+    inert(
+        &mut app,
+        vec![
+            Message::ScenarioCanvas(CanvasEvent::Spacing(old)),
+            Message::ScenarioCanvas(CanvasEvent::Spacing(spacing::Event::Cancel {
+                stamp: old.stamp(),
+                token: old.token(),
+            })),
+            Message::ScenarioCanvas(CanvasEvent::Spacing(spacing::Event::Finish {
+                stamp: old.stamp(),
+                token: old.token(),
+                screen: press_screen + Vector::new(0., 25.),
+            })),
+        ],
+        true,
+    );
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(
+        spacing::Event::Finish {
+            stamp: current.stamp(),
+            token: current.token(),
+            screen: press_screen + Vector::new(0., 25.),
+        },
+    )));
+    assert!(app.document.can_undo());
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[Target::ScenarioObject(message)]
+    );
+}
+
+#[test]
+fn legacy_singleton_selection_aba_retires_old_spacing_begin() {
+    for canvas in [false, true] {
+        let (mut app, _, _, lane, message) = setup(true);
+        choose(&mut app, message, multiselect::Choice::Add);
+        let old = super::super::scenario_spacing::tests::packet_for_app(
+            &app,
+            spacing::Target::Message(message),
+        );
+        for id in [lane, message] {
+            let event = if canvas {
+                Message::ScenarioCanvas(CanvasEvent::Select(app.scenario_context().unwrap(), id))
+            } else {
+                Message::Select(id)
+            };
+            let _ = app.update(event);
+            assert_eq!(app.selected, id);
+            assert_eq!(
+                app.multiselect_snapshot().unwrap().targets(),
+                &[Target::ScenarioObject(id)]
+            );
+        }
+        assert_ne!(app.scenario_context().unwrap(), old.stamp().context);
+        inert(
+            &mut app,
+            vec![Message::ScenarioCanvas(CanvasEvent::Spacing(old))],
+            true,
+        );
+        let current = super::super::scenario_spacing::tests::packet_for_app(
+            &app,
+            spacing::Target::Message(message),
+        );
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(current)));
+        assert_eq!(app.behavior.scenario.spacing_token(), Some(current.token()));
+    }
+}
+
+#[test]
+fn pending_primary_edit_is_not_applied_by_selection_input() {
+    let (mut app, _, _, lane, message) = setup(true);
+    choose(&mut app, message, multiselect::Choice::Add);
+    let _ = app.update(Message::Field(
+        "/name".into(),
+        "Pending primary name".into(),
+    ));
+    assert!(app.draft_dirty());
+    let event = capture(
+        &app,
+        Intent::Choose(Target::ScenarioObject(lane), multiselect::Choice::Add),
+    );
+    inert(&mut app, vec![packet(event)], false);
+    assert!(app.draft_dirty());
+    assert_ne!(app.project().named(message), "Pending primary name");
+}

crates/oa-desktop/src/app/scenario_removal.rs

@@ -0,0 +1,213 @@
+//! One captured Scenario selection, one impact review, one document transaction.
+use super::*;
+use crate::behavior::scenario::{self, group_removal, selection};
+use crate::diagram_selection::Snapshot;
+use crate::diagram_usage::Target;
+use crate::model_menu;
+
+#[cfg(test)]
+mod tests;
+pub(crate) mod view;
+
+#[derive(Debug, Clone)]
+pub(crate) enum Event {
+    Begin {
+        context: scenario::Context,
+        snapshot: Box<Snapshot>,
+    },
+    Query {
+        token: u64,
+        query: String,
+    },
+    Page {
+        token: u64,
+        page: usize,
+    },
+    Cancel {
+        token: u64,
+    },
+}
+
+pub(crate) struct Review {
+    pub(crate) context: scenario::Context,
+    pub(crate) snapshot: Snapshot,
+    pub(crate) plan: group_removal::Plan,
+    pub(crate) query: String,
+    pub(crate) page: usize,
+}
+
+pub(crate) fn begin(app: &App) -> Option<Message> {
+    let context = app.scenario_context()?;
+    let snapshot = app.multiselect_snapshot()?;
+    (snapshot.targets().len() > 1).then_some(Message::ScenarioRemoval(Box::new(Event::Begin {
+        context,
+        snapshot: Box::new(snapshot),
+    })))
+}
+
+impl App {
+    pub(crate) fn scenario_removal_enabled(&self) -> bool {
+        self.scenario_reorder_enabled() && self.scenario_reorder.session.is_none()
+    }
+
+    fn scenario_removal_matches(&self, context: scenario::Context, snapshot: &Snapshot) -> bool {
+        if self.scenario_context() != Some(context)
+            || !self
+                .diagram_selection
+                .as_ref()
+                .is_some_and(|selected| selected.matches(snapshot, selection::context(context)))
+        {
+            return false;
+        }
+        let visible = selection::visible(self.project(), context, self.selected);
+        snapshot
+            .targets()
+            .iter()
+            .all(|target| visible.contains(target))
+    }
+
+    pub(super) fn scenario_removal_event(&mut self, event: Event) -> Task<Message> {
+        match event {
+            Event::Begin { context, snapshot } => {
+                // Admission precedes every shared input/selection boundary. A
+                // stale packet must not prune the set or retire a newer editor.
+                if !self.scenario_removal_matches(context, &snapshot)
+                    || !self.scenario_removal_enabled()
+                    || snapshot.targets().len() < 2
+                {
+                    return Task::none();
+                }
+                let plan = match group_removal::prepare(
+                    self.project(),
+                    context.scenario,
+                    snapshot.targets(),
+                ) {
+                    Ok(plan) => plan,
+                    Err(reason) => {
+                        self.status = reason;
+                        return Task::none();
+                    }
+                };
+                let Some(Target::ScenarioObject(primary)) = snapshot.primary() else {
+                    return Task::none();
+                };
+                let primary = *primary;
+                self.scenario_reorder_cancel();
+                self.source_interaction();
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                let context = self.scenario_context().expect("admitted Scenario");
+                let snapshot = self.multiselect_snapshot().expect("admitted selection");
+                let mut request = model_menu::Request::object(primary, iced::Point::ORIGIN);
+                request.scenario = Some(Box::new(context));
+                request.selection_target = Some(Box::new(Target::ScenarioObject(primary)));
+                self.menu_sequence = self.menu_sequence.wrapping_add(1);
+                self.delete_target = model_menu::Opened::new(self, request, self.menu_sequence)
+                    .map(|opened| diagram_removal::Confirmation {
+                        snapshot: opened,
+                        selection: self.selected,
+                        placement: None,
+                        behavior_owner: Some(context.scenario),
+                        process: None,
+                        saved: None,
+                        scenario: Some(Review {
+                            context,
+                            snapshot,
+                            plan,
+                            query: String::new(),
+                            page: 0,
+                        }),
+                    });
+                self.delete_pending = self.delete_target.is_some();
+            }
+            Event::Query { token, query } => {
+                if let Some(target) = self
+                    .delete_target
+                    .as_mut()
+                    .filter(|target| target.snapshot.token == token)
+                    && let Some(review) = target.scenario.as_mut()
+                {
+                    review.query = query;
+                    review.page = 0;
+                }
+            }
+            Event::Page { token, page } => {
+                if let Some(target) = self
+                    .delete_target
+                    .as_mut()
+                    .filter(|target| target.snapshot.token == token)
+                    && let Some(review) = target.scenario.as_mut()
+                {
+                    review.page = page;
+                }
+            }
+            Event::Cancel { token } => {
+                if self.delete_target.as_ref().is_some_and(|target| {
+                    target.snapshot.token == token && target.scenario.is_some()
+                }) {
+                    self.delete_target = None;
+                    self.delete_pending = false;
+                    self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                    self.status = "Removal cancelled. Model and selection unchanged.".into();
+                }
+            }
+        }
+        Task::none()
+    }
+
+    pub(crate) fn scenario_removal_review_valid(
+        &self,
+        target: &diagram_removal::Confirmation,
+    ) -> bool {
+        let Some(review) = &target.scenario else {
+            return false;
+        };
+        self.delete_pending
+            && !self.busy
+            && target.snapshot.valid(self)
+            && self.scenario_removal_matches(review.context, &review.snapshot)
+            && self.selected == target.selection
+            && !self.source_dirty()
+            && !self.draft_dirty()
+            && !self.behavior.has_pending()
+            && !self.source_rename.open()
+            && self.scenario_reorder.session.is_none()
+            && self.behavior.scenario.spacing_token().is_none()
+            && self.behavior.scenario.canvas_tool(review.context.scenario)
+                == scenario::CanvasTool::Select
+    }
+
+    pub(super) fn confirm_scenario_removal(&mut self, token: u64) {
+        let Some(target) = self
+            .delete_target
+            .as_ref()
+            .filter(|target| target.snapshot.token == token && target.scenario.is_some())
+        else {
+            return;
+        };
+        let valid = self.scenario_removal_review_valid(target);
+        let target = self.delete_target.take().expect("captured review");
+        self.delete_pending = false;
+        self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        if !valid {
+            self.status =
+                "Removal review expired. Nothing was removed; review the current selection again."
+                    .into();
+            return;
+        }
+        let review = target.scenario.expect("Scenario review");
+        match self.document.execute(review.plan.command) {
+            Ok(_) => {
+                self.selected = review.context.scenario;
+                self.selected_node = None;
+                self.behavior.active_owner = Some(review.context.scenario);
+                self.sync();
+                self.reconcile_multiselect();
+                self.status = format!(
+                    "Removed {} selected Scenario objects in one change. Referenced definitions preserved. Undo restores the model.",
+                    review.snapshot.targets().len()
+                );
+            }
+            Err(error) => self.status = format!("Nothing removed: {error}"),
+        }
+    }
+}

crates/oa-desktop/src/app/scenario_removal/tests.rs

@@ -0,0 +1,758 @@
+use super::*;
+use crate::behavior::scenario::{CanvasEvent, direct_tests};
+use crate::behavior::scenario_layout::Representation;
+use oa_core::{Diagram, DiagramLayout, Layer, OccurrenceBody, ProjectionKind, ScenarioLayout};
+
+struct Fixture {
+    app: App,
+    owner: Id,
+    call: Id,
+    reply: Id,
+    tail: Id,
+    exchange: Id,
+}
+
+fn setup(saved: bool) -> Fixture {
+    let f = direct_tests::fixture();
+    let mut project = f.project;
+    let mut tail = project
+        .make_element(
+            Kind::Occurrence,
+            Layer::Oa,
+            "Unselected tail",
+            Some(f.owner),
+        )
+        .unwrap();
+    if let Some(SharedBody::Occurrence { body, .. }) = tail.shared_mut() {
+        *body = OccurrenceBody::Action {
+            action: None,
+            lifeline: None,
+        };
+    }
+    let tail_id = tail.id;
+    project.elements.insert(tail_id, tail);
+    project
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(tail_id);
+    let diagram = Id::new_v4();
+    project.diagrams.insert(
+        diagram,
+        Diagram {
+            id: diagram,
+            alias: "removal_view".into(),
+            name: "Removal view".into(),
+            description: "Preserved authored view".into(),
+            layer: Layer::Oa,
+            projection: ProjectionKind::Scenario { scenario: f.owner },
+            nodes: Default::default(),
+            routes: vec![],
+            view_options: Default::default(),
+            layout: Some(DiagramLayout::Scenario(ScenarioLayout::default())),
+        },
+    );
+    let other = project
+        .make_element(Kind::Scenario, Layer::Oa, "Unrelated Scenario", None)
+        .unwrap();
+    let other_owner = other.id;
+    project.elements.insert(other_owner, other);
+    let mut other_view = project.diagrams[&diagram].clone();
+    other_view.id = Id::new_v4();
+    other_view.alias = "unrelated_removal_view".into();
+    other_view.name = "Unrelated saved view".into();
+    other_view.projection = ProjectionKind::Scenario {
+        scenario: other_owner,
+    };
+    project.diagrams.insert(other_view.id, other_view);
+    let mut app = App::with_project(project);
+    let _ = app.update(Message::Select(f.owner));
+    let _ = app.update(if saved {
+        Message::Diagram(Choice {
+            id: diagram,
+            label: "Saved".into(),
+        })
+    } else {
+        Message::Page(Page::Behavior)
+    });
+    // Deliberately reverse semantic order; the primary is call, not the last step.
+    for (id, choice) in [
+        (f.reply, multiselect::Choice::Replace),
+        (f.call, multiselect::Choice::Add),
+    ] {
+        let event = selection::Event {
+            context: app.scenario_context().unwrap(),
+            snapshot: app.multiselect_snapshot().unwrap(),
+            intent: selection::Intent::Choose(Target::ScenarioObject(id), choice),
+        };
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+            event,
+        ))));
+    }
+    app.window_size = iced::Size::new(1600., 1000.);
+    let context = app.scenario_context().unwrap();
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Viewport(
+        context,
+        iced::Size::new(900., 600.),
+    )));
+    assert!(app.scenario_removal_enabled());
+    Fixture {
+        app,
+        owner: f.owner,
+        call: f.call,
+        reply: f.reply,
+        tail: tail_id,
+        exchange: f.exchange,
+    }
+}
+
+fn send(app: &mut App, event: Event) {
+    let _ = app.update(Message::ScenarioRemoval(Box::new(event)));
+}
+fn captured(app: &App) -> Event {
+    Event::Begin {
+        context: app.scenario_context().unwrap(),
+        snapshot: Box::new(app.multiselect_snapshot().unwrap()),
+    }
+}
+fn open(app: &mut App) -> u64 {
+    let event = captured(app);
+    send(app, event);
+    let target = app
+        .delete_target
+        .as_ref()
+        .expect("whole-selection review opened");
+    assert!(app.delete_pending && target.scenario.is_some());
+    assert!(
+        target.snapshot.valid(app),
+        "review captures refreshed modal epoch"
+    );
+    target.snapshot.token
+}
+
+#[test]
+fn scenario_group_removal_is_one_exact_model_source_transaction_in_both_representations() {
+    for saved in [false, true] {
+        let Fixture {
+            mut app,
+            owner,
+            call,
+            reply,
+            tail,
+            exchange,
+        } = setup(saved);
+        let baseline = app.document.snapshot();
+        let selected = app.multiselect_snapshot().unwrap();
+        let camera = app.behavior.scenario.camera_boundary();
+        let token = open(&mut app);
+        let review = app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .scenario
+            .as_ref()
+            .unwrap();
+        assert_eq!(review.snapshot.targets(), selected.targets());
+        assert_eq!(review.snapshot.primary(), selected.primary());
+        assert_eq!(review.plan.removed, [call, reply].into_iter().collect());
+        assert!(review.plan.changed.contains(&owner));
+        assert!(!review.plan.removed.contains(&exchange));
+        assert_eq!(app.document.bundle(), &baseline.bundle);
+        assert!(!app.document.can_undo());
+        let _ = app.update(Message::ConfirmDelete(token));
+        let mut expected = baseline.decoded.project.clone();
+        expected.elements.remove(&call);
+        expected.elements.remove(&reply);
+        *expected
+            .elements
+            .get_mut(&owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap() = vec![tail];
+        assert_eq!(app.project(), &expected);
+        assert!(app.project().contains(exchange));
+        assert!(!app.delete_pending && app.delete_target.is_none());
+        assert!(app.multiselect_snapshot().unwrap().targets().is_empty());
+        assert!(app.behavior.scenario.camera_boundary() == camera);
+        let removed = app.document.bundle().clone();
+        assert_ne!(removed, baseline.bundle);
+        let reopened = Document::from_bundle(removed.clone(), Default::default()).unwrap();
+        assert_eq!(reopened.project(), &expected);
+        let _ = app.update(Message::ConfirmDelete(token));
+        assert_eq!(app.document.bundle(), &removed);
+        let _ = app.update(Message::Undo);
+        assert_eq!(app.project(), &baseline.decoded.project);
+        assert_eq!(app.document.bundle(), &baseline.bundle);
+        assert!(
+            !app.document.can_undo(),
+            "one Undo restores the entire group"
+        );
+        let _ = app.update(Message::Redo);
+        assert_eq!(app.document.bundle(), &removed);
+        assert_eq!(app.project(), &expected);
+    }
+}
+
+#[test]
+fn scenario_group_removal_source_write_failure_preserves_snapshot_selection_camera_and_redo() {
+    use oa_core::source_project::{self, ProjectLimits};
+
+    let mut project = Project::empty();
+    let owner = project
+        .add_element(Kind::Scenario, Layer::Oa, "Conversation", None)
+        .unwrap();
+    let lanes = ["a", "b"].map(|alias| {
+        let id = project
+            .add_element(Kind::Lifeline, Layer::Oa, alias, Some(owner))
+            .unwrap();
+        project.elements.get_mut(&id).unwrap().alias = alias.into();
+        id
+    });
+    let mut messages = Vec::new();
+    for index in 0..256 {
+        let mut message = project
+            .make_element(
+                Kind::Occurrence,
+                Layer::Oa,
+                &format!("Message {index}"),
+                Some(owner),
+            )
+            .unwrap();
+        let SharedBody::Occurrence { body, .. } = message.shared_mut().unwrap() else {
+            panic!("message occurrence");
+        };
+        *body = OccurrenceBody::Exchange {
+            exchange: None,
+            sender: Some(lanes[0]),
+            receiver: Some(lanes[1]),
+            message_kind: oa_core::MessageKind::Asynchronous,
+            reply_to: None,
+            values: vec![],
+            operation: None,
+        };
+        messages.push(message.id);
+        project.elements.insert(message.id, message);
+    }
+    *project
+        .elements
+        .get_mut(&owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = messages.clone();
+    let diagram = Id::new_v4();
+    project.diagrams.insert(
+        diagram,
+        Diagram {
+            id: diagram,
+            alias: "removal_view".into(),
+            name: "Removal view".into(),
+            description: String::new(),
+            layer: Layer::Oa,
+            projection: ProjectionKind::Scenario { scenario: owner },
+            view_options: Default::default(),
+            nodes: Default::default(),
+            routes: vec![],
+            layout: Some(DiagramLayout::Scenario(ScenarioLayout::default())),
+        },
+    );
+    oa_core::validate_candidate(&project).unwrap();
+    let bundle = source_project::format_bundle(&project);
+    let bytes = |bundle: &source_project::SourceBundle| {
+        bundle.files.values().map(String::len).sum::<usize>()
+    };
+    let targets = lanes.map(Target::ScenarioObject);
+    let plan = group_removal::prepare(&project, owner, &targets).unwrap();
+    assert_eq!(plan.removed, lanes.into_iter().collect());
+    let mut expected = project.clone();
+    for lane in lanes {
+        expected.elements.remove(&lane);
+    }
+    for id in &messages {
+        let SharedBody::Occurrence {
+            body: OccurrenceBody::Exchange {
+                sender, receiver, ..
+            },
+            ..
+        } = expected.elements.get_mut(id).unwrap().shared_mut().unwrap()
+        else {
+            panic!("surviving message");
+        };
+        *sender = None;
+        *receiver = None;
+    }
+    oa_core::validate_candidate(&expected).unwrap();
+    let mut unrestricted = Document::from_bundle(bundle.clone(), Default::default()).unwrap();
+    unrestricted.execute(plan.command.clone()).unwrap();
+    assert_eq!(unrestricted.project(), &expected);
+    // Removal can grow losslessly edited source: each authored @a/@b becomes
+    // explicit none in a surviving message. Prove net growth after deletion,
+    // rather than assuming a budget failure or changing private Document limits.
+    assert!(bytes(unrestricted.bundle()) > bytes(&bundle));
+    let mut limits = ProjectLimits::default();
+    limits.model.max_source_bytes = bytes(&bundle);
+    let mut bounded = Document::from_bundle(bundle.clone(), limits).unwrap();
+    let error = bounded.execute(plan.command).unwrap_err();
+    assert!(
+        error
+            .diagnostics()
+            .iter()
+            .any(|diagnostic| diagnostic.diagnostic.code == "source_limit")
+    );
+    let refusal = format!("Nothing removed: {error}");
+
+    for saved in [false, true] {
+        for with_redo in [false, true] {
+            let mut app = App::with_project(project.clone());
+            app.document = Document::from_bundle(bundle.clone(), limits).unwrap();
+            let redo = if with_redo {
+                // A genuine earlier rename fits the same budget. Undo leaves
+                // its exact model/source snapshot available before this review.
+                app.document
+                    .execute(Command::Rename(owner, "Short".into()))
+                    .unwrap();
+                let future = app.document.snapshot();
+                assert!(app.document.undo());
+                Some(future)
+            } else {
+                None
+            };
+            app.sync();
+            let _ = app.update(Message::Select(owner));
+            let _ = app.update(if saved {
+                Message::Diagram(Choice {
+                    id: diagram,
+                    label: "Saved".into(),
+                })
+            } else {
+                Message::Page(Page::Behavior)
+            });
+            for (id, choice) in [
+                (lanes[1], multiselect::Choice::Replace),
+                (lanes[0], multiselect::Choice::Add),
+            ] {
+                let event = selection::Event {
+                    context: app.scenario_context().unwrap(),
+                    snapshot: app.multiselect_snapshot().unwrap(),
+                    intent: selection::Intent::Choose(Target::ScenarioObject(id), choice),
+                };
+                let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+                    event,
+                ))));
+            }
+            app.window_size = iced::Size::new(1600., 1000.);
+            let context = app.scenario_context().unwrap();
+            let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Viewport(
+                context,
+                iced::Size::new(900., 600.),
+            )));
+            assert!(app.scenario_removal_enabled());
+            let baseline = app.document.snapshot();
+            let revision = app.document.revision();
+            let selected = app.multiselect_snapshot().unwrap();
+            assert_eq!(
+                selected.targets(),
+                &[targets[1].clone(), targets[0].clone()]
+            );
+            let context = app.scenario_context().unwrap();
+            let camera = app.behavior.scenario.camera_boundary();
+            let navigation = (
+                app.page,
+                app.active_diagram,
+                app.selected,
+                app.selected_node,
+                app.behavior.active_owner,
+            );
+            let editor = app.source_editor.text();
+            assert!(!app.document.dirty() && !app.document.can_undo());
+            assert_eq!(app.document.can_redo(), with_redo);
+            let token = open(&mut app);
+            let review = app.delete_target.as_ref().unwrap();
+            assert!(app.scenario_removal_review_valid(review));
+            assert_eq!(review.scenario.as_ref().unwrap().plan.removed, plan.removed);
+            let epoch = app.canvas_epoch;
+            let _ = app.update(Message::ConfirmDelete(token));
+            assert_eq!(app.status, refusal);
+            assert!(!app.delete_pending && app.delete_target.is_none());
+            assert_ne!(app.canvas_epoch, epoch, "failed confirmation retires input");
+            assert!(std::sync::Arc::ptr_eq(&baseline, &app.document.snapshot()));
+            assert_eq!(app.project(), &baseline.decoded.project);
+            assert_eq!(app.document.bundle(), &baseline.bundle);
+            assert_eq!(app.document.revision(), revision);
+            assert!(!app.document.dirty() && !app.document.can_undo());
+            assert_eq!(app.document.can_redo(), with_redo);
+            let retained = app.multiselect_snapshot().unwrap();
+            assert_eq!(retained.targets(), selected.targets());
+            assert_eq!(retained.primary(), selected.primary());
+            assert_eq!(retained.generation(), selected.generation());
+            let after = app.scenario_context().unwrap();
+            assert_eq!(after.document, context.document);
+            assert_eq!(after.revision, context.revision);
+            assert_eq!(after.representation, context.representation);
+            assert_eq!(after.visit, context.visit);
+            assert!(app.behavior.scenario.camera_boundary() == camera);
+            assert_eq!(
+                (
+                    app.page,
+                    app.active_diagram,
+                    app.selected,
+                    app.selected_node,
+                    app.behavior.active_owner,
+                ),
+                navigation
+            );
+            assert_eq!(app.source_editor.text(), editor);
+            assert_eq!(app.source_workspace.bundle(), baseline.bundle);
+            assert!(!app.source_dirty() && !app.draft_dirty());
+            let epoch = app.canvas_epoch;
+            let _ = app.update(Message::ConfirmDelete(token));
+            assert_eq!(app.canvas_epoch, epoch);
+            assert_eq!(app.multiselect_snapshot().unwrap(), retained);
+            assert_eq!(app.status, refusal);
+            assert!(std::sync::Arc::ptr_eq(&baseline, &app.document.snapshot()));
+            if let Some(future) = redo {
+                let _ = app.update(Message::Redo);
+                assert_eq!(app.project(), &future.decoded.project);
+                assert_eq!(app.document.bundle(), &future.bundle);
+                assert!(!app.document.can_redo());
+                let _ = app.update(Message::Undo);
+                assert_eq!(app.project(), &baseline.decoded.project);
+                assert_eq!(app.document.bundle(), &baseline.bundle);
+                assert!(!app.document.can_undo() && !app.document.dirty());
+            }
+        }
+    }
+}
+
+#[test]
+fn scenario_group_removal_old_modal_packets_do_not_touch_the_new_review() {
+    let mut f = setup(true);
+    let old_begin = captured(&f.app);
+    let first = open(&mut f.app);
+    send(&mut f.app, Event::Cancel { token: first });
+    let second = open(&mut f.app);
+    assert_ne!(first, second);
+    let epoch = f.app.canvas_epoch;
+    let selected = f.app.multiselect_snapshot().unwrap();
+    let source = f.app.document.bundle().clone();
+    for message in [
+        Message::ScenarioRemoval(Box::new(old_begin)),
+        Message::ScenarioRemoval(Box::new(Event::Cancel { token: first })),
+        Message::ScenarioRemoval(Box::new(Event::Query {
+            token: first,
+            query: "stale".into(),
+        })),
+        Message::ScenarioRemoval(Box::new(Event::Page {
+            token: first,
+            page: 99,
+        })),
+        Message::ConfirmDelete(first),
+        Message::CancelDelete,
+    ] {
+        let _ = f.app.update(message);
+        let target = f.app.delete_target.as_ref().unwrap();
+        assert_eq!(target.snapshot.token, second);
+        assert!(target.scenario.as_ref().unwrap().query.is_empty());
+        assert_eq!(target.scenario.as_ref().unwrap().page, 0);
+        assert_eq!(f.app.canvas_epoch, epoch);
+        assert_eq!(f.app.multiselect_snapshot().unwrap(), selected);
+        assert_eq!(f.app.document.bundle(), &source);
+    }
+    send(
+        &mut f.app,
+        Event::Query {
+            token: second,
+            query: "reply".into(),
+        },
+    );
+    send(
+        &mut f.app,
+        Event::Page {
+            token: second,
+            page: 1,
+        },
+    );
+    assert_eq!(f.app.canvas_epoch, epoch);
+    assert_eq!(f.app.document.bundle(), &source);
+    send(&mut f.app, Event::Cancel { token: second });
+    assert!(!f.app.delete_pending);
+    assert_eq!(
+        f.app.multiselect_snapshot().unwrap().targets(),
+        selected.targets()
+    );
+    assert_eq!(
+        f.app.multiselect_snapshot().unwrap().primary(),
+        selected.primary()
+    );
+    assert!(!f.app.document.can_undo());
+}
+
+#[test]
+fn scenario_group_removal_confirm_expires_for_each_context_or_selection_change() {
+    for change in 0..5 {
+        let mut f = setup(true);
+        let token = open(&mut f.app);
+        match change {
+            0 => f.app.canvas_document = Id::new_v4(),
+            1 => {
+                let context = f.app.scenario_context().unwrap();
+                let _ = f.app.update(Message::ScenarioCanvas(CanvasEvent::Viewport(
+                    context,
+                    iced::Size::new(900., 560.),
+                )));
+                assert_ne!(f.app.canvas_epoch, context.epoch);
+            }
+            2 => {
+                f.app
+                    .document
+                    .execute(Command::Rename(f.owner, "New revision".into()))
+                    .unwrap();
+            }
+            3 => {
+                let context = f.app.scenario_context().unwrap();
+                f.app.behavior.scenario.enter_representation(
+                    context.document,
+                    f.owner,
+                    Representation::Derived { owner: f.owner },
+                );
+                f.app.behavior.scenario.enter_representation(
+                    context.document,
+                    f.owner,
+                    context.representation,
+                );
+                assert_ne!(f.app.scenario_context().unwrap().visit, context.visit);
+            }
+            _ => {
+                let selected = f.app.diagram_selection.as_mut().unwrap();
+                assert!(selected.set_primary(&Target::ScenarioObject(f.reply)));
+                assert!(selected.set_primary(&Target::ScenarioObject(f.call)));
+            }
+        }
+        let current = f.app.document.snapshot();
+        let _ = f.app.update(Message::ConfirmDelete(token));
+        assert_eq!(f.app.project(), &current.decoded.project);
+        assert_eq!(f.app.document.bundle(), &current.bundle);
+        assert!(!f.app.delete_pending && f.app.delete_target.is_none());
+        assert!(f.app.status.contains("expired"));
+    }
+}
+
+#[test]
+fn scenario_group_removal_cancel_preserves_existing_redo_and_full_selection() {
+    let mut f = setup(true);
+    let _ = f.app.update(Message::Command(Command::Rename(
+        f.tail,
+        "Redo remains available".into(),
+    )));
+    let renamed = f.app.document.bundle().clone();
+    let _ = f.app.update(Message::Undo);
+    assert!(f.app.document.can_redo());
+    // Rename inspects the renamed tail; Undo preserves that inspection. Restore
+    // the real group before testing cancellation of its removal review.
+    for (id, choice) in [
+        (f.reply, multiselect::Choice::Replace),
+        (f.call, multiselect::Choice::Add),
+    ] {
+        let event = selection::Event {
+            context: f.app.scenario_context().unwrap(),
+            snapshot: f.app.multiselect_snapshot().unwrap(),
+            intent: selection::Intent::Choose(Target::ScenarioObject(id), choice),
+        };
+        let _ = f
+            .app
+            .update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+                event,
+            ))));
+    }
+    let selected = f.app.multiselect_snapshot().unwrap();
+    assert_eq!(selected.targets().len(), 2);
+    assert!(f.app.document.can_redo());
+    let source = f.app.document.bundle().clone();
+    let token = open(&mut f.app);
+    send(&mut f.app, Event::Cancel { token });
+    assert_eq!(f.app.document.bundle(), &source);
+    assert_eq!(
+        f.app.multiselect_snapshot().unwrap().targets(),
+        selected.targets()
+    );
+    assert_eq!(
+        f.app.multiselect_snapshot().unwrap().primary(),
+        selected.primary()
+    );
+    assert!(f.app.document.can_redo() && !f.app.document.can_undo());
+    let _ = f.app.update(Message::Redo);
+    assert_eq!(f.app.document.bundle(), &renamed);
+}
+
+#[test]
+fn scenario_group_removal_does_not_retire_active_reorder_or_spacing() {
+    for spacing in [false, true] {
+        let mut f = setup(true);
+        if spacing {
+            let event = crate::app::scenario_spacing::tests::packet_for_app(
+                &f.app,
+                scenario::spacing::Target::Message(f.call),
+            );
+            let _ = f
+                .app
+                .update(Message::ScenarioCanvas(CanvasEvent::Spacing(event)));
+            assert!(f.app.behavior.scenario.spacing_token().is_some());
+        } else {
+            let event = crate::app::scenario_reorder::Event {
+                context: f.app.scenario_context().unwrap(),
+                snapshot: f.app.multiselect_snapshot().unwrap(),
+                token: Id::new_v4(),
+                intent: crate::app::scenario_reorder::Intent::Begin,
+            };
+            let _ = f.app.update(Message::ScenarioReorder(Box::new(event)));
+            assert!(f.app.scenario_reorder.session.is_some());
+        }
+        let epoch = f.app.canvas_epoch;
+        let spacing_token = f.app.behavior.scenario.spacing_token();
+        let reorder_token = f
+            .app
+            .scenario_reorder
+            .session
+            .as_ref()
+            .map(|session| session.token());
+        let source = f.app.document.bundle().clone();
+        let event = captured(&f.app);
+        send(&mut f.app, event);
+        assert!(f.app.delete_target.is_none());
+        assert_eq!(f.app.canvas_epoch, epoch);
+        assert_eq!(f.app.behavior.scenario.spacing_token(), spacing_token);
+        assert_eq!(
+            f.app
+                .scenario_reorder
+                .session
+                .as_ref()
+                .map(|session| session.token()),
+            reorder_token
+        );
+        assert_eq!(f.app.document.bundle(), &source);
+    }
+}
+
+#[test]
+fn scenario_group_removal_menu_does_not_select_its_clicked_subject() {
+    for unselected in [false, true] {
+        let mut f = setup(true);
+        let selection = f.app.multiselect_snapshot().unwrap();
+        let clicked = if unselected { f.tail } else { f.reply };
+        let mut request = model_menu::Request::object(clicked, iced::Point::ORIGIN);
+        request.scenario = f.app.scenario_context().map(Box::new);
+        request.selection_target = Some(Box::new(Target::ScenarioObject(clicked)));
+        let _ = f
+            .app
+            .update(Message::Menu(model_menu::Event::Open(request)));
+        let menu = f.app.model_menu.as_ref().expect("Scenario menu");
+        let token = menu.token;
+        let action = begin(&f.app).expect("captured group menu action");
+        let _ = f.app.update(Message::Menu(model_menu::Event::Invoke(
+            token,
+            Box::new(action),
+        )));
+        let review = f
+            .app
+            .delete_target
+            .as_ref()
+            .unwrap()
+            .scenario
+            .as_ref()
+            .unwrap();
+        assert_eq!(review.snapshot.targets(), selection.targets());
+        assert_eq!(review.snapshot.primary(), selection.primary());
+        assert_eq!(f.app.selected, f.call);
+        assert!(!review.plan.removed.contains(&f.tail));
+        assert!(f.app.project().contains(clicked));
+    }
+}
+
+#[test]
+fn scenario_group_removal_rejects_dirty_properties_and_legacy_singleton_messages() {
+    let mut f = setup(false);
+    let baseline = f.app.document.bundle().clone();
+    let selected = f.app.multiselect_snapshot().unwrap();
+    let epoch = f.app.canvas_epoch;
+    let _ = f.app.update(Message::Delete);
+    let _ = f.app.update(Message::ScenarioCanvas(CanvasEvent::Remove(
+        f.app.scenario_context().unwrap(),
+        f.call,
+    )));
+    assert!(f.app.delete_target.is_none());
+    assert_eq!(f.app.canvas_epoch, epoch);
+    assert_eq!(f.app.multiselect_snapshot().unwrap(), selected);
+    let _ = f.app.update(Message::Field(
+        "/name".into(),
+        "Unapplied group primary".into(),
+    ));
+    assert!(f.app.draft_dirty());
+    let event = captured(&f.app);
+    let epoch = f.app.canvas_epoch;
+    send(&mut f.app, event);
+    assert!(f.app.delete_target.is_none() && f.app.draft_dirty());
+    assert_eq!(f.app.canvas_epoch, epoch);
+    assert_eq!(f.app.document.bundle(), &baseline);
+    assert!(!f.app.document.can_undo());
+}
+
+#[tokio::test]
+async fn mounted_scenario_group_delete_captures_whole_set_and_repeat_does_not_confirm() {
+    use crate::behavior::canvas_workspace::tests::{Mounted, key};
+    use iced::{
+        keyboard::{self, key::Named},
+        mouse,
+    };
+    for shift in [false, true] {
+        let mut f = setup(true);
+        let mut mounted = Mounted::new(&mut f.app).await;
+        mounted
+            .batch(&mut f.app, &[key(Named::F6)], mouse::Cursor::Unavailable)
+            .await;
+        let selected = f.app.multiselect_snapshot().unwrap();
+        let source = f.app.document.bundle().clone();
+        let mut remove = key(Named::Delete);
+        if let iced::Event::Keyboard(keyboard::Event::KeyPressed { modifiers, .. }) = &mut remove {
+            *modifiers = if shift {
+                keyboard::Modifiers::SHIFT
+            } else {
+                keyboard::Modifiers::default()
+            };
+        }
+        let output = mounted
+            .batch(&mut f.app, &[remove.clone()], mouse::Cursor::Unavailable)
+            .await;
+        assert!(output.iter().any(|message| matches!(message, Message::ScenarioRemoval(event) if matches!(&**event, Event::Begin { snapshot, .. } if snapshot.targets()==selected.targets() && snapshot.primary()==selected.primary()))), "actual canvas Delete emits full captured group: {output:?}");
+        assert!(!output.iter().any(|message| matches!(
+            message,
+            Message::Delete | Message::ScenarioCanvas(CanvasEvent::Remove(..))
+        )));
+        let token = f
+            .app
+            .delete_target
+            .as_ref()
+            .expect("mounted group review")
+            .snapshot
+            .token;
+        if let iced::Event::Keyboard(keyboard::Event::KeyPressed { repeat, .. }) = &mut remove {
+            *repeat = true;
+        }
+        let output = mounted
+            .batch(&mut f.app, &[remove], mouse::Cursor::Unavailable)
+            .await;
+        assert!(
+            !output
+                .iter()
+                .any(|message| matches!(message, Message::ConfirmDelete(_)))
+        );
+        assert_eq!(f.app.delete_target.as_ref().unwrap().snapshot.token, token);
+        assert_eq!(f.app.document.bundle(), &source);
+        send(&mut f.app, Event::Cancel { token });
+        assert_eq!(
+            f.app.multiselect_snapshot().unwrap().targets(),
+            selected.targets()
+        );
+        assert!(!f.app.document.can_undo());
+    }
+}

crates/oa-desktop/src/app/scenario_removal/view.rs

@@ -0,0 +1,155 @@
+//! Review the complete captured removal impact before one explicit confirmation.
+use super::{Event, Review};
+use crate::app::{App, Message, diagram_removal};
+use crate::diagram_usage::Target;
+use crate::style;
+use iced::widget::{button, column, container, row, scrollable, text, text_input};
+use iced::{Element, Length::Fill};
+use oa_core::{Id, Project};
+use std::collections::BTreeMap;
+
+const PAGE_SIZE: usize = 6;
+
+struct ImpactRow {
+    label: String,
+    disposition: &'static str,
+}
+
+fn matching_rows(project: &Project, review: &Review) -> Vec<ImpactRow> {
+    let aliases: BTreeMap<Id, &str> = project.identities().into_iter().collect();
+    let query = review.query.trim().to_lowercase();
+    review
+        .plan
+        .removed
+        .iter()
+        .map(|id| {
+            let selected = review
+                .snapshot
+                .targets()
+                .contains(&Target::ScenarioObject(*id));
+            (
+                *id,
+                if selected {
+                    "Removed · selected"
+                } else {
+                    "Additional removed"
+                },
+            )
+        })
+        .chain(
+            review
+                .plan
+                .changed
+                .iter()
+                .map(|id| (*id, "Updated · preserved")),
+        )
+        .filter_map(|(id, disposition)| {
+            let name = project.named(id);
+            let identity = aliases
+                .get(&id)
+                .map_or_else(|| id.to_string(), |alias| format!("@{alias}"));
+            let label = if name == "Missing object" || name.is_empty() {
+                identity
+            } else {
+                format!("{name} ({identity})")
+            };
+            (query.is_empty()
+                || label.to_lowercase().contains(&query)
+                || id.to_string().contains(&query))
+            .then_some(ImpactRow { label, disposition })
+        })
+        .collect()
+}
+
+pub(crate) fn view<'a>(
+    app: &'a App,
+    target: &'a diagram_removal::Confirmation,
+) -> Element<'a, Message> {
+    let Some(review) = target.scenario.as_ref() else {
+        return text("Scenario removal review is unavailable.").into();
+    };
+    let token = target.snapshot.token;
+    let valid = app.scenario_removal_review_valid(target);
+    let rows = matching_rows(app.project(), review);
+    let pages = rows.len().div_ceil(PAGE_SIZE).max(1);
+    let page = review.page.min(pages - 1);
+    let mut impacts = column![].spacing(12).width(Fill);
+    for impact in rows.iter().skip(page * PAGE_SIZE).take(PAGE_SIZE) {
+        impacts = impacts.push(
+            column![
+                text(impact.disposition).size(12).color(style::MUTED),
+                text(impact.label.clone())
+                    .size(13)
+                    .width(Fill)
+                    .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            ]
+            .spacing(3)
+            .width(Fill),
+        );
+    }
+    if rows.is_empty() {
+        impacts = impacts.push(text("No matching affected records. Try a name or alias.").size(13));
+    }
+    let previous = button("Previous").on_press_maybe((page > 0).then(|| {
+        Message::ScenarioRemoval(Box::new(Event::Page {
+            token,
+            page: page - 1,
+        }))
+    }));
+    let next = button("Next").on_press_maybe((page + 1 < pages).then(|| {
+        Message::ScenarioRemoval(Box::new(Event::Page {
+            token,
+            page: page + 1,
+        }))
+    }));
+    let mut footer = column![].spacing(8).width(Fill);
+    if !valid {
+        footer = footer.push(
+            text("This review expired. Cancel and review the current selection again.")
+                .size(13)
+                .width(Fill)
+                .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        );
+    }
+    footer = footer.push(
+        row![
+            container(
+                button("Cancel")
+                    .padding(10)
+                    .on_press(Message::ScenarioRemoval(Box::new(Event::Cancel { token })))
+            )
+            .id("delete-cancel"),
+            container(
+                button("Remove from Scenario")
+                    .style(button::danger)
+                    .padding(10)
+                    .on_press_maybe(valid.then_some(Message::ConfirmDelete(token)))
+            )
+            .id("delete-confirm"),
+        ]
+        .spacing(10),
+    );
+    column![
+        text(format!("Remove {} Scenario objects?", review.snapshot.targets().len())).size(21),
+        text(format!("{} records removed · {} records updated", review.plan.removed.len(), review.plan.changed.len())).size(14),
+        text_input("Search affected names or aliases", &review.query)
+            .id("scenario-removal-query")
+            .on_input(move |query| Message::ScenarioRemoval(Box::new(Event::Query { token, query })))
+            .size(13),
+        row![previous, text(format!("Page {} of {} · {} matches", page + 1, pages, rows.len())).size(12), next]
+            .spacing(10).align_y(iced::Alignment::Center),
+        scrollable(column![
+            text("Removes local occurrences or participants and their owned descendants. Affected references are cleared; reusable definitions are preserved. Updated records include owning sequences and affected views. One Undo restores the entire change.")
+                .size(13).width(Fill).wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            impacts,
+        ].spacing(14).width(Fill))
+            .width(Fill).height(Fill).spacing(8).id("scenario-removal-impact"),
+        footer,
+    ]
+    .spacing(12)
+    .width(Fill)
+    // At the reviewed 732px window height, 570px content plus the modal's
+    // 52px padding leaves 110px outside the card. Only the impact body flexes.
+    .height((app.window_size.height - 160.).clamp(260., 570.))
+    .into()
+}

crates/oa-desktop/src/app/scenario_reorder.rs

@@ -0,0 +1,339 @@
+//! Exact-input adapter for an explicit semantic reorder operation.
+use super::*;
+use crate::behavior::scenario_layout::presentation::PresentationStatus;
+use crate::{
+    behavior::scenario::{
+        self,
+        reorder_session::{Outcome, Session},
+        selection,
+    },
+    diagram_selection::Snapshot,
+};
+
+#[derive(Default)]
+pub(crate) struct State {
+    pub(crate) session: Option<Session>,
+    pub(crate) query: String,
+    pub(crate) page: usize,
+    pub(crate) summary: Option<(scenario::Context, String)>,
+    summary_selection: Option<Snapshot>,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct Event {
+    pub(crate) context: scenario::Context,
+    pub(crate) snapshot: Snapshot,
+    pub(crate) token: Id,
+    pub(crate) intent: Intent,
+}
+#[derive(Debug, Clone)]
+pub(crate) enum Intent {
+    Begin,
+    Choose(scenario::Slot),
+    Query(String),
+    Page(usize),
+    Finish(scenario::Slot),
+    Cancel,
+}
+
+fn short_label(value: &str) -> String {
+    crate::views::short(value, 24)
+}
+
+/// Actual committed block order, independent of capture order or saved Y.
+fn result_neighborhood(project: &oa_core::Project, parent: Id, snapshot: &Snapshot) -> String {
+    let Some(order) = project
+        .elements
+        .get(&parent)
+        .and_then(|element| element.steps())
+    else {
+        return String::new();
+    };
+    let selected: Vec<_> = order
+        .iter()
+        .enumerate()
+        .filter(|(_, id)| {
+            snapshot
+                .targets()
+                .contains(&crate::diagram_usage::Target::ScenarioObject(**id))
+        })
+        .collect();
+    let Some((first, _)) = selected.first() else {
+        return String::new();
+    };
+    let last = selected.last().expect("nonempty block").0;
+    let label = |index: usize| format!("#{} @{}", index + 1, project.elements[&order[index]].alias);
+    let left = first
+        .checked_sub(1)
+        .map_or_else(|| "Start".to_owned(), label);
+    let right = if last + 1 < order.len() {
+        label(last + 1)
+    } else {
+        "End".to_owned()
+    };
+    let mut members = selected
+        .iter()
+        .take(3)
+        .map(|(index, _)| label(*index))
+        .collect::<Vec<_>>()
+        .join(", ");
+    if selected.len() > 3 {
+        members.push_str(&format!(", +{} more", selected.len() - 3));
+    }
+    format!("{left} → [{members}] → {right}")
+}
+
+impl App {
+    pub(crate) fn scenario_reorder_enabled(&self) -> bool {
+        self.spacing_enabled()
+            && diagram_removal::enabled(self)
+            && self.behavior.scenario.spacing_token().is_none()
+            && self.scenario_context().is_some_and(|context| {
+                self.behavior.scenario.canvas_tool(context.scenario) == scenario::CanvasTool::Select
+            })
+    }
+
+    pub(crate) fn scenario_reorder_cancel(&mut self) {
+        if self.scenario_reorder.session.take().is_some() {
+            self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        }
+        self.scenario_reorder.query.clear();
+        self.scenario_reorder.page = 0;
+        self.scenario_reorder.summary = None;
+        self.scenario_reorder.summary_selection = None;
+    }
+
+    pub(crate) fn scenario_reorder_reconcile(&mut self) {
+        if self
+            .scenario_reorder
+            .summary
+            .as_ref()
+            .is_some_and(|(context, _)| {
+                // A committed result is presentation, not a live authoring packet.
+                // Resizing diagnostics or moving the camera retires input epochs
+                // without changing the result's document, view or selection.
+                let same_result = self.scenario_context().is_some_and(|mut current| {
+                    current.epoch = context.epoch;
+                    current == *context
+                });
+                let same_selection = self
+                    .scenario_reorder
+                    .summary_selection
+                    .as_ref()
+                    .zip(self.diagram_selection.as_ref())
+                    .is_some_and(|(snapshot, selected)| {
+                        selected.matches(snapshot, snapshot.context())
+                    });
+                !same_result || !same_selection
+            })
+        {
+            self.scenario_reorder.summary = None;
+            self.scenario_reorder.summary_selection = None;
+        }
+        let Some(session) = self.scenario_reorder.session.as_ref() else {
+            return;
+        };
+        let valid = self.scenario_reorder_enabled()
+            && self
+                .scenario_context()
+                .zip(self.multiselect_snapshot())
+                .is_some_and(|(context, snapshot)| {
+                    session.matches(self.project(), context, &snapshot, session.token())
+                });
+        if !valid {
+            self.scenario_reorder_cancel();
+        }
+    }
+
+    pub(crate) fn scenario_reorder_event(&mut self, event: Event) -> Task<Message> {
+        // Reject stale envelopes before touching any newer operation or UI state.
+        if event.token.is_nil()
+            || self.scenario_context() != Some(event.context)
+            || !self
+                .diagram_selection
+                .as_ref()
+                .is_some_and(|selection_state| {
+                    selection_state.matches(&event.snapshot, selection::context(event.context))
+                })
+        {
+            return Task::none();
+        }
+        if matches!(&event.intent, Intent::Begin) {
+            if self.scenario_reorder.session.is_some() || !self.scenario_reorder_enabled() {
+                return Task::none();
+            }
+            // Retire the captured Begin before construction, including failed starts.
+            self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+            let context = self.scenario_context().expect("admitted scenario");
+            let snapshot = self.multiselect_snapshot().expect("admitted selection");
+            self.scenario_reorder.query.clear();
+            self.scenario_reorder.page = 0;
+            self.scenario_reorder.summary = None;
+            self.scenario_reorder.summary_selection = None;
+            match Session::new(
+                self.document.snapshot().decoded.project.clone().into(),
+                context,
+                snapshot,
+                event.token,
+            ) {
+                Ok(session) => {
+                    self.scenario_reorder.session = Some(session);
+                    self.status = "Choose a semantic destination, then apply reorder. Saved positions are preserved.".into();
+                    return scenario::reorder_view::focus_query(event.token);
+                }
+                Err(reason) => self.status = reason,
+            }
+            return Task::none();
+        }
+        let Some(session) = self.scenario_reorder.session.as_ref() else {
+            return Task::none();
+        };
+        if !session.matches(self.project(), event.context, &event.snapshot, event.token) {
+            return Task::none();
+        }
+        if let Intent::Finish(slot) = &event.intent
+            && session
+                .current_preview()
+                .is_none_or(|preview| preview.slot != *slot)
+        {
+            return Task::none();
+        }
+        if matches!(&event.intent, Intent::Cancel) {
+            self.scenario_reorder_cancel();
+            self.status = "Reorder cancelled. Sequence unchanged.".into();
+            return Task::none();
+        }
+        if !self.scenario_reorder_enabled() {
+            self.scenario_reorder_cancel();
+            return Task::none();
+        }
+        match event.intent {
+            Intent::Choose(slot) => {
+                let preview = self
+                    .scenario_reorder
+                    .session
+                    .as_mut()
+                    .expect("admitted session")
+                    .preview(slot);
+                self.status = match &preview.outcome {
+                    Outcome::Refused(reason) => reason.clone(),
+                    Outcome::Noop => "This destination leaves the semantic order unchanged.".into(),
+                    Outcome::Change => match preview.presentation.as_ref().map(|shown| shown.status()) {
+                        Some(PresentationStatus::Ready) => "Review the semantic order, then apply reorder. Saved positions are preserved.".into(),
+                        Some(PresentationStatus::Fallback { .. }) => "The new semantic order requires automatic display fallback. Apply keeps the requested saved view and its authored positions.".into(),
+                        _ => "The candidate cannot be displayed; reorder cannot be applied.".into(),
+                    },
+                };
+            }
+            Intent::Query(query) => {
+                self.scenario_reorder.query = query;
+                self.scenario_reorder.page = 0;
+            }
+            Intent::Page(page) => self.scenario_reorder.page = page,
+            Intent::Finish(slot) => {
+                let label = |id| {
+                    self.project().elements.get(&id).map_or_else(
+                        || id.to_string(),
+                        |element| {
+                            format!(
+                                "{} (@{})",
+                                short_label(&element.name),
+                                short_label(&element.alias)
+                            )
+                        },
+                    )
+                };
+                let parent_name = label(slot.parent);
+                let destination = slot.before.map_or_else(
+                    || "at the end".to_owned(),
+                    |anchor| format!("before {}", label(anchor)),
+                );
+                let session = self
+                    .scenario_reorder
+                    .session
+                    .take()
+                    .expect("admitted session");
+                let selection_visible = session
+                    .current_preview()
+                    .is_some_and(|preview| preview.selection_visible);
+                let result =
+                    session.finish(self.project(), event.context, &event.snapshot, event.token);
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                self.scenario_reorder.query.clear();
+                self.scenario_reorder.page = 0;
+                match result {
+                    Err(reason) => self.status = reason,
+                    Ok(completion) => {
+                        debug_assert_eq!(completion.representation, event.context.representation);
+                        if !selection_visible {
+                            self.status = "The candidate would hide a selected occurrence; reorder was not applied.".into();
+                        } else if matches!(
+                            completion.presentation_status,
+                            PresentationStatus::Unavailable { .. }
+                        ) {
+                            self.status =
+                                "The candidate cannot be displayed; reorder was not applied."
+                                    .into();
+                        } else if let Some(command) = completion.command {
+                            match self.document.execute(*command) {
+                                Ok(_) => {
+                                    if let Some(crate::diagram_usage::Target::ScenarioObject(
+                                        primary,
+                                    )) = completion.snapshot.primary()
+                                    {
+                                        self.selected = *primary;
+                                    }
+                                    self.sync();
+                                    self.reconcile_multiselect();
+                                    self.inspect_scenario_multiselect_primary();
+                                    let mut summary = format!(
+                                        "Moved {} selected occurrences {} in {}. {}. Saved positions are preserved.",
+                                        completion.snapshot.targets().len(),
+                                        destination,
+                                        parent_name,
+                                        result_neighborhood(
+                                            self.project(),
+                                            slot.parent,
+                                            &completion.snapshot
+                                        )
+                                    );
+                                    if matches!(
+                                        completion.presentation_status,
+                                        PresentationStatus::Fallback { .. }
+                                    ) {
+                                        summary.push_str(" Automatic display fallback is active.");
+                                    }
+                                    self.scenario_reorder.summary =
+                                        self.scenario_context().map(|context| (context, summary));
+                                    self.scenario_reorder.summary_selection =
+                                        self.multiselect_snapshot();
+                                    self.status = if matches!(
+                                        completion.presentation_status,
+                                        PresentationStatus::Fallback { .. }
+                                    ) {
+                                        "Semantic order updated. Automatic display fallback is active; the requested saved view and authored positions are preserved.".into()
+                                    } else {
+                                        "Semantic order updated. Saved positions are preserved."
+                                            .into()
+                                    };
+                                }
+                                Err(error) => {
+                                    self.status = format!("Reorder was not applied: {error}")
+                                }
+                            }
+                        } else {
+                            self.status = "Semantic order unchanged.".into();
+                        }
+                    }
+                }
+            }
+            Intent::Begin | Intent::Cancel => unreachable!(),
+        }
+        Task::none()
+    }
+}
+
+#[cfg(test)]
+mod summary_tests;
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/app/scenario_reorder/summary_tests.rs

@@ -0,0 +1,231 @@
+use super::*;
+use crate::behavior::scenario::{CanvasEvent, Slot, direct_tests};
+use crate::behavior::scenario_layout::Representation;
+use crate::diagram_usage::Target;
+use oa_core::{Diagram, DiagramLayout, Layer, OccurrenceBody, ProjectionKind, ScenarioLayout};
+
+fn committed() -> (App, Id, Id, oa_core::source_project::SourceBundle) {
+    let f = direct_tests::fixture();
+    let mut project = f.project;
+    let mut extra = project
+        .make_element(Kind::Occurrence, Layer::Oa, "Tail", Some(f.owner))
+        .unwrap();
+    if let Some(oa_core::SharedBody::Occurrence { body, .. }) = extra.shared_mut() {
+        *body = OccurrenceBody::Action {
+            action: None,
+            lifeline: None,
+        };
+    }
+    let extra_id = extra.id;
+    project.elements.insert(extra_id, extra);
+    project
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(extra_id);
+    let diagram = Id::new_v4();
+    project.diagrams.insert(
+        diagram,
+        Diagram {
+            id: diagram,
+            alias: "summary_view".into(),
+            name: "Summary view".into(),
+            description: String::new(),
+            layer: Layer::Oa,
+            projection: ProjectionKind::Scenario { scenario: f.owner },
+            nodes: Default::default(),
+            routes: vec![],
+            view_options: Default::default(),
+            layout: Some(DiagramLayout::Scenario(ScenarioLayout::default())),
+        },
+    );
+    let mut app = App::with_project(project);
+    let _ = app.update(Message::Select(f.owner));
+    let _ = app.update(Message::Diagram(Choice {
+        id: diagram,
+        label: "Summary view".into(),
+    }));
+    for (id, choice) in [
+        (f.call, multiselect::Choice::Replace),
+        (f.reply, multiselect::Choice::Add),
+    ] {
+        let event = selection::Event {
+            context: app.scenario_context().unwrap(),
+            snapshot: app.multiselect_snapshot().unwrap(),
+            intent: selection::Intent::Choose(Target::ScenarioObject(id), choice),
+        };
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+            event,
+        ))));
+    }
+    viewport(&mut app, 700.);
+    let baseline = app.document.bundle().clone();
+    dispatch(&mut app, Intent::Begin);
+    let slot = Slot {
+        parent: f.owner,
+        before: None,
+    };
+    dispatch(&mut app, Intent::Choose(slot));
+    dispatch(&mut app, Intent::Finish(slot));
+    assert_eq!(
+        app.project().elements[&f.owner].steps().unwrap(),
+        &[extra_id, f.call, f.reply]
+    );
+    assert!(app.scenario_reorder.summary.is_some(), "{}", app.status);
+    (app, f.owner, f.call, baseline)
+}
+
+fn dispatch(app: &mut App, intent: Intent) {
+    let event = Event {
+        context: app.scenario_context().unwrap(),
+        snapshot: app.multiselect_snapshot().unwrap(),
+        token: app
+            .scenario_reorder
+            .session
+            .as_ref()
+            .map_or_else(Id::new_v4, Session::token),
+        intent,
+    };
+    let _ = app.update(Message::ScenarioReorder(Box::new(event)));
+}
+
+fn viewport(app: &mut App, height: f32) {
+    let context = app.scenario_context().unwrap();
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Viewport(
+        context,
+        iced::Size::new(900., height),
+    )));
+}
+
+#[test]
+fn scenario_reorder_summary_survives_diagnostics_resize_and_camera_then_undo_clears() {
+    let (mut app, _, _, baseline) = committed();
+    let summary = app.scenario_reorder.summary.clone();
+    let changed = app.document.bundle().clone();
+    let epoch = app.canvas_epoch;
+    viewport(&mut app, 660.);
+    assert_ne!(
+        app.canvas_epoch, epoch,
+        "real diagnostics-height viewport change must retire input"
+    );
+    assert_eq!(app.scenario_reorder.summary, summary);
+    let context = app.scenario_context().unwrap();
+    let camera = app.behavior.scenario.camera_boundary();
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Camera(
+        context,
+        app.camera_epoch,
+        crate::behavior::canvas_workspace::Event::Pan(iced::Vector::new(24., 12.)),
+    )));
+    assert!(app.behavior.scenario.camera_boundary() != camera);
+    assert_eq!(app.scenario_reorder.summary, summary);
+    assert_eq!(app.document.bundle(), &changed);
+    let _ = app.update(Message::Undo);
+    assert!(app.scenario_reorder.summary.is_none());
+    assert!(app.scenario_reorder.summary_selection.is_none());
+    assert_eq!(app.document.bundle(), &baseline);
+}
+
+#[test]
+fn scenario_reorder_summary_retires_on_view_selection_and_new_operation() {
+    for action in 0..3 {
+        let (mut app, owner, call, _) = committed();
+        let source = app.document.bundle().clone();
+        match action {
+            0 => {
+                let context = app.scenario_context().unwrap();
+                let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Representation(
+                    context,
+                    Representation::Derived { owner },
+                )));
+                assert_eq!(
+                    app.scenario_context().unwrap().representation,
+                    Representation::Derived { owner }
+                );
+            }
+            1 => {
+                let event = selection::Event {
+                    context: app.scenario_context().unwrap(),
+                    snapshot: app.multiselect_snapshot().unwrap(),
+                    intent: selection::Intent::Collapse(Target::ScenarioObject(call)),
+                };
+                let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+                    event,
+                ))));
+            }
+            _ => {
+                dispatch(&mut app, Intent::Begin);
+                assert!(app.scenario_reorder.session.is_some());
+                dispatch(&mut app, Intent::Cancel);
+                assert!(app.scenario_reorder.session.is_none());
+                assert_eq!(app.status, "Reorder cancelled. Sequence unchanged.");
+            }
+        }
+        assert!(app.scenario_reorder.summary.is_none());
+        assert!(app.scenario_reorder.summary_selection.is_none());
+        assert_eq!(app.document.bundle(), &source);
+    }
+}
+
+#[test]
+fn scenario_reorder_summary_selection_generation_aba_is_not_a_camera_change() {
+    let (mut app, _, call, _) = committed();
+    let captured = app.multiselect_snapshot().unwrap();
+    let selected = app.diagram_selection.as_mut().unwrap();
+    assert!(selected.set_primary(&Target::ScenarioObject(call)));
+    assert!(selected.set_primary(captured.primary().unwrap()));
+    assert_eq!(selected.targets(), captured.targets());
+    assert_eq!(selected.primary(), captured.primary());
+    app.scenario_reorder_reconcile();
+    assert!(app.scenario_reorder.summary.is_none());
+}
+
+#[test]
+fn scenario_reorder_summary_clears_after_real_spacing_commit_without_another_event() {
+    use crate::behavior::scenario::spacing::{Event as Spacing, Target as SpacingTarget};
+    let (mut app, owner, call, _) = committed();
+    let reordered = app.document.snapshot();
+    let selection = app.multiselect_snapshot().unwrap();
+    let begin =
+        crate::app::scenario_spacing::tests::packet_for_app(&app, SpacingTarget::Message(call));
+    let Spacing::Begin { press_screen, .. } = begin else {
+        unreachable!()
+    };
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(begin)));
+    assert_eq!(app.behavior.scenario.spacing_token(), Some(begin.token()));
+    assert!(app.scenario_reorder.summary.is_some());
+    let screen = press_screen + iced::Vector::new(0., 24.);
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(
+        Spacing::Move {
+            stamp: begin.stamp(),
+            token: begin.token(),
+            screen,
+        },
+    )));
+    assert_eq!(app.document.bundle(), &reordered.bundle);
+    let finish = Spacing::Finish {
+        stamp: begin.stamp(),
+        token: begin.token(),
+        screen,
+    };
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(finish)));
+    assert_ne!(
+        app.document.bundle(),
+        &reordered.bundle,
+        "spacing must actually commit: {}",
+        app.status
+    );
+    assert_eq!(
+        app.project().elements[&owner].steps(),
+        reordered.decoded.project.elements[&owner].steps()
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        selection.targets()
+    );
+    assert!(app.scenario_reorder.summary.is_none());
+    assert!(app.scenario_reorder.summary_selection.is_none());
+    let _ = app.update(Message::Undo);
+    assert_eq!(app.document.bundle(), &reordered.bundle);
+}

crates/oa-desktop/src/app/scenario_spacing.rs

@@ -1,9 +1,33 @@
 //! Admit spacing packets before ordinary navigation can retire a newer reveal.
 use super::*;
-use behavior::scenario::spacing::{Event, controller::Finish};
+use crate::diagram_usage::Target;
+use behavior::scenario::{
+    selection,
+    spacing::{Event, Refusal, controller::Finish},
+};
 
 #[cfg(test)]
-mod tests;
+mod group_tests;
+#[cfg(test)]
+pub(super) mod tests;
+
+fn refusal_reason(refusal: &Refusal) -> String {
+    match refusal {
+        Refusal::InvalidSelection(reason) => (*reason).into(),
+        Refusal::TargetNotRendered(_) => {
+            "Every selected object must be a rendered local message or lifeline in this saved view."
+                .into()
+        }
+        Refusal::Geometry(_) => {
+            "These positions cannot be displayed together. The saved arrangement is unchanged."
+                .into()
+        }
+        Refusal::Command(reason) => reason.clone(),
+        _ => {
+            "The drag could not be applied in this view. The saved arrangement is unchanged.".into()
+        }
+    }
+}
 
 impl App {
     pub(super) fn spacing_enabled(&self) -> bool {
@@ -16,22 +40,54 @@ impl App {
     }
 
     pub(super) fn scenario_spacing(&mut self, event: Event) -> Task<Message> {
+        if self.scenario_reorder.session.is_some() {
+            return Task::none();
+        }
         let stamp = event.stamp();
         if self.scenario_context() != Some(stamp.context) || self.camera_epoch != stamp.camera_epoch
         {
             return Task::none();
         }
+        let Some(snapshot) = self.multiselect_snapshot() else {
+            return Task::none();
+        };
+        if snapshot.generation() != stamp.selection_generation
+            || snapshot.context() != selection::context(stamp.context)
+        {
+            return Task::none();
+        }
         let state = &self.behavior.scenario;
         let matches =
             state.spacing_token() == Some(event.token()) && state.spacing_stamp() == Some(stamp);
         if match event {
             Event::Begin { token, .. } => token.is_nil() || state.spacing_token().is_some(),
-            _ => !matches,
+            _ => {
+                !matches
+                    || !state.spacing_snapshot().is_some_and(|captured| {
+                        self.diagram_selection.as_ref().is_some_and(|selected| {
+                            selected.matches(captured, selection::context(stamp.context))
+                        })
+                    })
+            }
         } {
             return Task::none();
         }
+        if matches!(event, Event::Begin { .. }) {
+            let visible = selection::visible(self.project(), stamp.context, self.selected);
+            if !snapshot
+                .targets()
+                .iter()
+                .all(|target| visible.contains(target))
+            {
+                // This otherwise current Begin cannot be replayed after repair.
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                self.status =
+                    "Every selected object must still be visible before moving the group.".into();
+                return Task::none();
+            }
+        }
         if matches!(event, Event::Cancel { .. }) || !self.spacing_enabled() {
-            if self.behavior.scenario.cancel_spacing() {
+            if self.behavior.scenario.cancel_spacing() || matches!(event, Event::Begin { .. }) {
                 self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
             }
             return Task::none();
@@ -39,18 +95,38 @@ impl App {
         match event {
             Event::Begin { .. } => {
                 let mut state = std::mem::take(&mut self.behavior.scenario);
-                let result = state.begin_spacing(self.project(), event);
+                let result = state.begin_spacing_with_snapshot(self.project(), event, snapshot);
                 self.behavior.scenario = state;
-                if result.is_err() {
-                    self.status = "The drag could not start in this view. Try again.".into();
+                if let Err(error) = result {
+                    // Consume admitted failed starts too; a repeated Begin is stale.
+                    self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                    self.status = refusal_reason(&error);
                 }
             }
             Event::Move { screen, .. } => self.behavior.scenario.move_spacing(screen),
             Event::Finish { screen, .. } => {
+                // Full captured selection matched above, before taking the session.
+                let captured = self
+                    .behavior
+                    .scenario
+                    .spacing_snapshot()
+                    .cloned()
+                    .expect("admitted session snapshot");
+                let group = captured.targets().len() > 1;
                 let finished = self.behavior.scenario.finish_spacing(screen);
-                // Retire queued packets even for zero motion or a refused finish.
                 self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
                 match finished {
+                    Ok(Finish::Click(target)) if group => {
+                        let target = Target::ScenarioObject(target);
+                        // The controller only captures a pressed member of this set.
+                        if captured.targets().contains(&target) {
+                            self.diagram_selection
+                                .as_mut()
+                                .expect("admitted selection")
+                                .replace(target, |_| true);
+                            self.inspect_scenario_multiselect_primary();
+                        }
+                    }
                     Ok(Finish::Click(target)) => self.select(target),
                     Ok(Finish::Noop) => {}
                     Ok(Finish::Commit {
@@ -58,28 +134,38 @@ impl App {
                         selected,
                         scale,
                         pan,
-                    }) => {
-                        // Document prepares and writes the source candidate before
-                        // committing its snapshot. Failure leaves camera/selection
-                        // and source/history at their accepted values.
-                        match self.document.execute(*command) {
-                            Ok(_) => {
-                                self.selected = selected;
-                                self.selected_node = None;
-                                self.diagram_navigation_focus = None;
-                                self.behavior.scenario.accept_spacing_camera(scale, pan);
-                                self.sync();
-                                self.status = "Scenario spacing updated.".into();
+                    }) => match self.document.execute(*command) {
+                        Ok(_) => {
+                            self.selected = if group {
+                                match captured.primary() {
+                                    Some(Target::ScenarioObject(id)) => *id,
+                                    _ => selected,
+                                }
+                            } else {
+                                selected
+                            };
+                            self.selected_node = None;
+                            self.diagram_navigation_focus = None;
+                            self.behavior.scenario.accept_spacing_camera(scale, pan);
+                            self.sync();
+                            if group {
+                                self.inspect_scenario_multiselect_primary();
                             }
-                            Err(error) => self.status = format!("Spacing was not applied: {error}"),
+                            self.status = if group {
+                                format!(
+                                    "Spacing updated for {} selected objects. Scenario order is unchanged.",
+                                    captured.targets().len()
+                                )
+                            } else {
+                                "Scenario spacing updated.".into()
+                            };
                         }
-                    }
-                    Err(_) => {
-                        self.status =
-                            "That position cannot be applied. The saved arrangement is unchanged."
-                                .into()
-                    }
+                        Err(error) => self.status = format!("Spacing was not applied: {error}"),
+                    },
+                    Err(error) => self.status = refusal_reason(&error),
                 }
+                self.reconcile_multiselect();
+                self.scenario_reorder_reconcile();
             }
             Event::Cancel { .. } => unreachable!(),
         }

crates/oa-desktop/src/app/scenario_spacing/group_tests.rs

@@ -0,0 +1,374 @@
+use super::tests::{begin, finish, move_to, packet_for_app, send, setup};
+use super::*;
+use crate::behavior::scenario::{CanvasEvent, selection, spacing::Target};
+use crate::behavior::scenario_layout::Representation;
+use crate::diagram_usage::Target as SelectedTarget;
+use iced::Vector;
+use oa_core::{
+    DiagramLayout, OccurrenceEndpoint, ScenarioLanePosition, ScenarioLayout,
+    ScenarioMessagePosition,
+};
+
+fn id(app: &App, alias: &str) -> Id {
+    app.project()
+        .identities()
+        .into_iter()
+        .find(|(_, a)| *a == alias)
+        .unwrap()
+        .0
+}
+fn choose(app: &mut App, id: Id, choice: multiselect::Choice) {
+    let event = selection::Event {
+        context: app.scenario_context().unwrap(),
+        snapshot: app.multiselect_snapshot().unwrap(),
+        intent: selection::Intent::Choose(SelectedTarget::ScenarioObject(id), choice),
+    };
+    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(
+        event,
+    ))));
+}
+fn group(messages: bool, reverse: bool) -> (App, [Id; 2]) {
+    let (mut app, lane, message) = setup();
+    let ids = if messages {
+        [message, id(&app, "second")]
+    } else {
+        [lane, id(&app, "operator")]
+    };
+    let order = if reverse { [ids[1], ids[0]] } else { ids };
+    for member in order {
+        choose(&mut app, member, multiselect::Choice::Add);
+    }
+    (app, ids)
+}
+fn target(messages: bool, id: Id) -> Target {
+    if messages {
+        Target::Message(id)
+    } else {
+        Target::Lane(id)
+    }
+}
+fn delta(messages: bool, pixels: f32) -> Vector {
+    if messages {
+        Vector::new(0., pixels)
+    } else {
+        Vector::new(pixels, 0.)
+    }
+}
+
+#[test]
+fn either_pressed_member_moves_complete_group_and_preserves_primary_source_and_one_history_step() {
+    for messages in [false, true] {
+        for pressed_index in 0..2 {
+            let (mut app, ids) = group(messages, true);
+            // Automatic lane order depends on generated identities. Give this
+            // literal geometry oracle explicit authored starting coordinates.
+            let c = app.scenario_context().unwrap();
+            let Representation::Saved { diagram } = c.representation else {
+                unreachable!()
+            };
+            let mut initial = app.project().clone();
+            let mut members = ids.to_vec();
+            members.sort();
+            let mut layout = ScenarioLayout::default();
+            for member in members {
+                if messages {
+                    layout.messages.push(ScenarioMessagePosition {
+                        address: OccurrenceEndpoint {
+                            references: vec![],
+                            occurrence: member,
+                        },
+                        send_y: if member == ids[0] { 148. } else { 240. },
+                    });
+                } else {
+                    layout.lanes.push(ScenarioLanePosition {
+                        lifeline: member,
+                        x: if member == ids[0] { 160. } else { 400. },
+                    });
+                }
+            }
+            initial.diagrams.get_mut(&diagram).unwrap().layout =
+                Some(DiagramLayout::Scenario(layout));
+            app.document =
+                Document::from_project(initial, oa_core::source_project::ProjectLimits::default())
+                    .unwrap();
+            app.sync();
+            let original = app.document.snapshot();
+            let original_selection = app.multiselect_snapshot().unwrap();
+            let primary = app.selected;
+            let c = app.scenario_context().unwrap();
+            let Representation::Saved { diagram } = c.representation else {
+                unreachable!()
+            };
+            let (event, start, scale) = begin(&mut app, target(messages, ids[pressed_index]));
+            let world_delta = 24. / scale;
+            move_to(&mut app, event, start + delta(messages, 24.));
+            assert_eq!(app.project(), &original.decoded.project);
+            assert_eq!(app.document.bundle(), &original.bundle);
+            assert_eq!(app.selected, primary);
+            assert_eq!(
+                app.behavior.scenario.spacing_snapshot(),
+                Some(&original_selection)
+            );
+            let mut expected = original.decoded.project.clone();
+            let mut members = ids.to_vec();
+            members.sort();
+            let mut layout = ScenarioLayout::default();
+            for member in members {
+                if messages {
+                    let y: f32 = if member == ids[0] { 148. } else { 240. };
+                    layout.messages.push(ScenarioMessagePosition {
+                        address: OccurrenceEndpoint {
+                            references: vec![],
+                            occurrence: member,
+                        },
+                        send_y: (f64::from(y) + f64::from(world_delta)) as f32,
+                    });
+                } else {
+                    let x: f32 = if member == ids[0] { 160. } else { 400. };
+                    layout.lanes.push(ScenarioLanePosition {
+                        lifeline: member,
+                        x: (f64::from(x) + f64::from(world_delta)) as f32,
+                    });
+                }
+            }
+            expected.diagrams.get_mut(&diagram).unwrap().layout =
+                Some(DiagramLayout::Scenario(layout));
+            finish(&mut app, event, start + delta(messages, 24.));
+            assert_eq!(app.project(), &expected);
+            assert_eq!(app.selected, primary);
+            assert_eq!(
+                app.multiselect_snapshot().unwrap().targets(),
+                original_selection.targets()
+            );
+            assert_eq!(
+                app.multiselect_snapshot().unwrap().primary(),
+                original_selection.primary()
+            );
+            let saved = app.document.bundle().clone();
+            let _ = app.update(Message::ShortcutUndo(false));
+            assert_eq!(app.project(), &original.decoded.project);
+            assert_eq!(app.document.bundle(), &original.bundle);
+            assert!(!app.document.can_undo() && app.document.can_redo());
+            let _ = app.update(Message::ShortcutUndo(true));
+            assert_eq!(app.project(), &expected);
+            assert_eq!(app.document.bundle(), &saved);
+            let reopened =
+                Document::from_bundle(saved, oa_core::source_project::ProjectLimits::default())
+                    .unwrap();
+            assert_eq!(reopened.project(), &expected);
+        }
+    }
+}
+
+#[test]
+fn group_stationary_click_collapses_but_offaxis_outback_cancel_preserve_group_and_redo() {
+    for messages in [false, true] {
+        for mode in 0..4 {
+            let (mut app, ids) = group(messages, true);
+            let (seed, start, _) = begin(&mut app, target(messages, ids[0]));
+            finish(&mut app, seed, start + delta(messages, 20.));
+            let _ = app.update(Message::ShortcutUndo(false));
+            assert!(app.document.can_redo());
+            let original = app.document.snapshot();
+            let selected = app.multiselect_snapshot().unwrap();
+            let primary = app.selected;
+            let camera = app.behavior.scenario.camera_boundary();
+            let (event, start, _) = begin(&mut app, target(messages, ids[1]));
+            match mode {
+                0 => finish(&mut app, event, start),
+                1 => finish(&mut app, event, start + delta(!messages, 50.)),
+                2 => {
+                    move_to(&mut app, event, start + delta(messages, 30.));
+                    finish(&mut app, event, start);
+                }
+                _ => {
+                    move_to(&mut app, event, start + delta(messages, 30.));
+                    send(
+                        &mut app,
+                        Event::Cancel {
+                            stamp: event.stamp(),
+                            token: event.token(),
+                        },
+                    );
+                }
+            }
+            assert_eq!(app.project(), &original.decoded.project);
+            assert_eq!(app.document.bundle(), &original.bundle);
+            assert!(app.document.can_redo() && !app.document.can_undo());
+            assert!(camera == app.behavior.scenario.camera_boundary());
+            if mode == 0 {
+                assert_eq!(
+                    app.multiselect_snapshot().unwrap().targets(),
+                    &[SelectedTarget::ScenarioObject(ids[1])]
+                );
+                assert_eq!(app.selected, ids[1]);
+            } else {
+                assert_eq!(
+                    app.multiselect_snapshot().unwrap().targets(),
+                    selected.targets()
+                );
+                assert_eq!(app.selected, primary);
+            }
+        }
+    }
+}
+
+#[test]
+fn stale_group_packets_and_generation_forgery_do_not_disturb_a_newer_live_gesture() {
+    let (mut app, ids) = group(true, true);
+    let (old, start, _) = begin(&mut app, Target::Message(ids[0]));
+    send(
+        &mut app,
+        Event::Cancel {
+            stamp: old.stamp(),
+            token: old.token(),
+        },
+    );
+    let (current, current_start, _) = begin(&mut app, Target::Message(ids[1]));
+    let original = app.document.snapshot();
+    let selection = app.multiselect_snapshot();
+    let epoch = app.canvas_epoch;
+    let status = app.status.clone();
+    let mut forged = current;
+    if let Event::Begin { stamp, .. } = &mut forged {
+        stamp.selection_generation = stamp.selection_generation.wrapping_add(1);
+    }
+    for event in [
+        old,
+        forged,
+        Event::Move {
+            stamp: old.stamp(),
+            token: old.token(),
+            screen: start + Vector::new(0., 90.),
+        },
+        Event::Finish {
+            stamp: old.stamp(),
+            token: old.token(),
+            screen: start + Vector::new(0., 90.),
+        },
+        Event::Cancel {
+            stamp: old.stamp(),
+            token: old.token(),
+        },
+    ] {
+        send(&mut app, event);
+        assert_eq!(app.canvas_epoch, epoch);
+        assert_eq!(app.status, status);
+        assert_eq!(app.multiselect_snapshot(), selection);
+        assert_eq!(app.document.bundle(), &original.bundle);
+        assert_eq!(app.behavior.scenario.spacing_token(), Some(current.token()));
+    }
+    finish(&mut app, current, current_start + Vector::new(0., 24.));
+    assert!(app.document.can_undo());
+}
+
+#[test]
+fn mixed_group_drag_refuses_whole_set_without_primary_only_change_or_replay() {
+    let (mut app, lane, message) = setup();
+    choose(&mut app, message, multiselect::Choice::Add);
+    choose(&mut app, lane, multiselect::Choice::Add);
+    let event = packet_for_app(&app, Target::Message(message));
+    let original = app.document.snapshot();
+    let selected = app.multiselect_snapshot().unwrap();
+    let epoch = app.canvas_epoch;
+    send(&mut app, event);
+    assert_eq!(app.canvas_epoch, epoch);
+    let Event::Begin { press_screen, .. } = event else {
+        unreachable!()
+    };
+    move_to(&mut app, event, press_screen + Vector::new(0., 30.));
+    assert_eq!(app.project(), &original.decoded.project);
+    finish(&mut app, event, press_screen + Vector::new(0., 30.));
+    assert_ne!(app.canvas_epoch, epoch);
+    assert!(app.behavior.scenario.spacing_token().is_none());
+    assert_eq!(app.document.bundle(), &original.bundle);
+    assert_eq!(app.project(), &original.decoded.project);
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        selected.targets()
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().primary(),
+        selected.primary()
+    );
+    let status = app.status.clone();
+    let epoch = app.canvas_epoch;
+    send(&mut app, event);
+    assert_eq!(app.status, status);
+    assert_eq!(app.canvas_epoch, epoch);
+}
+
+#[test]
+fn mixed_group_stationary_click_on_either_role_still_selects_only_that_member() {
+    for lane_hit in [false, true] {
+        let (mut app, lane, message) = setup();
+        choose(&mut app, message, multiselect::Choice::Add);
+        choose(&mut app, lane, multiselect::Choice::Add);
+        let original = app.document.snapshot();
+        let member = if lane_hit { lane } else { message };
+        let (event, start, _) = begin(&mut app, target(!lane_hit, member));
+        finish(&mut app, event, start);
+        assert_eq!(
+            app.multiselect_snapshot().unwrap().targets(),
+            &[SelectedTarget::ScenarioObject(member)]
+        );
+        assert_eq!(app.selected, member);
+        assert_eq!(app.document.bundle(), &original.bundle);
+        assert!(!app.document.can_undo());
+    }
+}
+
+#[test]
+fn malformed_current_begin_consumes_its_lifetime_without_editing_or_replaying() {
+    let (mut app, ids) = group(true, true);
+    let mut event = packet_for_app(&app, Target::Message(ids[0]));
+    if let Event::Begin { canvas_bounds, .. } = &mut event {
+        canvas_bounds.width = 0.;
+    }
+    let original = app.document.snapshot();
+    let selection = app.multiselect_snapshot().unwrap();
+    let epoch = app.canvas_epoch;
+    send(&mut app, event);
+    assert_ne!(app.canvas_epoch, epoch);
+    assert!(app.behavior.scenario.spacing_token().is_none());
+    assert_eq!(app.document.bundle(), &original.bundle);
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        selection.targets()
+    );
+    let epoch = app.canvas_epoch;
+    let status = app.status.clone();
+    send(&mut app, event);
+    assert_eq!(app.canvas_epoch, epoch);
+    assert_eq!(app.status, status);
+}
+
+#[test]
+fn group_source_write_failure_is_atomic_and_preserves_selection_and_camera() {
+    let (mut app, ids) = group(true, true);
+    let bundle = app.document.bundle().clone();
+    let mut limits = oa_core::source_project::ProjectLimits::default();
+    limits.model.max_source_bytes = bundle.files.values().map(String::len).sum();
+    app.document = Document::from_bundle(bundle, limits).unwrap();
+    app.sync();
+    let original = app.document.snapshot();
+    let selection = app.multiselect_snapshot().unwrap();
+    let primary = app.selected;
+    let camera = app.behavior.scenario.camera_boundary();
+    let (event, start, _) = begin(&mut app, Target::Message(ids[1]));
+    finish(&mut app, event, start + Vector::new(0., 24.));
+    assert!(
+        app.status.starts_with("Spacing was not applied:"),
+        "{}",
+        app.status
+    );
+    assert_eq!(app.project(), &original.decoded.project);
+    assert_eq!(app.document.bundle(), &original.bundle);
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        selection.targets()
+    );
+    assert_eq!(app.selected, primary);
+    assert!(camera == app.behavior.scenario.camera_boundary());
+    assert!(!app.document.can_undo());
+}

crates/oa-desktop/src/app/scenario_spacing/tests.rs

@@ -8,7 +8,7 @@ use behavior::scenario::{
 };
 use iced::{Point, Size, Vector};
 
-fn setup() -> (App, Id, Id) {
+pub(super) fn setup() -> (App, Id, Id) {
     let (document, owner, diagram, lane, message) = fixture();
     let mut app = App::with_project(document.project().clone());
     let _ = app.update(Message::Select(owner));
@@ -88,14 +88,21 @@ fn stale_text_and_scenario_messages_do_not_retire_a_new_saved_spacing_gesture()
         "the current gesture remains usable"
     );
 }
-fn begin(app: &mut App, target: Target) -> (Event, Point, f32) {
-    let event = packet(
+pub(in crate::app) fn packet_for_app(app: &App, target: Target) -> Event {
+    let mut event = packet(
         app.project(),
         &app.behavior.scenario,
         app.scenario_context().unwrap(),
         app.camera_epoch,
         target,
     );
+    if let Event::Begin { stamp, .. } = &mut event {
+        stamp.selection_generation = app.multiselect_snapshot().unwrap().generation();
+    }
+    event
+}
+pub(super) fn begin(app: &mut App, target: Target) -> (Event, Point, f32) {
+    let event = packet_for_app(app, target);
     let Event::Begin {
         press_screen,
         scale,
@@ -108,10 +115,10 @@ fn begin(app: &mut App, target: Target) -> (Event, Point, f32) {
     assert_eq!(app.behavior.scenario.spacing_token(), Some(event.token()));
     (event, press_screen, scale)
 }
-fn send(app: &mut App, event: Event) {
+pub(super) fn send(app: &mut App, event: Event) {
     let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Spacing(event)));
 }
-fn move_to(app: &mut App, begin: Event, screen: Point) {
+pub(super) fn move_to(app: &mut App, begin: Event, screen: Point) {
     send(
         app,
         Event::Move {
@@ -121,7 +128,7 @@ fn move_to(app: &mut App, begin: Event, screen: Point) {
         },
     );
 }
-fn finish(app: &mut App, begin: Event, screen: Point) {
+pub(super) fn finish(app: &mut App, begin: Event, screen: Point) {
     send(
         app,
         Event::Finish {

crates/oa-desktop/src/app/state_diagram.rs

@@ -116,6 +116,7 @@ impl App {
         }
         match event {
             Event::Selection(event) => self.multiselect_event(event),
+            Event::ModelRemoval(event) => return self.saved_removal_event(*event),
             Event::Remove(intent) => self.remove_from_diagram(intent),
             Event::Viewport(_, size) => {
                 if size.width.is_finite()

crates/oa-desktop/src/app/state_picker_escape_tests.rs

@@ -10,11 +10,6 @@ async fn press_escape(mounted: &mut Mounted, app: &mut App) -> Vec<Message> {
         std::slice::from_ref(&input),
         mouse::Cursor::Unavailable,
     );
-    assert_eq!(
-        statuses,
-        [iced::event::Status::Captured],
-        "the mounted picker must capture Escape before App subscriptions"
-    );
     crate::app::escape::tests::subscriptions(app, input, statuses[0], &mut messages);
     for message in messages.iter().cloned() {
         let task = app.update(message);
@@ -46,11 +41,17 @@ async fn mounted_state_missing_picker_escape_preserves_exact_document_then_reope
     send(&mut app, Message::BehaviorDiagram(choice));
     let mut mounted = Mounted::new(&mut app).await;
     assert_eq!(state_edit::unplaced(app.project(), diagram), vec![f.b]);
-    // Locate the stable picker slot itself: selection controls may sit between
-    // it and the canvas. The single menu option opens below this slot.
-    let bounds = mounted.geometry(&app).bounds("state-missing-picker");
-    let picker = bounds.center();
-    let option = iced::Point::new(picker.x, bounds.y + bounds.height * 1.5);
+    let focus_id = iced::advanced::widget::Id::from("diagram-keyboard-owner");
+    let (_, canvas, _) = mounted
+        .geometry(&app)
+        .focused
+        .into_iter()
+        .find(|(id, _, _)| id.as_ref() == Some(&focus_id))
+        .unwrap();
+    // The existing picker is immediately above the measured canvas, separated
+    // by 8px. Its 12px text and 8px padding give a 31.6px row.
+    let picker = iced::Point::new(canvas.center_x(), canvas.y - 24.);
+    let option = iced::Point::new(picker.x, canvas.y + 8.);
     let before = app.document.snapshot();
     let original = app.project().clone();
     let source = app.document.bundle().clone();

crates/oa-desktop/src/behavior.rs

@@ -1243,6 +1243,7 @@ struct Scene {
     camera_pan: iced::Vector,
     interaction: Option<(scenario::Context, scenario::CanvasTool, bool)>,
     spacing_stamp: Option<scenario::spacing::Stamp>,
+    selection: Option<(scenario::Context, crate::diagram_selection::Snapshot)>,
     coordinate_input: bool,
     pending_placement: Option<(scenario::Slot, Option<Id>)>,
     lanes: BTreeMap<Id, f32>,
@@ -1262,6 +1263,8 @@ struct SequenceSlot {
 }
 #[derive(Default)]
 struct SequenceInput {
+    modifiers: iced::keyboard::Modifiers,
+    group_press: Option<ScenarioGroupPress>,
     context: Option<scenario::Context>,
     tool: scenario::CanvasTool,
     pointer: Option<Point>,
@@ -1269,6 +1272,13 @@ struct SequenceInput {
     source: Option<(Id, scenario::Slot)>,
     press: Option<SequencePress>,
 }
+struct ScenarioGroupPress {
+    context: scenario::Context,
+    snapshot: crate::diagram_selection::Snapshot,
+    target: crate::diagram_usage::Target,
+    start: Point,
+    moved: bool,
+}
 #[derive(Clone, Copy)]
 enum SequencePress {
     Spacing {
@@ -1309,11 +1319,48 @@ impl SequenceInput {
         cancel
     }
     fn cancel(&mut self) {
+        self.group_press = None;
         self.source = None;
         self.press = None;
     }
 }
 impl Scene {
+    fn selection_targets(&self) -> Vec<crate::diagram_usage::Target> {
+        let mut ids = std::collections::BTreeSet::new();
+        ids.extend(
+            self.boxes
+                .iter()
+                .filter(|b| !b.title.is_empty())
+                .map(|b| b.id),
+        );
+        ids.extend(self.lines.iter().map(|line| line.id));
+        ids.extend(self.activations.iter().map(|segment| segment.call));
+        ids.extend(self.render_lanes.keys().copied());
+        ids.extend(self.lifecycle.selection_markers().map(|(id, _)| id));
+        ids.into_iter()
+            .map(crate::diagram_usage::Target::ScenarioObject)
+            .collect()
+    }
+    fn is_selected(&self, id: Id) -> bool {
+        self.selection
+            .as_ref()
+            .map_or(id == self.selected, |(_, snapshot)| {
+                snapshot
+                    .targets()
+                    .contains(&crate::diagram_usage::Target::ScenarioObject(id))
+            })
+    }
+    fn is_group(&self) -> bool {
+        self.selection
+            .as_ref()
+            .is_some_and(|(_, snapshot)| snapshot.targets().len() > 1)
+    }
+    fn selection_action(&self, intent: scenario::selection::Intent) -> Option<Action<Message>> {
+        let (context, snapshot) = self.selection.as_ref()?;
+        Some(
+            Action::publish(scenario::selection::message(*context, snapshot, intent)).and_capture(),
+        )
+    }
     fn removal_target(&self, owner: Id, id: Id) -> bool {
         id != owner
             && (self.boxes.iter().any(|item| item.id == id)
@@ -1340,6 +1387,7 @@ impl Scene {
             selected,
             interaction: None,
             spacing_stamp: None,
+            selection: None,
             coordinate_input: true,
             pending_placement: None,
             lanes: BTreeMap::new(),
@@ -1982,7 +2030,24 @@ impl canvas::Program<Message> for Scene {
         bounds: Rectangle,
         cursor: mouse::Cursor,
     ) -> Option<Action<Message>> {
+        use crate::{app::multiselect::Choice, diagram_usage::Target};
+        use scenario::selection::Intent;
         use scenario::{CanvasEvent, CanvasTool};
+        if let canvas::Event::Keyboard(iced::keyboard::Event::ModifiersChanged(modifiers)) = event {
+            state.modifiers = *modifiers;
+            return None;
+        }
+        if matches!(event, canvas::Event::Window(iced::window::Event::Unfocused)) {
+            state.modifiers = iced::keyboard::Modifiers::default();
+        }
+        if state.group_press.as_ref().is_some_and(|press| {
+            self.selection.as_ref().is_none_or(|(context, snapshot)| {
+                *context != press.context || *snapshot != press.snapshot
+            })
+        }) {
+            state.cancel();
+        }
+
         let (context, tool, editable) = self
             .interaction
             .map_or((None, CanvasTool::Select, false), |(c, t, e)| {
@@ -2007,10 +2072,14 @@ impl canvas::Program<Message> for Scene {
         }
         state.bounds = Some(bounds);
         if (!editable || !self.coordinate_input)
+            && matches!(state.press, Some(SequencePress::Spacing { .. }))
             && let Some(cancelled) = state.cancel_spacing()
         {
             return Some(cancelled);
         }
+        if !editable {
+            state.cancel();
+        }
         // The viewport masks input outside its visible canvas bounds.
         let visible = cursor.position().is_some();
         if !visible
@@ -2037,6 +2106,9 @@ impl canvas::Program<Message> for Scene {
         let cursor = match event {
             canvas::Event::Mouse(mouse::Event::CursorMoved { position }) => {
                 state.pointer = Some(*position);
+                if let Some(press) = &mut state.group_press {
+                    press.moved |= position.distance(press.start) >= 3.;
+                }
                 if let Some(press) = &mut state.press {
                     match press {
                         SequencePress::Message { start, moved, .. }
@@ -2072,9 +2144,22 @@ impl canvas::Program<Message> for Scene {
                 && tool == CanvasTool::Select
                 && (modifiers.is_empty() || *modifiers == iced::keyboard::Modifiers::SHIFT)
                 && state.press.is_none()
+                && state.group_press.is_none()
                 && state.source.is_none() =>
             {
                 let context = context?;
+                if self.is_group() {
+                    let (_, snapshot) = self.selection.as_ref()?;
+                    return Some(
+                        Action::publish(Message::ScenarioRemoval(Box::new(
+                            crate::app::scenario_removal::Event::Begin {
+                                context,
+                                snapshot: Box::new(snapshot.clone()),
+                            },
+                        )))
+                        .and_capture(),
+                    );
+                }
                 if self.removal_target(context.scenario, self.selected) {
                     return Some(
                         Action::publish(Message::ScenarioCanvas(CanvasEvent::Remove(
@@ -2089,7 +2174,10 @@ impl canvas::Program<Message> for Scene {
             canvas::Event::Keyboard(iced::keyboard::Event::KeyPressed {
                 key: iced::keyboard::Key::Named(iced::keyboard::key::Named::Escape),
                 ..
-            }) if state.source.is_some() || state.press.is_some() => {
+            }) if state.source.is_some()
+                || state.press.is_some()
+                || state.group_press.is_some() =>
+            {
                 return state
                     .cancel_spacing()
                     .or_else(|| Some(Action::request_redraw().and_capture()));
@@ -2103,6 +2191,18 @@ impl canvas::Program<Message> for Scene {
             )
         });
         match event {
+            canvas::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right)) if editable => {
+                let (context, _) = self.selection.as_ref()?;
+                let hit = self.hit_item(world?)?;
+                let mut request = crate::model_menu::Request::object(hit.id, cursor.position()?);
+                request.scenario = Some(Box::new(*context));
+                request.selection_target = Some(Box::new(Target::ScenarioObject(hit.id)));
+                state.cancel();
+                Some(
+                    Action::publish(Message::Menu(crate::model_menu::Event::Open(request)))
+                        .and_capture(),
+                )
+            }
             canvas::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)) => {
                 if !visible {
                     return None;
@@ -2112,6 +2212,83 @@ impl canvas::Program<Message> for Scene {
                     if !editable {
                         return None;
                     }
+                    if let Some((selection_context, snapshot)) = &self.selection {
+                        let hit = self.hit_item(point).or_else(|| {
+                            (!self.is_group()
+                                && self.is_selected(self.selected)
+                                && matches!(
+                                    context.representation,
+                                    scenario_layout::Representation::Derived { .. }
+                                ))
+                            .then(|| {
+                                self.reorder_handle()
+                                    .filter(|handle| handle.contains(point))
+                            })
+                            .flatten()
+                            .map(|_| SceneHit {
+                                id: self.selected,
+                                role: SceneHitRole::Box,
+                            })
+                        });
+                        if tool != CanvasTool::Select && self.is_group() {
+                            return self.selection_action(Intent::Refuse(
+                                "Select one occurrence before using an authoring tool".into(),
+                            ));
+                        }
+                        if tool == CanvasTool::Select {
+                            if let Some(hit) = hit {
+                                let target = Target::ScenarioObject(hit.id);
+                                if state.modifiers.shift() {
+                                    state.cancel();
+                                    return self
+                                        .selection_action(Intent::Choose(target, Choice::Toggle));
+                                }
+                                let group_spacing_hit = self.coordinate_input
+                                    && self.spacing_stamp.is_some()
+                                    && matches!(
+                                        context.representation,
+                                        scenario_layout::Representation::Saved { .. }
+                                    )
+                                    && matches!(
+                                        hit.role,
+                                        SceneHitRole::LifelineHeader
+                                            | SceneHitRole::MessageBody
+                                            | SceneHitRole::MessageLabel
+                                    );
+                                if self.is_group() && self.is_selected(hit.id) && !group_spacing_hit
+                                {
+                                    state.group_press = Some(ScenarioGroupPress {
+                                        context: *selection_context,
+                                        snapshot: snapshot.clone(),
+                                        target,
+                                        start: cursor.position()?,
+                                        moved: false,
+                                    });
+                                    return Some(Action::request_redraw().and_capture());
+                                }
+                                // Preserve the existing first-press singleton
+                                // spacing/reorder gesture. Replacing a displayed
+                                // group is an explicit selection change first.
+                                if (self.is_group() && !self.is_selected(hit.id))
+                                    || !self.coordinate_input
+                                {
+                                    return self
+                                        .selection_action(Intent::Choose(target, Choice::Replace));
+                                }
+                            } else {
+                                state.cancel();
+                                if state.modifiers.shift() {
+                                    return Some(Action::capture());
+                                }
+                                // Background clearing shares this press with camera panning.
+                                return Some(Action::publish(scenario::selection::message(
+                                    *selection_context,
+                                    snapshot,
+                                    Intent::Clear,
+                                )));
+                            }
+                        }
+                    }
                     if !self.coordinate_input {
                         return self.hit(point).map(|id| {
                             Action::publish(Message::ScenarioCanvas(CanvasEvent::Select(
@@ -2214,6 +2391,27 @@ impl canvas::Program<Message> for Scene {
                     .map(|id| Action::publish(Message::Select(id)).and_capture())
             }
             canvas::Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)) => {
+                if let Some(press) = state.group_press.take() {
+                    if world.is_none() {
+                        return Some(Action::request_redraw());
+                    }
+                    let intent = if press.moved {
+                        Intent::Refuse(
+                            "This selection cannot be moved here; select one occurrence for its individual actions"
+                                .into(),
+                        )
+                    } else {
+                        Intent::Collapse(press.target)
+                    };
+                    return Some(
+                        Action::publish(scenario::selection::message(
+                            press.context,
+                            &press.snapshot,
+                            intent,
+                        ))
+                        .and_capture(),
+                    );
+                }
                 let press = state.press.take()?;
                 let context = context?;
                 match press {
@@ -2365,7 +2563,7 @@ impl canvas::Program<Message> for Scene {
                     }
                 }),
                 Stroke::default()
-                    .with_color(if guide.id == self.selected {
+                    .with_color(if self.is_selected(guide.id) {
                         style::TEAL
                     } else {
                         style::MUTED
@@ -2391,7 +2589,7 @@ impl canvas::Program<Message> for Scene {
             f.stroke(
                 &path,
                 Stroke::default()
-                    .with_color(if activation.call == self.selected {
+                    .with_color(if self.is_selected(activation.call) {
                         style::TEAL
                     } else {
                         style::BOUNDARY
@@ -2408,7 +2606,7 @@ impl canvas::Program<Message> for Scene {
                 b.marker,
                 Some(Kind::Region | Kind::StateMachine | Kind::Occurrence)
             );
-            let color = if b.id == self.selected {
+            let color = if self.is_selected(b.id) {
                 style::TEAL
             } else {
                 style::BOUNDARY
@@ -2430,7 +2628,7 @@ impl canvas::Program<Message> for Scene {
             }
         }
         for l in self.lines.iter().filter(|line| !line.label.is_empty()) {
-            let color = if l.id == self.selected {
+            let color = if self.is_selected(l.id) {
                 style::TEAL
             } else {
                 style::MUTED
@@ -2486,7 +2684,7 @@ impl canvas::Program<Message> for Scene {
                         content: short(&b.title, ((b.rect.width - 25.) / 7.) as usize),
                         position: Point::new(b.rect.x + 12., b.rect.y + 12.),
                         size: 13.into(),
-                        color: if b.id == self.selected {
+                        color: if self.is_selected(b.id) {
                             style::TEAL
                         } else {
                             style::INK
@@ -2516,6 +2714,19 @@ impl canvas::Program<Message> for Scene {
         }
         self.lifecycle
             .draw_markers(&mut f, self.selected, self.scale, self.camera_pan);
+        if self.selection.is_some() {
+            // Lifecycle glyphs use their exact painted hit identity too.
+            for (id, point) in self.lifecycle.selection_markers() {
+                if self.is_selected(id) {
+                    f.stroke(
+                        &Path::circle(point, 12.),
+                        Stroke::default()
+                            .with_color(style::TEAL)
+                            .with_width(if id == self.selected { 3. } else { 1.5 }),
+                    );
+                }
+            }
+        }
         if let Some((context, tool, editable)) = self.interaction {
             let active = editable
                 && self.coordinate_input
@@ -2542,6 +2753,8 @@ impl canvas::Program<Message> for Scene {
                     context.representation,
                     scenario_layout::Representation::Derived { .. }
                 )
+                && !self.is_group()
+                && self.is_selected(self.selected)
                 && let Some(handle) = self.reorder_handle()
             {
                 f.fill_rectangle(handle.position(), handle.size(), style::TEAL);

crates/oa-desktop/src/behavior/scenario.rs

@@ -6,6 +6,13 @@ use iced::widget::{Column, column, text_input};
 use std::{cell::RefCell, collections::BTreeSet};
 mod camera;
 pub(crate) mod focus;
+pub(crate) mod group_removal;
+pub(crate) mod group_reorder;
+pub(crate) mod reorder_session;
+#[cfg(test)]
+mod reorder_slot_experiments;
+pub(crate) mod reorder_view;
+pub(crate) mod selection;
 pub(crate) mod spacing;
 use super::scenario_layout::{
     Representation,
@@ -143,6 +150,7 @@ impl std::fmt::Display for CanvasTool {
 }
 #[derive(Debug, Clone)]
 pub enum CanvasEvent {
+    Selection(Box<selection::Event>),
     Spacing(spacing::Event),
     Scrolled(Context, ScrollArea, iced::Vector),
     Restored(Context, Id, ScrollArea, iced::Vector),
@@ -186,6 +194,7 @@ impl CanvasEvent {
     pub fn context(&self) -> Context {
         match self {
             Self::Spacing(event) => event.stamp().context,
+            Self::Selection(event) => event.context,
             Self::Scrolled(context, _, _)
             | Self::Restored(context, ..)
             | Self::Viewport(context, _)
@@ -1253,26 +1262,21 @@ pub(crate) fn reorder(
     occurrence: Id,
     slot: Slot,
 ) -> Result<Command, String> {
-    let to = slot_index(p, owner, slot)?;
-    if p.elements.get(&occurrence).and_then(|e| e.parent) != Some(slot.parent) {
-        return Err(
-            "Reorder inside the occurrence's current sequence; dragging never changes its operand."
-                .into(),
-        );
+    let prepared = group_reorder::Prepared::new(
+        std::sync::Arc::new(p.clone()),
+        owner,
+        &[crate::diagram_usage::Target::ScenarioObject(occurrence)],
+    )?;
+    match prepared.plan(slot)? {
+        group_reorder::Plan::Change(command) => Ok(*command),
+        group_reorder::Plan::Noop => Ok(Command::SetSteps(
+            slot.parent,
+            p.elements[&slot.parent]
+                .steps()
+                .expect("admitted sequence")
+                .clone(),
+        )),
     }
-    let mut steps = p.elements[&slot.parent]
-        .steps()
-        .expect("slot validated")
-        .clone();
-    let from = steps
-        .iter()
-        .position(|id| *id == occurrence)
-        .ok_or("This occurrence is not in the sequence.")?;
-    steps.remove(from);
-    steps.insert(to - usize::from(from < to), occurrence);
-    let command = Command::SetSteps(slot.parent, steps);
-    execute_batch(p, std::slice::from_ref(&command)).map_err(|error| error.to_string())?;
-    Ok(command)
 }
 fn compatible_binding(p: &Project, referenced: Id, local: Id) -> bool {
     represented(p, referenced)

crates/oa-desktop/src/behavior/scenario/group_removal.rs

@@ -0,0 +1,182 @@
+//! Whole-set local Scenario removal. UI visibility and input lifetime admission
+//! belong to the caller; this planner validates structural identity and semantics.
+use crate::diagram_usage::Target;
+use oa_core::{Command, Id, Kind, Layer, OccurrenceBody, Project, SharedBody, execute_batch};
+use std::collections::{BTreeMap, BTreeSet};
+
+#[derive(Debug)]
+pub(crate) struct Plan {
+    pub(crate) command: Command,
+    /// Actual deleted identities, including owned descendants and dependents.
+    pub(crate) removed: BTreeSet<Id>,
+    /// Surviving records changed by reference clearing, sequence edits or view
+    /// pruning. Embedded surviving placements are included alongside diagrams.
+    pub(crate) changed: BTreeSet<Id>,
+}
+
+fn step_body(project: &Project, id: Id) -> Option<&OccurrenceBody> {
+    match project.elements.get(&id)?.shared()? {
+        SharedBody::Occurrence { body, .. }
+            if matches!(
+                body,
+                OccurrenceBody::Exchange { .. }
+                    | OccurrenceBody::Action { .. }
+                    | OccurrenceBody::State { .. }
+                    | OccurrenceBody::ScenarioUse { .. }
+                    | OccurrenceBody::Fragment { .. }
+            ) =>
+        {
+            Some(body)
+        }
+        _ => None,
+    }
+}
+
+/// Follow the actual ordered/operand lists, not only parent pointers. Check the
+/// complete local tree so malformed siblings cannot become a permissive subset.
+fn local_occurrences(project: &Project, owner: Id, layer: Layer) -> Result<BTreeSet<Id>, String> {
+    let mut reachable = BTreeSet::new();
+    let mut sequences = vec![owner];
+    while let Some(parent) = sequences.pop() {
+        let steps = project.elements[&parent]
+            .steps()
+            .ok_or("The Scenario sequence is no longer available.")?;
+        for &id in steps {
+            let element = project
+                .elements
+                .get(&id)
+                .ok_or("A Scenario step is missing.")?;
+            let body =
+                step_body(project, id).ok_or("The Scenario contains an unsupported step.")?;
+            if element.parent != Some(parent) || element.layer() != layer || !reachable.insert(id) {
+                return Err("The Scenario lists must contain unique local occurrences of their actual parents.".into());
+            }
+            if let OccurrenceBody::Fragment { branches, .. } = body {
+                for &branch in branches {
+                    let element = project
+                        .elements
+                        .get(&branch)
+                        .ok_or("A Scenario operand is missing.")?;
+                    if element.parent != Some(id)
+                        || element.layer() != layer
+                        || !matches!(
+                            element.shared(),
+                            Some(SharedBody::Occurrence {
+                                body: OccurrenceBody::Branch { .. },
+                                ..
+                            })
+                        )
+                        || !reachable.insert(branch)
+                    {
+                        return Err("The Scenario fragment must list each actual local operand exactly once.".into());
+                    }
+                    sequences.push(branch);
+                }
+            }
+        }
+    }
+    Ok(reachable)
+}
+
+fn changed_records<T: PartialEq>(
+    before: &BTreeMap<Id, T>,
+    after: &BTreeMap<Id, T>,
+    changed: &mut BTreeSet<Id>,
+) {
+    changed.extend(
+        before
+            .iter()
+            .filter_map(|(&id, record)| after.get(&id).filter(|next| *next != record).map(|_| id)),
+    );
+}
+
+pub(crate) fn prepare(project: &Project, owner: Id, targets: &[Target]) -> Result<Plan, String> {
+    let owner_element = project
+        .elements
+        .get(&owner)
+        .filter(|element| element.kind() == Kind::Scenario)
+        .ok_or("This Scenario no longer exists.")?;
+    let mut selected = BTreeSet::new();
+    for target in targets {
+        let Target::ScenarioObject(id) = target else {
+            return Err("Remove only local Scenario participants and occurrences together.".into());
+        };
+        if !selected.insert(*id) {
+            return Err("Every selected Scenario subject must be unique.".into());
+        }
+    }
+    if selected.is_empty() {
+        return Err("Select at least one Scenario participant or occurrence to remove.".into());
+    }
+    oa_core::session::validate_candidate(project).map_err(|error| error.to_string())?;
+    let reachable = local_occurrences(project, owner, owner_element.layer())?;
+    for &id in &selected {
+        let element = project
+            .elements
+            .get(&id)
+            .ok_or("A selected Scenario subject no longer exists.")?;
+        let local = if element.kind() == Kind::Lifeline {
+            element.parent == Some(owner) && element.layer() == owner_element.layer()
+        } else {
+            reachable.contains(&id)
+        };
+        if !local {
+            return Err("Every selected subject must be a local participant or a listed occurrence/operand in this Scenario.".into());
+        }
+    }
+    // Admission above includes every original member. An admitted selected
+    // descendant is covered by its selected ancestor's core cascade, not dropped
+    // as an ineligible target. Sending both Delete commands would delete it twice.
+    let roots = selected.iter().copied().filter(|id| {
+        let mut parent = project.elements[id].parent;
+        while let Some(id) = parent {
+            if selected.contains(&id) {
+                return false;
+            }
+            parent = project.elements.get(&id).and_then(|element| element.parent);
+        }
+        true
+    });
+    let command = Command::Batch(roots.map(Command::Delete).collect());
+    // One candidate and one final semantic validation, with no intermediate
+    // Document transactions or singleton validation that can reject a valid union.
+    let candidate = execute_batch(project, std::slice::from_ref(&command))
+        .map_err(|error| error.to_string())?;
+    let retained: BTreeSet<_> = candidate
+        .identities()
+        .into_iter()
+        .map(|(id, _)| id)
+        .collect();
+    let removed: BTreeSet<_> = project
+        .identities()
+        .into_iter()
+        .map(|(id, _)| id)
+        .filter(|id| !retained.contains(id))
+        .collect();
+    if !selected.is_subset(&removed) {
+        return Err("The complete selected set could not be removed.".into());
+    }
+    let mut changed = BTreeSet::new();
+    changed_records(&project.elements, &candidate.elements, &mut changed);
+    changed_records(&project.relations, &candidate.relations, &mut changed);
+    changed_records(&project.diagrams, &candidate.diagrams, &mut changed);
+    changed_records(
+        &project.artifact_links,
+        &candidate.artifact_links,
+        &mut changed,
+    );
+    changed_records(&project.traces, &candidate.traces, &mut changed);
+    for (&id, diagram) in &project.diagrams {
+        if let Some(after) = candidate.diagrams.get(&id) {
+            changed_records(&diagram.nodes, &after.nodes, &mut changed);
+        }
+    }
+    Ok(Plan {
+        command,
+        removed,
+        changed,
+    })
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/behavior/scenario/group_removal/tests.rs

@@ -0,0 +1,824 @@
+use super::*;
+use crate::{behavior::topology::occurrence, document::Document};
+use oa_core::{
+    ArtifactLink, ArtifactRelation, Diagram, DiagramLayout, FragmentOperator, LifelineBinding,
+    MessageKind, OccurrenceEndpoint, Position, ProjectionKind, ScenarioLanePosition,
+    ScenarioLayout, ScenarioMessagePosition, Trace, TraceKind, language,
+};
+
+struct Fixture {
+    project: Project,
+    owner: Id,
+    work: [Id; 2],
+    lanes: [Id; 2],
+    messages: [Id; 2],
+    views: [Id; 2],
+}
+
+fn add(project: &mut Project, parent: Id, name: &str, body: OccurrenceBody) -> Id {
+    let element = occurrence(project, parent, name, body);
+    let id = element.id;
+    project.elements.insert(id, element);
+    project
+        .elements
+        .get_mut(&parent)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(id);
+    id
+}
+
+fn body(project: &mut Project, id: Id) -> &mut OccurrenceBody {
+    let SharedBody::Occurrence { body, .. } =
+        project.elements.get_mut(&id).unwrap().shared_mut().unwrap()
+    else {
+        panic!("occurrence")
+    };
+    body
+}
+
+fn action(project: &mut Project, parent: Id, name: &str) -> Id {
+    add(
+        project,
+        parent,
+        name,
+        OccurrenceBody::Action {
+            action: None,
+            lifeline: None,
+        },
+    )
+}
+
+fn operand(project: &mut Project, fragment: Id, name: &str) -> Id {
+    let element = occurrence(
+        project,
+        fragment,
+        name,
+        OccurrenceBody::Branch {
+            guard: "ready".into(),
+            occurrences: vec![],
+        },
+    );
+    let id = element.id;
+    project.elements.insert(id, element);
+    let OccurrenceBody::Fragment { branches, .. } = body(project, fragment) else {
+        panic!()
+    };
+    branches.push(id);
+    id
+}
+
+fn fixture(layer: Layer) -> Fixture {
+    let mut project = Project::empty();
+    let owner = project
+        .add_element(Kind::Scenario, layer, "Conversation", None)
+        .unwrap();
+    let work = ["Source work", "Target work"].map(|name| {
+        project
+            .add_element(
+                if layer == Layer::Oa {
+                    Kind::Activity
+                } else {
+                    Kind::Function
+                },
+                layer,
+                name,
+                None,
+            )
+            .unwrap()
+    });
+    let lanes = ["Left", "Right"].map(|name| {
+        project
+            .add_element(Kind::Lifeline, layer, name, Some(owner))
+            .unwrap()
+    });
+    for (lane, work) in lanes.into_iter().zip(work) {
+        *project
+            .elements
+            .get_mut(&lane)
+            .unwrap()
+            .shared_mut()
+            .unwrap() = SharedBody::Lifeline {
+            represented: Some(work),
+        };
+    }
+    let messages = ["First", "Second"].map(|name| {
+        add(
+            &mut project,
+            owner,
+            name,
+            OccurrenceBody::Exchange {
+                exchange: None,
+                sender: Some(lanes[0]),
+                receiver: Some(lanes[1]),
+                message_kind: MessageKind::Asynchronous,
+                reply_to: None,
+                values: vec![],
+                operation: None,
+            },
+        )
+    });
+    let views = ["Saved A", "Saved B"].map(|name| {
+        let id = Id::new_v4();
+        project.diagrams.insert(
+            id,
+            Diagram {
+                id,
+                alias: project.fresh_alias(name, "view", id),
+                name: name.into(),
+                description: "Keep authored metadata".into(),
+                layer,
+                projection: ProjectionKind::Scenario { scenario: owner },
+                view_options: Default::default(),
+                nodes: Default::default(),
+                routes: vec![],
+                layout: Some(DiagramLayout::Scenario(ScenarioLayout {
+                    lanes: vec![
+                        ScenarioLanePosition {
+                            lifeline: lanes[0],
+                            x: 140.,
+                        },
+                        ScenarioLanePosition {
+                            lifeline: lanes[1],
+                            x: 540.,
+                        },
+                    ],
+                    messages: messages
+                        .iter()
+                        .enumerate()
+                        .map(|(index, &occurrence)| ScenarioMessagePosition {
+                            address: OccurrenceEndpoint {
+                                occurrence,
+                                references: vec![],
+                            },
+                            send_y: 220. + index as f32 * 160.,
+                        })
+                        .collect(),
+                })),
+            },
+        );
+        id
+    });
+    oa_core::session::validate_candidate(&project).unwrap();
+    Fixture {
+        project,
+        owner,
+        work,
+        lanes,
+        messages,
+        views,
+    }
+}
+
+fn selected(ids: &[Id]) -> Vec<Target> {
+    ids.iter().copied().map(Target::ScenarioObject).collect()
+}
+
+fn layout(project: &mut Project, diagram: Id) -> &mut ScenarioLayout {
+    let Some(DiagramLayout::Scenario(layout)) =
+        &mut project.diagrams.get_mut(&diagram).unwrap().layout
+    else {
+        panic!()
+    };
+    layout
+}
+
+fn exact_transaction(project: &Project, plan: Plan, expected: &Project) {
+    assert!(matches!(plan.command, Command::Batch(_)));
+    assert_eq!(
+        &execute_batch(project, std::slice::from_ref(&plan.command)).unwrap(),
+        expected
+    );
+    let mut document = Document::from_project(project.clone(), Default::default()).unwrap();
+    let original = document.bundle().clone();
+    document.execute(plan.command).unwrap();
+    assert_eq!(document.project(), expected);
+    let changed = document.bundle().clone();
+    assert_eq!(
+        language::parse(&language::format(expected)).unwrap(),
+        *expected
+    );
+    assert_eq!(
+        Document::from_bundle(changed.clone(), Default::default())
+            .unwrap()
+            .project(),
+        expected
+    );
+    assert!(document.undo());
+    assert_eq!(document.project(), project);
+    assert_eq!(document.bundle(), &original);
+    assert!(!document.can_undo());
+    assert!(document.redo());
+    assert_eq!(document.project(), expected);
+    assert_eq!(document.bundle(), &changed);
+    assert!(!document.can_redo());
+}
+
+#[test]
+fn whole_messages_in_both_layers_preserve_definitions_and_exact_source_history() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = fixture(layer);
+        let baseline = f.project.clone();
+        let plan = prepare(&f.project, f.owner, &selected(&f.messages)).unwrap();
+        let reversed = prepare(
+            &f.project,
+            f.owner,
+            &selected(&[f.messages[1], f.messages[0]]),
+        )
+        .unwrap();
+        assert_eq!(plan.command, reversed.command);
+        assert_eq!(plan.removed, f.messages.into_iter().collect());
+        assert_eq!(
+            plan.changed,
+            [f.owner, f.views[0], f.views[1]].into_iter().collect()
+        );
+        let mut expected = f.project.clone();
+        for id in f.messages {
+            expected.elements.remove(&id);
+        }
+        expected
+            .elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .clear();
+        for view in f.views {
+            layout(&mut expected, view).messages.clear();
+        }
+        for id in f.work {
+            assert_eq!(expected.elements[&id], f.project.elements[&id]);
+        }
+        assert_eq!(f.project, baseline, "preparation is pure");
+        exact_transaction(&f.project, plan, &expected);
+    }
+}
+
+#[test]
+fn mixed_participant_and_message_union_clears_surviving_references_and_prunes_both_views() {
+    let mut f = fixture(Layer::Oa);
+    let local_action = add(
+        &mut f.project,
+        f.owner,
+        "Local action",
+        OccurrenceBody::Action {
+            action: Some(f.work[0]),
+            lifeline: Some(f.lanes[0]),
+        },
+    );
+    let observation = add(
+        &mut f.project,
+        f.owner,
+        "Observation",
+        OccurrenceBody::State {
+            state: None,
+            lifeline: Some(f.lanes[0]),
+        },
+    );
+    let definition = f
+        .project
+        .add_element(Kind::Scenario, Layer::Oa, "Reused definition", None)
+        .unwrap();
+    let remote = f
+        .project
+        .add_element(
+            Kind::Lifeline,
+            Layer::Oa,
+            "Remote participant",
+            Some(definition),
+        )
+        .unwrap();
+    *f.project
+        .elements
+        .get_mut(&remote)
+        .unwrap()
+        .shared_mut()
+        .unwrap() = SharedBody::Lifeline {
+        represented: Some(f.work[0]),
+    };
+    let use_id = add(
+        &mut f.project,
+        f.owner,
+        "Use definition",
+        OccurrenceBody::ScenarioUse {
+            scenario: Some(definition),
+            bindings: vec![LifelineBinding {
+                referenced: remote,
+                local: f.lanes[0],
+            }],
+        },
+    );
+    oa_core::session::validate_candidate(&f.project).unwrap();
+    let plan = prepare(&f.project, f.owner, &selected(&[f.lanes[0], f.messages[0]])).unwrap();
+    let mut expected = f.project.clone();
+    expected.elements.remove(&f.lanes[0]);
+    expected.elements.remove(&f.messages[0]);
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = vec![f.messages[1], local_action, observation, use_id];
+    let OccurrenceBody::Exchange { sender, .. } = body(&mut expected, f.messages[1]) else {
+        panic!()
+    };
+    *sender = None;
+    let OccurrenceBody::Action { lifeline, .. } = body(&mut expected, local_action) else {
+        panic!()
+    };
+    *lifeline = None;
+    let OccurrenceBody::State { lifeline, .. } = body(&mut expected, observation) else {
+        panic!()
+    };
+    *lifeline = None;
+    let OccurrenceBody::ScenarioUse { bindings, .. } = body(&mut expected, use_id) else {
+        panic!()
+    };
+    bindings.clear();
+    for view in f.views {
+        let rows = layout(&mut expected, view);
+        rows.lanes.remove(0);
+        rows.messages.remove(0);
+    }
+    assert_eq!(
+        plan.removed,
+        [f.lanes[0], f.messages[0]].into_iter().collect()
+    );
+    assert_eq!(
+        plan.changed,
+        [
+            f.owner,
+            f.messages[1],
+            local_action,
+            observation,
+            use_id,
+            f.views[0],
+            f.views[1]
+        ]
+        .into_iter()
+        .collect()
+    );
+    assert_eq!(
+        expected.elements[&definition],
+        f.project.elements[&definition]
+    );
+    assert_eq!(expected.elements[&remote], f.project.elements[&remote]);
+    exact_transaction(&f.project, plan, &expected);
+}
+
+#[test]
+fn call_removal_keeps_reply_as_warning_admitted_draft_and_reports_its_changed_identity() {
+    let mut f = fixture(Layer::Oa);
+    let OccurrenceBody::Exchange { message_kind, .. } = body(&mut f.project, f.messages[0]) else {
+        panic!()
+    };
+    *message_kind = MessageKind::Call;
+    let OccurrenceBody::Exchange {
+        sender,
+        receiver,
+        message_kind,
+        reply_to,
+        ..
+    } = body(&mut f.project, f.messages[1])
+    else {
+        panic!()
+    };
+    *sender = Some(f.lanes[1]);
+    *receiver = Some(f.lanes[0]);
+    *message_kind = MessageKind::Reply;
+    *reply_to = Some(f.messages[0]);
+    oa_core::session::validate_candidate(&f.project).unwrap();
+    let plan = prepare(&f.project, f.owner, &selected(&[f.messages[0], f.lanes[1]])).unwrap();
+    let mut expected = f.project.clone();
+    expected.elements.remove(&f.messages[0]);
+    expected.elements.remove(&f.lanes[1]);
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = vec![f.messages[1]];
+    let OccurrenceBody::Exchange {
+        sender, reply_to, ..
+    } = body(&mut expected, f.messages[1])
+    else {
+        panic!()
+    };
+    *sender = None;
+    *reply_to = None;
+    for view in f.views {
+        let rows = layout(&mut expected, view);
+        rows.lanes.remove(1);
+        rows.messages.remove(0);
+    }
+    assert_eq!(
+        plan.removed,
+        [f.messages[0], f.lanes[1]].into_iter().collect()
+    );
+    assert_eq!(
+        plan.changed,
+        [f.owner, f.messages[1], f.views[0], f.views[1]]
+            .into_iter()
+            .collect()
+    );
+    assert!(
+        oa_core::validation::validate(&expected)
+            .iter()
+            .any(|issue| issue.code == "missing_reply_call"
+                && issue.severity == oa_core::validation::Severity::Warning)
+    );
+    exact_transaction(&f.project, plan, &expected);
+}
+
+fn nested(f: &mut Fixture) -> (Id, [Id; 2], [Id; 2]) {
+    let fragment = add(
+        &mut f.project,
+        f.owner,
+        "Alternatives",
+        OccurrenceBody::Fragment {
+            operator: FragmentOperator::Alternative,
+            branches: vec![],
+        },
+    );
+    let branches = [
+        operand(&mut f.project, fragment, "Left operand"),
+        operand(&mut f.project, fragment, "Right operand"),
+    ];
+    let children = [
+        action(&mut f.project, branches[0], "Left action"),
+        action(&mut f.project, branches[1], "Right action"),
+    ];
+    (fragment, branches, children)
+}
+
+#[test]
+fn selected_ancestor_covers_all_descendants_after_admission_and_executes_once() {
+    let mut f = fixture(Layer::Oa);
+    let (fragment, branches, children) = nested(&mut f);
+    oa_core::session::validate_candidate(&f.project).unwrap();
+    assert!(
+        execute_batch(
+            &f.project,
+            &[Command::Delete(fragment), Command::Delete(children[0])]
+        )
+        .is_err(),
+        "naive cascading singleton deletes are order-dependent"
+    );
+    let members = [children[0], f.messages[1], fragment, branches[0]];
+    let plan = prepare(&f.project, f.owner, &selected(&members)).unwrap();
+    let roots: BTreeSet<_> = [fragment, f.messages[1]].into_iter().collect();
+    assert_eq!(
+        plan.command,
+        Command::Batch(roots.into_iter().map(Command::Delete).collect())
+    );
+    let removed = [
+        fragment,
+        branches[0],
+        branches[1],
+        children[0],
+        children[1],
+        f.messages[1],
+    ];
+    assert_eq!(plan.removed, removed.into_iter().collect());
+    assert_eq!(
+        plan.changed,
+        [f.owner, f.views[0], f.views[1]].into_iter().collect()
+    );
+    let mut expected = f.project.clone();
+    for id in removed {
+        expected.elements.remove(&id);
+    }
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = vec![f.messages[0]];
+    for view in f.views {
+        layout(&mut expected, view).messages.remove(1);
+    }
+    exact_transaction(&f.project, plan, &expected);
+}
+
+#[test]
+fn independent_operands_can_be_removed_together_without_a_reorder_parent_restriction() {
+    let mut f = fixture(Layer::Sa);
+    let (fragment, branches, children) = nested(&mut f);
+    let plan = prepare(
+        &f.project,
+        f.owner,
+        &selected(&[children[1], f.messages[0], children[0]]),
+    )
+    .unwrap();
+    let mut expected = f.project.clone();
+    for id in [children[0], children[1], f.messages[0]] {
+        expected.elements.remove(&id);
+    }
+    for branch in branches {
+        expected
+            .elements
+            .get_mut(&branch)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .clear();
+    }
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = vec![f.messages[1], fragment];
+    for view in f.views {
+        layout(&mut expected, view).messages.remove(0);
+    }
+    assert_eq!(
+        plan.changed,
+        [f.owner, branches[0], branches[1], f.views[0], f.views[1]]
+            .into_iter()
+            .collect()
+    );
+    exact_transaction(&f.project, plan, &expected);
+}
+
+#[test]
+fn branch_and_use_are_local_removal_targets_and_reused_definition_survives() {
+    let mut f = fixture(Layer::Oa);
+    let (fragment, branches, children) = nested(&mut f);
+    let definition = f
+        .project
+        .add_element(Kind::Scenario, Layer::Oa, "Definition", None)
+        .unwrap();
+    let use_id = add(
+        &mut f.project,
+        f.owner,
+        "Use",
+        OccurrenceBody::ScenarioUse {
+            scenario: Some(definition),
+            bindings: vec![],
+        },
+    );
+    let plan = prepare(&f.project, f.owner, &selected(&[branches[0], use_id])).unwrap();
+    let mut expected = f.project.clone();
+    for id in [branches[0], children[0], use_id] {
+        expected.elements.remove(&id);
+    }
+    let OccurrenceBody::Fragment {
+        branches: remaining,
+        ..
+    } = body(&mut expected, fragment)
+    else {
+        panic!()
+    };
+    *remaining = vec![branches[1]];
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = vec![f.messages[0], f.messages[1], fragment];
+    assert_eq!(
+        plan.removed,
+        [branches[0], children[0], use_id].into_iter().collect()
+    );
+    assert_eq!(plan.changed, [f.owner, fragment].into_iter().collect());
+    assert_eq!(
+        expected.elements[&definition],
+        f.project.elements[&definition]
+    );
+    exact_transaction(&f.project, plan, &expected);
+}
+
+#[test]
+fn impact_includes_placements_artifacts_traces_and_changed_surviving_constraints() {
+    let mut f = fixture(Layer::Oa);
+    let overview = f.project.ensure_diagram(Layer::Oa);
+    let node = f
+        .project
+        .place(overview, f.messages[0], Position { x: 100., y: 100. });
+    let other_node = f
+        .project
+        .place(overview, f.messages[1], Position { x: 400., y: 100. });
+    let counterpart = f
+        .project
+        .add_element(
+            Kind::Function,
+            Layer::Sa,
+            "Opposite-layer counterpart",
+            None,
+        )
+        .unwrap();
+    let trace = Id::new_v4();
+    f.project.traces.insert(
+        trace,
+        Trace {
+            id: trace,
+            alias: "manual_trace".into(),
+            name: "Manual trace".into(),
+            description: String::new(),
+            oa: f.messages[0],
+            sa: counterpart,
+            kind: TraceKind::Manual,
+            baseline: None,
+        },
+    );
+    let artifact = Id::new_v4();
+    f.project.artifact_links.insert(
+        artifact,
+        ArtifactLink {
+            id: artifact,
+            alias: "evidence".into(),
+            name: "Evidence".into(),
+            description: String::new(),
+            owner: f.messages[0],
+            relation: ArtifactRelation::References,
+            uri: "evidence.txt".into(),
+            revision: None,
+            fragment: None,
+        },
+    );
+    let constraint = f
+        .project
+        .add_element(Kind::Constraint, Layer::Oa, "Constraint", None)
+        .unwrap();
+    *f.project
+        .elements
+        .get_mut(&constraint)
+        .unwrap()
+        .shared_mut()
+        .unwrap() = SharedBody::Constraint {
+        expression: "review".into(),
+        constrained: f.messages.to_vec(),
+    };
+    oa_core::session::validate_candidate(&f.project).unwrap();
+    let plan = prepare(&f.project, f.owner, &selected(&[f.messages[0]])).unwrap();
+    let mut expected = f.project.clone();
+    expected.elements.remove(&f.messages[0]);
+    expected.traces.remove(&trace);
+    expected.artifact_links.remove(&artifact);
+    expected
+        .diagrams
+        .get_mut(&overview)
+        .unwrap()
+        .nodes
+        .remove(&node);
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = vec![f.messages[1]];
+    let SharedBody::Constraint { constrained, .. } = expected
+        .elements
+        .get_mut(&constraint)
+        .unwrap()
+        .shared_mut()
+        .unwrap()
+    else {
+        panic!()
+    };
+    *constrained = vec![f.messages[1]];
+    for view in f.views {
+        layout(&mut expected, view).messages.remove(0);
+    }
+    assert_eq!(
+        plan.removed,
+        [f.messages[0], node, trace, artifact].into_iter().collect()
+    );
+    assert_eq!(
+        plan.changed,
+        [f.owner, constraint, overview, f.views[0], f.views[1]]
+            .into_iter()
+            .collect()
+    );
+    assert_eq!(
+        expected.elements[&counterpart],
+        f.project.elements[&counterpart]
+    );
+    assert_eq!(
+        expected.diagrams[&overview].nodes[&other_node],
+        f.project.diagrams[&overview].nodes[&other_node]
+    );
+    exact_transaction(&f.project, plan, &expected);
+}
+
+#[test]
+fn whole_typed_selection_refuses_missing_foreign_definitions_and_duplicates_before_collapse() {
+    let mut f = fixture(Layer::Oa);
+    let (fragment, _, children) = nested(&mut f);
+    let other = f
+        .project
+        .add_element(Kind::Scenario, Layer::Oa, "Other", None)
+        .unwrap();
+    let foreign = f
+        .project
+        .add_element(Kind::Lifeline, Layer::Oa, "Foreign", Some(other))
+        .unwrap();
+    for targets in [
+        vec![],
+        vec![Target::Whole],
+        selected(&[f.messages[0], f.messages[0]]),
+        selected(&[f.messages[0], Id::nil()]),
+        selected(&[f.messages[0], f.owner]),
+        selected(&[f.messages[0], f.work[0]]),
+        selected(&[f.messages[0], foreign]),
+        vec![
+            Target::ScenarioObject(f.messages[0]),
+            Target::ProcessOccurrence(OccurrenceEndpoint {
+                occurrence: f.messages[1],
+                references: vec![],
+            }),
+        ],
+        selected(&[fragment, children[0], children[0]]),
+        selected(&[fragment, Id::nil()]),
+    ] {
+        let original = f.project.clone();
+        assert!(prepare(&f.project, f.owner, &targets).is_err());
+        assert_eq!(f.project, original);
+    }
+    assert!(prepare(&f.project, f.work[0], &selected(&f.messages)).is_err());
+}
+
+#[test]
+fn actual_list_reachability_and_complete_siblings_are_required() {
+    let mut f = fixture(Layer::Oa);
+    let (fragment, branches, children) = nested(&mut f);
+    let mut cases = Vec::new();
+    let mut missing_branch = f.project.clone();
+    let OccurrenceBody::Fragment {
+        branches: listed, ..
+    } = body(&mut missing_branch, fragment)
+    else {
+        panic!()
+    };
+    listed.clear();
+    cases.push(missing_branch);
+    let mut unlisted_child = f.project.clone();
+    unlisted_child
+        .elements
+        .get_mut(&branches[0])
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .clear();
+    cases.push(unlisted_child);
+    let mut dangling_sibling = f.project.clone();
+    dangling_sibling
+        .elements
+        .get_mut(&branches[1])
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(Id::new_v4());
+    cases.push(dangling_sibling);
+    let mut duplicate_sibling = f.project.clone();
+    duplicate_sibling
+        .elements
+        .get_mut(&branches[1])
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(children[1]);
+    cases.push(duplicate_sibling);
+    let mut wrong_parent = f.project.clone();
+    wrong_parent.elements.get_mut(&children[0]).unwrap().parent = Some(branches[1]);
+    cases.push(wrong_parent);
+    for project in cases {
+        assert!(
+            prepare(&project, f.owner, &selected(&[fragment, children[0]])).is_err(),
+            "ancestor coverage never conceals an invalid original member/tree"
+        );
+    }
+}
+
+#[test]
+fn invalid_baseline_cannot_be_silently_repaired_and_refusal_preserves_existing_redo() {
+    let f = fixture(Layer::Oa);
+    let mut invalid = f.project.clone();
+    let duplicate_alias = invalid.elements[&f.owner].alias.clone();
+    invalid.elements.get_mut(&f.messages[0]).unwrap().alias = duplicate_alias;
+    assert!(oa_core::session::validate_candidate(&invalid).is_err());
+    // The final deletion could repair this error, but the planner must admit a
+    // valid original baseline rather than quietly using deletion as repair.
+    assert!(execute_batch(&invalid, &[Command::Delete(f.messages[0])]).is_ok());
+    assert!(prepare(&invalid, f.owner, &selected(&[f.messages[0]])).is_err());
+    let mut document = Document::from_project(f.project.clone(), Default::default()).unwrap();
+    document
+        .execute(Command::Rename(f.messages[1], "Prior edit".into()))
+        .unwrap();
+    assert!(document.undo());
+    let before = document.bundle().clone();
+    let revision = document.revision();
+    assert!(
+        prepare(
+            document.project(),
+            f.owner,
+            &selected(&[f.messages[0], f.work[0]])
+        )
+        .is_err()
+    );
+    assert_eq!(document.bundle(), &before);
+    assert_eq!(document.revision(), revision);
+    assert!(document.can_redo());
+}

crates/oa-desktop/src/behavior/scenario/group_reorder.rs

@@ -0,0 +1,179 @@
+//! Frozen, all-or-nothing reorder of one immediate Scenario sequence.
+use super::Slot;
+use crate::diagram_usage::Target;
+use oa_core::{Command, Id, Kind, OccurrenceBody, Project, SharedBody, execute_batch};
+use std::{collections::BTreeSet, sync::Arc};
+
+#[derive(Debug)]
+pub(crate) enum Plan {
+    Noop,
+    Change(Box<Command>),
+}
+
+pub(crate) struct Prepared {
+    project: Arc<Project>,
+    parent: Id,
+    original: Vec<Id>,
+    selected: BTreeSet<Id>,
+}
+
+fn step_body(project: &Project, id: Id) -> Option<&OccurrenceBody> {
+    match project.elements.get(&id)?.shared()? {
+        SharedBody::Occurrence { body, .. }
+            if matches!(
+                body,
+                OccurrenceBody::Exchange { .. }
+                    | OccurrenceBody::Action { .. }
+                    | OccurrenceBody::State { .. }
+                    | OccurrenceBody::ScenarioUse { .. }
+                    | OccurrenceBody::Fragment { .. }
+            ) =>
+        {
+            Some(body)
+        }
+        _ => None,
+    }
+}
+
+// Follow the same structural edges that make rows visible; parent pointers alone
+// would admit children of an operand omitted from its fragment's branch list.
+fn reachable_parent(project: &Project, owner: Id, wanted: Id) -> bool {
+    let mut pending = vec![owner];
+    let mut visited = BTreeSet::new();
+    while let Some(parent) = pending.pop() {
+        if !visited.insert(parent) {
+            continue;
+        }
+        if parent == wanted {
+            return true;
+        }
+        let Some(steps) = project.elements.get(&parent).and_then(|e| e.steps()) else {
+            continue;
+        };
+        for id in steps {
+            if project.elements.get(id).and_then(|e| e.parent) != Some(parent) {
+                continue;
+            }
+            if let Some(OccurrenceBody::Fragment { branches, .. }) = step_body(project, *id) {
+                pending.extend(branches.iter().copied().filter(|branch| {
+                    project.elements.get(branch).is_some_and(|element| {
+                        element.parent == Some(*id)
+                            && matches!(
+                                element.shared(),
+                                Some(SharedBody::Occurrence {
+                                    body: OccurrenceBody::Branch { .. },
+                                    ..
+                                })
+                            )
+                    })
+                }));
+            }
+        }
+    }
+    false
+}
+
+impl Prepared {
+    pub(crate) fn new(
+        project: Arc<Project>,
+        owner: Id,
+        targets: &[Target],
+    ) -> Result<Self, String> {
+        if project.elements.get(&owner).map(|e| e.kind()) != Some(Kind::Scenario) {
+            return Err("This scenario no longer exists.".into());
+        }
+        let mut selected = BTreeSet::new();
+        let mut parent = None;
+        for target in targets {
+            let Target::ScenarioObject(id) = target else {
+                return Err("Select only ordered occurrences in this scenario.".into());
+            };
+            if !selected.insert(*id) || step_body(&project, *id).is_none() {
+                return Err(
+                    "Every selected subject must be a unique ordered scenario occurrence.".into(),
+                );
+            }
+            let actual = project.elements[id]
+                .parent
+                .ok_or("The occurrence has no sequence.")?;
+            if parent.is_some_and(|parent| parent != actual) {
+                return Err(
+                    "Reorder inside one immediate sequence; dragging never changes operands."
+                        .into(),
+                );
+            }
+            parent = Some(actual);
+        }
+        let parent = parent.ok_or("Select at least one occurrence.")?;
+        if !reachable_parent(&project, owner, parent) {
+            return Err("The selected sequence is not reachable in this scenario.".into());
+        }
+        let original = project.elements[&parent]
+            .steps()
+            .ok_or("The parent is not a sequence.")?
+            .clone();
+        let mut listed = BTreeSet::new();
+        for id in &original {
+            if !listed.insert(*id)
+                || step_body(&project, *id).is_none()
+                || project.elements[id].parent != Some(parent)
+            {
+                return Err("The complete sequence must contain unique, existing occurrences of this parent.".into());
+            }
+        }
+        if !selected.is_subset(&listed) {
+            return Err("A selected occurrence is not in this sequence.".into());
+        }
+        // Cache a validated immutable baseline, including descendants and other
+        // sequences. Advisory authoring diagnostics deliberately remain allowed.
+        oa_core::session::validate_candidate(&project).map_err(|e| e.to_string())?;
+        Ok(Self {
+            project,
+            parent,
+            original,
+            selected,
+        })
+    }
+
+    pub(crate) fn plan(&self, slot: Slot) -> Result<Plan, String> {
+        if slot.parent != self.parent {
+            return Err("Reorder inside the occurrence's current sequence; dragging never changes its operand.".into());
+        }
+        if let Some(anchor) = slot.before {
+            if !self.original.contains(&anchor) {
+                return Err("The insertion slot changed. Choose its position again.".into());
+            }
+            if self.selected.contains(&anchor) {
+                return Ok(Plan::Noop);
+            }
+        }
+        let mut steps: Vec<_> = self
+            .original
+            .iter()
+            .copied()
+            .filter(|id| !self.selected.contains(id))
+            .collect();
+        let at = slot.before.map_or(steps.len(), |anchor| {
+            steps
+                .iter()
+                .position(|id| *id == anchor)
+                .expect("admitted anchor")
+        });
+        steps.splice(
+            at..at,
+            self.original
+                .iter()
+                .copied()
+                .filter(|id| self.selected.contains(id)),
+        );
+        if steps == self.original {
+            return Ok(Plan::Noop);
+        }
+        let command = Command::SetSteps(self.parent, steps);
+        execute_batch(&self.project, std::slice::from_ref(&command)).map_err(|e| e.to_string())?;
+        Ok(Plan::Change(Box::new(command)))
+    }
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/behavior/scenario/group_reorder/tests.rs

@@ -0,0 +1,720 @@
+use super::*;
+use crate::{behavior::topology::occurrence, document::Document};
+use oa_core::{FragmentOperator, Layer, LifelineBinding, MessageKind, language};
+
+fn add(p: &mut Project, parent: Id, name: &str, body: OccurrenceBody) -> Id {
+    let e = occurrence(p, parent, name, body);
+    let id = e.id;
+    p.elements.insert(id, e);
+    p.elements
+        .get_mut(&parent)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(id);
+    id
+}
+fn row(p: &mut Project, parent: Id, name: &str) -> Id {
+    add(
+        p,
+        parent,
+        name,
+        OccurrenceBody::Action {
+            action: None,
+            lifeline: None,
+        },
+    )
+}
+fn operand(p: &mut Project, parent: Id, operator: FragmentOperator) -> (Id, Id) {
+    let fragment = add(
+        p,
+        parent,
+        "Fragment",
+        OccurrenceBody::Fragment {
+            operator,
+            branches: vec![],
+        },
+    );
+    let branch = occurrence(
+        p,
+        fragment,
+        "Operand",
+        OccurrenceBody::Branch {
+            guard: "ready".into(),
+            occurrences: vec![],
+        },
+    );
+    let id = branch.id;
+    p.elements.insert(id, branch);
+    if let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Fragment { branches, .. },
+        ..
+    }) = p.elements.get_mut(&fragment).unwrap().shared_mut()
+    {
+        branches.push(id);
+    }
+    (fragment, id)
+}
+fn prepare(p: &Project, owner: Id, ids: &[Id]) -> Result<Prepared, String> {
+    Prepared::new(
+        Arc::new(p.clone()),
+        owner,
+        &ids.iter()
+            .copied()
+            .map(Target::ScenarioObject)
+            .collect::<Vec<_>>(),
+    )
+}
+fn slot(parent: Id, before: Option<Id>) -> Slot {
+    Slot { parent, before }
+}
+fn ordered(p: &Project, parent: Id, ids: &[Id]) -> Project {
+    let mut expected = p.clone();
+    *expected
+        .elements
+        .get_mut(&parent)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = ids.to_vec();
+    expected
+}
+fn exact_transaction(p: &Project, plan: Plan, expected: Project) {
+    let Plan::Change(command) = plan else {
+        panic!("expected a change")
+    };
+    assert_eq!(
+        execute_batch(p, std::slice::from_ref(&command)).unwrap(),
+        expected
+    );
+    let mut doc = Document::from_project(p.clone(), Default::default()).unwrap();
+    let original_source = doc.bundle().clone();
+    doc.execute(*command).unwrap();
+    assert_eq!(doc.project(), &expected);
+    assert_eq!(
+        language::parse(&language::format(doc.project())).unwrap(),
+        expected
+    );
+    let changed_source = doc.bundle().clone();
+    assert_eq!(
+        Document::from_bundle(changed_source.clone(), Default::default())
+            .unwrap()
+            .project(),
+        &expected
+    );
+    assert!(doc.undo());
+    assert_eq!(doc.project(), p);
+    assert_eq!(doc.bundle(), &original_source);
+    assert!(!doc.can_undo());
+    assert!(doc.redo());
+    assert_eq!(doc.project(), &expected);
+    assert_eq!(doc.bundle(), &changed_source);
+    assert!(!doc.can_redo());
+}
+fn four(nested: bool) -> (Project, Id, Id, [Id; 4]) {
+    four_in_layer(nested, Layer::Oa)
+}
+fn four_in_layer(nested: bool, layer: Layer) -> (Project, Id, Id, [Id; 4]) {
+    let mut p = Project::empty();
+    let owner = p
+        .add_element(oa_core::Kind::Scenario, layer, "Scenario", None)
+        .unwrap();
+    let parent = if nested {
+        operand(&mut p, owner, FragmentOperator::Alternative).1
+    } else {
+        owner
+    };
+    let ids = ["A", "B", "C", "D"].map(|name| row(&mut p, parent, name));
+    oa_core::session::validate_candidate(&p).unwrap();
+    (p, owner, parent, ids)
+}
+
+#[test]
+fn root_and_operand_use_semantic_block_order_with_exact_history() {
+    for (nested, layer) in [
+        (false, Layer::Oa),
+        (true, Layer::Oa),
+        (false, Layer::Sa),
+        (true, Layer::Sa),
+    ] {
+        let (p, owner, parent, [a, b, c, d]) = four_in_layer(nested, layer);
+        let prepared = prepare(&p, owner, &[c, a]).unwrap();
+        exact_transaction(
+            &p,
+            prepared.plan(slot(parent, Some(d))).unwrap(),
+            ordered(&p, parent, &[b, a, c, d]),
+        );
+        exact_transaction(
+            &p,
+            prepared.plan(slot(parent, None)).unwrap(),
+            ordered(&p, parent, &[b, d, a, c]),
+        );
+    }
+}
+
+#[test]
+fn singleton_wrapper_noop_preserves_existing_redo_and_source() {
+    for nested in [false, true] {
+        let (p, owner, parent, [a, b, c, d]) = four(nested);
+        let mut doc = Document::from_project(p.clone(), Default::default()).unwrap();
+        let change = super::super::reorder(doc.project(), owner, a, slot(parent, None)).unwrap();
+        doc.execute(change).unwrap();
+        assert_eq!(doc.project(), &ordered(&p, parent, &[b, c, d, a]));
+        let changed = doc.bundle().clone();
+        assert!(doc.undo());
+        let source = doc.bundle().clone();
+        let revision = doc.revision();
+        for before in [Some(a), Some(b)] {
+            let noop =
+                super::super::reorder(doc.project(), owner, a, slot(parent, before)).unwrap();
+            doc.execute(noop).unwrap();
+            assert_eq!(doc.project(), &p);
+            assert_eq!(doc.bundle(), &source);
+            assert_eq!(doc.revision(), revision);
+            assert!(!doc.can_undo());
+            assert!(doc.can_redo());
+        }
+        assert!(doc.redo());
+        assert_eq!(doc.bundle(), &changed);
+    }
+}
+
+#[test]
+fn selected_anchor_and_exact_noop_preserve_redo_and_frozen_snapshot() {
+    let (p, owner, parent, [a, b, c, d]) = four(false);
+    let prepared = prepare(&p, owner, &[c, a]).unwrap();
+    let mut doc = Document::from_project(p.clone(), Default::default()).unwrap();
+    let Plan::Change(command) = prepared.plan(slot(parent, Some(d))).unwrap() else {
+        panic!()
+    };
+    doc.execute(*command).unwrap();
+    let changed = doc.bundle().clone();
+    assert!(doc.undo());
+    let source = doc.bundle().clone();
+    let revision = doc.revision();
+    for plan in [
+        prepared.plan(slot(parent, Some(c))),
+        prepare(&p, owner, &[a])
+            .unwrap()
+            .plan(slot(parent, Some(b))),
+        prepare(&p, owner, &[c, d])
+            .unwrap()
+            .plan(slot(parent, None)),
+    ] {
+        assert!(matches!(plan.unwrap(), Plan::Noop));
+        assert_eq!(doc.project(), &p);
+        assert_eq!(doc.bundle(), &source);
+        assert_eq!(doc.revision(), revision);
+        assert!(doc.can_redo());
+    }
+    assert!(doc.redo());
+    assert_eq!(doc.bundle(), &changed);
+    // The earlier prepared value still plans from its original owned snapshot.
+    exact_transaction(
+        &p,
+        prepared.plan(slot(parent, Some(d))).unwrap(),
+        ordered(&p, parent, &[b, a, c, d]),
+    );
+}
+
+#[test]
+fn admission_rejects_every_invalid_member_list_and_destination_before_noop() {
+    let (p, owner, parent, [a, b, c, d]) = four(false);
+    for ids in [vec![], vec![a, a], vec![a, Id::new_v4()]] {
+        assert!(prepare(&p, owner, &ids).is_err());
+    }
+    for target in [Target::Whole, Target::Placement(a)] {
+        assert!(
+            Prepared::new(
+                Arc::new(p.clone()),
+                owner,
+                &[Target::ScenarioObject(a), target]
+            )
+            .is_err()
+        );
+    }
+    let mut with_line = p.clone();
+    let line = with_line
+        .add_element(Kind::Lifeline, Layer::Oa, "Line", Some(owner))
+        .unwrap();
+    assert!(prepare(&with_line, owner, &[a, line]).is_err());
+    let mut nested = p.clone();
+    let (fragment, branch) = operand(&mut nested, owner, FragmentOperator::Alternative);
+    let child = row(&mut nested, branch, "Child");
+    assert!(prepare(&nested, owner, &[a, child]).is_err());
+    assert!(prepare(&nested, owner, &[fragment, child]).is_err());
+    let prepared = prepare(&p, owner, &[a, c]).unwrap();
+    assert!(prepared.plan(slot(branch, Some(a))).is_err());
+    assert!(prepared.plan(slot(parent, Some(Id::new_v4()))).is_err());
+    for list in [vec![a, b, c, b], vec![a, Id::new_v4(), c, d]] {
+        assert!(prepare(&ordered(&p, parent, &list), owner, &[a, c]).is_err());
+    }
+    let mut wrong_parent = p.clone();
+    wrong_parent.elements.get_mut(&b).unwrap().parent = Some(branch);
+    assert!(prepare(&wrong_parent, owner, &[a, c]).is_err());
+    for body in [
+        OccurrenceBody::Control {
+            kind: oa_core::ControlKind::Choice,
+        },
+        OccurrenceBody::SequenceReference { sequence: None },
+    ] {
+        let mut wrong_type = p.clone();
+        if let Some(SharedBody::Occurrence { body: actual, .. }) =
+            wrong_type.elements.get_mut(&b).unwrap().shared_mut()
+        {
+            *actual = body;
+        }
+        assert!(prepare(&wrong_type, owner, &[a, c]).is_err());
+    }
+    if let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Fragment { branches, .. },
+        ..
+    }) = nested.elements.get_mut(&fragment).unwrap().shared_mut()
+    {
+        branches.clear();
+    }
+    assert!(
+        prepare(&nested, owner, &[child]).is_err(),
+        "parent ancestry cannot admit omitted operand"
+    );
+}
+
+#[test]
+fn unlisted_warning_child_is_preserved_but_cannot_be_selected() {
+    let (mut p, owner, parent, [a, b, c, d]) = four(false);
+    let hidden = row(&mut p, parent, "Hidden draft");
+    p.elements
+        .get_mut(&parent)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .pop();
+    assert!(
+        oa_core::validation::validate(&p)
+            .iter()
+            .any(|i| i.code == "unordered_occurrence")
+    );
+    assert!(prepare(&p, owner, &[hidden]).is_err());
+    exact_transaction(
+        &p,
+        prepare(&p, owner, &[c, a])
+            .unwrap()
+            .plan(slot(parent, Some(d)))
+            .unwrap(),
+        ordered(&p, parent, &[b, a, c, d]),
+    );
+}
+
+#[test]
+fn call_reply_moves_as_explicit_stable_pair_and_invalid_baseline_refuses_noop() {
+    let f = super::super::direct_tests::fixture();
+    let mut p = f.project;
+    let x = row(&mut p, f.owner, "X");
+    let y = row(&mut p, f.owner, "Y");
+    p = ordered(&p, f.owner, &[f.call, x, f.reply, y]);
+    let prepared = prepare(&p, f.owner, &[f.reply, f.call]).unwrap();
+    exact_transaction(
+        &p,
+        prepared.plan(slot(f.owner, None)).unwrap(),
+        ordered(&p, f.owner, &[x, y, f.call, f.reply]),
+    );
+    assert!(
+        prepare(&p, f.owner, &[f.reply])
+            .unwrap()
+            .plan(slot(f.owner, Some(f.call)))
+            .unwrap_err()
+            .contains("reply_order")
+    );
+    let invalid = ordered(&p, f.owner, &[f.reply, x, f.call, y]);
+    assert!(prepare(&invalid, f.owner, &[x]).is_err());
+}
+
+#[test]
+fn nested_fragment_descendant_reply_is_validated_and_subtree_preserved() {
+    let f = super::super::direct_tests::fixture();
+    let mut p = f.project;
+    let x = row(&mut p, f.owner, "X");
+    let (fragment, outer) = operand(&mut p, f.owner, FragmentOperator::Alternative);
+    let (_, inner) = operand(&mut p, outer, FragmentOperator::Parallel);
+    p.elements.get_mut(&f.reply).unwrap().parent = Some(inner);
+    p.elements
+        .get_mut(&inner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(f.reply);
+    let y = row(&mut p, f.owner, "Y");
+    p = ordered(&p, f.owner, &[f.call, x, fragment, y]);
+    let prepared = prepare(&p, f.owner, &[fragment, x]).unwrap();
+    assert!(
+        prepared
+            .plan(slot(f.owner, Some(f.call)))
+            .unwrap_err()
+            .contains("reply_order")
+    );
+    exact_transaction(
+        &p,
+        prepared.plan(slot(f.owner, None)).unwrap(),
+        ordered(&p, f.owner, &[f.call, y, x, fragment]),
+    );
+}
+
+#[test]
+fn nested_lifetime_and_opaque_local_bindings_are_checked_without_expansion() {
+    let f = super::super::direct_tests::fixture();
+    let mut p = execute_batch(
+        &f.project,
+        &[Command::Delete(f.reply), Command::Delete(f.call)],
+    )
+    .unwrap();
+    let create = add(
+        &mut p,
+        f.owner,
+        "Create",
+        OccurrenceBody::Exchange {
+            exchange: None,
+            sender: Some(f.sender),
+            receiver: Some(f.receiver),
+            message_kind: MessageKind::Create,
+            reply_to: None,
+            values: vec![],
+            operation: None,
+        },
+    );
+    let x = row(&mut p, f.owner, "X");
+    let (fragment, outer) = operand(&mut p, f.owner, FragmentOperator::Alternative);
+    let (_, inner) = operand(&mut p, outer, FragmentOperator::Parallel);
+    add(
+        &mut p,
+        inner,
+        "Use local",
+        OccurrenceBody::Action {
+            action: None,
+            lifeline: Some(f.receiver),
+        },
+    );
+    let y = row(&mut p, f.owner, "Y");
+    let prepared = prepare(&p, f.owner, &[fragment, x]).unwrap();
+    assert!(
+        prepared
+            .plan(slot(f.owner, Some(create)))
+            .unwrap_err()
+            .contains("lifeline_lifetime")
+    );
+    exact_transaction(
+        &p,
+        prepared.plan(slot(f.owner, None)).unwrap(),
+        ordered(&p, f.owner, &[create, y, x, fragment]),
+    );
+    let definition = p
+        .add_element(Kind::Scenario, Layer::Oa, "Definition", None)
+        .unwrap();
+    let represented = match p.elements[&f.receiver].shared().unwrap() {
+        SharedBody::Lifeline { represented } => *represented,
+        _ => panic!(),
+    };
+    let remote = p
+        .add_element(Kind::Lifeline, Layer::Oa, "Formal", Some(definition))
+        .unwrap();
+    *p.elements.get_mut(&remote).unwrap().shared_mut().unwrap() =
+        SharedBody::Lifeline { represented };
+    let uses = ["First use", "Second use"].map(|name| {
+        add(
+            &mut p,
+            f.owner,
+            name,
+            OccurrenceBody::ScenarioUse {
+                scenario: Some(definition),
+                bindings: vec![LifelineBinding {
+                    referenced: remote,
+                    local: f.receiver,
+                }],
+            },
+        )
+    });
+    let prepared = prepare(&p, f.owner, &[uses[1], uses[0]]).unwrap();
+    assert!(
+        prepared
+            .plan(slot(f.owner, Some(create)))
+            .unwrap_err()
+            .contains("lifeline_lifetime")
+    );
+    exact_transaction(
+        &p,
+        prepared.plan(slot(f.owner, Some(x))).unwrap(),
+        ordered(&p, f.owner, &[create, uses[0], uses[1], x, fragment, y]),
+    );
+}
+
+fn delete_line(p: &mut Project, parent: Id, sender: Id, receiver: Id) {
+    add(
+        p,
+        parent,
+        "Delete participant",
+        OccurrenceBody::Exchange {
+            exchange: None,
+            sender: Some(sender),
+            receiver: Some(receiver),
+            message_kind: MessageKind::Delete,
+            reply_to: None,
+            values: vec![],
+            operation: None,
+        },
+    );
+}
+
+fn second_operand(p: &mut Project, fragment: Id) -> Id {
+    let branch = occurrence(
+        p,
+        fragment,
+        "Other operand",
+        OccurrenceBody::Branch {
+            guard: "otherwise".into(),
+            occurrences: vec![],
+        },
+    );
+    let id = branch.id;
+    p.elements.insert(id, branch);
+    let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Fragment { branches, .. },
+        ..
+    }) = p.elements.get_mut(&fragment).unwrap().shared_mut()
+    else {
+        panic!()
+    };
+    branches.push(id);
+    id
+}
+
+#[test]
+fn conditional_delete_rejects_moving_an_earlier_use_after_the_fragment() {
+    let f = super::super::direct_tests::fixture();
+    let mut p = f.project;
+    let use_line = add(
+        &mut p,
+        f.owner,
+        "Use participant",
+        OccurrenceBody::Action {
+            action: None,
+            lifeline: Some(f.receiver),
+        },
+    );
+    let x = row(&mut p, f.owner, "X");
+    let (_, branch) = operand(&mut p, f.owner, FragmentOperator::Alternative);
+    delete_line(&mut p, branch, f.sender, f.receiver);
+    row(&mut p, f.owner, "Y");
+    oa_core::session::validate_candidate(&p).unwrap();
+    let prepared = prepare(&p, f.owner, &[x, use_line]).unwrap();
+    assert!(
+        prepared
+            .plan(slot(f.owner, None))
+            .unwrap_err()
+            .contains("lifeline_lifetime")
+    );
+}
+
+#[test]
+fn exclusive_operand_move_is_legal_but_parallel_baseline_is_invalid() {
+    for operator in [FragmentOperator::Alternative, FragmentOperator::Parallel] {
+        let f = super::super::direct_tests::fixture();
+        let mut p = f.project;
+        let (fragment, left) = operand(&mut p, f.owner, operator);
+        let right = second_operand(&mut p, fragment);
+        delete_line(&mut p, left, f.sender, f.receiver);
+        let use_line = add(
+            &mut p,
+            right,
+            "Use participant",
+            OccurrenceBody::Action {
+                action: None,
+                lifeline: Some(f.receiver),
+            },
+        );
+        let x = row(&mut p, right, "X");
+        let y = row(&mut p, right, "Y");
+        if operator == FragmentOperator::Alternative {
+            oa_core::session::validate_candidate(&p).unwrap();
+            exact_transaction(
+                &p,
+                prepare(&p, f.owner, &[x, use_line])
+                    .unwrap()
+                    .plan(slot(right, None))
+                    .unwrap(),
+                ordered(&p, right, &[y, use_line, x]),
+            );
+        } else {
+            // This is an invalid input control, not a valid model broken by reorder.
+            assert!(
+                oa_core::session::validate_candidate(&p)
+                    .unwrap_err()
+                    .to_string()
+                    .contains("lifeline_lifetime")
+            );
+            assert!(prepare(&p, f.owner, &[x, use_line]).is_err());
+        }
+    }
+}
+
+#[test]
+fn repeated_reply_warning_does_not_block_independent_sibling_reorder() {
+    let f = super::super::direct_tests::fixture();
+    let mut p = f.project;
+    let (_, branch) = operand(&mut p, f.owner, FragmentOperator::Loop);
+    p.elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .retain(|id| *id != f.reply);
+    p.elements.get_mut(&f.reply).unwrap().parent = Some(branch);
+    p.elements
+        .get_mut(&branch)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(f.reply);
+    let x = row(&mut p, branch, "X");
+    let y = row(&mut p, branch, "Y");
+    let z = row(&mut p, branch, "Z");
+    let warning = |project: &Project| {
+        oa_core::validation::validate(project).iter().any(|issue| {
+            issue.element == Some(f.reply)
+                && issue.code == "reply_repetition"
+                && issue.severity == oa_core::validation::Severity::Warning
+        })
+    };
+    assert!(warning(&p));
+    let expected = ordered(&p, branch, &[f.reply, y, x, z]);
+    assert!(warning(&expected));
+    exact_transaction(
+        &p,
+        prepare(&p, f.owner, &[z, x])
+            .unwrap()
+            .plan(slot(branch, None))
+            .unwrap(),
+        expected,
+    );
+}
+
+#[test]
+fn semantic_reorder_preserves_affected_and_unrelated_authored_layouts() {
+    use oa_core::{
+        Diagram, DiagramLayout, OccurrenceEndpoint, ProjectionKind, ScenarioLanePosition,
+        ScenarioLayout, ScenarioMessagePosition,
+    };
+    let f = super::super::direct_tests::fixture();
+    let mut p = f.project;
+    let x = row(&mut p, f.owner, "X");
+    let y = row(&mut p, f.owner, "Y");
+    p = ordered(&p, f.owner, &[f.call, x, f.reply, y]);
+    for (alias, offset) in [("group_saved_a", 0.), ("group_saved_b", 1500.)] {
+        let id = Id::new_v4();
+        p.diagrams.insert(
+            id,
+            Diagram {
+                id,
+                alias: alias.into(),
+                name: alias.into(),
+                description: "Preserve my layout".into(),
+                layer: Layer::Oa,
+                projection: ProjectionKind::Scenario { scenario: f.owner },
+                view_options: Default::default(),
+                nodes: Default::default(),
+                routes: vec![],
+                layout: Some(DiagramLayout::Scenario(ScenarioLayout {
+                    lanes: vec![
+                        ScenarioLanePosition {
+                            lifeline: f.sender,
+                            x: -300. + offset,
+                        },
+                        ScenarioLanePosition {
+                            lifeline: f.receiver,
+                            x: 700. + offset,
+                        },
+                    ],
+                    messages: vec![
+                        ScenarioMessagePosition {
+                            address: OccurrenceEndpoint {
+                                references: vec![],
+                                occurrence: f.call,
+                            },
+                            send_y: 123. + offset,
+                        },
+                        ScenarioMessagePosition {
+                            address: OccurrenceEndpoint {
+                                references: vec![],
+                                occurrence: f.reply,
+                            },
+                            send_y: 567. + offset,
+                        },
+                    ],
+                })),
+            },
+        );
+    }
+    let unrelated = p
+        .add_element(Kind::Scenario, Layer::Oa, "Unrelated scenario", None)
+        .unwrap();
+    let line = p
+        .add_element(
+            Kind::Lifeline,
+            Layer::Oa,
+            "Unrelated clock",
+            Some(unrelated),
+        )
+        .unwrap();
+    let timer = add(
+        &mut p,
+        unrelated,
+        "Wait",
+        OccurrenceBody::Exchange {
+            exchange: None,
+            sender: Some(line),
+            receiver: None,
+            message_kind: MessageKind::Timer {
+                expression: "5 s".into(),
+            },
+            reply_to: None,
+            values: vec![],
+            operation: None,
+        },
+    );
+    let diagram = Id::new_v4();
+    p.diagrams.insert(
+        diagram,
+        Diagram {
+            id: diagram,
+            alias: "group_unrelated_saved".into(),
+            name: "Unrelated arrangement".into(),
+            description: "Do not touch this view".into(),
+            layer: Layer::Oa,
+            projection: ProjectionKind::Scenario {
+                scenario: unrelated,
+            },
+            view_options: Default::default(),
+            nodes: Default::default(),
+            routes: vec![],
+            layout: Some(DiagramLayout::Scenario(ScenarioLayout {
+                lanes: vec![ScenarioLanePosition {
+                    lifeline: line,
+                    x: -123.,
+                }],
+                messages: vec![ScenarioMessagePosition {
+                    address: OccurrenceEndpoint {
+                        references: vec![],
+                        occurrence: timer,
+                    },
+                    send_y: 987.,
+                }],
+            })),
+        },
+    );
+    oa_core::session::validate_candidate(&p).unwrap();
+    exact_transaction(
+        &p,
+        prepare(&p, f.owner, &[f.reply, f.call])
+            .unwrap()
+            .plan(slot(f.owner, None))
+            .unwrap(),
+        ordered(&p, f.owner, &[x, y, f.call, f.reply]),
+    );
+}

crates/oa-desktop/src/behavior/scenario/presentation_tests.rs

@@ -218,6 +218,7 @@ fn complete_fallback_scene_selects_but_cannot_capture_or_finish_coordinate_gestu
     let stamp = spacing::Stamp {
         context,
         camera_epoch: 17,
+        selection_generation: 0,
     };
     ready_scene.coordinate_input = true;
     ready_scene.interaction = Some((context, CanvasTool::Select, true));

crates/oa-desktop/src/behavior/scenario/reorder_session.rs

@@ -0,0 +1,241 @@
+//! Immutable semantic reorder operation, independent of its destination UI.
+use super::{
+    Context, Slot,
+    group_reorder::{Plan, Prepared},
+    presentation, selection,
+};
+use crate::{diagram_selection::Snapshot, diagram_usage::Target};
+use oa_core::{Command, Id, Project, execute_batch};
+use std::sync::Arc;
+
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) enum Outcome {
+    Change,
+    Noop,
+    Refused(String),
+}
+
+pub(crate) struct Preview {
+    pub(crate) slot: Slot,
+    pub(crate) before: Vec<Id>,
+    pub(crate) after: Vec<Id>,
+    pub(crate) outcome: Outcome,
+    /// Geometry status is independent of semantic validity; requested Saved
+    /// representation is retained even when presentation reports fallback.
+    pub(crate) presentation: Option<presentation::ScenarioPresentation>,
+    pub(crate) selection_visible: bool,
+    command: Option<Box<Command>>,
+}
+
+pub(crate) struct Completion {
+    pub(crate) command: Option<Box<Command>>,
+    pub(crate) snapshot: Snapshot,
+    pub(crate) representation: super::Representation,
+    pub(crate) presentation_status: presentation::PresentationStatus,
+}
+
+pub(crate) struct Session {
+    project: Arc<Project>,
+    context: Context,
+    snapshot: Snapshot,
+    token: Id,
+    primary: Id,
+    parent: Id,
+    before: Vec<Id>,
+    prepared: Prepared,
+    preview: Option<Preview>,
+    #[cfg(test)]
+    proposal_builds: usize,
+}
+
+impl Session {
+    pub(crate) fn new(
+        project: Arc<Project>,
+        context: Context,
+        snapshot: Snapshot,
+        token: Id,
+    ) -> Result<Self, String> {
+        if token.is_nil()
+            || context.document.is_nil()
+            || context.visit.is_nil()
+            || snapshot.context() != selection::context(context)
+            || presentation::checked_owner(&project, context.representation)
+                != Some(context.scenario)
+        {
+            return Err("The reorder input no longer matches this scenario view.".into());
+        }
+        let Some(Target::ScenarioObject(primary)) = snapshot.primary() else {
+            return Err("Select ordered scenario occurrences.".into());
+        };
+        let primary = *primary;
+        let visible = selection::visible(&project, context, primary);
+        if !snapshot
+            .targets()
+            .contains(&Target::ScenarioObject(primary))
+            || snapshot
+                .targets()
+                .iter()
+                .any(|target| !visible.contains(target))
+        {
+            return Err("Every selected occurrence must be visible in this scenario view.".into());
+        }
+        let prepared = Prepared::new(project.clone(), context.scenario, snapshot.targets())?;
+        let parent = project.elements[&primary]
+            .parent
+            .expect("prepared occurrence parent");
+        let before = project.elements[&parent]
+            .steps()
+            .expect("prepared sequence")
+            .clone();
+        Ok(Self {
+            project,
+            context,
+            snapshot,
+            token,
+            primary,
+            parent,
+            before,
+            prepared,
+            preview: None,
+            #[cfg(test)]
+            proposal_builds: 0,
+        })
+    }
+
+    pub(crate) fn context(&self) -> Context {
+        self.context
+    }
+    pub(crate) fn token(&self) -> Id {
+        self.token
+    }
+    pub(crate) fn snapshot(&self) -> &Snapshot {
+        &self.snapshot
+    }
+    pub(crate) fn parent(&self) -> Id {
+        self.parent
+    }
+    pub(crate) fn before(&self) -> &[Id] {
+        &self.before
+    }
+
+    pub(crate) fn current_preview(&self) -> Option<&Preview> {
+        self.preview.as_ref()
+    }
+
+    #[cfg(test)]
+    pub(crate) fn current_preview_mut(&mut self) -> Option<&mut Preview> {
+        self.preview.as_mut()
+    }
+
+    pub(crate) fn matches(
+        &self,
+        current: &Project,
+        context: Context,
+        snapshot: &Snapshot,
+        token: Id,
+    ) -> bool {
+        current == self.project.as_ref()
+            && context == self.context
+            && snapshot == &self.snapshot
+            && token == self.token
+    }
+
+    pub(crate) fn preview(&mut self, slot: Slot) -> &Preview {
+        if self
+            .preview
+            .as_ref()
+            .is_none_or(|preview| preview.slot != slot)
+        {
+            #[cfg(test)]
+            {
+                self.proposal_builds += 1;
+            }
+            let result = self.prepared.plan(slot).and_then(|plan| match plan {
+                Plan::Noop => Ok((None, self.project.clone())),
+                Plan::Change(command) => {
+                    let candidate =
+                        execute_batch(&self.project, std::slice::from_ref(command.as_ref()))
+                            .map_err(|error| error.to_string())?;
+                    Ok((Some(command), Arc::new(candidate)))
+                }
+            });
+            let preview = match result {
+                Ok((command, candidate)) => {
+                    let shown = presentation::present(
+                        &candidate,
+                        self.context.representation,
+                        self.primary,
+                    );
+                    let visible = shown
+                        .scene()
+                        .map_or_else(Vec::new, |scene| scene.selection_targets());
+                    let selection_visible = self
+                        .snapshot
+                        .targets()
+                        .iter()
+                        .all(|target| visible.contains(target));
+                    Preview {
+                        slot,
+                        before: self.before.clone(),
+                        after: candidate.elements[&self.parent]
+                            .steps()
+                            .expect("validated sequence")
+                            .clone(),
+                        outcome: if command.is_some() {
+                            Outcome::Change
+                        } else {
+                            Outcome::Noop
+                        },
+                        presentation: Some(shown),
+                        selection_visible,
+                        command,
+                    }
+                }
+                Err(reason) => Preview {
+                    slot,
+                    before: self.before.clone(),
+                    after: self.before.clone(),
+                    outcome: Outcome::Refused(reason),
+                    presentation: None,
+                    selection_visible: false,
+                    command: None,
+                },
+            };
+            self.preview = Some(preview);
+        }
+        self.preview.as_ref().expect("explicit destination preview")
+    }
+
+    /// Consume once; never execute a Document transaction or alter selection.
+    pub(crate) fn finish(
+        self,
+        current: &Project,
+        context: Context,
+        snapshot: &Snapshot,
+        token: Id,
+    ) -> Result<Completion, String> {
+        if !self.matches(current, context, snapshot, token) {
+            return Err("The reorder input changed; choose the operation again.".into());
+        }
+        let preview = self
+            .preview
+            .ok_or("Choose an explicit destination before applying reorder.")?;
+        if let Outcome::Refused(reason) = preview.outcome {
+            return Err(reason);
+        }
+        let presentation_status = preview
+            .presentation
+            .expect("valid plan presentation")
+            .status()
+            .clone();
+        Ok(Completion {
+            command: preview.command,
+            snapshot: self.snapshot,
+            representation: self.context.representation,
+            presentation_status,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/behavior/scenario/reorder_session/tests.rs

@@ -0,0 +1,354 @@
+use super::*;
+use crate::{
+    behavior::{
+        scenario::{Representation, direct_tests},
+        topology::occurrence,
+    },
+    diagram_selection::Selection,
+};
+use oa_core::{Diagram, DiagramLayout, Layer, OccurrenceBody, ProjectionKind, ScenarioLayout};
+
+fn row(project: &mut Project, parent: Id, name: &str) -> Id {
+    let element = occurrence(
+        project,
+        parent,
+        name,
+        OccurrenceBody::Action {
+            action: None,
+            lifeline: None,
+        },
+    );
+    let id = element.id;
+    project.elements.insert(id, element);
+    project
+        .elements
+        .get_mut(&parent)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(id);
+    id
+}
+fn snapshot(context: Context, ids: &[Id]) -> Snapshot {
+    let mut selection = Selection::new(selection::context(context).scope);
+    for id in ids {
+        selection.add(Target::ScenarioObject(*id), |_| true);
+    }
+    selection.snapshot(selection::context(context)).unwrap()
+}
+fn session(project: &Project, context: Context, ids: &[Id]) -> Session {
+    Session::new(
+        Arc::new(project.clone()),
+        context,
+        snapshot(context, ids),
+        Id::new_v4(),
+    )
+    .unwrap()
+}
+
+#[test]
+fn explicit_destination_cache_and_exact_whole_model_saved_presentation() {
+    for mode in 0..3 {
+        let f = direct_tests::fixture();
+        let mut project = f.project;
+        let x = row(&mut project, f.owner, "X");
+        let y = row(&mut project, f.owner, "Y");
+        let mut context = direct_tests::context(f.owner);
+        for name in ["A", "B"] {
+            let id = Id::new_v4();
+            project.diagrams.insert(
+                id,
+                Diagram {
+                    id,
+                    alias: name.into(),
+                    name: name.into(),
+                    description: "Keep this view".into(),
+                    layer: Layer::Oa,
+                    projection: ProjectionKind::Scenario { scenario: f.owner },
+                    nodes: Default::default(),
+                    routes: vec![],
+                    view_options: Default::default(),
+                    layout: Some(DiagramLayout::Scenario(ScenarioLayout {
+                        lanes: vec![oa_core::ScenarioLanePosition {
+                            lifeline: f.sender,
+                            x: if name == "A" { 180. } else { 220. },
+                        }],
+                        messages: [(f.call, 600.), (f.reply, 800.)]
+                            .into_iter()
+                            .map(|(occurrence, send_y)| oa_core::ScenarioMessagePosition {
+                                address: oa_core::OccurrenceEndpoint {
+                                    references: vec![],
+                                    occurrence,
+                                },
+                                send_y,
+                            })
+                            .collect(),
+                    })),
+                },
+            );
+            if mode != 0 && name == "A" {
+                context.representation = Representation::Saved { diagram: id };
+                if mode == 2 {
+                    project.diagrams.get_mut(&id).unwrap().layout =
+                        Some(DiagramLayout::Scenario(ScenarioLayout {
+                            lanes: vec![],
+                            messages: [(f.call, 600.), (f.reply, 200.)]
+                                .into_iter()
+                                .map(|(occurrence, send_y)| oa_core::ScenarioMessagePosition {
+                                    address: oa_core::OccurrenceEndpoint {
+                                        references: vec![],
+                                        occurrence,
+                                    },
+                                    send_y,
+                                })
+                                .collect(),
+                        }));
+                }
+            }
+        }
+        let mut operation = session(&project, context, &[f.reply, f.call]);
+        assert_eq!(operation.parent(), f.owner);
+        assert_eq!(operation.before(), &[f.call, f.reply, x, y]);
+        assert_eq!(operation.context(), context);
+        let original_snapshot = operation.snapshot().clone();
+        let token = operation.token();
+        let slot = Slot {
+            parent: f.owner,
+            before: None,
+        };
+        let preview = operation.preview(slot);
+        assert_eq!(preview.before, [f.call, f.reply, x, y]);
+        assert_eq!(preview.after, [x, y, f.call, f.reply]);
+        assert_eq!(preview.outcome, Outcome::Change);
+        assert_eq!(
+            preview.presentation.as_ref().unwrap().requested(),
+            context.representation
+        );
+        assert_eq!(operation.proposal_builds, 1);
+        operation.preview(slot);
+        assert_eq!(operation.proposal_builds, 1);
+        operation.preview(Slot {
+            parent: f.owner,
+            before: Some(f.call),
+        });
+        assert_eq!(operation.proposal_builds, 2);
+        operation.preview(slot);
+        assert_eq!(operation.proposal_builds, 3);
+        assert_eq!(operation.preview.as_ref().unwrap().slot, slot);
+        let completion = operation
+            .finish(&project, context, &original_snapshot, token)
+            .unwrap();
+        assert_eq!(completion.snapshot, original_snapshot);
+        assert_eq!(completion.representation, context.representation);
+        if mode == 2 {
+            assert!(matches!(
+                completion.presentation_status,
+                presentation::PresentationStatus::Fallback { .. }
+            ));
+        } else {
+            assert!(matches!(
+                completion.presentation_status,
+                presentation::PresentationStatus::Ready
+            ));
+        }
+        let mut expected = project.clone();
+        *expected
+            .elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap() = vec![x, y, f.call, f.reply];
+        assert_eq!(
+            execute_batch(&project, &[*completion.command.unwrap()]).unwrap(),
+            expected
+        );
+        assert_eq!(expected.diagrams, project.diagrams);
+    }
+}
+
+#[test]
+fn no_destination_is_not_noop_and_selected_anchor_is_explicit_noop() {
+    let f = direct_tests::fixture();
+    let context = direct_tests::context(f.owner);
+    let mut operation = session(&f.project, context, &[f.call, f.reply]);
+    let captured = operation.snapshot().clone();
+    let token = operation.token();
+    assert!(
+        operation
+            .finish(&f.project, context, &captured, token)
+            .is_err()
+    );
+    operation = session(&f.project, context, &[f.call, f.reply]);
+    let token = operation.token();
+    assert_eq!(
+        operation
+            .preview(Slot {
+                parent: f.owner,
+                before: Some(f.reply)
+            })
+            .outcome,
+        Outcome::Noop
+    );
+    assert!(
+        operation
+            .finish(&f.project, context, &captured, token)
+            .unwrap()
+            .command
+            .is_none()
+    );
+}
+
+#[test]
+fn temporal_candidate_refuses_without_changing_baseline_or_selection() {
+    let f = direct_tests::fixture();
+    let context = direct_tests::context(f.owner);
+    let mut project = f.project;
+    let later = row(&mut project, f.owner, "Later action");
+    let mut operation = session(&project, context, &[f.reply]);
+    let captured = operation.snapshot().clone();
+    let token = operation.token();
+    // A previously valid proposal must not survive a new refused destination.
+    let valid = operation.preview(Slot {
+        parent: f.owner,
+        before: None,
+    });
+    assert_eq!(valid.outcome, Outcome::Change);
+    assert_eq!(valid.after, [f.call, later, f.reply]);
+    let preview = operation.preview(Slot {
+        parent: f.owner,
+        before: Some(f.call),
+    });
+    assert!(matches!(&preview.outcome, Outcome::Refused(reason) if reason.contains("reply_order")));
+    assert!(preview.presentation.is_none());
+    assert_eq!(preview.before, preview.after);
+    assert!(
+        operation
+            .finish(&project, context, &captured, token)
+            .is_err()
+    );
+}
+
+#[test]
+fn mixed_cross_parent_and_unrendered_sets_never_reduce_to_primary() {
+    let f = direct_tests::fixture();
+    let context = direct_tests::context(f.owner);
+    let mut project = f.project;
+    let other = project
+        .add_element(oa_core::Kind::Scenario, Layer::Oa, "Other", None)
+        .unwrap();
+    let foreign = row(&mut project, other, "Foreign");
+    let fragment = occurrence(
+        &project,
+        f.owner,
+        "Fragment",
+        OccurrenceBody::Fragment {
+            operator: oa_core::FragmentOperator::Alternative,
+            branches: vec![],
+        },
+    );
+    let fragment_id = fragment.id;
+    project.elements.insert(fragment_id, fragment);
+    project
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(fragment_id);
+    let branch = occurrence(
+        &project,
+        fragment_id,
+        "Branch",
+        OccurrenceBody::Branch {
+            guard: "ready".into(),
+            occurrences: vec![],
+        },
+    );
+    let branch_id = branch.id;
+    project.elements.insert(branch_id, branch);
+    if let Some(oa_core::SharedBody::Occurrence {
+        body: OccurrenceBody::Fragment { branches, .. },
+        ..
+    }) = project.elements.get_mut(&fragment_id).unwrap().shared_mut()
+    {
+        branches.push(branch_id);
+    }
+    let nested = row(&mut project, branch_id, "Nested");
+    assert!(
+        selection::visible(&project, context, f.call).contains(&Target::ScenarioObject(nested))
+    );
+    for ids in [
+        vec![f.sender, f.call],
+        vec![nested, f.call],
+        vec![foreign, f.call],
+        vec![Id::new_v4(), f.call],
+    ] {
+        assert!(
+            Session::new(
+                Arc::new(project.clone()),
+                context,
+                snapshot(context, &ids),
+                Id::new_v4()
+            )
+            .is_err()
+        );
+    }
+}
+
+#[test]
+fn stale_finish_checks_every_immutable_input_and_constructor_rejects_nil_lifetimes() {
+    let f = direct_tests::fixture();
+    let context = direct_tests::context(f.owner);
+    for altered in 0..8 {
+        let mut operation = session(&f.project, context, &[f.call, f.reply]);
+        let mut token = operation.token();
+        let mut captured = operation.snapshot().clone();
+        let mut current = f.project.clone();
+        let mut live = context;
+        operation.preview(Slot {
+            parent: f.owner,
+            before: None,
+        });
+        match altered {
+            0 => {
+                current.elements.get_mut(&f.call).unwrap().name.push('!');
+            }
+            1 => live.epoch += 1,
+            2 => captured = snapshot(context, &[f.reply, f.call]),
+            3 => token = Id::new_v4(),
+            4 => live.visit = Id::new_v4(),
+            5 => live.document = Id::new_v4(),
+            6 => live.revision += 1,
+            _ => {
+                let mut selection = Selection::new(selection::context(context).scope);
+                selection.add(Target::ScenarioObject(f.call), |_| true);
+                selection.add(Target::ScenarioObject(f.reply), |_| true);
+                selection.set_primary(&Target::ScenarioObject(f.call));
+                selection.set_primary(&Target::ScenarioObject(f.reply));
+                captured = selection.snapshot(selection::context(context)).unwrap();
+                assert_eq!(captured.targets(), operation.snapshot().targets());
+                assert_eq!(captured.primary(), operation.snapshot().primary());
+                assert_ne!(captured.generation(), operation.snapshot().generation());
+            }
+        }
+        assert!(operation.finish(&current, live, &captured, token).is_err());
+    }
+    for altered in 0..3 {
+        let mut live = context;
+        let mut token = Id::new_v4();
+        match altered {
+            0 => live.document = Id::nil(),
+            1 => live.visit = Id::nil(),
+            _ => token = Id::nil(),
+        }
+        assert!(
+            Session::new(
+                Arc::new(f.project.clone()),
+                live,
+                snapshot(live, &[f.call]),
+                token
+            )
+            .is_err()
+        );
+    }
+}

crates/oa-desktop/src/behavior/scenario/reorder_slot_experiments.rs

@@ -0,0 +1,234 @@
+//! Candidate-input experiment, not an accepted new interaction policy.
+//! Exercise production presentation, nearest-Y picking, and exact semantic slots.
+use super::{Representation, Slot, group_reorder, presentation};
+use crate::{behavior::Scene, diagram_usage::Target};
+use iced::Point;
+use oa_core::{
+    Diagram, DiagramLayout, Id, OccurrenceEndpoint, Project, ProjectionKind, ScenarioLayout,
+    ScenarioMessagePosition, execute_batch, language, validation,
+};
+use std::sync::Arc;
+
+struct Fixture {
+    project: Project,
+    owner: Id,
+    diagram: Id,
+    ids: [Id; 4],
+}
+
+fn fixture(ys: [f32; 4]) -> Fixture {
+    let mut project = language::parse(SOURCE).unwrap();
+    let named = |name: &str| {
+        project
+            .identities()
+            .into_iter()
+            .find(|(_, alias)| *alias == name)
+            .unwrap()
+            .0
+    };
+    let owner = named("conversation");
+    let ids = [named("a"), named("b"), named("c"), named("d")];
+    let diagram = Id::new_v4();
+    project.diagrams.insert(
+        diagram,
+        Diagram {
+            id: diagram,
+            alias: "saved".into(),
+            name: "Authored coordinates".into(),
+            description: String::new(),
+            layer: project.elements[&owner].layer(),
+            projection: ProjectionKind::Scenario { scenario: owner },
+            view_options: Default::default(),
+            nodes: Default::default(),
+            routes: vec![],
+            layout: Some(DiagramLayout::Scenario(ScenarioLayout {
+                lanes: vec![],
+                messages: ids
+                    .into_iter()
+                    .zip(ys)
+                    .map(|(occurrence, send_y)| ScenarioMessagePosition {
+                        address: OccurrenceEndpoint {
+                            occurrence,
+                            references: vec![],
+                        },
+                        send_y,
+                    })
+                    .collect(),
+            })),
+        },
+    );
+    assert!(
+        validation::validate(&project)
+            .iter()
+            .all(|issue| issue.severity != validation::Severity::Error)
+    );
+    Fixture {
+        project,
+        owner,
+        diagram,
+        ids,
+    }
+}
+
+fn shown(f: &Fixture) -> presentation::ScenarioPresentation {
+    let shown = presentation::present(
+        &f.project,
+        Representation::Saved { diagram: f.diagram },
+        f.ids[0],
+    );
+    assert_eq!(shown.status(), &presentation::PresentationStatus::Ready);
+    assert_eq!(shown.requested(), shown.geometry_representation().unwrap());
+    shown
+}
+
+fn before(f: &Fixture, id: Id) -> Slot {
+    Slot {
+        parent: f.owner,
+        before: Some(id),
+    }
+}
+
+fn y(scene: &Scene, slot: Slot) -> f32 {
+    scene.slots.iter().find(|item| item.slot == slot).unwrap().y
+}
+
+fn picked(scene: &Scene, f: &Fixture, world_y: f32) -> Slot {
+    scene
+        .slot_at(Point::new(100., world_y), Some(f.owner))
+        .unwrap()
+        .slot
+}
+
+fn exact_change(f: &Fixture, selected: &[Id], slot: Slot, order: &[Id]) {
+    let prepared = group_reorder::Prepared::new(
+        Arc::new(f.project.clone()),
+        f.owner,
+        &selected
+            .iter()
+            .copied()
+            .map(Target::ScenarioObject)
+            .collect::<Vec<_>>(),
+    )
+    .unwrap();
+    let group_reorder::Plan::Change(command) = prepared.plan(slot).unwrap() else {
+        panic!("expected an actual semantic change")
+    };
+    let actual = execute_batch(&f.project, std::slice::from_ref(command.as_ref())).unwrap();
+    let mut expected = f.project.clone();
+    *expected
+        .elements
+        .get_mut(&f.owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap() = order.to_vec();
+    // Literal full-model oracle: every authored position and other field survives.
+    assert_eq!(actual, expected);
+    assert_eq!(
+        language::parse(&language::format(&actual)).unwrap(),
+        expected
+    );
+    assert_eq!(
+        presentation::present(
+            &actual,
+            Representation::Saved { diagram: f.diagram },
+            selected[0]
+        )
+        .status(),
+        &presentation::PresentationStatus::Ready
+    );
+}
+
+#[test]
+fn crossed_saved_slots_are_reachable_but_screen_order_is_not_semantic_order() {
+    let f = fixture([200., 500., 300., 400.]);
+    let [a, b, c, d] = f.ids;
+    let shown = shown(&f);
+    let scene = shown.scene().unwrap();
+    assert_eq!(
+        f.ids.map(|id| y(scene, before(&f, id))),
+        [158., 458., 258., 358.]
+    );
+    let mut spatial = f.ids.to_vec();
+    spatial.sort_by(|a, b| y(scene, before(&f, *a)).total_cmp(&y(scene, before(&f, *b))));
+    assert_eq!(spatial, [a, c, d, b]);
+    for id in f.ids {
+        assert_eq!(picked(scene, &f, y(scene, before(&f, id))), before(&f, id));
+    }
+    exact_change(&f, &[c, a], before(&f, d), &[b, a, c, d]);
+}
+
+#[test]
+fn equal_saved_slots_hide_one_destination_while_exact_chooser_can_select_it() {
+    let f = fixture([200., 300., 300., 500.]);
+    let [a, b, c, d] = f.ids;
+    let shown = shown(&f);
+    let scene = shown.scene().unwrap();
+    assert_eq!(y(scene, before(&f, b)), 258.);
+    assert_eq!(y(scene, before(&f, c)), 258.);
+    assert!(
+        scene
+            .slots
+            .iter()
+            .position(|item| item.slot == before(&f, b))
+            < scene
+                .slots
+                .iter()
+                .position(|item| item.slot == before(&f, c))
+    );
+    // The two distances are identical for every finite Y; min_by keeps the first
+    // tie. The sample exercises that production behavior, not an exhaustive proof.
+    for quarter_pixel in -4000..=12000 {
+        assert_ne!(picked(scene, &f, quarter_pixel as f32 / 4.), before(&f, c));
+    }
+    assert_eq!(picked(scene, &f, 258.), before(&f, b));
+    exact_change(&f, &[d, a], before(&f, c), &[b, a, d, c]);
+    exact_change(&f, &[d, a], picked(scene, &f, 258.), &[a, d, b, c]);
+}
+
+#[test]
+fn close_saved_slots_have_subpixel_hit_regions_without_becoming_unreachable_continuously() {
+    let f = fixture([200., 300., 300.125, 300.25]);
+    let [_, b, c, d] = f.ids;
+    let shown = shown(&f);
+    let scene = shown.scene().unwrap();
+    assert_eq!(y(scene, before(&f, b)), 258.);
+    assert_eq!(y(scene, before(&f, c)), 258.125);
+    assert_eq!(y(scene, before(&f, d)), 258.25);
+    assert_eq!(picked(scene, &f, 258.125), before(&f, c));
+    // Fixed scale=1/pan=0: C's open Voronoi interval is only
+    // (258.0625, 258.1875). Integer-pixel samples miss it. This does not assert
+    // that all platforms quantize pointer input to integer coordinates.
+    for screen_y in 0..=600 {
+        assert_ne!(picked(scene, &f, screen_y as f32), before(&f, c));
+    }
+}
+
+#[test]
+fn offscreen_saved_slot_needs_camera_change_or_nonspatial_destination_input() {
+    let f = fixture([200., 300., 400., 2000.]);
+    let [a, b, c, d] = f.ids;
+    let shown = shown(&f);
+    let scene = shown.scene().unwrap();
+    assert_eq!(y(scene, before(&f, d)), 1958.);
+    // Fixed scale=1/pan=0 and a 600px-high canvas. The C/D midpoint is
+    // 1158, beyond the whole viewport, so D cannot win within that viewport.
+    for quarter_pixel in 0..=2400 {
+        assert_ne!(picked(scene, &f, quarter_pixel as f32 / 4.), before(&f, d));
+    }
+    assert_eq!(picked(scene, &f, 1958.), before(&f, d));
+    exact_change(&f, &[c, a], before(&f, d), &[b, a, c, d]);
+}
+
+const SOURCE: &str = r#"arcadia 7;
+project slot_probe "Slot probe" id "71000000-0000-4000-8000-000000000001" {
+ oa_activity source "Source" id "71000000-0000-4000-8000-000000000002" {}
+ oa_activity target "Target" id "71000000-0000-4000-8000-000000000003" {}
+ oa_scenario conversation "Conversation" id "71000000-0000-4000-8000-000000000004" { viewpoint OperationalActivity; steps [@a, @b, @c, @d]; }
+ oa_lifeline left "Left" id "71000000-0000-4000-8000-000000000005" { parent @conversation; represented @source; }
+ oa_lifeline right "Right" id "71000000-0000-4000-8000-000000000006" { parent @conversation; represented @target; }
+ oa_occurrence a "A" id "71000000-0000-4000-8000-000000000007" { parent @conversation; body { Exchange { exchange none; sender @left; receiver @right; message_kind Asynchronous; }; }; }
+ oa_occurrence b "B" id "71000000-0000-4000-8000-000000000008" { parent @conversation; body { Exchange { exchange none; sender @left; receiver @right; message_kind Asynchronous; }; }; }
+ oa_occurrence c "C" id "71000000-0000-4000-8000-000000000009" { parent @conversation; body { Exchange { exchange none; sender @left; receiver @right; message_kind Asynchronous; }; }; }
+ oa_occurrence d "D" id "71000000-0000-4000-8000-00000000000a" { parent @conversation; body { Exchange { exchange none; sender @left; receiver @right; message_kind Asynchronous; }; }; }
+}
+"#;

crates/oa-desktop/src/behavior/scenario/reorder_view.rs

@@ -0,0 +1,323 @@
+//! Identity-based destination choice, independent of saved screen coordinates.
+use super::*;
+use crate::app::scenario_reorder::{Event, Intent};
+use crate::behavior::scenario_layout::presentation::PresentationStatus;
+use iced::widget::{column, opaque, scrollable};
+
+const PAGE_SIZE: usize = 5;
+
+pub(crate) fn query_id(token: Id) -> iced::widget::Id {
+    iced::widget::Id::from(format!("scenario-reorder-query:{token}"))
+}
+
+pub(crate) fn focus_query(token: Id) -> iced::Task<Message> {
+    use iced::advanced::widget::{Operation, operation};
+    struct Find {
+        target: iced::widget::Id,
+        present: bool,
+    }
+    impl Operation for Find {
+        fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+            visit(self);
+        }
+        fn focusable(
+            &mut self,
+            id: Option<&iced::widget::Id>,
+            _: iced::Rectangle,
+            _: &mut dyn operation::Focusable,
+        ) {
+            self.present |= id == Some(&self.target);
+        }
+        fn finish(&self) -> operation::Outcome<()> {
+            if self.present {
+                operation::Outcome::Chain(Box::new(operation::focusable::focus(
+                    self.target.clone(),
+                )))
+            } else {
+                operation::Outcome::None
+            }
+        }
+    }
+    // Generic focus would blur every current widget if the old token vanished.
+    // Discover the exact target without changing focus before chaining it.
+    iced::advanced::widget::operate(Find {
+        target: query_id(token),
+        present: false,
+    })
+    .discard()
+}
+
+pub(crate) fn apply_message(app: &App) -> Option<Message> {
+    if !app.scenario_reorder_enabled() {
+        return None;
+    }
+    let session = app.scenario_reorder.session.as_ref()?;
+    let preview = session.current_preview()?;
+    (preview.selection_visible
+        && !matches!(preview.outcome, reorder_session::Outcome::Refused(_))
+        && matches!(
+            preview.presentation.as_ref()?.status(),
+            PresentationStatus::Ready | PresentationStatus::Fallback { .. }
+        ))
+    .then(|| message(session, Intent::Finish(preview.slot)))
+}
+
+pub(crate) fn message(session: &reorder_session::Session, intent: Intent) -> Message {
+    Message::ScenarioReorder(Box::new(Event {
+        context: session.context(),
+        snapshot: session.snapshot().clone(),
+        token: session.token(),
+        intent,
+    }))
+}
+
+pub(crate) fn begin(app: &App) -> Option<Message> {
+    (app.scenario_reorder_enabled() && app.scenario_reorder.session.is_none()).then_some(())?;
+    let snapshot = app.multiselect_snapshot()?;
+    if snapshot.targets().is_empty() {
+        return None;
+    }
+    Some(Message::ScenarioReorder(Box::new(Event {
+        context: app.scenario_context()?,
+        snapshot,
+        token: Id::new_v4(),
+        intent: Intent::Begin,
+    })))
+}
+
+fn label(p: &Project, id: Id) -> String {
+    p.elements.get(&id).map_or_else(
+        || id.to_string(),
+        |e| format!("{} (@{})", short(&e.name, 38), e.alias),
+    )
+}
+
+fn destination(p: &Project, before: &[Id], slot: Slot) -> String {
+    slot.before.map_or_else(
+        || "End of sequence".into(),
+        |id| {
+            let position = before
+                .iter()
+                .position(|item| *item == id)
+                .map_or(0, |i| i + 1);
+            format!("Before {position}. {}", label(p, id))
+        },
+    )
+}
+
+fn order(p: &Project, ids: &[Id], snapshot: &crate::diagram_selection::Snapshot) -> String {
+    // A bounded neighborhood keeps the moved block and its immediate neighbors
+    // visible. Ellipses explicitly mark omitted, unchanged sequence members.
+    let selected = |id: &Id| {
+        snapshot
+            .targets()
+            .contains(&crate::diagram_usage::Target::ScenarioObject(*id))
+    };
+    let mut parts = Vec::new();
+    let mut omitted = false;
+    for (index, id) in ids.iter().enumerate() {
+        let near = selected(id)
+            || index.checked_sub(1).is_some_and(|i| selected(&ids[i]))
+            || ids.get(index + 1).is_some_and(selected);
+        if !near {
+            omitted = true;
+            continue;
+        }
+        if omitted {
+            parts.push("…".into());
+            omitted = false;
+        }
+        parts.push(format!(
+            "{}{}. {}",
+            if selected(id) { "• " } else { "" },
+            index + 1,
+            label(p, *id)
+        ));
+    }
+    if omitted {
+        parts.push("…".into());
+    }
+    parts.join("\n")
+}
+
+pub(super) fn panel(app: &App, viewport: Option<Size>) -> Option<Element<'_, Message>> {
+    let session = app.scenario_reorder.session.as_ref()?;
+    let p = app.project();
+    let state = &app.scenario_reorder;
+    let query = state.query.to_lowercase();
+    let slots = session
+        .before()
+        .iter()
+        .copied()
+        .map(Some)
+        .chain(std::iter::once(None))
+        .enumerate()
+        .map(|(index, before)| {
+            let slot = Slot {
+                parent: session.parent(),
+                before,
+            };
+            let title = before.map_or_else(
+                || "End of sequence".into(),
+                |id| format!("Before {}. {}", index + 1, label(p, id)),
+            );
+            (slot, title)
+        })
+        .filter(|(slot, title)| {
+            title.to_lowercase().contains(&query)
+                || slot
+                    .before
+                    .and_then(|id| p.elements.get(&id))
+                    .is_some_and(|e| {
+                        e.name.to_lowercase().contains(&query)
+                            || e.alias.to_lowercase().contains(&query)
+                    })
+        })
+        .collect::<Vec<_>>();
+    let pages = slots.len().div_ceil(PAGE_SIZE).max(1);
+    let page = state.page.min(pages - 1);
+    let mut choices = column![].spacing(4).width(Fill);
+    for (slot, title) in slots.iter().skip(page * PAGE_SIZE).take(PAGE_SIZE) {
+        choices = choices.push(
+            button(
+                text(title.clone())
+                    .size(12)
+                    .width(Fill)
+                    .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+            )
+            .width(Fill)
+            .on_press(message(session, Intent::Choose(*slot))),
+        );
+    }
+    if slots.is_empty() {
+        choices = choices
+            .push(text("No matching destination. Try its name, alias or position.").size(12));
+    }
+    let mut body = column![
+        text(format!(
+            "Reorder {} selected",
+            session.snapshot().targets().len()
+        ))
+        .size(17),
+        text(format!("Sequence: {}", label(p, session.parent())))
+            .size(12)
+            .width(Fill)
+            .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        text("Changes execution order; saved positions stay as authored.").size(12),
+        text_input("Find destination by name, alias or position", &state.query)
+            .id(query_id(session.token()))
+            .on_input(move |query| message(session, Intent::Query(query)))
+            .on_submit_maybe(
+                (slots.len() == 1).then(|| message(session, Intent::Choose(slots[0].0)))
+            )
+            .size(13),
+        choices,
+        row![
+            button("Previous")
+                .on_press_maybe((page > 0).then(|| message(session, Intent::Page(page - 1)))),
+            text(format!("{} / {pages}", page + 1)).size(12),
+            button("Next").on_press_maybe(
+                (page + 1 < pages).then(|| message(session, Intent::Page(page + 1)))
+            )
+        ]
+        .spacing(8),
+    ]
+    .spacing(8)
+    .width(Fill);
+    let mut apply = None;
+    let mut footer =
+        column![text("Enter previews a unique match. Ctrl+Enter applies; Esc cancels.").size(12)]
+            .spacing(6);
+    if let Some(preview) = session.current_preview() {
+        footer = footer.push(
+            text(format!(
+                "Destination: {}",
+                destination(p, session.before(), preview.slot)
+            ))
+            .size(13)
+            .width(Fill)
+            .wrapping(iced::widget::text::Wrapping::WordOrGlyph),
+        );
+        let comparison = row![
+            container(
+                column![
+                    text("Before").size(13),
+                    text(order(p, &preview.before, session.snapshot()))
+                        .size(12)
+                        .width(Fill)
+                        .wrapping(iced::widget::text::Wrapping::WordOrGlyph)
+                ]
+                .width(Fill)
+            )
+            .width(Fill)
+            .id("scenario-reorder-before"),
+            container(
+                column![
+                    text("After • selected").size(13),
+                    text(order(p, &preview.after, session.snapshot()))
+                        .size(12)
+                        .width(Fill)
+                        .wrapping(iced::widget::text::Wrapping::WordOrGlyph)
+                ]
+                .width(Fill)
+            )
+            .width(Fill)
+            .id("scenario-reorder-after")
+        ]
+        .spacing(10)
+        .width(Fill);
+        body = body.push(comparison);
+        let feedback = match &preview.outcome {
+            reorder_session::Outcome::Refused(reason) => reason.clone(),
+            _ if !preview.selection_visible => {
+                "This destination would hide a selected occurrence; choose another destination."
+                    .into()
+            }
+            _ => match preview.presentation.as_ref().map(|shown| shown.status()) {
+                Some(PresentationStatus::Unavailable { .. }) | None => {
+                    "This order cannot be displayed; choose another destination.".into()
+                }
+                Some(status) => {
+                    apply = Some(message(session, Intent::Finish(preview.slot)));
+                    if matches!(status, PresentationStatus::Fallback { .. }) {
+                        "Apply will display an automatic arrangement. Your requested saved view and authored positions are retained; they are not repaired.".into()
+                    } else if matches!(preview.outcome, reorder_session::Outcome::Noop) {
+                        "This destination keeps the current order; Apply will close without an edit.".into()
+                    } else {
+                        "The selected occurrences move together in their existing order. One Undo restores the sequence.".into()
+                    }
+                }
+            },
+        };
+        footer = footer.push(text(feedback).size(12));
+    } else {
+        body = body.push(text("Choose a destination to preview the new sequence.").size(12));
+    }
+    let height = viewport.map_or(500., |size| (size.height - 32.).max(100.));
+    let card = column![
+        scrollable(body)
+            .height(Fill)
+            .width(Fill)
+            .spacing(8)
+            .id("scenario-reorder-body"),
+        footer,
+        row![
+            button("Cancel (Esc)").on_press(message(session, Intent::Cancel)),
+            button("Apply order (Ctrl+Enter)").on_press_maybe(apply)
+        ]
+        .spacing(8)
+    ]
+    .spacing(10);
+    Some(
+        container(opaque(
+            container(card)
+                .padding(12)
+                .width(480)
+                .height(height.min(630.))
+                .style(style::card),
+        ))
+        .align_right(Fill)
+        .padding(8)
+        .into(),
+    )
+}

crates/oa-desktop/src/behavior/scenario/selection.rs

@@ -0,0 +1,54 @@
+//! Captured exact Scenario selection input; membership grants no movement permission.
+use super::{Context, presentation};
+use crate::{
+    app::multiselect::Choice,
+    diagram_selection,
+    diagram_usage::{Surface, Target},
+};
+use oa_core::{Id, Project};
+#[derive(Debug, Clone)]
+pub(crate) struct Event {
+    pub context: Context,
+    pub snapshot: diagram_selection::Snapshot,
+    pub intent: Intent,
+}
+#[derive(Debug, Clone)]
+pub(crate) enum Intent {
+    Choose(Target, Choice),
+    Clear,
+    Collapse(Target),
+    Refuse(String),
+}
+pub(crate) fn context(context: Context) -> diagram_selection::Context {
+    diagram_selection::Context {
+        scope: diagram_selection::Scope {
+            document: context.document,
+            surface: match context.representation {
+                super::Representation::Derived { owner } => Surface::Scenario(owner),
+                super::Representation::Saved { diagram } => Surface::Saved(diagram),
+            },
+        },
+        revision: context.revision,
+        epoch: context.epoch,
+    }
+}
+pub(crate) fn visible(project: &Project, context: Context, selected: Id) -> Vec<Target> {
+    let shown = presentation::present(project, context.representation, selected);
+    shown
+        .scene()
+        .map_or_else(Vec::new, |scene| scene.selection_targets())
+}
+pub(crate) fn message(
+    context: Context,
+    snapshot: &diagram_selection::Snapshot,
+    intent: Intent,
+) -> crate::app::Message {
+    crate::app::Message::ScenarioCanvas(super::CanvasEvent::Selection(Box::new(Event {
+        context,
+        snapshot: snapshot.clone(),
+        intent,
+    })))
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/behavior/scenario/selection/tests.rs

@@ -0,0 +1,268 @@
+use super::*;
+use crate::behavior::{
+    Scene, SequenceInput,
+    scenario::{self, CanvasEvent, CanvasTool},
+};
+use crate::diagram_selection::Selection;
+use iced::{
+    Point, Rectangle, Vector, mouse,
+    widget::canvas::{self, Program},
+};
+
+fn fixture(group: bool) -> (scenario::direct_tests::Fixture, Scene, Point) {
+    let f = scenario::direct_tests::fixture();
+    let context = scenario::direct_tests::context(f.owner);
+    let mut scene = Scene::sequence(&f.project, f.owner, f.reply);
+    scene.interaction = Some((context, CanvasTool::Select, true));
+    let mut selection = Selection::new(super::context(context).scope);
+    selection.add(Target::ScenarioObject(f.call), |_| true);
+    if group {
+        selection.add(Target::ScenarioObject(f.reply), |_| true);
+    }
+    scene.selection = Some((
+        context,
+        selection.snapshot(super::context(context)).unwrap(),
+    ));
+    let line = scene.lines.iter().find(|line| line.id == f.call).unwrap();
+    let point = line.label_at + Vector::new(8., 8.);
+    assert_eq!(scene.hit(point), Some(f.call));
+    (f, scene, point)
+}
+fn send(
+    scene: &Scene,
+    state: &mut SequenceInput,
+    event: canvas::Event,
+    point: Option<Point>,
+) -> Option<CanvasEvent> {
+    scene
+        .update(
+            state,
+            &event,
+            Rectangle::new(Point::ORIGIN, scene.size),
+            point.map_or(mouse::Cursor::Unavailable, mouse::Cursor::Available),
+        )
+        .and_then(|action| action.into_inner().0)
+        .and_then(|message| match message {
+            crate::app::Message::ScenarioCanvas(event) => Some(event),
+            _ => None,
+        })
+}
+fn mouse_event(event: mouse::Event) -> canvas::Event {
+    canvas::Event::Mouse(event)
+}
+
+#[test]
+fn saved_group_body_press_emits_one_spacing_lifetime_without_collapsing_selection() {
+    use crate::behavior::scenario::spacing::{self, Event};
+    use crate::behavior::scenario_layout::{Representation, resolve};
+    let (doc, owner, diagram, _, first) = spacing::controller::tests::fixture();
+    let second = doc
+        .project()
+        .identities()
+        .into_iter()
+        .find(|(_, a)| *a == "second")
+        .unwrap()
+        .0;
+    let mut context = scenario::direct_tests::context(owner);
+    context.representation = Representation::Saved { diagram };
+    let mut scene = resolve(doc.project(), context.representation, second)
+        .unwrap()
+        .scene;
+    let mut selection = Selection::new(super::context(context).scope);
+    selection.add(Target::ScenarioObject(first), |_| true);
+    selection.add(Target::ScenarioObject(second), |_| true);
+    let snapshot = selection.snapshot(super::context(context)).unwrap();
+    let stamp = spacing::Stamp {
+        context,
+        camera_epoch: 9,
+        selection_generation: snapshot.generation(),
+    };
+    scene.selection = Some((context, snapshot.clone()));
+    scene.selected = second;
+    scene.interaction = Some((context, CanvasTool::Select, true));
+    scene.coordinate_input = true;
+    scene.spacing_stamp = Some(stamp);
+    let line = scene.lines.iter().find(|line| line.id == first).unwrap();
+    let point = Point::new((line.points[0].x + line.points[1].x) / 2., line.points[0].y);
+    assert_eq!(scene.hit(point), Some(first));
+    let mut input = SequenceInput::default();
+    let Some(CanvasEvent::Spacing(Event::Begin {
+        stamp: got,
+        token,
+        target,
+        ..
+    })) = send(
+        &scene,
+        &mut input,
+        mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+        Some(point),
+    )
+    else {
+        panic!("group spacing begins on first press")
+    };
+    assert_eq!(got, stamp);
+    assert_eq!(target, spacing::Target::Message(first));
+    assert!(input.group_press.is_none());
+    let moved = point + Vector::new(0., 24.);
+    assert!(
+        matches!(send(&scene,&mut input,mouse_event(mouse::Event::CursorMoved{position:moved}),Some(moved)),Some(CanvasEvent::Spacing(Event::Move{stamp:s,token:t,..})) if s==stamp && t==token)
+    );
+    assert!(
+        matches!(send(&scene,&mut input,mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),Some(moved)),Some(CanvasEvent::Spacing(Event::Finish{stamp:s,token:t,..})) if s==stamp && t==token)
+    );
+    assert_eq!(scene.selection, Some((context, snapshot)));
+    assert_eq!(scene.selected, second);
+    assert!(input.press.is_none() && input.group_press.is_none());
+}
+#[test]
+fn group_press_retains_snapshot_and_collapses_only_stationary_release_once() {
+    let (f, scene, point) = fixture(true);
+    let mut state = SequenceInput::default();
+    assert!(
+        send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+            Some(point)
+        )
+        .is_none()
+    );
+    assert!(state.press.is_none());
+    let captured = state.group_press.as_ref().unwrap().snapshot.clone();
+    assert_eq!(captured.primary(), Some(&Target::ScenarioObject(f.reply)));
+    let Some(CanvasEvent::Selection(event)) = send(
+        &scene,
+        &mut state,
+        mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),
+        Some(point),
+    ) else {
+        panic!("captured collapse")
+    };
+    assert_eq!(event.snapshot, captured);
+    assert!(matches!(event.intent, Intent::Collapse(Target::ScenarioObject(id)) if id == f.call));
+    assert!(
+        send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),
+            Some(point)
+        )
+        .is_none()
+    );
+}
+#[test]
+fn crossed_threshold_return_to_origin_refuses_whole_set_and_outside_release_cancels() {
+    for outside in [false, true] {
+        let (_, scene, point) = fixture(true);
+        let mut state = SequenceInput::default();
+        send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+            Some(point),
+        );
+        let moved = point + Vector::new(12., 0.);
+        send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::CursorMoved { position: moved }),
+            Some(moved),
+        );
+        send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::CursorMoved { position: point }),
+            Some(point),
+        );
+        let event = send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),
+            (!outside).then_some(point),
+        );
+        if outside {
+            assert!(event.is_none());
+        } else {
+            let Some(CanvasEvent::Selection(event)) = event else {
+                panic!("whole-set refusal")
+            };
+            assert!(matches!(event.intent, Intent::Refuse(_)));
+            assert_eq!(event.snapshot.targets().len(), 2);
+        }
+        assert!(state.group_press.is_none() && state.press.is_none());
+    }
+}
+#[test]
+fn passive_shift_survives_context_refresh_and_window_loss_clears_it() {
+    let (f, mut scene, point) = fixture(false);
+    let mut state = SequenceInput::default();
+    assert!(
+        send(
+            &scene,
+            &mut state,
+            canvas::Event::Keyboard(iced::keyboard::Event::ModifiersChanged(
+                iced::keyboard::Modifiers::SHIFT
+            )),
+            Some(point)
+        )
+        .is_none()
+    );
+    let Some(CanvasEvent::Selection(event)) = send(
+        &scene,
+        &mut state,
+        mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+        Some(point),
+    ) else {
+        panic!("toggle")
+    };
+    assert!(
+        matches!(event.intent, Intent::Choose(Target::ScenarioObject(id), Choice::Toggle) if id == f.call)
+    );
+    assert!(state.press.is_none());
+    scene.interaction.as_mut().unwrap().0.epoch += 1;
+    send(
+        &scene,
+        &mut state,
+        canvas::Event::Window(iced::window::Event::Unfocused),
+        None,
+    );
+    assert!(state.modifiers.is_empty());
+}
+#[test]
+fn stale_selection_and_fallback_release_do_not_move_primary() {
+    let (_, mut scene, point) = fixture(true);
+    scene.coordinate_input = false;
+    let mut state = SequenceInput::default();
+    send(
+        &scene,
+        &mut state,
+        mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+        Some(point),
+    );
+    let Some(CanvasEvent::Selection(event)) = send(
+        &scene,
+        &mut state,
+        mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),
+        Some(point),
+    ) else {
+        panic!("fallback stationary selection remains usable")
+    };
+    assert!(matches!(event.intent, Intent::Collapse(_)));
+    send(
+        &scene,
+        &mut state,
+        mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+        Some(point),
+    );
+    scene.selection.as_mut().unwrap().0.visit = Id::new_v4();
+    assert!(
+        send(
+            &scene,
+            &mut state,
+            mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),
+            Some(point)
+        )
+        .is_none()
+    );
+    assert!(state.group_press.is_none());
+}

crates/oa-desktop/src/behavior/scenario/spacing.rs

@@ -5,13 +5,17 @@
 use crate::behavior::scenario_layout::{
     GeometryIssue, Representation, ResolvedScenarioPlan, presentation::checked_owner, resolve,
 };
+use crate::diagram_usage::Target as SelectionTarget;
 use oa_core::{
     Command, Id, Kind, OccurrenceBody, OccurrenceEndpoint, Project, ScenarioLanePosition,
     ScenarioMessagePosition, SharedBody, execute_batch,
 };
+use std::collections::BTreeSet;
 
 pub(crate) mod controller;
 #[cfg(test)]
+mod group_tests;
+#[cfg(test)]
 mod tests;
 pub(crate) use controller::{Event, Stamp};
 
@@ -30,6 +34,7 @@ impl Target {
 
 #[derive(Debug, PartialEq, Eq)]
 pub(crate) enum Refusal {
+    InvalidSelection(&'static str),
     InvalidSavedView(Id),
     TargetNotRendered(Target),
     InvalidDelta,
@@ -45,6 +50,7 @@ pub(super) struct Drag {
     diagram: Id,
     target: Target,
     origin: f32,
+    other_origins: Vec<(Target, f32)>,
     original_geometry: ResolvedScenarioPlan,
 }
 
@@ -58,17 +64,135 @@ pub(super) struct Preview {
 /// Capture an accepted, actually drawn target. A Saved view displaying automatic
 /// fallback is not an editable original, even if the target appears in fallback.
 pub(super) fn capture(project: &Project, diagram: Id, target: Target) -> Result<Drag, Refusal> {
-    let representation = Representation::Saved { diagram };
-    let owner = checked_owner(project, representation).ok_or(Refusal::InvalidSavedView(diagram))?;
-    let geometry = resolve(project, representation, target.id()).map_err(Refusal::Geometry)?;
+    capture_targets(project, diagram, target, &[target])
+}
+
+/// The exact selected set is one operation, never an eligible subset. Selection
+/// order and the pressed member do not determine persistence order.
+pub(super) fn capture_group(
+    project: &Project,
+    diagram: Id,
+    pressed: Target,
+    targets: &[SelectionTarget],
+) -> Result<Drag, Refusal> {
+    if targets.is_empty() {
+        return Err(Refusal::InvalidSelection(
+            "Select at least one occurrence to move.",
+        ));
+    }
+    let mut seen = BTreeSet::new();
+    let mut members = Vec::with_capacity(targets.len());
+    for selected in targets {
+        let SelectionTarget::ScenarioObject(id) = selected else {
+            return Err(Refusal::InvalidSelection(
+                "Move only local Scenario lifelines or messages.",
+            ));
+        };
+        if !seen.insert(*id) {
+            return Err(Refusal::InvalidSelection(
+                "The selection contains a duplicate occurrence.",
+            ));
+        }
+        let target = match pressed {
+            Target::Lane(_) => Target::Lane(*id),
+            Target::Message(_) => Target::Message(*id),
+        };
+        let Some(element) = project.elements.get(id) else {
+            return Err(Refusal::TargetNotRendered(target));
+        };
+        let same_role = match target {
+            Target::Lane(_) => element.kind() == Kind::Lifeline,
+            Target::Message(_) => matches!(
+                element.shared(),
+                Some(SharedBody::Occurrence {
+                    body: OccurrenceBody::Exchange { .. },
+                    ..
+                })
+            ),
+        };
+        if !same_role {
+            return Err(Refusal::InvalidSelection(
+                "Move a group of lifelines or a group of messages; mixed and other occurrence types are not supported.",
+            ));
+        }
+        members.push(target);
+    }
+    if !members.contains(&pressed) {
+        return Err(Refusal::InvalidSelection(
+            "The pressed occurrence is not in the captured selection.",
+        ));
+    }
+    members.sort_by_key(|target| target.id());
+    capture_targets(project, diagram, pressed, &members)
+}
+
+// Require the actual local sequence/operand path, not just an ancestor pointer.
+// Cross-operand groups are allowed; no member changes its existing parent.
+fn local_message(project: &Project, owner: Id, id: Id) -> bool {
+    let mut current = id;
+    let mut visited = BTreeSet::new();
+    while current != owner && visited.insert(current) {
+        let Some(element) = project.elements.get(&current) else {
+            return false;
+        };
+        let Some(parent) = element.parent.and_then(|id| project.elements.get(&id)) else {
+            return false;
+        };
+        if element.layer() != project.elements[&owner].layer() {
+            return false;
+        }
+        let listed = match parent.shared() {
+            Some(SharedBody::Occurrence {
+                body: OccurrenceBody::Fragment { branches, .. },
+                ..
+            }) => {
+                matches!(
+                    element.shared(),
+                    Some(SharedBody::Occurrence {
+                        body: OccurrenceBody::Branch { .. },
+                        ..
+                    })
+                ) && branches.iter().filter(|&&id| id == current).count() == 1
+            }
+            _ => parent
+                .steps()
+                .is_some_and(|steps| steps.iter().filter(|&&id| id == current).count() == 1),
+        };
+        if !listed {
+            return false;
+        }
+        current = parent.id;
+    }
+    current == owner
+}
+
+fn captured_origin(
+    project: &Project,
+    owner: Id,
+    geometry: &ResolvedScenarioPlan,
+    target: Target,
+) -> Result<f32, Refusal> {
     let element = project.elements.get(&target.id());
     let origin = match target {
         Target::Lane(id)
-            if element.is_some_and(|e| e.kind() == Kind::Lifeline && e.parent == Some(owner)) =>
+            if element.is_some_and(|e| {
+                e.kind() == Kind::Lifeline
+                    && e.parent == Some(owner)
+                    && e.layer() == project.elements[&owner].layer()
+            }) =>
         {
-            // Unassigned lifelines still have drawn headers. `scene.lanes`
-            // excludes them only from semantic message-endpoint hit testing.
-            geometry.scene.render_lanes.get(&id).copied()
+            // Unassigned headers are still rendered local targets.
+            let headers = geometry
+                .scene
+                .boxes
+                .iter()
+                .filter(|item| {
+                    item.id == id && item.role == crate::behavior::SceneHitRole::LifelineHeader
+                })
+                .count();
+            (headers == 1)
+                .then(|| geometry.scene.render_lanes.get(&id).copied())
+                .flatten()
         }
         Target::Message(id)
             if element.is_some_and(|e| {
@@ -79,17 +203,16 @@ pub(super) fn capture(project: &Project, diagram: Id, target: Target) -> Result<
                         ..
                     })
                 )
-            }) =>
+            }) && local_message(project, owner, id) =>
         {
-            // A lifecycle row can denote receive y; the public position means
-            // send y. Read the actual outgoing endpoint, including self calls.
-            geometry
-                .scene
-                .lines
-                .iter()
-                .find(|line| line.id == id)
+            // A lifecycle receive row is not the stored send coordinate. Reject
+            // ambiguous repeated drawing IDs rather than choosing the first.
+            let mut lines = geometry.scene.lines.iter().filter(|line| line.id == id);
+            let first = lines
+                .next()
                 .and_then(|line| line.points.first())
-                .map(|point| point.y)
+                .map(|point| point.y);
+            if lines.next().is_some() { None } else { first }
         }
         _ => None,
     }
@@ -97,11 +220,38 @@ pub(super) fn capture(project: &Project, diagram: Id, target: Target) -> Result<
     if !origin.is_finite() {
         return Err(Refusal::TargetNotRendered(target));
     }
+    Ok(origin)
+}
+
+fn capture_targets(
+    project: &Project,
+    diagram: Id,
+    target: Target,
+    targets: &[Target],
+) -> Result<Drag, Refusal> {
+    let representation = Representation::Saved { diagram };
+    let owner = checked_owner(project, representation).ok_or(Refusal::InvalidSavedView(diagram))?;
+    let geometry = resolve(project, representation, target.id()).map_err(Refusal::Geometry)?;
+    let origins = targets
+        .iter()
+        .map(|member| {
+            captured_origin(project, owner, &geometry, *member).map(|origin| (*member, origin))
+        })
+        .collect::<Result<Vec<_>, _>>()?;
+    let origin = origins
+        .iter()
+        .find(|(member, _)| *member == target)
+        .expect("admitted pressed member")
+        .1;
     Ok(Drag {
         original: project.clone(),
         diagram,
         target,
         origin,
+        other_origins: origins
+            .into_iter()
+            .filter(|(member, _)| *member != target)
+            .collect(),
         original_geometry: geometry,
     })
 }
@@ -117,28 +267,50 @@ impl Drag {
         if original_delta == 0. {
             return Ok(None);
         }
-        let position = (f64::from(self.origin) + f64::from(original_delta)) as f32;
-        if position == self.origin {
+        let mut commands = Vec::new();
+        for (target, origin) in
+            std::iter::once((self.target, self.origin)).chain(self.other_origins.iter().copied())
+        {
+            let position = (f64::from(origin) + f64::from(original_delta)) as f32;
+            if !position.is_finite() || position.abs() > oa_core::MAX_COORDINATE {
+                return Err(Refusal::Command(
+                    "Scenario positions must be finite and within the shared coordinate bounds."
+                        .into(),
+                ));
+            }
+            if position == origin {
+                continue;
+            }
+            let command = match target {
+                Target::Lane(lifeline) => Command::SetScenarioLanePosition {
+                    diagram: self.diagram,
+                    position: ScenarioLanePosition {
+                        lifeline,
+                        x: position,
+                    },
+                },
+                Target::Message(occurrence) => Command::SetScenarioMessagePosition {
+                    diagram: self.diagram,
+                    position: ScenarioMessagePosition {
+                        address: OccurrenceEndpoint {
+                            references: vec![],
+                            occurrence,
+                        },
+                        send_y: position,
+                    },
+                },
+            };
+            commands.push((target.id(), command));
+        }
+        if commands.is_empty() {
             return Ok(None);
         }
-        let command = match self.target {
-            Target::Lane(lifeline) => Command::SetScenarioLanePosition {
-                diagram: self.diagram,
-                position: ScenarioLanePosition {
-                    lifeline,
-                    x: position,
-                },
-            },
-            Target::Message(occurrence) => Command::SetScenarioMessagePosition {
-                diagram: self.diagram,
-                position: ScenarioMessagePosition {
-                    address: OccurrenceEndpoint {
-                        references: vec![],
-                        occurrence,
-                    },
-                    send_y: position,
-                },
-            },
+        commands.sort_by_key(|(id, _)| *id);
+        let mut commands: Vec<_> = commands.into_iter().map(|(_, command)| command).collect();
+        let command = if self.other_origins.is_empty() {
+            commands.pop().expect("changed singleton")
+        } else {
+            Command::Batch(commands)
         };
         let project = execute_batch(&self.original, std::slice::from_ref(&command))
             .map_err(|error| Refusal::Command(error.to_string()))?;

crates/oa-desktop/src/behavior/scenario/spacing/controller.rs

@@ -5,6 +5,7 @@ use crate::behavior::{
     scenario::{CanvasTool, Context, State},
     scenario_layout::Diagnostic,
 };
+use crate::{diagram_selection::Snapshot, diagram_usage::Target as SelectionTarget};
 use iced::{Point, Rectangle, Vector};
 
 #[cfg(test)]
@@ -16,6 +17,7 @@ mod timing_tests;
 pub struct Stamp {
     pub(crate) context: Context,
     pub(crate) camera_epoch: u64,
+    pub(crate) selection_generation: u64,
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -72,11 +74,14 @@ pub(crate) struct Session {
     drag: Drag,
     preview: Option<Preview>,
     refusal: Option<Refusal>,
+    group_refusal: Option<Refusal>,
     ever_crossed: bool,
+    snapshot: Option<Snapshot>,
 }
 
 pub(in crate::behavior) struct Paint<'a> {
     pub(in crate::behavior) scene: &'a Scene,
+    pub(in crate::behavior) selected_count: usize,
     #[cfg(test)]
     pub(in crate::behavior) bounds: Rectangle,
     pub(in crate::behavior) refusal: Option<&'a Refusal>,
@@ -98,7 +103,21 @@ pub(crate) enum Finish {
 
 impl Session {
     fn configure(&self, scene: &mut Scene) {
-        scene.selected = self.drag.target.id();
+        scene.selected = self
+            .snapshot
+            .as_ref()
+            .filter(|s| s.targets().len() > 1)
+            .and_then(|s| match s.primary() {
+                Some(SelectionTarget::ScenarioObject(id)) => Some(*id),
+                _ => None,
+            })
+            .unwrap_or(self.drag.target.id());
+        scene.selection = self
+            .snapshot
+            .as_ref()
+            .filter(|s| s.targets().len() > 1)
+            .cloned()
+            .map(|s| (self.stamp.context, s));
         scene.scale = self.scale;
         scene.camera_pan = self.pan;
         scene.interaction = Some((self.stamp.context, CanvasTool::Select, true));
@@ -117,8 +136,18 @@ impl Session {
             Target::Lane(_) => screen.x - self.press_screen.x,
             Target::Message(_) => screen.y - self.press_screen.y,
         };
-        self.ever_crossed |= distance.abs() >= 3.;
-        if !self.ever_crossed {
+        self.ever_crossed |= if self
+            .snapshot
+            .as_ref()
+            .is_some_and(|s| s.targets().len() > 1)
+        {
+            screen.distance(self.press_screen) >= 3.
+        } else {
+            distance.abs() >= 3.
+        };
+        if !self.ever_crossed || self.group_refusal.is_some() {
+            // A rejected whole set may retain a pressed singleton only as its
+            // original display witness. It must never prepare a partial move.
             return;
         }
         match self.drag.prepare(distance / self.scale) {
@@ -139,6 +168,9 @@ impl State {
     pub(crate) fn spacing_stamp(&self) -> Option<Stamp> {
         self.spacing.as_ref().map(|s| s.stamp)
     }
+    pub(crate) fn spacing_snapshot(&self) -> Option<&Snapshot> {
+        self.spacing.as_ref()?.snapshot.as_ref()
+    }
     pub(crate) fn cancel_spacing(&mut self) -> bool {
         self.spacing.take().is_some()
     }
@@ -149,28 +181,55 @@ impl State {
         camera_epoch: u64,
     ) -> Option<Paint<'_>> {
         let session = self.spacing.as_ref()?;
-        if session.stamp
-            != (Stamp {
-                context,
-                camera_epoch,
-            })
-        {
+        if session.stamp.context != context || session.stamp.camera_epoch != camera_epoch {
             return None;
         }
         let original = &session.drag.original_geometry;
         let shown = session.preview.as_ref().map_or(original, |p| &p.geometry);
         Some(Paint {
             scene: &shown.scene,
+            selected_count: session
+                .snapshot
+                .as_ref()
+                .map_or(1, |s| s.targets().len().max(1)),
             #[cfg(test)]
             bounds: shown.bounds,
-            refusal: session.refusal.as_ref(),
+            refusal: session.refusal.as_ref().or_else(|| {
+                session
+                    .ever_crossed
+                    .then_some(session.group_refusal.as_ref())
+                    .flatten()
+            }),
             original_diagnostics: &original.plan.diagnostics,
             original_latent: &original.latent_messages,
             diagnostics: &shown.plan.diagnostics,
         })
     }
 
+    #[cfg(test)]
     pub(crate) fn begin_spacing(&mut self, project: &Project, event: Event) -> Result<(), Refusal> {
+        self.begin_spacing_capture(project, event, None)
+    }
+    pub(crate) fn begin_spacing_with_snapshot(
+        &mut self,
+        project: &Project,
+        event: Event,
+        snapshot: Snapshot,
+    ) -> Result<(), Refusal> {
+        if snapshot.generation() != event.stamp().selection_generation
+            || snapshot.context()
+                != crate::behavior::scenario::selection::context(event.stamp().context)
+        {
+            return Err(Refusal::InvalidGesture);
+        }
+        self.begin_spacing_capture(project, event, Some(snapshot))
+    }
+    fn begin_spacing_capture(
+        &mut self,
+        project: &Project,
+        event: Event,
+        snapshot: Option<Snapshot>,
+    ) -> Result<(), Refusal> {
         let Event::Begin {
             stamp,
             token,
@@ -216,7 +275,34 @@ impl State {
         let Representation::Saved { diagram } = context.representation else {
             return Err(Refusal::InvalidGesture);
         };
-        let mut drag = capture(project, diagram, target)?;
+        let mut group_refusal = None;
+        let mut drag = if let Some(selected) = snapshot.as_ref().filter(|s| s.targets().len() > 1) {
+            if !selected
+                .targets()
+                .contains(&SelectionTarget::ScenarioObject(target.id()))
+            {
+                return Err(Refusal::TargetNotHit(target));
+            }
+            match capture_group(project, diagram, target, selected.targets()) {
+                Ok(drag) => drag,
+                Err(error)
+                    if matches!(
+                        &error,
+                        Refusal::InvalidSelection(_) | Refusal::TargetNotRendered(_)
+                    ) =>
+                {
+                    // Selection clicks do not require movement eligibility.
+                    // This capture supplies original paint and the exact hit
+                    // only; group_refusal forbids calling its prepare method.
+                    let original = capture(project, diagram, target)?;
+                    group_refusal = Some(error);
+                    original
+                }
+                Err(error) => return Err(error),
+            }
+        } else {
+            capture(project, diagram, target)?
+        };
         let camera = self.presentation.camera(drag.original_geometry.bounds);
         if self.presentation.viewport != Some(canvas_bounds.size())
             || camera.scale != scale
@@ -246,7 +332,19 @@ impl State {
         }
         // Configure baseline without changing the persistent camera or selection.
         let scene = &mut drag.original_geometry.scene;
-        scene.selected = target.id();
+        scene.selected = snapshot
+            .as_ref()
+            .filter(|s| s.targets().len() > 1)
+            .and_then(|s| match s.primary() {
+                Some(SelectionTarget::ScenarioObject(id)) => Some(*id),
+                _ => None,
+            })
+            .unwrap_or(target.id());
+        scene.selection = snapshot
+            .as_ref()
+            .filter(|s| s.targets().len() > 1)
+            .cloned()
+            .map(|s| (context, s));
         scene.scale = scale;
         scene.camera_pan = pan;
         scene.interaction = Some((context, CanvasTool::Select, true));
@@ -262,7 +360,9 @@ impl State {
             drag,
             preview: None,
             refusal: None,
+            group_refusal,
             ever_crossed: false,
+            snapshot,
         });
         Ok(())
     }
@@ -282,6 +382,9 @@ impl State {
         if !session.ever_crossed {
             return Ok(Finish::Click(session.drag.target.id()));
         }
+        if let Some(error) = session.group_refusal {
+            return Err(error);
+        }
         Ok(match session.preview {
             None => Finish::Noop,
             Some(preview) => Finish::Commit {

crates/oa-desktop/src/behavior/scenario/spacing/controller/tests.rs

@@ -95,6 +95,7 @@ pub(crate) fn packet(
         stamp: Stamp {
             context,
             camera_epoch,
+            selection_generation: 0,
         },
         token: Id::new_v4(),
         target,
@@ -135,6 +136,55 @@ fn press(event: Event) -> Point {
     press_screen
 }
 
+#[test]
+fn group_preview_keeps_captured_members_and_nonpressed_primary() {
+    use crate::diagram_selection::Selection;
+    use crate::diagram_usage::Target as Selected;
+    let (doc, mut state, mut event) = setup(true);
+    let context = event.stamp().context;
+    let first = match event {
+        Event::Begin { target, .. } => target.id(),
+        _ => unreachable!(),
+    };
+    let second = doc
+        .project()
+        .identities()
+        .into_iter()
+        .find(|(_, alias)| *alias == "second")
+        .unwrap()
+        .0;
+    let selection_context = crate::behavior::scenario::selection::context(context);
+    let mut selection = Selection::new(selection_context.scope);
+    selection.add(Selected::ScenarioObject(first), |_| true);
+    selection.add(Selected::ScenarioObject(second), |_| true);
+    let snapshot = selection.snapshot(selection_context).unwrap();
+    if let Event::Begin { stamp, .. } = &mut event {
+        stamp.selection_generation = snapshot.generation();
+    }
+    let start = press(event);
+    state
+        .begin_spacing_with_snapshot(doc.project(), event, snapshot.clone())
+        .unwrap();
+    for delta in [Vector::new(0., 0.), Vector::new(0., 24.)] {
+        state.move_spacing(start + delta);
+        let paint = state
+            .spacing_paint(context, event.stamp().camera_epoch)
+            .unwrap();
+        assert_eq!(paint.scene.selected, second);
+        assert_eq!(
+            paint.scene.selection.as_ref().unwrap(),
+            &(context, snapshot.clone())
+        );
+        assert_eq!(paint.selected_count, 2);
+    }
+    state.move_spacing(start + Vector::new(50., 0.));
+    assert!(matches!(
+        state.finish_spacing(start + Vector::new(50., 0.)).unwrap(),
+        Finish::Noop
+    ));
+    assert!(!doc.can_undo());
+}
+
 #[test]
 fn real_preview_moves_only_active_axis_from_original_and_never_changes_document() {
     for message in [false, true] {

crates/oa-desktop/src/behavior/scenario/spacing/group_tests.rs

@@ -0,0 +1,675 @@
+use super::*;
+use crate::document::Document;
+use oa_core::{Diagram, DiagramLayout, Layer, ProjectionKind, ScenarioLayout, language};
+
+fn id(project: &Project, alias: &str) -> Id {
+    project
+        .identities()
+        .into_iter()
+        .find(|(_, name)| *name == alias)
+        .unwrap()
+        .0
+}
+
+fn fixture(layout: Option<ScenarioLayout>) -> (Document, Id, Id) {
+    let mut project = language::parse(FIXTURE).unwrap();
+    let owner = id(&project, "conversation");
+    let right = id(&project, "right");
+    let mut views = Vec::new();
+    for (alias, layout) in [
+        ("active_view", layout),
+        (
+            "untouched_view",
+            Some(ScenarioLayout {
+                lanes: vec![ScenarioLanePosition {
+                    lifeline: right,
+                    x: 700.,
+                }],
+                messages: vec![],
+            }),
+        ),
+    ] {
+        let diagram = Id::new_v4();
+        project.diagrams.insert(
+            diagram,
+            Diagram {
+                id: diagram,
+                alias: alias.into(),
+                name: alias.into(),
+                description: "Preserve authored view metadata".into(),
+                layer: Layer::Oa,
+                projection: ProjectionKind::Scenario { scenario: owner },
+                nodes: Default::default(),
+                routes: vec![],
+                view_options: Default::default(),
+                layout: layout.map(DiagramLayout::Scenario),
+            },
+        );
+        views.push(diagram);
+    }
+    (
+        Document::from_project(project, Default::default()).unwrap(),
+        views[0],
+        views[1],
+    )
+}
+
+fn targets(ids: &[Id]) -> Vec<SelectionTarget> {
+    ids.iter()
+        .copied()
+        .map(SelectionTarget::ScenarioObject)
+        .collect()
+}
+
+fn message(occurrence: Id, send_y: f32) -> ScenarioMessagePosition {
+    ScenarioMessagePosition {
+        address: OccurrenceEndpoint {
+            references: vec![],
+            occurrence,
+        },
+        send_y,
+    }
+}
+
+// Literal expected authored payload, not another execution of planner commands.
+fn expected(
+    project: &Project,
+    diagram: Id,
+    lanes: Vec<ScenarioLanePosition>,
+    messages: Vec<ScenarioMessagePosition>,
+) -> Project {
+    let mut result = project.clone();
+    result.diagrams.get_mut(&diagram).unwrap().layout =
+        Some(DiagramLayout::Scenario(ScenarioLayout { lanes, messages }));
+    result
+}
+
+fn exact_transaction(mut document: Document, preview: Preview, expected: Project) {
+    let original = document.snapshot();
+    let revision = document.revision();
+    assert_eq!(preview.project, expected);
+    assert!(matches!(&preview.command, Command::Batch(_)));
+    document.execute(preview.command).unwrap();
+    assert_eq!(document.project(), &expected);
+    assert_eq!(document.revision(), revision + 1);
+    let changed = document.bundle().clone();
+    assert_ne!(changed, original.bundle);
+    assert_eq!(
+        language::parse(&language::format(document.project())).unwrap(),
+        expected
+    );
+    assert!(document.undo());
+    assert_eq!(document.project(), &original.decoded.project);
+    assert_eq!(document.bundle(), &original.bundle);
+    assert!(!document.can_undo());
+    assert!(document.redo());
+    assert_eq!(document.project(), &expected);
+    assert_eq!(document.bundle(), &changed);
+    assert!(!document.can_redo());
+    let reopened = Document::from_bundle(changed, Default::default()).unwrap();
+    assert_eq!(reopened.project(), &expected);
+    assert!(!reopened.dirty() && !reopened.can_undo());
+}
+
+#[test]
+fn group_messages_move_from_each_original_with_press_and_selection_order_independent() {
+    let (document, diagram, other) = fixture(None);
+    let before = document.project();
+    let first = id(before, "first");
+    let second = id(before, "second");
+    let wanted = expected(
+        before,
+        diagram,
+        vec![],
+        vec![message(first, 188.), message(second, 280.)],
+    );
+    for members in [[first, second], [second, first]] {
+        for pressed in [first, second] {
+            let drag = capture_group(
+                before,
+                diagram,
+                Target::Message(pressed),
+                &targets(&members),
+            )
+            .unwrap();
+            let preview = drag.prepare(40.).unwrap().unwrap();
+            assert_eq!(preview.project, wanted);
+            assert_eq!(preview.project.diagrams[&other], before.diagrams[&other]);
+            assert_eq!(drag.original, *before);
+        }
+    }
+    let preview = capture_group(
+        before,
+        diagram,
+        Target::Message(second),
+        &targets(&[second, first]),
+    )
+    .unwrap()
+    .prepare(40.)
+    .unwrap()
+    .unwrap();
+    exact_transaction(document, preview, wanted);
+}
+
+#[test]
+fn group_lanes_vacate_each_others_space_in_one_candidate_and_one_history_entry() {
+    let (document, diagram, _) = fixture(None);
+    let before = document.project();
+    let left = id(before, "left");
+    let right = id(before, "right");
+    // Moving only Left into Right's old x cannot render a distinct-endpoint arrow.
+    assert!(matches!(
+        capture(before, diagram, Target::Lane(left))
+            .unwrap()
+            .prepare(240.),
+        Err(Refusal::Geometry(_))
+    ));
+    let wanted = expected(
+        before,
+        diagram,
+        vec![
+            ScenarioLanePosition {
+                lifeline: left,
+                x: 400.,
+            },
+            ScenarioLanePosition {
+                lifeline: right,
+                x: 640.,
+            },
+        ],
+        vec![],
+    );
+    for pressed in [left, right] {
+        let preview = capture_group(
+            before,
+            diagram,
+            Target::Lane(pressed),
+            &targets(&[right, left]),
+        )
+        .unwrap()
+        .prepare(240.)
+        .unwrap()
+        .unwrap();
+        assert_eq!(preview.project, wanted);
+        assert_eq!(preview.geometry.scene.render_lanes[&left], 400.);
+        assert_eq!(preview.geometry.scene.render_lanes[&right], 640.);
+    }
+    let preview = capture_group(
+        before,
+        diagram,
+        Target::Lane(right),
+        &targets(&[left, right]),
+    )
+    .unwrap()
+    .prepare(240.)
+    .unwrap()
+    .unwrap();
+    exact_transaction(document, preview, wanted);
+}
+
+#[test]
+fn self_call_and_reply_are_validated_together_but_partial_candidate_is_refused() {
+    let (document, diagram, _) = fixture(None);
+    let before = document.project();
+    let call = id(before, "call");
+    let reply = id(before, "reply");
+    let first = id(before, "first");
+    assert!(matches!(
+        capture(before, diagram, Target::Message(call))
+            .unwrap()
+            .prepare(118.),
+        Err(Refusal::Geometry(_))
+    ));
+    let drag = capture_group(
+        before,
+        diagram,
+        Target::Message(reply),
+        &targets(&[reply, call]),
+    )
+    .unwrap();
+    let preview = drag.prepare(118.).unwrap().unwrap();
+    assert_eq!(
+        preview.project,
+        expected(
+            before,
+            diagram,
+            vec![],
+            vec![message(call, 450.), message(reply, 542.)]
+        )
+    );
+    let line = preview
+        .geometry
+        .scene
+        .lines
+        .iter()
+        .find(|line| line.id == call)
+        .unwrap();
+    assert_eq!(line.points.first().unwrap().y, 450.);
+    assert_eq!(line.points.last().unwrap().y, 474.);
+    let partial = capture_group(
+        before,
+        diagram,
+        Target::Message(first),
+        &targets(&[first, call]),
+    )
+    .unwrap();
+    assert!(matches!(partial.prepare(118.), Err(Refusal::Geometry(_))));
+    assert_eq!(partial.original, *before);
+    assert!(!document.can_undo());
+}
+
+#[test]
+fn exact_set_admission_rejects_empty_duplicates_mixed_unsupported_missing_and_unpressed() {
+    let (document, diagram, _) = fixture(None);
+    let before = document.project();
+    let first = id(before, "first");
+    let second = id(before, "second");
+    let left = id(before, "left");
+    let source = id(before, "source");
+    let unfinished = id(before, "unfinished");
+    for selection in [
+        vec![],
+        targets(&[first, first]),
+        targets(&[first, left]),
+        targets(&[first, source]),
+        targets(&[first, Id::new_v4()]),
+        targets(&[second]),
+        targets(&[first, unfinished]),
+        vec![
+            SelectionTarget::ScenarioObject(first),
+            SelectionTarget::Whole,
+        ],
+        vec![
+            SelectionTarget::ScenarioObject(first),
+            SelectionTarget::Placement(second),
+        ],
+    ] {
+        assert!(
+            capture_group(before, diagram, Target::Message(first), &selection).is_err(),
+            "{selection:?}"
+        );
+    }
+    assert!(
+        capture_group(
+            before,
+            Id::nil(),
+            Target::Message(first),
+            &targets(&[first, second])
+        )
+        .is_err()
+    );
+    assert!(
+        capture_group(
+            before,
+            diagram,
+            Target::Lane(first),
+            &targets(&[first, second])
+        )
+        .is_err()
+    );
+    assert!(!document.dirty() && !document.can_undo());
+}
+
+#[test]
+fn foreign_unlisted_and_ambiguous_local_messages_cannot_enter_a_group() {
+    let (document, diagram, _) = fixture(None);
+    let before = document.project();
+    let first = id(before, "first");
+    let second = id(before, "second");
+    let owner = id(before, "conversation");
+    for case in 0..3 {
+        let mut project = before.clone();
+        match case {
+            0 => {
+                let foreign = project
+                    .add_element(Kind::Scenario, Layer::Oa, "Foreign", None)
+                    .unwrap();
+                project.elements.get_mut(&second).unwrap().parent = Some(foreign);
+            }
+            1 => project
+                .elements
+                .get_mut(&owner)
+                .unwrap()
+                .steps_mut()
+                .unwrap()
+                .retain(|id| *id != second),
+            _ => project
+                .elements
+                .get_mut(&owner)
+                .unwrap()
+                .steps_mut()
+                .unwrap()
+                .push(second),
+        }
+        assert!(
+            capture_group(
+                &project,
+                diagram,
+                Target::Message(first),
+                &targets(&[first, second])
+            )
+            .is_err()
+        );
+    }
+}
+
+#[test]
+fn fallback_baseline_is_refused_before_any_zero_motion_can_be_planned() {
+    let (document, diagram, _) = fixture(None);
+    let call = id(document.project(), "call");
+    let reply = id(document.project(), "reply");
+    let invalid = expected(
+        document.project(),
+        diagram,
+        vec![],
+        vec![message(call, 450.)],
+    );
+    let shown = crate::behavior::scenario_layout::presentation::present(
+        &invalid,
+        Representation::Saved { diagram },
+        call,
+    );
+    assert!(shown.capabilities().geometry_navigation);
+    assert!(!shown.capabilities().coordinate_input);
+    assert!(matches!(
+        capture_group(
+            &invalid,
+            diagram,
+            Target::Message(reply),
+            &targets(&[reply, call])
+        ),
+        Err(Refusal::Geometry(_))
+    ));
+}
+
+#[test]
+fn group_noops_preserve_sparse_overrides_complete_source_and_existing_redo() {
+    for sparse in [true, false] {
+        let (mut document, diagram, _) = fixture((!sparse).then(ScenarioLayout::default));
+        let first = id(document.project(), "first");
+        let second = id(document.project(), "second");
+        let owner = id(document.project(), "conversation");
+        document
+            .execute(Command::Rename(owner, "Redo sentinel".into()))
+            .unwrap();
+        let redo = document.snapshot();
+        assert!(document.undo());
+        let original = document.snapshot();
+        let revision = document.revision();
+        let drag = capture_group(
+            document.project(),
+            diagram,
+            Target::Message(second),
+            &targets(&[second, first]),
+        )
+        .unwrap();
+        assert!(drag.prepare(30.).unwrap().is_some());
+        for delta in [0., -0., f32::from_bits(1)] {
+            assert!(drag.prepare(delta).unwrap().is_none());
+        }
+        assert!(std::sync::Arc::ptr_eq(&original, &document.snapshot()));
+        assert_eq!(document.bundle(), &original.bundle);
+        assert_eq!(document.revision(), revision);
+        assert_eq!(drag.original, original.decoded.project);
+        assert!(document.redo());
+        assert_eq!(document.project(), &redo.decoded.project);
+        assert_eq!(document.bundle(), &redo.bundle);
+    }
+}
+
+#[test]
+fn subprecision_unchanged_member_does_not_materialize_an_absent_override() {
+    let (document, diagram, _) = fixture(None);
+    let first = id(document.project(), "first");
+    let second = id(document.project(), "second");
+    let project = expected(
+        document.project(),
+        diagram,
+        vec![],
+        vec![message(first, 0.)],
+    );
+    let delta = 0.000001_f32;
+    assert_eq!(240_f32 + delta, 240.);
+    let preview = capture_group(
+        &project,
+        diagram,
+        Target::Message(second),
+        &targets(&[second, first]),
+    )
+    .unwrap()
+    .prepare(delta)
+    .unwrap()
+    .unwrap();
+    assert_eq!(
+        preview.project,
+        expected(&project, diagram, vec![], vec![message(first, delta)])
+    );
+    assert!(matches!(preview.command, Command::Batch(ref commands) if commands.len() == 1));
+}
+
+#[test]
+fn invalid_delta_or_one_out_of_bounds_member_refuses_the_whole_group() {
+    let (document, diagram, _) = fixture(None);
+    let left = id(document.project(), "left");
+    let right = id(document.project(), "right");
+    let project = expected(
+        document.project(),
+        diagram,
+        vec![ScenarioLanePosition {
+            lifeline: right,
+            x: 999_990.,
+        }],
+        vec![],
+    );
+    let drag = capture_group(
+        &project,
+        diagram,
+        Target::Lane(left),
+        &targets(&[left, right]),
+    )
+    .unwrap();
+    for delta in [f32::NAN, f32::INFINITY, f32::NEG_INFINITY] {
+        assert!(matches!(drag.prepare(delta), Err(Refusal::InvalidDelta)));
+    }
+    for delta in [20., f32::MAX, -f32::MAX] {
+        assert!(matches!(drag.prepare(delta), Err(Refusal::Command(_))));
+    }
+    assert_eq!(drag.original, project);
+    assert!(drag.prepare(0.).unwrap().is_none());
+}
+
+#[test]
+fn singleton_capture_group_retains_existing_singleton_command_and_result() {
+    let (document, diagram, _) = fixture(None);
+    for target in [
+        Target::Lane(id(document.project(), "right")),
+        Target::Message(id(document.project(), "second")),
+    ] {
+        let single = capture(document.project(), diagram, target)
+            .unwrap()
+            .prepare(25.)
+            .unwrap()
+            .unwrap();
+        let group = capture_group(
+            document.project(),
+            diagram,
+            target,
+            &targets(&[target.id()]),
+        )
+        .unwrap()
+        .prepare(25.)
+        .unwrap()
+        .unwrap();
+        assert_eq!(group.project, single.project);
+        assert!(!matches!(group.command, Command::Batch(_)));
+    }
+}
+
+#[test]
+fn existing_layout_order_and_unselected_values_are_preserved_exactly() {
+    let (document, diagram, _) = fixture(None);
+    let first = id(document.project(), "first");
+    let second = id(document.project(), "second");
+    let reply = id(document.project(), "reply");
+    let right = id(document.project(), "right");
+    let lanes = vec![ScenarioLanePosition {
+        lifeline: right,
+        x: 400.,
+    }];
+    let project = expected(
+        document.project(),
+        diagram,
+        lanes.clone(),
+        vec![message(reply, 424.), message(first, 148.)],
+    );
+    let preview = capture_group(
+        &project,
+        diagram,
+        Target::Message(second),
+        &targets(&[second, first]),
+    )
+    .unwrap()
+    .prepare(40.)
+    .unwrap()
+    .unwrap();
+    assert_eq!(
+        preview.project,
+        expected(
+            &project,
+            diagram,
+            lanes,
+            vec![
+                message(reply, 424.),
+                message(first, 188.),
+                message(second, 280.)
+            ]
+        )
+    );
+}
+
+#[test]
+fn local_messages_in_different_operands_move_without_reparenting_or_reordering() {
+    use crate::behavior::topology::occurrence;
+    let (document, diagram, _) = fixture(None);
+    let mut project = document.project().clone();
+    let owner = id(&project, "conversation");
+    let first = id(&project, "first");
+    let second = id(&project, "second");
+    let fragment = occurrence(
+        &project,
+        owner,
+        "Alternatives",
+        OccurrenceBody::Fragment {
+            operator: oa_core::FragmentOperator::Alternative,
+            branches: vec![],
+        },
+    );
+    let frame = fragment.id;
+    project.elements.insert(frame, fragment);
+    let mut branches = Vec::new();
+    for member in [first, second] {
+        let branch = occurrence(
+            &project,
+            frame,
+            "Operand",
+            OccurrenceBody::Branch {
+                guard: "ready".into(),
+                occurrences: vec![member],
+            },
+        );
+        let branch_id = branch.id;
+        project.elements.insert(branch_id, branch);
+        project.elements.get_mut(&member).unwrap().parent = Some(branch_id);
+        branches.push(branch_id);
+    }
+    if let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Fragment {
+            branches: items, ..
+        },
+        ..
+    }) = project.elements.get_mut(&frame).unwrap().shared_mut()
+    {
+        *items = branches.clone();
+    } else {
+        unreachable!();
+    }
+    let steps = project
+        .elements
+        .get_mut(&owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap();
+    steps.retain(|id| ![first, second].contains(id));
+    steps.insert(0, frame);
+    let document = Document::from_project(project, Default::default()).unwrap();
+    let project = document.project();
+    let baseline = resolve(project, Representation::Saved { diagram }, first).unwrap();
+    let original_send = |id| {
+        baseline
+            .scene
+            .lines
+            .iter()
+            .find(|line| line.id == id)
+            .unwrap()
+            .points[0]
+            .y
+    };
+    let preview = capture_group(
+        project,
+        diagram,
+        Target::Message(second),
+        &targets(&[second, first]),
+    )
+    .unwrap()
+    .prepare(-5.)
+    .unwrap()
+    .unwrap();
+    assert_eq!(
+        preview.project,
+        expected(
+            project,
+            diagram,
+            vec![],
+            vec![
+                message(first, original_send(first) - 5.),
+                message(second, original_send(second) - 5.)
+            ]
+        )
+    );
+    assert_eq!(preview.project.elements, project.elements);
+    let mut omitted = project.clone();
+    if let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Fragment {
+            branches: items, ..
+        },
+        ..
+    }) = omitted.elements.get_mut(&frame).unwrap().shared_mut()
+    {
+        items.retain(|id| *id != branches[1]);
+    }
+    assert!(
+        capture_group(
+            &omitted,
+            diagram,
+            Target::Message(first),
+            &targets(&[first, second])
+        )
+        .is_err()
+    );
+}
+
+const FIXTURE: &str = r#"arcadia 7;
+project spacing_group "Saved group spacing" id "71000000-0000-4000-8000-000000000001" {
+ oa_activity source "Source" id "71000000-0000-4000-8000-000000000002" {}
+ oa_activity target "Target" id "71000000-0000-4000-8000-000000000003" {}
+ interaction exchange "Repeated exchange" id "71000000-0000-4000-8000-000000000004" { source @source; target @target; }
+ oa_scenario conversation "Conversation" id "71000000-0000-4000-8000-000000000005" { viewpoint OperationalActivity; steps [@first, @second, @call, @reply, @unfinished]; }
+ oa_lifeline left "Left" id "71000000-0000-4000-8000-000000000006" { parent @conversation; represented @source; }
+ oa_lifeline right "Right" id "71000000-0000-4000-8000-000000000007" { parent @conversation; represented @target; }
+ oa_occurrence first "First" id "71000000-0000-4000-8000-000000000008" { parent @conversation; body { Exchange { exchange @exchange; sender @left; receiver @right; message_kind Asynchronous; }; }; }
+ oa_occurrence second "Second" id "71000000-0000-4000-8000-000000000009" { parent @conversation; body { Exchange { exchange @exchange; sender @left; receiver @right; message_kind Asynchronous; }; }; }
+ oa_occurrence call "Call" id "71000000-0000-4000-8000-00000000000a" { parent @conversation; body { Exchange { exchange none; sender @right; receiver @right; message_kind Call; }; }; }
+ oa_occurrence reply "Reply" id "71000000-0000-4000-8000-00000000000b" { parent @conversation; body { Exchange { exchange none; sender @right; receiver @right; message_kind Reply; reply_to @call; }; }; }
+ oa_occurrence unfinished "Unfinished" id "71000000-0000-4000-8000-00000000000c" { parent @conversation; body { Exchange { exchange @exchange; sender @left; receiver none; message_kind Asynchronous; }; }; }
+}
+"#;

crates/oa-desktop/src/behavior/scenario/workspace.rs

@@ -75,6 +75,7 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         .spacing(8)
         .into();
     };
+    let snapshot = app.multiselect_snapshot();
     let tool = state.canvas_tool(owner);
     let clean = !app.behavior.has_pending() && !app.draft_dirty() && !app.source_dirty();
     // Resolve once per accepted view. An active spacing session owns its exact
@@ -90,7 +91,8 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         },
         ScenarioPresentation::capabilities,
     );
-    let coordinate_input = clean && capabilities.coordinate_input;
+    let coordinate_input =
+        clean && capabilities.coordinate_input && app.scenario_reorder.session.is_none();
     let notice = if let Some(paint) = &preview {
         display_notice_parts(
             p,
@@ -123,6 +125,7 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         scenario_view: Some((context.representation, context.visit)),
     };
     let keyboard = clean
+        && app.scenario_reorder.session.is_none()
         && capabilities.geometry_navigation
         && super::super::canvas_workspace::keyboard_enabled(app);
     let camera = move |e| Message::ScenarioCanvas(CanvasEvent::Camera(context, scope.epoch, e));
@@ -138,15 +141,21 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         scene.scale = camera_state.scale;
         scene.camera_pan = camera_state.pan;
         scene.interaction = Some((context, tool, clean));
+        scene.selection = snapshot.clone().map(|snapshot| (context, snapshot));
         scene.spacing_stamp = (coordinate_input
             && !app.source_rename.open()
             && keyboard
             && matches!(context.representation, Representation::Saved { .. }))
-        .then_some(spacing::Stamp {
-            context,
-            camera_epoch: app.camera_epoch,
-        });
-        scene.coordinate_input = capabilities.coordinate_input;
+        .then(|| {
+            snapshot.as_ref().map(|snapshot| spacing::Stamp {
+                context,
+                camera_epoch: app.camera_epoch,
+                selection_generation: snapshot.generation(),
+            })
+        })
+        .flatten();
+        scene.coordinate_input =
+            capabilities.coordinate_input && app.scenario_reorder.session.is_none();
         scene.pending_placement = coordinate_input
             .then(|| state.pending_placement(owner))
             .flatten();
@@ -158,8 +167,27 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         // Keep this Stack in both branches: replacing the Canvas with a wrapper
         // on Begin would discard its pointer capture before Move/Finish.
         let mut layers = iced::widget::stack![raw_canvas];
+        if let Some((_, summary)) = &app.scenario_reorder.summary {
+            layers = layers.push(
+                container(iced::widget::opaque(
+                    container(
+                        text(format!("{summary} Use Undo to restore the previous order.")).size(12),
+                    )
+                    .padding(8)
+                    .style(style::card),
+                ))
+                .align_bottom(Fill)
+                .width(Fill)
+                .padding(8),
+            );
+        }
         if let Some(paint) = &preview {
             let feedback = spacing_feedback(p, paint.refusal, paint.diagnostics);
+            let feedback = if paint.selected_count > 1 {
+                format!("{} selected - {feedback}", paint.selected_count)
+            } else {
+                feedback
+            };
             layers = layers.push(
                 container(
                     container(text(feedback).size(12))
@@ -196,7 +224,46 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         container(text("No supported canvas geometry is available. Inspect the model or open its source to repair this view."))
             .id("scenario-viewport-unavailable").padding(16).width(Fill).height(Fill).style(style::card).into()
     };
-    let mut navigation = row![out.width(Fill)].spacing(6);
+    // The chooser must sit outside Viewport: that camera wrapper deliberately
+    // consumes Space, arrows and wheel before its child receives input.
+    let mut canvas_layers = iced::widget::stack![canvas];
+    if let Some(panel) = reorder_view::panel(app, presentation.viewport) {
+        canvas_layers = canvas_layers.push(panel);
+    }
+    let canvas = canvas_layers.into();
+    let selected_count = snapshot.as_ref().map_or(0, |s| s.targets().len());
+    let mut navigation = row![
+        out.width(Fill),
+        text(format!("{selected_count} selected")).size(12)
+    ]
+    .spacing(6);
+    let reorder = reorder_view::begin(app);
+    navigation = navigation.push(super::super::canvas_workspace::Control::new(
+        button(text("Reorder…").size(12))
+            .padding(6)
+            .on_press_maybe(reorder.clone()),
+        scope,
+        "Reorder",
+        keyboard,
+        reorder,
+        camera,
+    ));
+    if selected_count > 1 {
+        let removal = app
+            .scenario_removal_enabled()
+            .then(|| crate::app::scenario_removal::begin(app))
+            .flatten();
+        navigation = navigation.push(super::super::canvas_workspace::Control::new(
+            button(text("Remove…").size(12))
+                .padding(6)
+                .on_press_maybe(removal.clone()),
+            scope,
+            "Remove selected",
+            keyboard,
+            removal,
+            camera,
+        ));
+    }
     if state.can_back(p, context) {
         navigation =
             navigation.push(button(text("Back").size(12)).padding(6).on_press_maybe(
@@ -262,7 +329,12 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
     let entries = [
         (
             "S",
-            if matches!(context.representation, Representation::Saved { .. }) {
+            if selected_count > 1 && matches!(context.representation, Representation::Saved { .. })
+            {
+                "Drag messages vertically or lifelines horizontally; Shift-click to change selection"
+            } else if selected_count > 1 {
+                "Shift-click to change selection; click a member to select only it"
+            } else if matches!(context.representation, Representation::Saved { .. }) {
                 "Select / move messages and lifelines"
             } else {
                 "Select / reorder occurrences"
@@ -343,7 +415,15 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
         }),
     );
     let mut details = column![
-        text(format!("Selected: {}", p.named(app.selected))).size(12),
+        text(if selected_count > 1 {
+            format!(
+                "{selected_count} selected; properties: {}",
+                p.named(app.selected)
+            )
+        } else {
+            format!("Selected: {}", p.named(app.selected))
+        })
+        .size(12),
         container(button(text("Properties").size(12)).on_press_maybe(
             (clean && properties_target(p, context, app.selected)).then_some(
                 Message::ScenarioCanvas(CanvasEvent::Properties(context, app.selected)),
@@ -367,7 +447,7 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
     let details = details_pane(
         context,
         state.scroll_restore(context, ScrollArea::Page),
-        sequence_rows(p, context, owner, details, clean).into(),
+        sequence_rows(p, context, owner, details, clean, snapshot.as_ref()).into(),
     );
     let mut form_panel = editor_panel(
         Id::nil(),
@@ -685,7 +765,9 @@ pub fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Element<'a
                 .into();
         }
     }
-    let editor = if pending {
+    let editor = if app.scenario_reorder.session.is_some() {
+        None
+    } else if pending {
         Some(form_panel)
     } else {
         presentation.shelf.map(|_| details)
@@ -724,9 +806,13 @@ fn display_notice_parts<'a>(
             for diagnostic in diagnostics.iter().take(3) {
                 let explanation = match diagnostic {
                     Diagnostic::SourceOrderCrossing { before, after, .. } => format!(
-                        "Saved spacing places '{}' below '{}'. The Scenario order is unchanged.",
-                        p.named(*before),
-                        p.named(*after)
+                        "Saved positions place @{} below @{}, contrary to execution order.",
+                        p.elements
+                            .get(before)
+                            .map_or("?", |element| element.alias.as_str()),
+                        p.elements
+                            .get(after)
+                            .map_or("?", |element| element.alias.as_str())
                     ),
                     Diagnostic::FrameExtendsPastFollowingAnchor { frame, following } => format!(
                         "Saved spacing makes '{}' overlap '{}'. Both keep their saved positions.",
@@ -751,7 +837,7 @@ fn display_notice_parts<'a>(
             if let Some(issue) = requested_issues.first() {
                 notice = notice.push(text(geometry_problem(p, issue)).size(12));
             }
-            notice = notice.push(text("Selection, navigation and Fit remain available. Canvas insertion and reordering are unavailable until the saved positions are repaired.").size(12));
+            notice = notice.push(text("Selection, navigation and Fit remain available. Coordinate editing requires repaired saved positions. Reorder uses explicit sequence destinations and previews its display consequences.").size(12));
         }
         PresentationStatus::Unavailable { .. } => {
             notice = notice.push(text("This view is unavailable. Its identity or automatic geometry cannot be resolved; the model and source remain available for inspection and repair.").size(12));
@@ -908,7 +994,24 @@ fn sequence_rows<'a>(
     owner: Id,
     mut out: Column<'a, Message>,
     enabled: bool,
+    snapshot: Option<&crate::diagram_selection::Snapshot>,
 ) -> Column<'a, Message> {
+    let choose = |id| {
+        snapshot.map_or_else(
+            || Message::ScenarioCanvas(CanvasEvent::Select(context, id)),
+            |snapshot| {
+                selection::message(
+                    context,
+                    snapshot,
+                    selection::Intent::Choose(
+                        crate::diagram_usage::Target::ScenarioObject(id),
+                        crate::app::multiselect::Choice::Replace,
+                    ),
+                )
+            },
+        )
+    };
+    let order_enabled = enabled && snapshot.is_none_or(|snapshot| snapshot.targets().len() <= 1);
     if let Some(SharedBody::Occurrence {
         body: OccurrenceBody::Fragment { branches, .. },
         ..
@@ -917,10 +1020,10 @@ fn sequence_rows<'a>(
         for branch in branches {
             out = out.push(sequence_action(
                 &format!("Operand: {}", p.named(*branch)),
-                Message::Select(*branch),
+                choose(*branch),
                 enabled,
             ));
-            out = sequence_rows(p, context, *branch, out, enabled);
+            out = sequence_rows(p, context, *branch, out, enabled, snapshot);
         }
     }
     if let Some(steps) = p.elements.get(&owner).and_then(|e| e.steps()) {
@@ -929,17 +1032,17 @@ fn sequence_rows<'a>(
                 row![
                     sequence_action(
                         &format!("{}. {}", i + 1, p.named(*id)),
-                        Message::Select(*id),
+                        choose(*id),
                         enabled
                     )
                     .width(Fill),
                     button("↑")
                         .padding(8)
-                        .on_press_maybe((enabled && i > 0).then_some(Message::Command(
+                        .on_press_maybe((order_enabled && i > 0).then_some(Message::Command(
                             Command::MoveStep(owner, i, i.saturating_sub(1))
                         ))),
                     button("↓").padding(8).on_press_maybe(
-                        (enabled && i + 1 < steps.len())
+                        (order_enabled && i + 1 < steps.len())
                             .then_some(Message::Command(Command::MoveStep(owner, i, i + 1)))
                     )
                 ]
@@ -960,7 +1063,7 @@ fn sequence_rows<'a>(
                     enabled,
                 ));
             }
-            out = sequence_rows(p, context, *id, out, enabled);
+            out = sequence_rows(p, context, *id, out, enabled, snapshot);
         }
     }
     out

crates/oa-desktop/src/behavior/scenario/workspace/details_tests.rs

@@ -388,13 +388,16 @@ fn opening_scenario_properties_cancels_held_spacing_and_rejects_its_late_finish(
         CanvasEvent::Viewport(c, Size::new(900., 600.))
     });
     open_details(&mut app);
-    let begin = packet(
+    let mut begin = packet(
         app.project(),
         &app.behavior.scenario,
         app.scenario_context().unwrap(),
         app.camera_epoch,
         Target::Message(message),
     );
+    if let Spacing::Begin { stamp, .. } = &mut begin {
+        stamp.selection_generation = app.multiselect_snapshot().unwrap().generation();
+    }
     let Spacing::Begin { press_screen, .. } = begin else {
         panic!()
     };
@@ -443,3 +446,180 @@ fn opening_scenario_properties_cancels_held_spacing_and_rejects_its_late_finish(
     assert!(Arc::ptr_eq(&snapshot, &app.document.snapshot()));
     assert!(!app.document.can_undo() && !app.document.can_redo());
 }
+
+#[tokio::test]
+async fn saved_selection_shift_survives_properties_focus_busy_rebuild_and_clears_on_window_loss() {
+    use crate::app::multiselect::Choice;
+    use crate::behavior::canvas_workspace::tests::focused;
+    use crate::diagram_usage::Target;
+
+    fn at(mounted: &mut Mounted, app: &App, target: Id) -> Point {
+        let context = app.scenario_context().unwrap();
+        let geometry = resolve(app.project(), context.representation, app.selected).unwrap();
+        let line = geometry
+            .scene
+            .lines
+            .iter()
+            .find(|line| line.id == target)
+            .unwrap();
+        let world = line.label_at + Vector::new(8., 8.);
+        assert_eq!(geometry.scene.hit_item(world).unwrap().id, target);
+        let bounds = mounted.geometry(app).bounds("scenario-viewport");
+        let camera = app.behavior.scenario.presentation.camera(geometry.bounds);
+        let point = bounds.position() + camera.pan + Vector::new(world.x, world.y) * camera.scale;
+        assert!(bounds.contains(point));
+        point
+    }
+    async fn focus_name(mounted: &mut Mounted, app: &mut App) -> Point {
+        let shown = mounted.geometry(app);
+        let (inspector, offset) = shown.scrolls[&widget::Id::new("inspector")];
+        let input = shown
+            .text_inputs
+            .iter()
+            .map(|bounds| bounds.center() - offset)
+            .filter(|point| inspector.contains(*point))
+            .min_by(|a, b| a.y.total_cmp(&b.y))
+            .expect("visible Name input");
+        mounted.click(app, input).await;
+        assert!(!focused(mounted, app, "viewport"));
+        assert!(
+            mounted
+                .geometry(app)
+                .focused
+                .iter()
+                .any(|(_, bounds, yes)| *yes && bounds.contains(input + offset))
+        );
+        assert!(!app.draft_dirty());
+        input
+    }
+    let shift = |held| {
+        iced::Event::Keyboard(keyboard::Event::ModifiersChanged(if held {
+            keyboard::Modifiers::SHIFT
+        } else {
+            keyboard::Modifiers::empty()
+        }))
+    };
+    let (mut app, diagram, first) = setup();
+    let second = id(&app, "updated_report");
+    let mut mounted = Mounted::new(&mut app).await;
+    open_details(&mut app);
+    mounted.settle(&mut app).await;
+    let shown = mounted.geometry(&app);
+    let (details, offset) = shown.scrolls[&widget::Id::new("scenario-details")];
+    let properties = shown.bounds("scenario-properties").center() - offset;
+    assert!(details.contains(properties));
+    mounted.click(&mut app, properties).await;
+    mounted.settle(&mut app).await;
+    let input = focus_name(&mut mounted, &mut app).await;
+    let before = app.document.snapshot();
+    let camera = stored_camera(&app);
+    let context = app.scenario_context().unwrap();
+    let selected = app.multiselect_snapshot().unwrap();
+    assert_eq!(selected.targets(), &[Target::ScenarioObject(first)]);
+    let passive = mounted
+        .batch(&mut app, &[shift(true)], mouse::Cursor::Available(input))
+        .await;
+    assert!(
+        !passive
+            .iter()
+            .any(|message| matches!(message, Message::ScenarioCanvas(_)))
+    );
+    assert!(!focused(&mut mounted, &app, "viewport"));
+    assert_eq!(app.multiselect_snapshot().unwrap(), selected);
+    let second_at = at(&mut mounted, &app, second);
+    let messages = mounted.click(&mut app, second_at).await;
+    assert_eq!(messages.iter().filter(|message| matches!(message,
+        Message::ScenarioCanvas(CanvasEvent::Selection(event))
+        if matches!(&event.intent, selection::Intent::Choose(Target::ScenarioObject(id), Choice::Toggle) if *id == second))).count(), 1);
+    assert!(!messages.iter().any(|message| matches!(
+        message,
+        Message::ScenarioCanvas(CanvasEvent::Spacing(_) | CanvasEvent::Reorder { .. })
+    )));
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[
+            Target::ScenarioObject(first),
+            Target::ScenarioObject(second)
+        ]
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().primary(),
+        Some(&Target::ScenarioObject(second))
+    );
+
+    app.busy = true;
+    mounted.settle(&mut app).await;
+    mounted
+        .batch(
+            &mut app,
+            &[shift(false)],
+            mouse::Cursor::Available(second_at),
+        )
+        .await;
+    app.busy = false;
+    mounted.settle(&mut app).await;
+    let first_at = at(&mut mounted, &app, first);
+    let messages = mounted.click(&mut app, first_at).await;
+    // Saved group clicks now complete the captured spacing lifetime; its
+    // stationary outcome must retain the same selection-only collapse.
+    assert!(messages.iter().any(|message| matches!(
+        message,
+        Message::ScenarioCanvas(CanvasEvent::Spacing(
+            super::super::spacing::Event::Finish { .. }
+        ))
+    )));
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[Target::ScenarioObject(first)]
+    );
+
+    let input = focus_name(&mut mounted, &mut app).await;
+    app.busy = true;
+    mounted.settle(&mut app).await;
+    mounted
+        .batch(&mut app, &[shift(true)], mouse::Cursor::Available(input))
+        .await;
+    app.busy = false;
+    mounted.settle(&mut app).await;
+    let second_at = at(&mut mounted, &app, second);
+    mounted.click(&mut app, second_at).await;
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[
+            Target::ScenarioObject(first),
+            Target::ScenarioObject(second)
+        ]
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().primary(),
+        Some(&Target::ScenarioObject(second))
+    );
+    mounted
+        .batch(
+            &mut app,
+            &[iced::Event::Window(iced::window::Event::Unfocused)],
+            mouse::Cursor::Unavailable,
+        )
+        .await;
+    let first_at = at(&mut mounted, &app, first);
+    mounted.click(&mut app, first_at).await;
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[Target::ScenarioObject(first)]
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().primary(),
+        Some(&Target::ScenarioObject(first))
+    );
+    assert_eq!(app.active_diagram, Some(diagram));
+    assert_eq!(
+        app.scenario_context().unwrap().representation,
+        context.representation
+    );
+    assert_eq!(app.scenario_context().unwrap().visit, context.visit);
+    assert_eq!(stored_camera(&app), camera);
+    assert!(Arc::ptr_eq(&before, &app.document.snapshot()));
+    assert_eq!(app.document.bundle(), &before.bundle);
+    assert!(!app.document.can_undo() && !app.document.can_redo());
+    assert!(app.behavior.scenario.spacing_token().is_none());
+}

crates/oa-desktop/src/behavior/scenario/workspace/spacing_tests.rs

@@ -436,3 +436,204 @@ async fn saved_drag_return_to_origin_preserves_redo_selection_and_original_fit_c
     assert_eq!(app.project(), &redo.decoded.project);
     assert_eq!(app.document.bundle(), &redo.bundle);
 }
+
+#[tokio::test]
+async fn saved_first_press_spaces_unselected_message_with_existing_singleton_selection() {
+    use crate::diagram_usage::Target;
+    let (mut app, mut mounted, diagram) = setup(false).await;
+    let initial = id(&app, "initial_report");
+    let target = id(&app, "updated_report");
+    let context = app.scenario_context().unwrap();
+    let snapshot = app.multiselect_snapshot().unwrap();
+    let task = app.update(selection::message(
+        context,
+        &snapshot,
+        selection::Intent::Choose(
+            Target::ScenarioObject(initial),
+            crate::app::multiselect::Choice::Replace,
+        ),
+    ));
+    mounted.perform(&mut app, task).await;
+    mounted.settle(&mut app).await;
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[Target::ScenarioObject(initial)]
+    );
+    let before = app.document.snapshot();
+    let revision = app.document.revision();
+    let context = app.scenario_context().unwrap();
+    let camera = stored_camera(&app);
+    let projected = screen(&mut mounted, &app, Point::new(400., 252.));
+    let start = Point::new(projected.x.round(), projected.y.round());
+    let geometry = resolved(&app);
+    let effective = app.behavior.scenario.presentation.camera(geometry.bounds);
+    assert_eq!(effective.scale, 0.5);
+    let bounds = mounted.geometry(&app).bounds("scenario-viewport");
+    let world = Point::new(
+        (start.x - bounds.x - effective.pan.x) / effective.scale,
+        (start.y - bounds.y - effective.pan.y) / effective.scale,
+    );
+    let hit = geometry.scene.hit_item(world).unwrap();
+    assert_eq!(hit.id, target);
+    assert_eq!(hit.role, crate::behavior::SceneHitRole::MessageBody);
+    let messages = press(&mut mounted, &mut app, start).await;
+    assert_eq!(
+        messages
+            .iter()
+            .filter(|message| matches!(
+                message,
+                Message::ScenarioCanvas(CanvasEvent::Spacing(spacing::Event::Begin { .. }))
+            ))
+            .count(),
+        1
+    );
+    assert!(
+        !messages
+            .iter()
+            .any(|message| matches!(message, Message::ScenarioCanvas(CanvasEvent::Selection(_))))
+    );
+    let token = app
+        .behavior
+        .scenario
+        .spacing_token()
+        .expect("first press starts saved spacing despite different selected singleton");
+    assert!(Arc::ptr_eq(&before, &app.document.snapshot()));
+    let end = start + Vector::new(0., 10.);
+    move_to(&mut mounted, &mut app, end).await;
+    mounted.settle(&mut app).await;
+    assert_eq!(app.behavior.scenario.spacing_token(), Some(token));
+    let messages = release(&mut mounted, &mut app, end).await;
+    assert_eq!(
+        messages
+            .iter()
+            .filter(|message| matches!(
+                message,
+                Message::ScenarioCanvas(CanvasEvent::Spacing(spacing::Event::Finish { .. }))
+            ))
+            .count(),
+        1
+    );
+    let mut expected = before.decoded.project.clone();
+    set_expected_message(&mut expected, diagram, target, 272.);
+    assert_eq!(app.project(), &expected);
+    assert_eq!(app.document.revision(), revision + 1);
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().targets(),
+        &[Target::ScenarioObject(target)]
+    );
+    assert_eq!(
+        app.multiselect_snapshot().unwrap().primary(),
+        Some(&Target::ScenarioObject(target))
+    );
+    assert!(app.behavior.scenario.spacing_token().is_none());
+    assert_eq!(stored_camera(&app), camera);
+    assert_eq!(
+        app.scenario_context().unwrap().representation,
+        context.representation
+    );
+    assert_eq!(app.scenario_context().unwrap().visit, context.visit);
+    assert_reopens_exactly(&app);
+    let after = app.document.snapshot();
+    let revision = app.document.revision();
+    let duplicate = release(&mut mounted, &mut app, end).await;
+    assert!(!duplicate.iter().any(|message| matches!(
+        message,
+        Message::ScenarioCanvas(CanvasEvent::Spacing(spacing::Event::Finish { .. }))
+    )));
+    assert_eq!(app.document.revision(), revision);
+    assert!(Arc::ptr_eq(&after, &app.document.snapshot()));
+    let task = app.update(Message::Undo);
+    mounted.perform(&mut app, task).await;
+    assert_eq!(app.project(), &before.decoded.project);
+    assert_eq!(app.document.bundle(), &before.bundle);
+    assert!(!app.document.can_undo() && app.document.can_redo());
+    let task = app.update(Message::Redo);
+    mounted.perform(&mut app, task).await;
+    assert_eq!(app.project(), &after.decoded.project);
+    assert_eq!(app.document.bundle(), &after.bundle);
+}
+
+#[tokio::test]
+async fn saved_blank_left_drag_clears_selection_and_pans_on_that_same_press() {
+    use crate::diagram_usage::Target;
+    for group in [false, true] {
+        for same_batch in [false, true] {
+            let (mut app, mut mounted, _) = setup(false).await;
+            let first = id(&app, "initial_report");
+            let second = id(&app, "updated_report");
+            for target in [Some(first), group.then_some(second)].into_iter().flatten() {
+                let context = app.scenario_context().unwrap();
+                let snapshot = app.multiselect_snapshot().unwrap();
+                let task = app.update(selection::message(
+                    context,
+                    &snapshot,
+                    selection::Intent::Choose(
+                        Target::ScenarioObject(target),
+                        crate::app::multiselect::Choice::Add,
+                    ),
+                ));
+                mounted.perform(&mut app, task).await;
+            }
+            mounted.settle(&mut app).await;
+            assert_eq!(
+                app.multiselect_snapshot().unwrap().targets().len(),
+                if group { 2 } else { 1 }
+            );
+            let before = app.document.snapshot();
+            let context = app.scenario_context().unwrap();
+            let bounds = mounted.geometry(&app).bounds("scenario-viewport");
+            let start = bounds.position() + Vector::new(bounds.width - 25., bounds.height - 25.);
+            let delta = Vector::new(-25., -20.);
+            let end = start + delta;
+            let geometry = resolved(&app);
+            let camera = app.behavior.scenario.presentation.camera(geometry.bounds);
+            let world = Point::new(
+                (start.x - bounds.x - camera.pan.x) / camera.scale,
+                (start.y - bounds.y - camera.pan.y) / camera.scale,
+            );
+            assert!(
+                geometry.scene.hit_item(world).is_none(),
+                "test must start on actual blank geometry"
+            );
+            let stored = stored_camera(&app);
+            let messages = if same_batch {
+                mounted
+                    .batch(
+                        &mut app,
+                        &[
+                            mouse_event(mouse::Event::CursorMoved { position: start }),
+                            mouse_event(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                            mouse_event(mouse::Event::CursorMoved { position: end }),
+                            mouse_event(mouse::Event::ButtonReleased(mouse::Button::Left)),
+                        ],
+                        mouse::Cursor::Available(end),
+                    )
+                    .await
+            } else {
+                let mut messages = press(&mut mounted, &mut app, start).await;
+                assert!(app.multiselect_snapshot().unwrap().targets().is_empty());
+                mounted.settle(&mut app).await;
+                messages.extend(move_to(&mut mounted, &mut app, end).await);
+                messages.extend(release(&mut mounted, &mut app, end).await);
+                messages
+            };
+            assert_eq!(messages.iter().filter(|message| matches!(message, Message::ScenarioCanvas(CanvasEvent::Selection(event)) if matches!(&event.intent, selection::Intent::Clear))).count(), 1);
+            assert!(app.multiselect_snapshot().unwrap().targets().is_empty());
+            let actual = stored_camera(&app);
+            let difference = actual.0 - (stored.0 + delta);
+            assert!(
+                difference.x.hypot(difference.y) < 0.01,
+                "same-press pan lost after Clear: group={group}, same_batch={same_batch}, {stored:?} -> {actual:?}"
+            );
+            assert_eq!(actual.1, stored.1);
+            assert_eq!(
+                app.scenario_context().unwrap().representation,
+                context.representation
+            );
+            assert_eq!(app.scenario_context().unwrap().visit, context.visit);
+            assert!(Arc::ptr_eq(&before, &app.document.snapshot()));
+            assert_eq!(app.document.bundle(), &before.bundle);
+            assert!(!app.document.can_undo() && !app.document.can_redo());
+        }
+    }
+}

crates/oa-desktop/src/behavior/scenario_lifecycle/render.rs

@@ -234,6 +234,13 @@ impl Rendering {
             .collect()
     }
 
+    /// Exact painted marker subjects and centers for shared selection adapters.
+    pub(in crate::behavior) fn selection_markers(&self) -> impl Iterator<Item = (Id, Point)> + '_ {
+        self.markers
+            .iter()
+            .map(|marker| (marker.event.occurrence, marker.center))
+    }
+
     pub(in crate::behavior) fn marker_at(&self, point: Point) -> Option<Id> {
         self.markers
             .iter()

crates/oa-desktop/src/behavior/state_canvas.rs

@@ -29,6 +29,7 @@ use std::{
 pub const GUIDANCE_HEIGHT: f32 = 42.;
 
 pub struct StateCanvas<'a> {
+    pub removal_input: &'a crate::removal_input::Lifetime,
     pub project: &'a Project,
     pub diagram: Id,
     pub context: Context,
@@ -44,6 +45,8 @@ pub struct StateCanvas<'a> {
 
 #[derive(Default)]
 pub struct State {
+    removal_lease: Option<crate::removal_input::Lease>,
+    removal_viewport: Option<(f32, Vector, Rectangle)>,
     context: Option<Context>,
     tool: Option<Tool>,
     pointer: Option<Point>,
@@ -877,6 +880,21 @@ impl StateCanvas<'_> {
             }
             if selection.targets().len() > 1 && *key == Key::Named(Named::Delete) {
                 let snapshot = selection.snapshot(selection_context(self.context))?;
+                if *modifiers == keyboard::Modifiers::SHIFT {
+                    let Some(input_generation) = self.removal_input.idle() else {
+                        return Some(Action::capture());
+                    };
+                    return Some(
+                        Action::publish(Event::ModelRemoval(Box::new(
+                            crate::app::saved_removal::Event::Begin {
+                                input_generation,
+                                context: self.context,
+                                snapshot: Box::new(snapshot),
+                            },
+                        )))
+                        .and_capture(),
+                    );
+                }
                 let event = if modifiers.is_empty()
                     && crate::app::multiselect::placements(&snapshot).is_some()
                 {
@@ -885,7 +903,7 @@ impl StateCanvas<'_> {
                     SelectionEvent::Refuse(snapshot, if modifiers.is_empty() {
                         "Hide requires only placed elements. Rows, ports and transitions cannot be hidden as a placement group."
                     } else {
-                        "Group model deletion requires an aggregate impact review and is not available yet. Use Hide selected for placements."
+                        "Use Shift+Delete to review model deletion or Hide selected for placements."
                     }.into())
                 };
                 return Some(Action::publish(Event::Selection(event)).and_capture());
@@ -1511,9 +1529,8 @@ fn kind_for_tool(tool: Tool) -> Kind {
     }
 }
 
-impl canvas::Program<Event> for StateCanvas<'_> {
-    type State = State;
-    fn update(
+impl StateCanvas<'_> {
+    fn update_input(
         &self,
         state: &mut State,
         event: &canvas::Event,
@@ -2002,6 +2019,51 @@ impl canvas::Program<Event> for StateCanvas<'_> {
             _ => None,
         }
     }
+}
+impl canvas::Program<Event> for StateCanvas<'_> {
+    type State = State;
+    fn update(
+        &self,
+        state: &mut State,
+        event: &canvas::Event,
+        bounds: Rectangle,
+        cursor: mouse::Cursor,
+    ) -> Option<Action<Event>> {
+        self.removal_input.sync(
+            &mut state.removal_lease,
+            state.press.is_some()
+                || state.group.is_some()
+                || state.source.is_some()
+                || state.bend.is_some()
+                || state.pan_from.is_some(),
+        );
+        self.removal_input.observe(event);
+        let viewport = (self.zoom, self.pan, bounds);
+        if state
+            .removal_viewport
+            .is_some_and(|previous| previous != viewport)
+        {
+            self.removal_input.revoke_idle();
+        }
+        state.removal_viewport = Some(viewport);
+        let action = self.update_input(state, event, bounds, cursor);
+        if matches!(
+            event,
+            canvas::Event::Window(iced::window::Event::Unfocused | iced::window::Event::Resized(_))
+                | canvas::Event::Mouse(mouse::Event::CursorLeft)
+        ) {
+            state.reset();
+        }
+        self.removal_input.sync(
+            &mut state.removal_lease,
+            state.press.is_some()
+                || state.group.is_some()
+                || state.source.is_some()
+                || state.bend.is_some()
+                || state.pan_from.is_some(),
+        );
+        action
+    }
     fn draw(
         &self,
         state: &State,
@@ -2597,6 +2659,7 @@ mod tests {
     include!("state_multiselect_canvas_tests.rs");
 
     struct Fixture {
+        removal_input: crate::removal_input::Lifetime,
         project: Project,
         diagram: Id,
         machine: Id,
@@ -2658,6 +2721,7 @@ mod tests {
         }
         validate_candidate(&project).unwrap();
         Fixture {
+            removal_input: Default::default(),
             project,
             diagram,
             machine,
@@ -2858,6 +2922,7 @@ mod tests {
 
     fn canvas(f: &Fixture, tool: Tool, zoom: f32) -> StateCanvas<'_> {
         StateCanvas {
+            removal_input: &f.removal_input,
             project: &f.project,
             diagram: f.diagram,
             context: Context {

crates/oa-desktop/src/behavior/state_edit.rs

@@ -26,6 +26,7 @@ pub enum Tool {
 #[derive(Debug, Clone)]
 pub enum Event {
     Selection(crate::app::multiselect::Event),
+    ModelRemoval(Box<crate::app::saved_removal::Event>),
     Remove(crate::app::diagram_removal::Intent),
     Choose(Tool),
     CreateView(Id),
@@ -104,7 +105,9 @@ impl Event {
         match self {
             Self::Remove(intent) => Some(intent.context),
             // Group events carry their own exact selection envelope.
-            Self::Selection(_) | Self::Choose(_) | Self::CreateView(_) => None,
+            Self::Selection(_) | Self::ModelRemoval(_) | Self::Choose(_) | Self::CreateView(_) => {
+                None
+            }
             Self::Select(c, _)
             | Self::Pan(c, _)
             | Self::Zoom(c, _)

crates/oa-desktop/src/behavior/state_multiselect_canvas_tests.rs

@@ -328,7 +328,10 @@ fn state_group_delete_and_escape_respect_held_gesture_and_full_set() {
     let mut state = State::default();
     use keyboard::key::Named;
     assert!(matches!(group_key(&canvas, &mut state, Named::Delete, keyboard::Modifiers::empty()), Some(Event::Selection(SelectionEvent::Hide(_)))));
-    assert!(matches!(group_key(&canvas, &mut state, Named::Delete, keyboard::Modifiers::SHIFT), Some(Event::Selection(SelectionEvent::Refuse(_, _)))));
+    let Some(Event::ModelRemoval(removal)) = group_key(&canvas, &mut state, Named::Delete, keyboard::Modifiers::SHIFT) else {
+        panic!("Shift+Delete must capture the complete model-removal group");
+    };
+    assert!(matches!(*removal, crate::app::saved_removal::Event::Begin { snapshot, .. } if snapshot.targets() == selection.targets()));
     let at = screen(&canvas, header(&canvas, f.a));
     motion(&canvas, &mut state, at, at);
     input(&canvas, &mut state, mouse::Event::ButtonPressed(mouse::Button::Left), at);

crates/oa-desktop/src/behavior/state_view.rs

@@ -43,6 +43,7 @@ pub fn diagram(app: &App, machine: Id) -> Option<Id> {
 fn event(e: Event) -> Message {
     match e {
         Event::Selection(selection) => Message::DiagramSelection(selection),
+        Event::ModelRemoval(removal) => Message::SavedRemoval(removal),
         other => Message::StateDiagram(other),
     }
 }
@@ -169,6 +170,7 @@ pub fn view<'a>(app: &'a App, machine: Id, mut out: Column<'a, Message>) -> Elem
         );
     }
     let canvas: Element<'_, Event> = canvas::Canvas::new(super::state_canvas::StateCanvas {
+        removal_input: &app.saved_removal_input,
         project: p,
         diagram: id,
         context,
@@ -187,7 +189,7 @@ pub fn view<'a>(app: &'a App, machine: Id, mut out: Column<'a, Message>) -> Elem
     .into();
     out = out.push(
         column![
-            container(missing_controls).id("state-missing-picker"),
+            missing_controls,
             selection_controls(app),
             crate::diagram::focus::wrap(
                 canvas.map(event),
@@ -223,15 +225,22 @@ fn selection_controls(app: &App) -> Element<'_, Message> {
                 Message::DiagramSelection(SelectionEvent::Hide(snapshot.clone())),
             ));
         }
+        controls = controls.push(
+            button(text("Delete from model…").size(12))
+                .padding([6, 8])
+                .on_press_maybe(
+                    crate::app::saved_removal::begin(app).filter(|_| app.saved_removal_enabled()),
+                ),
+        );
         controls = controls
             .push(action(
-                "Clear selection",
+                "Clear",
                 Message::DiagramSelection(SelectionEvent::Clear(snapshot.context())),
             ))
             .push(
                 label(format!(
-                    "Properties edit only {}",
-                    crate::views::short(app.project().named(app.selected), 18)
+                    "Edit only {}",
+                    crate::views::short(app.project().named(app.selected), 12)
                 ))
                 .wrapping(iced::widget::text::Wrapping::None),
             );

crates/oa-desktop/src/behavior/topology.rs

@@ -5,7 +5,9 @@ use iced::widget::{Column, text_input};
 use std::collections::BTreeSet;
 pub(crate) mod contextual;
 mod direct;
+pub(crate) mod group_removal;
 pub(crate) mod group_reorder;
+use crate::removal_input;
 mod usages;
 mod view;
 #[cfg(test)]
@@ -80,6 +82,7 @@ impl std::fmt::Display for ControlChoice {
 }
 #[derive(Default)]
 pub struct State {
+    removal_input: removal_input::Lifetime,
     identity: Option<(Id, Id)>,
     tool: CanvasTool,
     expanded: BTreeSet<Id>,
@@ -128,6 +131,10 @@ struct Draft {
     contextual: Option<contextual::Draft>,
 }
 impl State {
+    pub(crate) fn removal_generation(&self) -> Option<u64> {
+        self.removal_input.idle()
+    }
+
     pub(crate) fn camera_boundary(&self) -> impl PartialEq + use<> {
         (
             self.tool,
@@ -1104,6 +1111,7 @@ const PAINT_PASSES: [PaintPass; 5] = [
 ];
 mod contextual_routing;
 struct Graph<'a> {
+    removal_input: removal_input::Lifetime,
     project: &'a Project,
     interaction: Option<(Context, CanvasTool, bool)>,
     camera_pan: iced::Vector,
@@ -1401,6 +1409,7 @@ impl<'a> Graph<'a> {
         }
         Self {
             project: p,
+            removal_input: removal_input::Lifetime::default(),
             interaction: None,
             camera_pan: iced::Vector::ZERO,
             pending_insertion: None,

crates/oa-desktop/src/behavior/topology/direct_selection.rs

@@ -6,6 +6,7 @@ use crate::diagram_selection::Snapshot;
 use crate::diagram_usage::Target;
 
 pub(super) struct GroupPress {
+    _removal_lease: super::super::removal_input::Lease,
     snapshot: Snapshot,
     target: Target,
     start: Point,
@@ -108,6 +109,12 @@ impl Graph<'_> {
         cursor: mouse::Cursor,
     ) -> Option<Action<Message>> {
         use iced::keyboard::{Event as KeyEvent, Key, key::Named};
+        if matches!(
+            event,
+            canvas::Event::Window(iced::window::Event::Unfocused | iced::window::Event::Resized(_))
+        ) {
+            self.removal_input.revoke_idle();
+        }
         match event {
             canvas::Event::Keyboard(KeyEvent::ModifiersChanged(modifiers))
             | canvas::Event::Keyboard(KeyEvent::KeyPressed { modifiers, .. })
@@ -205,21 +212,46 @@ impl Graph<'_> {
             return None;
         }
         let publish = |event| Some(Action::publish(Message::DiagramSelection(event)).and_capture());
-        if matches!(
-            event,
-            canvas::Event::Keyboard(KeyEvent::KeyPressed {
-                key: Key::Named(Named::Delete),
-                repeat: false,
-                ..
-            })
-        ) && (snapshot.targets().len() > 1
-            || snapshot.targets().iter().any(|t| match t {
-                Target::ProcessPreviewLink { .. } => true,
-                Target::ProcessOccurrence(endpoint) => !endpoint.references.is_empty(),
-                _ => false,
-            }))
+        if let canvas::Event::Keyboard(KeyEvent::KeyPressed {
+            key: Key::Named(Named::Delete),
+            modifiers,
+            repeat,
+            ..
+        }) = event
+            && (snapshot.targets().len() > 1
+                || snapshot.targets().iter().any(|t| match t {
+                    Target::ProcessPreviewLink { .. } => true,
+                    Target::ProcessOccurrence(endpoint) => !endpoint.references.is_empty(),
+                    _ => false,
+                }))
         {
-            return publish(SelectionEvent::Refuse(snapshot.clone(), "Remove is unavailable for this selection. Open the referenced definition to edit qualified contributions; group removal needs an aggregate review.".into()));
+            if *repeat
+                || tool != CanvasTool::Select
+                || !(modifiers.is_empty() || *modifiers == iced::keyboard::Modifiers::SHIFT)
+                || state.press.is_some()
+                || state.source.is_some()
+            {
+                return Some(Action::capture());
+            }
+            if snapshot.targets().len() > 1 {
+                let Some(input_generation) = self.removal_input.idle() else {
+                    return Some(Action::capture());
+                };
+                return Some(
+                    Action::publish(Message::ProcessRemoval(Box::new(
+                        crate::app::process_removal::Event::Begin {
+                            input_generation,
+                            context,
+                            snapshot: Box::new(snapshot.clone()),
+                        },
+                    )))
+                    .and_capture(),
+                );
+            }
+            return publish(SelectionEvent::Refuse(
+                snapshot.clone(),
+                "Open the referenced definition to remove qualified contributions.".into(),
+            ));
         }
         let pointer = match event {
             canvas::Event::Mouse(mouse::Event::CursorMoved { position }) => Some(*position),
@@ -228,6 +260,9 @@ impl Graph<'_> {
         if !bounds.contains(pointer) {
             return None;
         }
+        if matches!(event, canvas::Event::Mouse(mouse::Event::ButtonPressed(_))) {
+            self.removal_input.revoke_idle();
+        }
         let world = Point::new(
             (pointer.x - bounds.x - self.camera_pan.x) / self.scale,
             (pointer.y - bounds.y - self.camera_pan.y) / self.scale,
@@ -310,7 +345,11 @@ impl Graph<'_> {
         state.tool = tool;
         state.bounds = Some(bounds);
         state.pointer = Some(pointer);
+        let Some(lease) = self.removal_input.acquire() else {
+            return Some(Action::capture());
+        };
         state.group = Some(GroupPress {
+            _removal_lease: lease,
             snapshot: snapshot.clone(),
             target,
             start: pointer,

crates/oa-desktop/src/behavior/topology/direct_selection_tests.rs

@@ -171,7 +171,7 @@ fn selected_anchor_noop_and_irreversible_threshold_never_collapse_after_motion()
 }
 
 #[test]
-fn whole_mixed_set_refuses_drag_delete_and_connect_without_singleton_bypass() {
+fn whole_mixed_set_reviews_delete_and_refuses_drag_and_connect_without_singleton_bypass() {
     let f = fixture(Layer::Sa);
     let mut graph = graph(&f, &[local(f.nodes[0]), Target::ProcessLink(f.link)]);
     graph.selected = f.link;
@@ -187,7 +187,7 @@ fn whole_mixed_set_refuses_drag_delete_and_connect_without_singleton_bypass() {
     };
     assert!(matches!(
         send(&graph, &mut input, canvas::Event::Keyboard(key), start),
-        Some(Message::DiagramSelection(SelectionEvent::Refuse(_, _)))
+        Some(Message::ProcessRemoval(event)) if matches!(&*event, crate::app::process_removal::Event::Begin { snapshot, .. } if snapshot.targets().len() == 2)
     ));
     graph.interaction.as_mut().unwrap().1 = CanvasTool::Connect;
     assert!(matches!(
@@ -401,3 +401,99 @@ fn mixed_group_at_endpoint_card_refuses_whole_drag_without_hidden_singleton_hand
         }
     }
 }
+
+#[test]
+fn group_delete_modifiers_repeat_and_active_gesture_never_emit_singleton_or_confirmation() {
+    use iced::keyboard::{Event as KeyEvent, Modifiers, key::Named};
+    let f = fixture(Layer::Oa);
+    let graph = graph(&f, &[local(f.nodes[0]), Target::ProcessLink(f.link)]);
+    let start = point(&graph, f.nodes[0], false);
+    for modifiers in [
+        Modifiers::empty(),
+        Modifiers::SHIFT,
+        Modifiers::CTRL,
+        Modifiers::ALT,
+    ] {
+        for repeat in [false, true] {
+            let iced::Event::Keyboard(mut key) =
+                crate::behavior::canvas_workspace::tests::key(Named::Delete)
+            else {
+                panic!("key")
+            };
+            if let KeyEvent::KeyPressed {
+                modifiers: value,
+                repeat: value_repeat,
+                ..
+            } = &mut key
+            {
+                *value = modifiers;
+                *value_repeat = repeat;
+            }
+            let message = send(
+                &graph,
+                &mut Input::default(),
+                canvas::Event::Keyboard(key),
+                start,
+            );
+            if !repeat && (modifiers.is_empty() || modifiers == Modifiers::SHIFT) {
+                assert!(
+                    matches!(message, Some(Message::ProcessRemoval(event)) if matches!(&*event, crate::app::process_removal::Event::Begin { snapshot, .. } if Some(&**snapshot) == graph.selection.as_ref()))
+                );
+            } else {
+                assert!(message.is_none());
+            }
+        }
+    }
+    let mut input = Input::default();
+    press(&graph, &mut input, start);
+    let iced::Event::Keyboard(key) = crate::behavior::canvas_workspace::tests::key(Named::Delete)
+    else {
+        panic!("key")
+    };
+    assert!(send(&graph, &mut input, canvas::Event::Keyboard(key), start).is_none());
+    assert!(input.group.is_some());
+}
+
+#[test]
+fn process_removal_gesture_lease_retires_on_release_cancel_and_widget_state_drop() {
+    let f = fixture(Layer::Oa);
+    for end in ["release", "escape", "drop", "unfocus"] {
+        let graph = graph(&f, &[local(f.nodes[0]), Target::ProcessLink(f.link)]);
+        let before = graph.removal_input.idle().unwrap();
+        let at = point(&graph, f.nodes[0], false);
+        let mut input = Input::default();
+        assert!(press(&graph, &mut input, at).is_none());
+        assert!(input.group.is_some());
+        assert!(graph.removal_input.idle().is_none());
+        match end {
+            "release" => {
+                release(&graph, &mut input, at);
+            }
+            "escape" => {
+                let iced::Event::Keyboard(key) = crate::behavior::canvas_workspace::tests::key(
+                    iced::keyboard::key::Named::Escape,
+                ) else {
+                    panic!("key")
+                };
+                send(&graph, &mut input, canvas::Event::Keyboard(key), at);
+            }
+            "unfocus" => {
+                send(
+                    &graph,
+                    &mut input,
+                    canvas::Event::Window(iced::window::Event::Unfocused),
+                    at,
+                );
+            }
+            _ => {
+                drop(input);
+            }
+        }
+        assert!(graph.removal_input.idle().is_some());
+        assert_ne!(
+            graph.removal_input.idle(),
+            Some(before),
+            "{end} cannot restore an old Begin generation"
+        );
+    }
+}

crates/oa-desktop/src/behavior/topology/group_removal.rs

@@ -0,0 +1,148 @@
+//! Exact local Process/FunctionalChain removal and definition-level interpretation
+//! effects. Visibility, source drafts and captured UI lifetime belong to the App.
+use super::*;
+use crate::diagram_usage::Target;
+#[cfg(test)]
+use crate::removal_effects::Interpretation;
+pub(crate) use crate::removal_effects::InterpretationChange;
+
+#[derive(Debug)]
+pub(crate) struct Plan {
+    pub(crate) command: Command,
+    pub(crate) removed: BTreeSet<Id>,
+    pub(crate) changed: BTreeSet<Id>,
+    pub(crate) interpretation: Vec<InterpretationChange>,
+    /// Definitions whose authored topology changed, including changes that do
+    /// not switch interpretation. Values are surviving transitive callers.
+    pub(crate) affected_uses: BTreeMap<Id, BTreeSet<Id>>,
+}
+
+fn changed_records<T: PartialEq>(
+    before: &BTreeMap<Id, T>,
+    after: &BTreeMap<Id, T>,
+    changed: &mut BTreeSet<Id>,
+) {
+    changed.extend(
+        before
+            .iter()
+            .filter_map(|(&id, record)| after.get(&id).filter(|next| *next != record).map(|_| id)),
+    );
+}
+
+pub(crate) fn prepare(project: &Project, owner: Id, targets: &[Target]) -> Result<Plan, String> {
+    let element = project
+        .elements
+        .get(&owner)
+        .filter(|e| matches!(e.kind(), Kind::Process | Kind::FunctionalChain))
+        .ok_or("Choose an existing Process or Functional Chain.")?;
+    if targets.is_empty() {
+        return Err("Select at least one local contribution or maintained link to remove.".into());
+    }
+    oa_core::session::validate_candidate(project).map_err(|error| error.to_string())?;
+    let mut listed = BTreeSet::new();
+    for &id in element
+        .steps()
+        .ok_or("This owner has no contribution order.")?
+    {
+        if !is_contribution(project, owner, id)
+            || project.elements[&id].layer() != element.layer()
+            || !listed.insert(id)
+        {
+            return Err(
+                "Every process step must name a unique local contribution before removal.".into(),
+            );
+        }
+    }
+    let mut selected = BTreeSet::new();
+    let mut occurrences = BTreeSet::new();
+    let mut links = BTreeSet::new();
+    // Admit ALL original typed targets before any dependency normalization.
+    for target in targets {
+        let id = match target {
+            Target::ProcessOccurrence(endpoint) => {
+                if !endpoint.references.is_empty() {
+                    return Err("Open the referenced definition to remove its contents.".into());
+                }
+                if !listed.contains(&endpoint.occurrence) {
+                    return Err("Every selected contribution must be listed directly in this process.".into());
+                }
+                occurrences.insert(endpoint.occurrence);
+                endpoint.occurrence
+            }
+            Target::ProcessLink(id) => {
+                let relation = project.relations.get(id).ok_or("A selected maintained link no longer exists.")?;
+                let local = match &relation.body {
+                    RelationBody::SequenceLink { source, target, .. } => listed.contains(source) && listed.contains(target),
+                    RelationBody::ContextualLink { owner: actual, .. } => *actual == owner,
+                    _ => false,
+                };
+                if !local {
+                    return Err("Every selected link must be maintained locally by this process, with listed local endpoints for sequence links.".into());
+                }
+                links.insert(*id);
+                *id
+            }
+            _ => return Err("Remove only local process contributions and maintained links together; referenced preview links are read-only here.".into()),
+        };
+        if !selected.insert(id) {
+            return Err("Every selected process subject must be unique.".into());
+        }
+    }
+    // Contribution kinds cannot contain one another; only admitted links can be
+    // covered by an occurrence cascade. Ancestry alone misses incident links.
+    let covered: BTreeSet<_> = occurrences
+        .iter()
+        .flat_map(|id| oa_core::references::deletion_impact(project, *id))
+        .collect();
+    let command = Command::Batch(
+        occurrences
+            .into_iter()
+            .chain(links.into_iter().filter(|id| !covered.contains(id)))
+            .map(Command::Delete)
+            .collect(),
+    );
+    let candidate = execute_batch(project, std::slice::from_ref(&command))
+        .map_err(|error| error.to_string())?;
+    let original: BTreeSet<_> = project.identities().into_iter().map(|(id, _)| id).collect();
+    let retained: BTreeSet<_> = candidate
+        .identities()
+        .into_iter()
+        .map(|(id, _)| id)
+        .collect();
+    if !retained.is_subset(&original) {
+        return Err("Removal unexpectedly created model identities; no change was applied.".into());
+    }
+    let removed: BTreeSet<_> = original.difference(&retained).copied().collect();
+    if !selected.is_subset(&removed) {
+        return Err("The complete selected set could not be removed.".into());
+    }
+    let mut changed = BTreeSet::new();
+    changed_records(&project.elements, &candidate.elements, &mut changed);
+    changed_records(&project.relations, &candidate.relations, &mut changed);
+    changed_records(&project.diagrams, &candidate.diagrams, &mut changed);
+    changed_records(
+        &project.artifact_links,
+        &candidate.artifact_links,
+        &mut changed,
+    );
+    changed_records(&project.traces, &candidate.traces, &mut changed);
+    for (&id, diagram) in &project.diagrams {
+        if let Some(after) = candidate.diagrams.get(&id) {
+            changed_records(&diagram.nodes, &after.nodes, &mut changed);
+        }
+    }
+    let crate::removal_effects::DerivedEffects {
+        interpretation,
+        affected_uses,
+    } = crate::removal_effects::analyze(project, &candidate, &removed, &changed);
+    Ok(Plan {
+        command,
+        removed,
+        changed,
+        interpretation,
+        affected_uses,
+    })
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/behavior/topology/group_removal/tests.rs

@@ -0,0 +1,909 @@
+use super::*;
+use crate::document::Document;
+use oa_core::{MessageKind, source_project::ProjectLimits};
+
+fn endpoint(id: Id) -> OccurrenceEndpoint {
+    OccurrenceEndpoint {
+        references: vec![],
+        occurrence: id,
+    }
+}
+
+fn local(id: Id) -> Target {
+    Target::ProcessOccurrence(endpoint(id))
+}
+
+fn add(project: &mut Project, owner: Id, name: &str, body: OccurrenceBody) -> Id {
+    let element = occurrence(project, owner, name, body);
+    let id = element.id;
+    project.elements.insert(id, element);
+    project
+        .elements
+        .get_mut(&owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(id);
+    id
+}
+
+fn action(project: &mut Project, owner: Id, name: &str, work: Id) -> Id {
+    add(
+        project,
+        owner,
+        name,
+        OccurrenceBody::Action {
+            action: Some(work),
+            lifeline: None,
+        },
+    )
+}
+
+fn exchange_step(project: &mut Project, owner: Id, name: &str, exchange: Id) -> Id {
+    add(
+        project,
+        owner,
+        name,
+        OccurrenceBody::Exchange {
+            exchange: Some(exchange),
+            sender: None,
+            receiver: None,
+            message_kind: MessageKind::Asynchronous,
+            reply_to: None,
+            values: vec![],
+            operation: None,
+        },
+    )
+}
+
+fn sequence(project: &mut Project, layer: Layer, name: &str) -> Id {
+    project
+        .add_element(
+            if layer == Layer::Oa {
+                Kind::Process
+            } else {
+                Kind::FunctionalChain
+            },
+            layer,
+            name,
+            None,
+        )
+        .unwrap()
+}
+
+fn reuse(project: &mut Project, owner: Id, name: &str, definition: Id) -> Id {
+    add(
+        project,
+        owner,
+        name,
+        OccurrenceBody::SequenceReference {
+            sequence: Some(definition),
+        },
+    )
+}
+
+fn maintained(project: &mut Project, source: Id, target: Id) -> Id {
+    let Command::CreateRelation(relation) = link(project, source, target, "authored guard") else {
+        panic!()
+    };
+    let id = relation.id;
+    project.relations.insert(id, relation);
+    id
+}
+
+fn contextual(
+    project: &mut Project,
+    owner: Id,
+    source: OccurrenceEndpoint,
+    target: OccurrenceEndpoint,
+    purpose: ContextualLinkPurpose,
+) -> Id {
+    let Command::CreateRelation(mut relation) =
+        link(project, source.occurrence, target.occurrence, "")
+    else {
+        panic!()
+    };
+    let id = relation.id;
+    relation.body = RelationBody::ContextualLink {
+        owner,
+        source,
+        target,
+        purpose,
+    };
+    project.relations.insert(id, relation);
+    id
+}
+
+fn precedence() -> ContextualLinkPurpose {
+    ContextualLinkPurpose::Precedence {
+        guard: "caller guard".into(),
+    }
+}
+
+fn qualified(references: &[Id], occurrence: Id) -> OccurrenceEndpoint {
+    OccurrenceEndpoint {
+        references: references.to_vec(),
+        occurrence,
+    }
+}
+
+fn interpretation(
+    local: Option<Vec<Id>>,
+    expanded: Option<Vec<Id>>,
+    contextual: bool,
+) -> Interpretation {
+    Interpretation {
+        local_order: local,
+        expanded_order: expanded,
+        contextual_analysis: contextual,
+    }
+}
+
+fn expected_without(project: &Project, owner: Id, elements: &[Id], relations: &[Id]) -> Project {
+    let mut expected = project.clone();
+    for id in elements {
+        expected.elements.remove(id);
+    }
+    for id in relations {
+        expected.relations.remove(id);
+    }
+    expected
+        .elements
+        .get_mut(&owner)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .retain(|id| !elements.contains(id));
+    expected
+}
+
+fn assert_history(project: &Project, expected: &Project, command: Command) {
+    let mut doc = Document::from_project(project.clone(), ProjectLimits::default()).unwrap();
+    let original = doc.bundle().clone();
+    doc.execute(command).unwrap();
+    assert_eq!(doc.project(), expected);
+    let after = doc.bundle().clone();
+    let reopened = Document::from_bundle(after.clone(), ProjectLimits::default()).unwrap();
+    assert_eq!(reopened.project(), expected);
+    assert!(doc.undo());
+    assert_eq!(doc.project(), project);
+    assert_eq!(doc.bundle(), &original);
+    assert!(!doc.can_undo());
+    assert!(doc.redo());
+    assert_eq!(doc.project(), expected);
+    assert_eq!(doc.bundle(), &after);
+    assert!(!doc.can_redo());
+}
+
+#[test]
+fn process_group_removal_mixed_cards_preserve_sources_definitions_and_other_uses() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (f, _) = super::super::direct_tests::empty_exchange_fixture(layer);
+        let mut p = f.p;
+        let definition = sequence(&mut p, layer, "Reusable");
+        let leaf = action(&mut p, definition, "Leaf", f.work[0]);
+        let a = action(&mut p, f.owner, "Action", f.work[0]);
+        let e = exchange_step(&mut p, f.owner, "Exchange", f.exchange);
+        let c = add(
+            &mut p,
+            f.owner,
+            "Control",
+            OccurrenceBody::Control {
+                kind: ControlKind::Choice,
+            },
+        );
+        let r = reuse(&mut p, f.owner, "First use", definition);
+        let r2 = reuse(&mut p, f.owner, "Preserved use", definition);
+        let plan = prepare(&p, f.owner, &[local(r), local(c), local(e), local(a)]).unwrap();
+        assert_eq!(plan.removed, BTreeSet::from([a, e, c, r]));
+        assert_eq!(plan.changed, BTreeSet::from([f.owner]));
+        assert!(plan.interpretation.is_empty());
+        let expected = expected_without(&p, f.owner, &[a, e, c, r], &[]);
+        assert_eq!(expected.elements[&f.owner].steps().unwrap(), &[r2]);
+        assert!(expected.contains(leaf));
+        assert_history(&p, &expected, plan.command);
+    }
+}
+
+#[test]
+fn process_group_removal_dependent_selected_links_are_normalized_after_whole_set_admission() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = super::super::direct_tests::fixture(layer);
+        let mut p = f.p;
+        let [a, b, c] = f.nodes;
+        let parallel = maintained(&mut p, a, b);
+        let adjacent = maintained(&mut p, b, c);
+        let context = contextual(
+            &mut p,
+            f.owner,
+            endpoint(a),
+            endpoint(b),
+            ContextualLinkPurpose::Exchange {
+                exchange: f.exchange,
+            },
+        );
+        let targets = vec![
+            Target::ProcessLink(f.link),
+            local(a),
+            Target::ProcessLink(parallel),
+            local(b),
+            Target::ProcessLink(context),
+        ];
+        let first = prepare(&p, f.owner, &targets).unwrap();
+        let mut reverse = targets.clone();
+        reverse.reverse();
+        let second = prepare(&p, f.owner, &reverse).unwrap();
+        assert_eq!(first.command, second.command);
+        assert_eq!(
+            first.removed,
+            BTreeSet::from([a, b, f.link, parallel, adjacent, context])
+        );
+        assert_eq!(first.changed, BTreeSet::from([f.owner]));
+        assert_eq!(
+            first.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(None, None, true),
+                after: interpretation(None, None, false),
+                callers: BTreeSet::new(),
+            }]
+        );
+        let Command::Batch(commands) = &first.command else {
+            panic!()
+        };
+        assert_eq!(
+            commands.len(),
+            2,
+            "All selected links are covered by admitted card roots"
+        );
+        let expected =
+            expected_without(&p, f.owner, &[a, b], &[f.link, parallel, adjacent, context]);
+        assert_history(&p, &expected, first.command);
+    }
+}
+
+#[test]
+fn process_group_removal_refuses_every_invalid_original_typed_member() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = super::super::direct_tests::fixture(layer);
+        let mut p = f.p;
+        let other = sequence(&mut p, layer, "Other");
+        let foreign = action(&mut p, other, "Foreign", f.work[0]);
+        let foreign_other = action(&mut p, other, "Other foreign", f.work[0]);
+        let unlisted = action(&mut p, f.owner, "Owned but unlisted", f.work[0]);
+        p.elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .retain(|id| *id != unlisted);
+        let unlisted_link = maintained(&mut p, unlisted, f.nodes[0]);
+        let foreign_context = contextual(
+            &mut p,
+            other,
+            endpoint(foreign),
+            endpoint(foreign_other),
+            ContextualLinkPurpose::CommonWork { work: f.work[0] },
+        );
+        // Use two separate qualified paths with the same leaf: neither can be
+        // silently reduced to that leaf or to an outer reference occurrence.
+        let r1 = reuse(&mut p, f.owner, "Use one", other);
+        let r2 = reuse(&mut p, f.owner, "Use two", other);
+        let missing = Id::new_v4();
+        let bad = vec![
+            Target::Whole,
+            Target::Placement(f.nodes[0]),
+            Target::Port {
+                port: f.work[0],
+                placement: f.nodes[0],
+            },
+            Target::Edge(f.link),
+            Target::StateRow {
+                placement: f.nodes[0],
+                relation: f.link,
+            },
+            Target::AllocationGrouping {
+                relation: f.link,
+                work_placement: f.nodes[0],
+                performer_placement: f.nodes[1],
+            },
+            Target::ScenarioObject(f.nodes[0]),
+            Target::ProcessPreviewLink {
+                relation: f.link,
+                source: endpoint(f.nodes[0]),
+                target: endpoint(f.nodes[1]),
+            },
+            Target::ProcessOccurrence(qualified(&[r1], foreign)),
+            Target::ProcessOccurrence(qualified(&[r2], foreign)),
+            local(foreign),
+            local(unlisted),
+            local(missing),
+            local(f.work[0]),
+            Target::ProcessLink(unlisted_link),
+            Target::ProcessLink(foreign_context),
+            Target::ProcessLink(f.exchange),
+            Target::ProcessLink(missing),
+            Target::ProcessLink(f.nodes[0]),
+        ];
+        oa_core::session::validate_candidate(&p).unwrap();
+        let source = oa_core::language::format(&p);
+        for target in bad {
+            assert!(
+                prepare(&p, f.owner, &[local(f.nodes[0]), target.clone()]).is_err(),
+                "{target:?}"
+            );
+            assert!(prepare(&p, f.owner, &[target, local(f.nodes[0])]).is_err());
+        }
+        assert!(prepare(&p, f.owner, &[]).is_err());
+        assert!(prepare(&p, f.owner, &[local(f.nodes[0]), local(f.nodes[0])]).is_err());
+        assert!(
+            prepare(
+                &p,
+                f.owner,
+                &[Target::ProcessLink(f.link), Target::ProcessLink(f.link)]
+            )
+            .is_err()
+        );
+        assert!(prepare(&p, f.work[0], &[local(f.nodes[0])]).is_err());
+        assert!(prepare(&p, missing, &[local(f.nodes[0])]).is_err());
+        assert_eq!(oa_core::language::format(&p), source);
+        let mut duplicate_steps = p.clone();
+        duplicate_steps
+            .elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .push(f.nodes[0]);
+        assert!(prepare(&duplicate_steps, f.owner, &[local(f.nodes[1])]).is_err());
+        let mut wrong_parent = p.clone();
+        wrong_parent.elements.get_mut(&f.nodes[0]).unwrap().parent = Some(other);
+        assert!(prepare(&wrong_parent, f.owner, &[local(f.nodes[1])]).is_err());
+        let mut missing_step = p.clone();
+        missing_step
+            .elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .push(missing);
+        assert!(prepare(&missing_step, f.owner, &[local(f.nodes[1])]).is_err());
+    }
+}
+
+#[test]
+fn process_group_removal_last_markers_and_legacy_interior_report_literal_orders() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (f, _) = super::super::direct_tests::empty_exchange_fixture(layer);
+        let mut p = f.p;
+        let a = action(&mut p, f.owner, "Marker", f.work[0]);
+        let e1 = exchange_step(&mut p, f.owner, "First", f.exchange);
+        let c = add(
+            &mut p,
+            f.owner,
+            "Control",
+            OccurrenceBody::Control {
+                kind: ControlKind::Choice,
+            },
+        );
+        let e2 = exchange_step(&mut p, f.owner, "Middle", f.exchange);
+        let e3 = exchange_step(&mut p, f.owner, "Last", f.exchange);
+        let caller = sequence(&mut p, layer, "Caller");
+        reuse(&mut p, caller, "Reference", f.owner);
+        let outer = sequence(&mut p, layer, "Outer");
+        reuse(&mut p, outer, "Transitive reference", caller);
+        let plan = prepare(&p, f.owner, &[local(c), local(a)]).unwrap();
+        assert_eq!(
+            plan.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(None, None, false),
+                after: interpretation(Some(vec![e1, e2, e3]), Some(vec![e1, e2, e3]), false),
+                callers: BTreeSet::from([caller, outer]),
+            }]
+        );
+        let expected = expected_without(&p, f.owner, &[a, c], &[]);
+        assert_history(&p, &expected, plan.command);
+        let bridge = prepare(&expected, f.owner, &[local(e2)]).unwrap();
+        assert_eq!(
+            bridge.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(Some(vec![e1, e2, e3]), Some(vec![e1, e2, e3]), false),
+                after: interpretation(Some(vec![e1, e3]), Some(vec![e1, e3]), false),
+                callers: BTreeSet::from([caller, outer]),
+            }]
+        );
+        assert_eq!(bridge.removed, BTreeSet::from([e2]));
+        assert_history(
+            &expected,
+            &expected_without(&expected, f.owner, &[e2], &[]),
+            bridge.command,
+        );
+    }
+}
+
+#[test]
+fn process_group_removal_last_link_and_zero_or_one_exchange_have_no_invented_objects() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (f, next) = super::super::direct_tests::empty_exchange_fixture(layer);
+        let mut p = f.p;
+        let e1 = exchange_step(&mut p, f.owner, "First", f.exchange);
+        let e2 = exchange_step(&mut p, f.owner, "Second", next);
+        let link = maintained(&mut p, e1, e2);
+        let plan = prepare(&p, f.owner, &[Target::ProcessLink(link)]).unwrap();
+        assert_eq!(plan.removed, BTreeSet::from([link]));
+        assert!(plan.changed.is_empty());
+        assert_eq!(
+            plan.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(None, None, false),
+                after: interpretation(Some(vec![e1, e2]), Some(vec![e1, e2]), false),
+                callers: BTreeSet::new(),
+            }]
+        );
+        assert_history(
+            &p,
+            &expected_without(&p, f.owner, &[], &[link]),
+            plan.command,
+        );
+        for remaining in [vec![], vec![e1]] {
+            let mut model = expected_without(&p, f.owner, &[e2], &[link]);
+            if remaining.is_empty() {
+                model = expected_without(&model, f.owner, &[e1], &[]);
+            }
+            let marker = action(&mut model, f.owner, "Marker", f.work[0]);
+            let plan = prepare(&model, f.owner, &[local(marker)]).unwrap();
+            assert_eq!(
+                plan.interpretation,
+                vec![InterpretationChange {
+                    owner: f.owner,
+                    before: interpretation(None, None, false),
+                    after: interpretation(Some(remaining.clone()), Some(remaining), false),
+                    callers: BTreeSet::new(),
+                }]
+            );
+            assert_history(
+                &model,
+                &expected_without(&model, f.owner, &[marker], &[]),
+                plan.command,
+            );
+        }
+    }
+}
+
+#[test]
+fn process_group_removal_global_contextual_dependencies_and_caller_modes_are_separate_from_record_deltas()
+ {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = super::super::direct_tests::fixture(layer);
+        let mut p = f.p;
+        let caller = sequence(&mut p, layer, "Caller");
+        let r1 = reuse(&mut p, caller, "Use one", f.owner);
+        let r2 = reuse(&mut p, caller, "Use two", f.owner);
+        let outer = sequence(&mut p, layer, "Outer");
+        let outer_use = reuse(&mut p, outer, "Outer use", caller);
+        let caller_link = contextual(
+            &mut p,
+            caller,
+            qualified(&[r1], f.nodes[0]),
+            qualified(&[r2], f.nodes[1]),
+            precedence(),
+        );
+        let outer_link = contextual(
+            &mut p,
+            outer,
+            qualified(&[outer_use, r1], f.nodes[0]),
+            qualified(&[outer_use, r2], f.nodes[1]),
+            precedence(),
+        );
+        let top = sequence(&mut p, layer, "Top");
+        reuse(&mut p, top, "Top use", outer);
+        let plan = prepare(&p, f.owner, &[local(f.nodes[0])]).unwrap();
+        assert_eq!(
+            plan.removed,
+            BTreeSet::from([f.nodes[0], f.link, caller_link, outer_link])
+        );
+        assert_eq!(plan.changed, BTreeSet::from([f.owner]));
+        let by_owner: BTreeMap<_, _> = plan
+            .interpretation
+            .iter()
+            .map(|change| (change.owner, change))
+            .collect();
+        assert_eq!(
+            by_owner.keys().copied().collect::<BTreeSet<_>>(),
+            BTreeSet::from([caller, outer, top])
+        );
+        for id in [caller, outer, top] {
+            assert_eq!(by_owner[&id].before, interpretation(None, None, true));
+            assert_eq!(by_owner[&id].after, interpretation(None, None, false));
+        }
+        assert_eq!(by_owner[&caller].callers, BTreeSet::from([outer, top]));
+        assert_eq!(by_owner[&outer].callers, BTreeSet::from([top]));
+        assert!(by_owner[&top].callers.is_empty());
+        assert_eq!(
+            plan.affected_uses,
+            BTreeMap::from([
+                (f.owner, BTreeSet::from([caller, outer, top])),
+                (caller, BTreeSet::from([outer, top])),
+                (outer, BTreeSet::from([top])),
+            ])
+        );
+        let expected = expected_without(
+            &p,
+            f.owner,
+            &[f.nodes[0]],
+            &[f.link, caller_link, outer_link],
+        );
+        assert_history(&p, &expected, plan.command);
+        // Removing an outer reuse removes only that use and paths through it.
+        let outer_plan =
+            prepare(&p, caller, &[local(r1), Target::ProcessLink(caller_link)]).unwrap();
+        assert_eq!(
+            outer_plan.removed,
+            BTreeSet::from([r1, caller_link, outer_link])
+        );
+        let expected = expected_without(&p, caller, &[r1], &[caller_link, outer_link]);
+        assert_history(&p, &expected, outer_plan.command);
+    }
+}
+
+#[test]
+fn process_group_removal_qualified_local_relations_preserve_every_purpose_source() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        for purpose_kind in 0..3 {
+            let f = super::super::direct_tests::fixture(layer);
+            let mut p = f.p;
+            let owner = sequence(&mut p, layer, "Assembly");
+            let r1 = reuse(&mut p, owner, "First", f.owner);
+            let r2 = reuse(&mut p, owner, "Second", f.owner);
+            let (target, purpose) = match purpose_kind {
+                0 => (f.nodes[1], precedence()),
+                1 => (
+                    f.nodes[1],
+                    ContextualLinkPurpose::Exchange {
+                        exchange: f.exchange,
+                    },
+                ),
+                _ => (
+                    f.nodes[0],
+                    ContextualLinkPurpose::CommonWork { work: f.work[0] },
+                ),
+            };
+            let relation = contextual(
+                &mut p,
+                owner,
+                qualified(&[r1], f.nodes[0]),
+                qualified(&[r2], target),
+                purpose,
+            );
+            let plan = prepare(&p, owner, &[Target::ProcessLink(relation)]).unwrap();
+            assert_eq!(plan.removed, BTreeSet::from([relation]));
+            assert!(plan.changed.is_empty());
+            assert_eq!(
+                plan.interpretation,
+                vec![InterpretationChange {
+                    owner,
+                    before: interpretation(None, None, true),
+                    after: interpretation(None, None, false),
+                    callers: BTreeSet::new(),
+                }]
+            );
+            assert_history(
+                &p,
+                &expected_without(&p, owner, &[], &[relation]),
+                plan.command,
+            );
+        }
+    }
+}
+
+#[test]
+fn process_group_removal_predicate_discriminators_include_contextual_only_and_unlisted_contributions()
+ {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (f, _) = super::super::direct_tests::empty_exchange_fixture(layer);
+        let mut p = f.p;
+        let e1 = exchange_step(&mut p, f.owner, "First", f.exchange);
+        let e2 = exchange_step(&mut p, f.owner, "Second", f.exchange);
+        // Core-valid incomplete source: desktop lists only exchanges, while the
+        // index includes two unlisted actions and their CommonWork relation.
+        let a1 = action(&mut p, f.owner, "Unlisted one", f.work[0]);
+        let a2 = action(&mut p, f.owner, "Unlisted two", f.work[0]);
+        p.elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .retain(|id| *id != a1 && *id != a2);
+        let relation = contextual(
+            &mut p,
+            f.owner,
+            endpoint(a1),
+            endpoint(a2),
+            ContextualLinkPurpose::CommonWork { work: f.work[0] },
+        );
+        let plan = prepare(&p, f.owner, &[Target::ProcessLink(relation)]).unwrap();
+        assert_eq!(
+            plan.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(Some(vec![e1, e2]), None, true),
+                after: interpretation(Some(vec![e1, e2]), None, false),
+                callers: BTreeSet::new(),
+            }]
+        );
+        let mut p = expected_without(&p, f.owner, &[a1, a2], &[relation]);
+        let unlisted = action(&mut p, f.owner, "Unlisted marker", f.work[0]);
+        p.elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .retain(|id| *id != unlisted);
+        let plan = prepare(&p, f.owner, &[local(e1)]).unwrap();
+        assert_eq!(
+            plan.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(Some(vec![e1, e2]), None, false),
+                after: interpretation(Some(vec![e2]), None, false),
+                callers: BTreeSet::new(),
+            }]
+        );
+        assert!(prepare(&p, f.owner, &[local(unlisted), local(e1)]).is_err());
+        let p = expected_without(&p, f.owner, &[unlisted], &[]);
+        let mut p = p;
+        let extra = exchange_step(&mut p, f.owner, "Unlisted exchange", f.exchange);
+        p.elements
+            .get_mut(&f.owner)
+            .unwrap()
+            .steps_mut()
+            .unwrap()
+            .retain(|id| *id != extra);
+        let plan = prepare(&p, f.owner, &[local(e1)]).unwrap();
+        assert_eq!(
+            plan.interpretation,
+            vec![InterpretationChange {
+                owner: f.owner,
+                before: interpretation(Some(vec![e1, e2]), Some(vec![e1, e2, extra]), false),
+                after: interpretation(Some(vec![e2]), Some(vec![e2, extra]), false),
+                callers: BTreeSet::new(),
+            }]
+        );
+        assert_history(&p, &expected_without(&p, f.owner, &[e1], &[]), plan.command);
+    }
+}
+
+#[test]
+fn process_group_removal_explicit_topology_still_reports_transitive_reused_effects() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = super::super::direct_tests::fixture(layer);
+        let mut p = f.p;
+        maintained(&mut p, f.nodes[1], f.nodes[2]);
+        let caller = sequence(&mut p, layer, "Caller");
+        reuse(&mut p, caller, "First use", f.owner);
+        reuse(&mut p, caller, "Repeated use", f.owner);
+        let outer = sequence(&mut p, layer, "Outer");
+        reuse(&mut p, outer, "Transitive use", caller);
+        for target in [local(f.nodes[0]), Target::ProcessLink(f.link)] {
+            let plan = prepare(&p, f.owner, &[target]).unwrap();
+            assert!(
+                plan.interpretation.is_empty(),
+                "Explicit modes remain unchanged"
+            );
+            assert_eq!(
+                plan.affected_uses,
+                BTreeMap::from([(f.owner, BTreeSet::from([caller, outer]))])
+            );
+            assert!(!plan.changed.contains(&caller));
+            assert!(!plan.changed.contains(&outer));
+        }
+    }
+}
+
+#[test]
+fn process_group_removal_mixed_covered_and_independent_selected_links_delete_each_once() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = super::super::direct_tests::fixture(layer);
+        let mut p = f.p;
+        let [a, b, c] = f.nodes;
+        let independent = maintained(&mut p, b, c);
+        let targets = [
+            Target::ProcessLink(independent),
+            Target::ProcessLink(f.link),
+            local(a),
+        ];
+        let plan = prepare(&p, f.owner, &targets).unwrap();
+        let reverse = prepare(&p, f.owner, &targets.into_iter().rev().collect::<Vec<_>>()).unwrap();
+        assert_eq!(plan.command, reverse.command);
+        assert_eq!(plan.removed, BTreeSet::from([a, f.link, independent]));
+        assert_eq!(plan.changed, BTreeSet::from([f.owner]));
+        let Command::Batch(commands) = &plan.command else {
+            panic!()
+        };
+        assert_eq!(
+            commands,
+            &[Command::Delete(a), Command::Delete(independent)]
+        );
+        assert!(plan.interpretation.is_empty());
+        let expected = expected_without(&p, f.owner, &[a], &[f.link, independent]);
+        assert_eq!(expected.elements[&f.owner].steps().unwrap(), &[b, c]);
+        assert_history(&p, &expected, plan.command);
+    }
+}
+
+#[test]
+fn process_group_removal_exact_attachments_traces_placements_and_diagram_impact() {
+    use oa_core::{ArtifactLink, ArtifactRelation, EdgeRoute, Position, Trace, TraceKind};
+
+    for layer in [Layer::Oa, Layer::Sa] {
+        let f = super::super::direct_tests::fixture(layer);
+        let mut p = f.p;
+        let [a, b, _] = f.nodes;
+        let overview = p.ensure_diagram(layer);
+        // Overview explicitly includes Occurrence in ProjectionKind::includes;
+        // saved placement validation admits these same-layer semantic elements.
+        assert!(p.diagrams[&overview].projection.includes(Kind::Occurrence));
+        let node = p.place(overview, a, Position { x: 100., y: 100. });
+        let kept_node = p.place(overview, b, Position { x: 400., y: 100. });
+        p.diagrams
+            .get_mut(&overview)
+            .unwrap()
+            .routes
+            .push(EdgeRoute {
+                edge: f.link,
+                source_attachment: None,
+                target_attachment: None,
+                waypoints: vec![Position { x: 300., y: 80. }],
+                label: None,
+            });
+        let other_view = Id::new_v4();
+        let mut view = p.diagrams[&overview].clone();
+        view.id = other_view;
+        view.alias = p.fresh_alias("second_overview", "view", other_view);
+        view.name = "Second overview".into();
+        view.nodes.clear();
+        view.routes.clear();
+        p.diagrams.insert(other_view, view);
+        let other_node = p.place(other_view, a, Position { x: 220., y: 160. });
+        let opposite = if layer == Layer::Oa {
+            Layer::Sa
+        } else {
+            Layer::Oa
+        };
+        let counterpart = p
+            .add_element(
+                if opposite == Layer::Oa {
+                    Kind::Activity
+                } else {
+                    Kind::Function
+                },
+                opposite,
+                "Preserved counterpart",
+                None,
+            )
+            .unwrap();
+        let unrelated_view = p.ensure_diagram(opposite);
+        p.place(unrelated_view, counterpart, Position { x: 50., y: 75. });
+        let traces: [Id; 2] = [a, b].map(|subject| {
+            let id = Id::new_v4();
+            p.traces.insert(
+                id,
+                Trace {
+                    id,
+                    alias: p.fresh_alias("manual_trace", "trace", id),
+                    name: "Manual correspondence".into(),
+                    description: "Preserve counterpart".into(),
+                    oa: if layer == Layer::Oa {
+                        subject
+                    } else {
+                        counterpart
+                    },
+                    sa: if layer == Layer::Sa {
+                        subject
+                    } else {
+                        counterpart
+                    },
+                    kind: TraceKind::Manual,
+                    baseline: None,
+                },
+            );
+            id
+        });
+        // Include an attachment owned by the dependent placement: core impact
+        // must follow the fixed point rather than only direct semantic subjects.
+        let artifacts: [Id; 4] = [a, node, f.link, b].map(|owner| {
+            let id = Id::new_v4();
+            p.artifact_links.insert(
+                id,
+                ArtifactLink {
+                    id,
+                    alias: p.fresh_alias("evidence", "artifact", id),
+                    name: "Evidence".into(),
+                    description: "Authored evidence".into(),
+                    owner,
+                    relation: ArtifactRelation::References,
+                    uri: "evidence.txt".into(),
+                    revision: Some("v1".into()),
+                    fragment: Some("review".into()),
+                },
+            );
+            id
+        });
+        let constraint = p
+            .add_element(Kind::Constraint, layer, "Surviving constraint", None)
+            .unwrap();
+        *p.elements
+            .get_mut(&constraint)
+            .unwrap()
+            .shared_mut()
+            .unwrap() = SharedBody::Constraint {
+            expression: "review".into(),
+            constrained: vec![a, b],
+        };
+        oa_core::session::validate_candidate(&p).unwrap();
+        let plan = prepare(&p, f.owner, &[local(a)]).unwrap();
+        assert_eq!(
+            plan.removed,
+            BTreeSet::from([
+                a,
+                f.link,
+                node,
+                other_node,
+                traces[0],
+                artifacts[0],
+                artifacts[1],
+                artifacts[2],
+            ])
+        );
+        assert_eq!(
+            plan.changed,
+            BTreeSet::from([f.owner, overview, other_view, constraint])
+        );
+        assert_eq!(
+            plan.affected_uses,
+            BTreeMap::from([(f.owner, BTreeSet::new())])
+        );
+        let mut expected = expected_without(&p, f.owner, &[a], &[f.link]);
+        expected.traces.remove(&traces[0]);
+        for id in &artifacts[..3] {
+            expected.artifact_links.remove(id);
+        }
+        expected
+            .diagrams
+            .get_mut(&overview)
+            .unwrap()
+            .nodes
+            .remove(&node);
+        expected.diagrams.get_mut(&overview).unwrap().routes.clear();
+        expected
+            .diagrams
+            .get_mut(&other_view)
+            .unwrap()
+            .nodes
+            .remove(&other_node);
+        let Some(SharedBody::Constraint { constrained, .. }) =
+            expected.elements.get_mut(&constraint).unwrap().shared_mut()
+        else {
+            panic!()
+        };
+        *constrained = vec![b];
+        assert_eq!(expected.elements[&counterpart], p.elements[&counterpart]);
+        assert_eq!(
+            expected.diagrams[&overview].nodes[&kept_node],
+            p.diagrams[&overview].nodes[&kept_node]
+        );
+        assert_eq!(
+            expected.diagrams[&unrelated_view],
+            p.diagrams[&unrelated_view]
+        );
+        assert_eq!(expected.traces[&traces[1]], p.traces[&traces[1]]);
+        assert_eq!(
+            expected.artifact_links[&artifacts[3]],
+            p.artifact_links[&artifacts[3]]
+        );
+        assert_history(&p, &expected, plan.command);
+    }
+}

crates/oa-desktop/src/behavior/topology/view.rs

@@ -185,6 +185,7 @@ pub(super) fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Ele
         &state.contextual_expanded,
     );
     graph.selection = app.multiselect_snapshot();
+    graph.removal_input = state.removal_input.clone();
     graph.selected_preview = state
         .qualified_selection(p, owner)
         .filter(|address| {
@@ -574,6 +575,15 @@ fn selection_controls(app: &App) -> Element<'_, Message> {
         .align_y(iced::Center)
         .height(32);
     if let Some(snapshot) = snapshot.filter(|s| !s.targets().is_empty()) {
+        if snapshot.targets().len() > 1 {
+            controls = controls.push(
+                button("Remove selected…").on_press_maybe(
+                    app.process_removal_enabled()
+                        .then(|| crate::app::process_removal::begin(app))
+                        .flatten(),
+                ),
+            );
+        }
         controls = controls.push(button("Clear selection").on_press_maybe(
             enabled.then(|| Message::DiagramSelection(SelectionEvent::Clear(snapshot.context()))),
         ));

crates/oa-desktop/src/diagram.rs

@@ -43,6 +43,7 @@ pub use port_labels::PortLabels;
 #[path = "diagram/focus.rs"]
 pub(crate) mod focus;
 pub(crate) mod group_gesture;
+pub(crate) mod group_removal;
 mod multiselect;
 #[cfg(test)]
 mod multiselect_tests;
@@ -52,6 +53,7 @@ pub use work_drag::WorkFeedback;
 
 #[derive(Clone, Copy)]
 pub struct DiagramCanvas<'a> {
+    pub removal_input: &'a crate::removal_input::Lifetime,
     pub selection: Option<&'a crate::diagram_selection::Selection>,
     pub allocation: Option<crate::app::allocation_drag::Capability<'a>>,
     pub project: &'a Project,
@@ -71,6 +73,8 @@ pub struct DiagramCanvas<'a> {
 }
 #[derive(Default)]
 pub struct State {
+    removal_lease: Option<crate::removal_input::Lease>,
+    removal_viewport: Option<(f32, Vector, Rectangle)>,
     modifiers: iced::keyboard::Modifiers,
     group: Option<multiselect::Press>,
     work: Option<Arc<crate::app::allocation_drag::Press>>,
@@ -606,9 +610,8 @@ impl DiagramCanvas<'_> {
         });
     }
 }
-impl canvas::Program<Message> for DiagramCanvas<'_> {
-    type State = State;
-    fn update(
+impl DiagramCanvas<'_> {
+    fn update_input(
         &self,
         state: &mut State,
         event: &canvas::Event,
@@ -1243,6 +1246,67 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
             _ => None,
         }
     }
+}
+impl canvas::Program<Message> for DiagramCanvas<'_> {
+    type State = State;
+    fn update(
+        &self,
+        state: &mut State,
+        event: &canvas::Event,
+        bounds: Rectangle,
+        cursor: mouse::Cursor,
+    ) -> Option<Action<Message>> {
+        self.removal_input.sync(
+            &mut state.removal_lease,
+            state.group.is_some()
+                || state.work.is_some()
+                || state.drag.is_some()
+                || state.pan_start.is_some()
+                || state.route_drag.is_some()
+                || state.connection_press.is_some()
+                || state.port_drag.is_some(),
+        );
+        self.removal_input.observe(event);
+        let viewport = (self.zoom, self.pan, bounds);
+        if state
+            .removal_viewport
+            .is_some_and(|previous| previous != viewport)
+        {
+            self.removal_input.revoke_idle();
+        }
+        state.removal_viewport = Some(viewport);
+        let action = self.update_input(state, event, bounds, cursor);
+        if matches!(
+            event,
+            canvas::Event::Window(iced::window::Event::Unfocused | iced::window::Event::Resized(_))
+                | canvas::Event::Mouse(mouse::Event::CursorLeft)
+        ) {
+            // The viewport can synthesize Unfocused when it takes camera input.
+            // Never leave a private drag or its lease waiting for a lost release.
+            state.group = None;
+            state.work = None;
+            state.drag = None;
+            state.preview = None;
+            state.pan_start = None;
+            state.route_drag = None;
+            state.attachment_viewport = None;
+            state.connection_press = None;
+            state.connection_hover = None;
+            state.port_drag = None;
+            state.pointer = None;
+        }
+        self.removal_input.sync(
+            &mut state.removal_lease,
+            state.group.is_some()
+                || state.work.is_some()
+                || state.drag.is_some()
+                || state.pan_start.is_some()
+                || state.route_drag.is_some()
+                || state.connection_press.is_some()
+                || state.port_drag.is_some(),
+        );
+        action
+    }
     fn draw(
         &self,
         state: &State,
@@ -2328,6 +2392,7 @@ mod tests {
             y: original.y - 200.,
         };
         let canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,
@@ -2406,6 +2471,7 @@ mod tests {
             .unwrap()
             .id;
         let canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,
@@ -2535,6 +2601,7 @@ mod tests {
             };
             let session = Session::new(&p, &view, context, Tool::FunctionalExchange);
             let canvas = DiagramCanvas {
+                removal_input: &crate::removal_input::Lifetime::default(),
                 selection: None,
                 project: &p,
                 view_index: None,
@@ -2711,6 +2778,7 @@ mod tests {
         for zoom in [0.5, 1., 1.5] {
             let (p, diagram, edge) = route_fixture();
             let canvas = DiagramCanvas {
+                removal_input: &crate::removal_input::Lifetime::default(),
                 selection: None,
                 project: &p,
                 view_index: None,
@@ -2790,6 +2858,7 @@ mod tests {
     fn fast_drags_commit_the_release_cursor_without_a_final_motion_event() {
         let (p, diagram, edge) = route_fixture();
         let canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,
@@ -2890,6 +2959,7 @@ mod tests {
     fn route_cache_ignores_pan_zoom_and_cancelled_drag_cannot_commit() {
         let (p, diagram, edge) = route_fixture();
         let mut canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,
@@ -3021,6 +3091,7 @@ mod tests {
             assert!(!svg.contains("data-navigation=\"source\""));
             assert!(svg.contains("data-navigation=\"target\""));
             let mut canvas = DiagramCanvas {
+                removal_input: &crate::removal_input::Lifetime::default(),
                 selection: None,
                 project: &p,
                 view_index: None,
@@ -3078,6 +3149,7 @@ mod tests {
             offset: Position { x: 0., y: -160. },
         });
         let mut canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,
@@ -3155,6 +3227,7 @@ mod tests {
             },
         });
         let canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,
@@ -3191,6 +3264,7 @@ mod tests {
         routed.edges.insert(duplicate, duplicate_route);
         let selected = edge.max(duplicate); // UUID ordering must not override selection.
         let canvas = DiagramCanvas {
+            removal_input: &crate::removal_input::Lifetime::default(),
             selection: None,
             project: &p,
             view_index: None,

crates/oa-desktop/src/diagram/allocation_group_tests.rs

@@ -98,6 +98,7 @@ fn fixture(control: Control, cover: Option<Kind>) -> Fixture {
 }
 fn canvas(app: &App) -> DiagramCanvas<'_> {
     DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: app.diagram_selection.as_ref(),
         allocation: Some(app.allocation_capability()),
         project: app.project(),

crates/oa-desktop/src/diagram/attachment_tests.rs

@@ -34,6 +34,7 @@ fn fixture() -> App {
 
 fn canvas(app: &App, zoom: f32) -> DiagramCanvas<'_> {
     DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: None,
         allocation: None,
         project: app.project(),

crates/oa-desktop/src/diagram/focus.rs

@@ -206,6 +206,16 @@ impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Owner<'_, Mes
             // The focus task runs after the native batch. Retain focus for its
             // traversal count, but reject later keys in this same batch now.
             state.traversing = true;
+            self.content.as_widget_mut().update(
+                &mut tree.children[0],
+                &InputEvent::Window(iced::window::Event::Unfocused),
+                layout,
+                cursor,
+                renderer,
+                clipboard,
+                shell,
+                viewport,
+            );
             shell.publish((self.traverse)(modifiers.shift()));
             shell.capture_event();
             return;

crates/oa-desktop/src/diagram/group_removal.rs

@@ -0,0 +1,161 @@
+//! Pure, whole-selection Delete from model planning for saved architecture and
+//! State views. UI lifetime, drafts and confirmation remain the caller's concern.
+use crate::diagram_usage::Target;
+use oa_core::{
+    Command, Id, Kind, Project, execute_batch, projection, references, validate_candidate,
+};
+use std::collections::{BTreeMap, BTreeSet};
+
+#[derive(Debug)]
+pub(crate) struct Plan {
+    pub(crate) command: Command,
+    /// Semantic identities resolved from every admitted exact target.
+    pub(crate) selected: BTreeSet<Id>,
+    /// Actual identity and surviving-record differences after the complete batch.
+    pub(crate) removed: BTreeSet<Id>,
+    pub(crate) changed: BTreeSet<Id>,
+    pub(crate) interpretation: Vec<crate::removal_effects::InterpretationChange>,
+    /// Changed or deleted definitions and surviving transitive callers.
+    pub(crate) affected_uses: BTreeMap<Id, BTreeSet<Id>>,
+}
+
+pub(crate) fn prepare(project: &Project, diagram: Id, targets: &[Target]) -> Result<Plan, String> {
+    let saved = project
+        .diagrams
+        .get(&diagram)
+        .ok_or("The saved view no longer exists.")?;
+    if !saved.projection.is_architecture() && saved.projection.state_machine().is_none() {
+        return Err("Delete from model supports saved Architecture and State views here.".into());
+    }
+    if targets.is_empty() {
+        return Err("Select at least one visible model object to delete.".into());
+    }
+    validate_candidate(project).map_err(|error| error.to_string())?;
+    let view = projection::project_diagram(project, saved);
+    let mut selected = BTreeSet::new();
+    // Resolve every original typed identity BEFORE removing any cascade overlap.
+    // A stale/hidden/wrong-kind target cannot become admissible because another
+    // selection member would happen to delete its semantic identity.
+    for (index, target) in targets.iter().enumerate() {
+        if targets[..index].contains(target) {
+            return Err("Every selected exact target must be unique.".into());
+        }
+        let id = match target {
+            Target::Placement(id) => saved.nodes.get(id)
+                .filter(|node| view.nodes.iter().any(|visible| visible.id == *id && visible.element == node.element))
+                .map(|node| node.element)
+                .ok_or("A selected placement is no longer visible in this saved view.")?,
+            Target::Port { port, placement } => {
+                let owner = saved.nodes.get(placement)
+                    .ok_or("A selected port's exact owner placement no longer exists in this view.")?;
+                if !view.ports.iter().any(|visible| visible.element == *port && visible.owner == *placement)
+                    || !project.elements.get(port).is_some_and(|element| element.kind() == Kind::Port && element.parent == Some(owner.element))
+                {
+                    return Err("A selected port is no longer visible on its exact owner placement.".into());
+                }
+                *port
+            }
+            Target::Edge(id) => {
+                if !view.edges.iter().any(|edge| edge.id == *id)
+                    || !(project.relations.contains_key(id) || project.traces.contains_key(id))
+                {
+                    return Err("Every selected edge must be a visible stored relation or trace; inferred edges are read-only.".into());
+                }
+                *id
+            }
+            Target::StateRow { placement, relation } => {
+                if !crate::behavior::state_canvas::visible_row_target(project, diagram, &view, *placement, *relation) {
+                    return Err("A selected State row is no longer visible on its exact placement.".into());
+                }
+                *relation
+            }
+            _ => return Err("The complete selection must contain only visible placements, ports, stored edges or State rows; grouping and read-only targets cannot be deleted here.".into()),
+        };
+        selected.insert(id);
+    }
+
+    // Prefer cascades covering the most remaining selected subjects. Selecting a
+    // parent together with its child/port/incident relation must not issue Delete
+    // for an identity already removed by that parent. Stable ID order breaks ties.
+    // Core defers conditional exchange-allocation cleanup until batch completion;
+    // admission and the final result are therefore never singleton-validated.
+    let impacts: BTreeMap<_, _> = selected
+        .iter()
+        .map(|&id| (id, references::deletion_impact(project, id)))
+        .collect();
+    let mut pending = selected.clone();
+    let mut commands = Vec::new();
+    while !pending.is_empty() {
+        let id = *pending
+            .iter()
+            .max_by_key(|&&id| {
+                (
+                    impacts[&id].intersection(&pending).count(),
+                    std::cmp::Reverse(id),
+                )
+            })
+            .unwrap();
+        commands.push(Command::Delete(id));
+        pending.retain(|remaining| !impacts[&id].contains(remaining));
+    }
+    let command = Command::Batch(commands);
+    let candidate = execute_batch(project, std::slice::from_ref(&command))
+        .map_err(|error| error.to_string())?;
+    let original: BTreeSet<_> = project.identities().into_iter().map(|(id, _)| id).collect();
+    let retained: BTreeSet<_> = candidate
+        .identities()
+        .into_iter()
+        .map(|(id, _)| id)
+        .collect();
+    if !retained.is_subset(&original) {
+        return Err("Removal unexpectedly created model identities; no change was applied.".into());
+    }
+    let removed: BTreeSet<_> = original.difference(&retained).copied().collect();
+    if !selected.is_subset(&removed) {
+        return Err("The complete selected set could not be removed.".into());
+    }
+    let mut changed = BTreeSet::new();
+    changed_records(&project.elements, &candidate.elements, &mut changed);
+    changed_records(&project.relations, &candidate.relations, &mut changed);
+    changed_records(&project.diagrams, &candidate.diagrams, &mut changed);
+    changed_records(&project.traces, &candidate.traces, &mut changed);
+    changed_records(
+        &project.artifact_links,
+        &candidate.artifact_links,
+        &mut changed,
+    );
+    for (&id, diagram) in &project.diagrams {
+        if let Some(after) = candidate.diagrams.get(&id) {
+            changed_records(&diagram.nodes, &after.nodes, &mut changed);
+        }
+    }
+    let crate::removal_effects::DerivedEffects {
+        interpretation,
+        affected_uses,
+    } = crate::removal_effects::analyze(project, &candidate, &removed, &changed);
+    Ok(Plan {
+        command,
+        selected,
+        removed,
+        changed,
+        interpretation,
+        affected_uses,
+    })
+}
+
+fn changed_records<T: PartialEq>(
+    before: &BTreeMap<Id, T>,
+    after: &BTreeMap<Id, T>,
+    changed: &mut BTreeSet<Id>,
+) {
+    changed.extend(
+        before
+            .iter()
+            .filter_map(|(&id, record)| after.get(&id).filter(|next| *next != record).map(|_| id)),
+    );
+}
+
+#[cfg(test)]
+mod conditional_tests;
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/diagram/group_removal/conditional_tests.rs

@@ -0,0 +1,302 @@
+//! Independent conditional-cascade checks for overlapping selected endpoint allocations.
+use super::prepare;
+use crate::diagram_usage::Target;
+use oa_core::*;
+use std::collections::BTreeSet;
+
+struct Fixture {
+    project: Project,
+    diagram: Id,
+    selected_allocations: [Id; 2],
+    exchange_allocation: Id,
+    functional_exchange: Id,
+}
+
+fn relation(project: &mut Project, number: u128, alias: &str, body: RelationBody) -> Id {
+    let id = Id::from_u128(number);
+    assert!(
+        project
+            .relations
+            .insert(
+                id,
+                Relation {
+                    id,
+                    alias: alias.into(),
+                    name: alias.into(),
+                    description: String::new(),
+                    body,
+                }
+            )
+            .is_none()
+    );
+    id
+}
+
+fn fixture(reverse_ids: bool, invalid_dual_mapping: bool) -> Fixture {
+    let mut project = Project::empty();
+    let performer = project
+        .add_element(Kind::System, Layer::Sa, "Send performer", None)
+        .unwrap();
+    let receiver = if invalid_dual_mapping {
+        performer
+    } else {
+        project
+            .add_element(Kind::SystemActor, Layer::Sa, "Receive performer", None)
+            .unwrap()
+    };
+    let source = project
+        .add_element(Kind::Function, Layer::Sa, "Send", None)
+        .unwrap();
+    let target = project
+        .add_element(Kind::Function, Layer::Sa, "Receive", None)
+        .unwrap();
+    let retained = project.relate(RelationKind::Allocation, "Performs send", performer, source);
+    project.relate(
+        RelationKind::Allocation,
+        "Performs receive",
+        receiver,
+        target,
+    );
+    let functional_exchange = project.relate(
+        RelationKind::FunctionalExchange,
+        "Information",
+        source,
+        target,
+    );
+    let (output, input) = match project.relations[&functional_exchange].body {
+        RelationBody::FunctionalExchange {
+            source_port,
+            target_port,
+            ..
+        } => (source_port, target_port),
+        _ => unreachable!(),
+    };
+    let mut component_ports = vec![];
+    for (owner, name) in [
+        (performer, "First component port"),
+        (receiver, "Second component port"),
+    ] {
+        let id = Id::new_v4();
+        let port = make_port(
+            &project,
+            id,
+            owner,
+            name,
+            PortContract::Component {
+                kind: ComponentPortKind::Flow,
+                orientation: ComponentPortOrientation::InOut,
+            },
+        )
+        .unwrap();
+        project.elements.insert(id, port);
+        component_ports.push(id);
+    }
+    let [a, b] = [component_ports[0], component_ports[1]];
+    let boundary = relation(
+        &mut project,
+        300,
+        "boundary",
+        RelationBody::BoundaryExchange {
+            source: a,
+            target: b,
+            oriented: false,
+            items: vec![],
+        },
+    );
+    // Either endpoint allocation is required. Their overlapping conditional
+    // cascade must remove the exchange allocation once, after one whole batch.
+    let numbers = if reverse_ids { [200, 100] } else { [100, 200] };
+    let first = relation(
+        &mut project,
+        numbers[0],
+        "first_output",
+        RelationBody::PortAllocation {
+            source: a,
+            target: output,
+        },
+    );
+    let second = relation(
+        &mut project,
+        numbers[1],
+        "second_input",
+        RelationBody::PortAllocation {
+            source: b,
+            target: input,
+        },
+    );
+    if invalid_dual_mapping {
+        // Two simultaneous direct/reverse mappings would need the same actual
+        // performer at both ends, violating the different-boundary-owners rule.
+        relation(
+            &mut project,
+            400,
+            "first_input",
+            RelationBody::PortAllocation {
+                source: a,
+                target: input,
+            },
+        );
+        relation(
+            &mut project,
+            500,
+            "second_output",
+            RelationBody::PortAllocation {
+                source: b,
+                target: output,
+            },
+        );
+    }
+    let exchange_allocation = relation(
+        &mut project,
+        150,
+        "realizes_exchange",
+        RelationBody::ExchangeAllocation {
+            source: boundary,
+            target: functional_exchange,
+        },
+    );
+    let diagram = project.ensure_diagram(Layer::Sa);
+    project.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Overview;
+    for (element, x) in [
+        (performer, 40.),
+        (receiver, 1360.),
+        (source, 480.),
+        (target, 920.),
+    ] {
+        project.place(diagram, element, Position { x, y: 200. });
+    }
+    project.diagrams.get_mut(&diagram).unwrap().routes = [first, retained]
+        .into_iter()
+        .map(|edge| EdgeRoute {
+            edge,
+            source_attachment: None,
+            target_attachment: None,
+            waypoints: vec![Position { x: 360., y: 350. }],
+            label: None,
+        })
+        .collect();
+    Fixture {
+        project,
+        diagram,
+        selected_allocations: [first, second],
+        exchange_allocation,
+        functional_exchange,
+    }
+}
+
+#[test]
+fn overlapping_conditional_allocation_loss_is_reviewed_from_final_candidate() {
+    for reverse_ids in [false, true] {
+        let f = fixture(reverse_ids, false);
+        validate_candidate(&f.project)
+            .expect("Separate actual performers and required endpoint mappings are valid");
+        for selected in f.selected_allocations {
+            assert!(
+                references::deletion_impact(&f.project, selected).contains(&f.exchange_allocation),
+                "Both selected allocations overlap on the same conditional dependent"
+            );
+            let singleton = execute_batch(&f.project, &[Command::Delete(selected)]).unwrap();
+            assert!(!singleton.relations.contains_key(&f.exchange_allocation));
+        }
+        let targets = f.selected_allocations.map(Target::Edge);
+        let plan = prepare(&f.project, f.diagram, &targets).unwrap();
+        let reversed = prepare(
+            &f.project,
+            f.diagram,
+            &[targets[1].clone(), targets[0].clone()],
+        )
+        .unwrap();
+        assert_eq!(
+            serde_json::to_value(&plan.command).unwrap(),
+            serde_json::to_value(&reversed.command).unwrap(),
+            "Click order must not change normalization"
+        );
+        let removed = BTreeSet::from([
+            f.selected_allocations[0],
+            f.selected_allocations[1],
+            f.exchange_allocation,
+        ]);
+        assert_eq!(plan.selected, BTreeSet::from(f.selected_allocations));
+        assert_eq!(plan.removed, removed);
+        assert_eq!(plan.changed, BTreeSet::from([f.diagram]));
+        // Literal record oracle, independent of deletion_impact / planner output.
+        let mut expected = f.project.clone();
+        for id in removed {
+            expected.relations.remove(&id);
+        }
+        expected
+            .diagrams
+            .get_mut(&f.diagram)
+            .unwrap()
+            .routes
+            .remove(0);
+        let actual = execute_batch(&f.project, &[plan.command]).unwrap();
+        assert_eq!(
+            actual, expected,
+            "Only two port allocations, their conditional exchange allocation and the deleted edge's authored route change"
+        );
+    }
+}
+
+#[test]
+fn direct_exchange_cascade_and_conditional_support_loss_share_one_batch() {
+    for reverse_ids in [false, true] {
+        let f = fixture(reverse_ids, false);
+        validate_candidate(&f.project)
+            .expect("Separate actual performers and required endpoint mappings are valid");
+        let targets = [
+            Target::Edge(f.selected_allocations[0]),
+            Target::Edge(f.functional_exchange),
+            Target::Edge(f.selected_allocations[1]),
+        ];
+        let plan = prepare(&f.project, f.diagram, &targets).unwrap();
+        let removed = BTreeSet::from([
+            f.selected_allocations[0],
+            f.selected_allocations[1],
+            f.functional_exchange,
+            f.exchange_allocation,
+        ]);
+        assert_eq!(
+            plan.selected,
+            BTreeSet::from([
+                f.selected_allocations[0],
+                f.selected_allocations[1],
+                f.functional_exchange
+            ])
+        );
+        assert_eq!(plan.removed, removed);
+        assert_eq!(plan.changed, BTreeSet::from([f.diagram]));
+        let mut expected = f.project.clone();
+        for id in removed {
+            expected.relations.remove(&id);
+        }
+        expected
+            .diagrams
+            .get_mut(&f.diagram)
+            .unwrap()
+            .routes
+            .remove(0);
+        assert_eq!(
+            execute_batch(&f.project, &[plan.command]).unwrap(),
+            expected
+        );
+    }
+}
+
+#[test]
+fn alternative_pairing_counterexample_is_not_a_valid_saved_model() {
+    let f = fixture(false, true);
+    assert!(validation::validate(&f.project).iter().any(
+        |issue| issue.code == "boundary_owner" && issue.severity == validation::Severity::Error
+    ));
+    let before = f.project.clone();
+    assert!(
+        prepare(
+            &f.project,
+            f.diagram,
+            &f.selected_allocations.map(Target::Edge)
+        )
+        .is_err()
+    );
+    assert_eq!(f.project, before);
+}

crates/oa-desktop/src/diagram/lifecycle_tests.rs

@@ -53,6 +53,7 @@ fn bounds() -> Rectangle {
 }
 fn canvas(app: &App) -> DiagramCanvas<'_> {
     DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: None,
         project: app.project(),
         view_index: None,

crates/oa-desktop/src/diagram/multiselect.rs

@@ -178,10 +178,25 @@ impl DiagramCanvas<'_> {
             }
             if selection.targets().len() > 1 && *key == Key::Named(Named::Delete) {
                 let snapshot = selection.snapshot(context(self.context))?;
+                if *modifiers == iced::keyboard::Modifiers::SHIFT {
+                    let Some(input_generation) = self.removal_input.idle() else {
+                        return Some(Action::capture());
+                    };
+                    return Some(
+                        Action::publish(Message::SavedRemoval(Box::new(
+                            crate::app::saved_removal::Event::Begin {
+                                input_generation,
+                                context: self.context,
+                                snapshot: Box::new(snapshot),
+                            },
+                        )))
+                        .and_capture(),
+                    );
+                }
                 let action = if modifiers.is_empty() {
                     Event::Hide(snapshot)
                 } else {
-                    Event::Refuse(snapshot, "Use Hide selected to remove placements. Group model-deletion review is not available yet.".into())
+                    Event::Refuse(snapshot, "Use plain Delete to hide placements or Shift+Delete to review deletion from the model.".into())
                 };
                 return Some(Action::publish(Message::DiagramSelection(action)).and_capture());
             }

crates/oa-desktop/src/diagram/multiselect_tests.rs

@@ -18,6 +18,7 @@ fn bounds() -> Rectangle {
 }
 
 struct Fixture {
+    removal_input: crate::removal_input::Lifetime,
     project: Project,
     diagram: Id,
     a: Id,
@@ -70,6 +71,7 @@ impl Fixture {
         .collect();
         validate_candidate(&project).unwrap();
         Self {
+            removal_input: Default::default(),
             project,
             diagram,
             a,
@@ -105,6 +107,7 @@ impl Fixture {
             _ => self.diagram,
         };
         DiagramCanvas {
+            removal_input: &self.removal_input,
             selection: Some(selection),
             project: &self.project,
             view_index: None,

crates/oa-desktop/src/diagram/pointer_tests.rs

@@ -61,6 +61,7 @@ fn screen(p: Position, zoom: f32) -> Point {
 }
 fn canvas(app: &App, zoom: f32) -> DiagramCanvas<'_> {
     DiagramCanvas {
+        removal_input: &app.saved_removal_input,
         selection: None,
         project: app.project(),
         view_index: None,

crates/oa-desktop/src/diagram/port_hit_tests.rs

@@ -1,7 +1,13 @@
 use super::*;
 
-fn canvas(project: &Project, diagram: Id, zoom: f32) -> DiagramCanvas<'_> {
+fn canvas<'a>(
+    project: &'a Project,
+    diagram: Id,
+    zoom: f32,
+    removal_input: &'a crate::removal_input::Lifetime,
+) -> DiagramCanvas<'a> {
     DiagramCanvas {
+        removal_input,
         selection: None,
         project,
         view_index: None,
@@ -58,7 +64,8 @@ fn nearest_port_center_wins_on_all_borders_and_zoom_levels() {
             ..Default::default()
         };
         for zoom in [0.0001, 0.35, 1., 3.] {
-            let canvas = canvas(&project, diagram, zoom);
+            let removal_input = crate::removal_input::Lifetime::default();
+            let canvas = canvas(&project, diagram, zoom, &removal_input);
             for _ in 0..2 {
                 for port in &view.ports {
                     assert_eq!(
@@ -91,7 +98,8 @@ fn coincident_ports_keep_selection_then_use_stable_identity() {
             .collect(),
         ..Default::default()
     };
-    let mut canvas = canvas(&project, diagram, 0.35);
+    let removal_input = crate::removal_input::Lifetime::default();
+    let mut canvas = canvas(&project, diagram, 0.35, &removal_input);
     let at = local(&canvas, view.ports[0].position);
     for _ in 0..2 {
         canvas.selected = Id::nil();
@@ -147,7 +155,8 @@ fn nested_owner_palette_selection_drag_and_context_menu_pick_the_same_port() {
         })
         .collect();
     validate_candidate(&project).unwrap();
-    let canvas = canvas(&project, diagram, 0.35);
+    let removal_input = crate::removal_input::Lifetime::default();
+    let canvas = canvas(&project, diagram, 0.35, &removal_input);
     let view = project_view(&project, diagram);
     let bounds = Rectangle::new(Point::new(200., 80.), Size::new(800., 600.));
     for port in &view.ports {

crates/oa-desktop/src/diagram/port_labels.rs

@@ -177,6 +177,7 @@ mod tests {
 
     fn program(app: &App) -> PortLabels<'_> {
         PortLabels(DiagramCanvas {
+            removal_input: &app.saved_removal_input,
             selection: None,
             project: app.project(),
             view_index: None,

crates/oa-desktop/src/diagram_selection.rs

@@ -184,6 +184,10 @@ impl Selection {
 }
 
 impl Snapshot {
+    pub(crate) fn generation(&self) -> u64 {
+        self.generation
+    }
+
     pub fn context(&self) -> Context {
         self.context
     }

crates/oa-desktop/src/main.rs

@@ -26,6 +26,8 @@ mod port_edit;
 mod port_preview;
 mod port_workflow;
 mod recovery;
+mod removal_effects;
+mod removal_input;
 mod route_edit;
 mod semantic_review;
 mod source_annotations;

crates/oa-desktop/src/model_menu.rs

@@ -19,6 +19,7 @@ pub struct Request {
     pub creation_point: Option<Position>,
     pub canvas: Option<route_edit::Context>,
     pub process: Option<Box<crate::behavior::topology::Context>>,
+    pub scenario: Option<Box<crate::behavior::scenario::Context>>,
     pub source_file: Option<String>,
 }
 impl Request {
@@ -34,6 +35,7 @@ impl Request {
             creation_point: None,
             canvas: None,
             process: None,
+            scenario: None,
             source_file: None,
         }
     }
@@ -55,6 +57,7 @@ pub struct Opened {
     page: Page,
     layer: Layer,
     diagram: Option<Id>,
+    scenario_selection: Option<crate::diagram_selection::Snapshot>,
 }
 impl Opened {
     pub fn new(app: &App, request: Request, token: u64) -> Option<Self> {
@@ -67,9 +70,24 @@ impl Opened {
                 .process
                 .as_deref()
                 .is_some_and(|c| Some(*c) != app.topology_context())
+            || request
+                .scenario
+                .as_deref()
+                .is_some_and(|c| Some(*c) != app.scenario_context())
         {
             return None;
         }
+        let scenario_selection = if request.scenario.is_some()
+            || request.process.is_some()
+            || (request.canvas.is_some()
+                && app
+                    .multiselect_snapshot()
+                    .is_some_and(|s| s.targets().len() > 1))
+        {
+            Some(app.multiselect_snapshot()?)
+        } else {
+            None
+        };
         Some(Self {
             token,
             request,
@@ -79,6 +97,7 @@ impl Opened {
             page: app.page,
             layer: app.layer,
             diagram: current_diagram(app),
+            scenario_selection,
         })
     }
     pub fn valid(&self, app: &App) -> bool {
@@ -99,6 +118,15 @@ impl Opened {
                 .process
                 .as_deref()
                 .is_none_or(|c| Some(*c) == app.topology_context())
+            && self
+                .request
+                .scenario
+                .as_deref()
+                .is_none_or(|c| Some(*c) == app.scenario_context())
+            && self
+                .scenario_selection
+                .as_ref()
+                .is_none_or(|captured| app.multiselect_snapshot().as_ref() == Some(captured))
             && self
                 .request
                 .source_file
@@ -109,9 +137,19 @@ impl Opened {
 
 fn target_matches(app: &App, request: &Request) -> bool {
     use crate::diagram_usage::Target;
+    if request.scenario.is_some()
+        && (request.canvas.is_some() || request.process.is_some() || request.placement.is_some())
+    {
+        return false;
+    }
     let Some(target) = request.selection_target.as_deref() else {
         return true;
     };
+    if let Some(context) = request.scenario.as_deref() {
+        return Some(*context) == app.scenario_context()
+            && matches!(target, Target::ScenarioObject(id) if *id == request.object)
+            && app.multiselect_target_visible(target);
+    }
     if (request.canvas.is_none() && request.process.is_none())
         || !app.multiselect_target_visible(target)
     {
@@ -159,6 +197,17 @@ fn current_diagram(app: &App) -> Option<Id> {
     if app.page == Page::Behavior {
         app.topology_context()
             .map(|context| context.owner)
+            .or_else(|| {
+                app.scenario_context()
+                    .map(|context| match context.representation {
+                        crate::behavior::scenario_layout::Representation::Derived { owner } => {
+                            owner
+                        }
+                        crate::behavior::scenario_layout::Representation::Saved { diagram } => {
+                            diagram
+                        }
+                    })
+            })
             .or_else(|| app.state_context().map(|context| context.diagram))
     } else {
         app.active_diagram
@@ -172,49 +221,56 @@ pub fn open(object: Id, anchor: Point) -> Message {
 pub fn trigger(app: &App) -> iced::Element<'_, Message> {
     crate::context_menu::Area::left(
         crate::views::action("Actions ▾", Message::Menu(Event::Close)),
-        move |anchor| {
-            let mut request = Request::object(app.selected, anchor);
-            if app.page == Page::Diagram {
-                request.placement = app.selected_node;
-                request.bend = app
-                    .selected_bend
-                    .filter(|(id, _)| *id == app.selected)
-                    .map(|(_, i)| i);
-                request.canvas = app.route_context();
-            } else if app.page == Page::Behavior {
-                request.canvas = app.state_context();
-                request.process = app.topology_context().map(Box::new);
-                if let Some(target) = app.diagram_selection.as_ref().and_then(|s| s.primary()) {
-                    request.selection_target = Some(Box::new(target.clone()));
-                    request.placement = match target {
-                        crate::diagram_usage::Target::Placement(id) => {
-                            if let Some(node) = request
-                                .canvas
-                                .and_then(|c| app.project().diagrams.get(&c.diagram))
-                                .and_then(|d| d.nodes.get(id))
-                            {
-                                request.object = node.element;
-                            }
-                            Some(*id)
-                        }
-                        _ => None,
-                    };
-                } else if let Some(context) = request.canvas
-                    && let Some(node) = app.project().diagrams[&context.diagram]
-                        .nodes
-                        .values()
-                        .find(|node| node.element == app.selected || node.id == app.selected)
-                {
-                    request.object = node.element;
-                    request.placement = Some(node.id);
-                }
-            }
-            Message::Menu(Event::Open(request))
-        },
+        move |anchor| Message::Menu(Event::Open(actions_request(app, anchor))),
     )
     .into()
 }
 
+fn actions_request(app: &App, anchor: Point) -> Request {
+    let mut request = Request::object(app.selected, anchor);
+    if app.page == Page::Diagram {
+        request.placement = app.selected_node;
+        request.bend = app
+            .selected_bend
+            .filter(|(id, _)| *id == app.selected)
+            .map(|(_, i)| i);
+        request.canvas = app.route_context();
+    } else if app.page == Page::Behavior {
+        request.canvas = app.state_context();
+        request.process = app.topology_context().map(Box::new);
+        request.scenario = app.scenario_context().map(Box::new);
+        if let Some(target) = app.diagram_selection.as_ref().and_then(|s| s.primary()) {
+            request.selection_target = Some(Box::new(target.clone()));
+            request.placement = match target {
+                crate::diagram_usage::Target::Placement(id) => {
+                    if let Some(node) = request
+                        .canvas
+                        .and_then(|c| app.project().diagrams.get(&c.diagram))
+                        .and_then(|d| d.nodes.get(id))
+                    {
+                        request.object = node.element;
+                    }
+                    Some(*id)
+                }
+                crate::diagram_usage::Target::ScenarioObject(id) => {
+                    request.object = *id;
+                    None
+                }
+                _ => None,
+            };
+        } else if let Some(context) = request.canvas
+            && let Some(node) = app.project().diagrams[&context.diagram]
+                .nodes
+                .values()
+                .find(|node| node.element == app.selected || node.id == app.selected)
+        {
+            request.object = node.element;
+            request.placement = Some(node.id);
+        }
+    }
+    request
+}
+
 pub fn popup(app: &App) -> Option<Menu<Message>> {
     let opened = app.model_menu.as_ref().filter(|menu| menu.valid(app))?;
     let request = &opened.request;
@@ -261,6 +317,78 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
         });
     }
     let mut entries = vec![Entry::title(crate::views::short(p.named(id), 38))];
+    if let Some(context) = request.scenario.as_deref().copied() {
+        use crate::app::multiselect::Choice;
+        use crate::behavior::scenario::{CanvasEvent, selection};
+        let snapshot = opened.scenario_selection.as_ref()?;
+        let selection_message = |intent| {
+            Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(selection::Event {
+                context,
+                snapshot: snapshot.clone(),
+                intent,
+            })))
+        };
+        if let Some(target) = request.selection_target.as_deref() {
+            let selected = snapshot.targets().contains(target);
+            entries.push(item(
+                if selected {
+                    "Remove from selection"
+                } else {
+                    "Add to selection"
+                },
+                selection_message(selection::Intent::Choose(
+                    target.clone(),
+                    if selected {
+                        Choice::Remove
+                    } else {
+                        Choice::Add
+                    },
+                )),
+                true,
+            ));
+            if snapshot.targets().len() > 1 {
+                if selected {
+                    entries.push(item(
+                        "Inspect this element",
+                        selection_message(selection::Intent::Choose(
+                            target.clone(),
+                            Choice::Inspect,
+                        )),
+                        true,
+                    ));
+                }
+                entries.push(item(
+                    "Select only this element",
+                    selection_message(selection::Intent::Choose(target.clone(), Choice::Replace)),
+                    true,
+                ));
+            }
+            entries.push(Entry::separator());
+        }
+        // A menu on an unselected subject must not expose singleton model actions
+        // while the canvas still depicts a group. Selection changes are explicit.
+        if snapshot.targets().len() > 1 {
+            entries.push(Entry::title(format!(
+                "{} selected",
+                snapshot.targets().len()
+            )));
+            entries.push(Entry::title(
+                "Use Reorder above the canvas to change sequence order",
+            ));
+            if let Some(removal) = crate::app::scenario_removal::begin(app) {
+                entries.push(item("Remove selected from Scenario…", removal, true));
+            }
+            entries.push(Entry::title(
+                "Select one occurrence for its individual actions",
+            ));
+            return Some(Menu {
+                token: opened.token,
+                anchor: request.anchor,
+                entries,
+                on_close: Message::Menu(Event::Close),
+            });
+        }
+    }
     if (request.canvas.is_some() || request.process.is_some())
         && let Some(context) = app.multiselect_context()
     {
@@ -314,22 +442,50 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
                 )),
                 true,
             ));
+            // Navigation belongs to the exact clicked preview, even when it
+            // is outside the current group. Keep it alongside aggregate removal
+            // without selecting that preview or exposing singleton mutations.
+            let qualified_definition = request.process.as_deref().copied().and_then(|context| {
+                let endpoint = match request.selection_target.as_deref() {
+                    Some(Target::ProcessOccurrence(endpoint))
+                        if !endpoint.references.is_empty() =>
+                    {
+                        Some(endpoint.clone())
+                    }
+                    Some(Target::ProcessPreviewLink { source, .. }) => Some(source.clone()),
+                    _ => None,
+                }?;
+                Some((context, endpoint))
+            });
+            if let Some((context, endpoint)) = &qualified_definition {
+                entries.push(Entry::title("Reused contents · read-only in this process"));
+                entries.push(item(
+                    "Open referenced definition",
+                    Message::TopologyCanvas(crate::behavior::topology::CanvasEvent::OpenQualified(
+                        *context,
+                        endpoint.clone(),
+                    )),
+                    true,
+                ));
+            }
             if let Some(snapshot) = app.multiselect_snapshot().filter(|s| s.targets().len() > 1)
-                && selected
+                && (selected || request.process.is_some() || request.canvas.is_some())
             {
                 entries.push(Entry::title(format!(
                     "{} selected",
                     snapshot.targets().len()
                 )));
-                entries.push(item(
-                    "Inspect this element",
-                    Message::DiagramSelection(SelectionEvent::Choose(
-                        context,
-                        target.clone(),
-                        Choice::Inspect,
-                    )),
-                    true,
-                ));
+                if selected {
+                    entries.push(item(
+                        "Inspect this element",
+                        Message::DiagramSelection(SelectionEvent::Choose(
+                            context,
+                            target.clone(),
+                            Choice::Inspect,
+                        )),
+                        true,
+                    ));
+                }
                 entries.push(item(
                     "Select only this element",
                     Message::DiagramSelection(SelectionEvent::Choose(
@@ -343,9 +499,13 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
                     entries.push(Entry::title(
                         "Drag contributions within one column to reorder",
                     ));
-                    entries.push(Entry::disabled(
-                        "Hide unavailable · cards are model contributions",
-                    ));
+                    if let Some(removal) = crate::app::process_removal::begin(app) {
+                        entries.push(item(
+                            "Remove selected contributions / links…",
+                            removal,
+                            true,
+                        ));
+                    }
                 } else {
                     entries.push(item(
                         "Hide selected placements",
@@ -353,9 +513,11 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
                         crate::app::multiselect::placements(&snapshot).is_some(),
                     ));
                 }
-                entries.push(Entry::disabled(
-                    "Delete selected from model (not yet available)",
-                ));
+                if request.process.is_none()
+                    && let Some(removal) = crate::app::saved_removal::begin(app)
+                {
+                    entries.push(item("Delete selected from model…", removal, true));
+                }
                 return Some(Menu {
                     token: opened.token,
                     anchor: request.anchor,
@@ -364,34 +526,13 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
                 });
             }
             entries.push(Entry::separator());
-            if let Some(context) = request.process.as_deref().copied() {
-                let endpoint = match request.selection_target.as_deref() {
-                    Some(Target::ProcessOccurrence(endpoint))
-                        if !endpoint.references.is_empty() =>
-                    {
-                        Some(endpoint.clone())
-                    }
-                    Some(Target::ProcessPreviewLink { source, .. }) => Some(source.clone()),
-                    _ => None,
-                };
-                if let Some(endpoint) = endpoint {
-                    entries.push(Entry::title("Reused contents · read-only in this process"));
-                    entries.push(item(
-                        "Open referenced definition",
-                        Message::TopologyCanvas(
-                            crate::behavior::topology::CanvasEvent::OpenQualified(
-                                context, endpoint,
-                            ),
-                        ),
-                        true,
-                    ));
-                    return Some(Menu {
-                        token: opened.token,
-                        anchor: request.anchor,
-                        entries,
-                        on_close: Message::Menu(Event::Close),
-                    });
-                }
+            if qualified_definition.is_some() {
+                return Some(Menu {
+                    token: opened.token,
+                    anchor: request.anchor,
+                    entries,
+                    on_close: Message::Menu(Event::Close),
+                });
             }
         }
     }
@@ -798,6 +939,10 @@ fn relation_actions(kind: Kind) -> &'static [(&'static str, RelationKind, bool)]
     }
 }
 
+#[cfg(test)]
+#[path = "model_menu_scenario_tests.rs"]
+mod scenario_tests;
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/oa-desktop/src/model_menu_scenario_tests.rs

@@ -0,0 +1,319 @@
+use super::*;
+use crate::{
+    app::multiselect::Choice,
+    behavior::scenario::{CanvasEvent, Context, selection},
+    behavior::scenario_layout::Representation,
+    diagram_usage::Target,
+};
+
+fn saved(project: &mut Project, owner: Id, name: &str) -> Id {
+    let id = Id::new_v4();
+    project.diagrams.insert(
+        id,
+        Diagram {
+            id,
+            alias: format!("scenario_menu_view_{}", project.diagrams.len()),
+            name: name.into(),
+            description: String::new(),
+            layer: Layer::Oa,
+            projection: ProjectionKind::Scenario { scenario: owner },
+            layout: None,
+            routes: vec![],
+            nodes: Default::default(),
+            view_options: Default::default(),
+        },
+    );
+    id
+}
+
+fn fixture() -> (App, [Id; 3], Id, [Id; 2]) {
+    let (mut project, [owner, _, _], [first, second, hidden]) =
+        crate::behavior::scenario::direct_tests::navigation_fixture();
+    let mut third = project.elements[&first].clone();
+    third.id = Id::new_v4();
+    third.alias = "third_menu_reference".into();
+    third.name = "Third reference".into();
+    let third_id = third.id;
+    project = execute_batch(&project, &[Command::CreateElement(third)]).unwrap();
+    let views = [
+        saved(&mut project, owner, "A"),
+        saved(&mut project, owner, "B"),
+    ];
+    let mut app = App::with_project(project);
+    send(&mut app, Message::Select(owner));
+    send(&mut app, Message::Page(Page::Behavior));
+    (app, [first, second, third_id], hidden, views)
+}
+
+fn send(app: &mut App, message: Message) {
+    let _ = app.update(message);
+}
+
+fn choose(app: &mut App, id: Id, choice: Choice) {
+    let event = selection::Event {
+        context: app.scenario_context().unwrap(),
+        snapshot: app.multiselect_snapshot().unwrap(),
+        intent: selection::Intent::Choose(Target::ScenarioObject(id), choice),
+    };
+    send(
+        app,
+        Message::ScenarioCanvas(CanvasEvent::Selection(Box::new(event))),
+    );
+}
+
+fn request(app: &App, id: Id) -> Request {
+    let mut request = Request::object(id, Point::new(120., 80.));
+    request.scenario = app.scenario_context().map(Box::new);
+    request.selection_target = Some(Box::new(Target::ScenarioObject(id)));
+    request
+}
+
+fn action(app: &App, caption: &str) -> Message {
+    popup(app)
+        .unwrap()
+        .entries
+        .into_iter()
+        .find_map(|entry| match entry {
+            Entry::Action { label, message, .. } if label == caption => message,
+            _ => None,
+        })
+        .unwrap_or_else(|| panic!("Expected enabled Scenario menu action {caption}"))
+}
+
+#[test]
+fn scenario_requests_require_exact_visible_target_and_complete_exclusive_context() {
+    let (mut app, [first, second, _], hidden, [view, _]) = fixture();
+    choose(&mut app, first, Choice::Replace);
+    let valid = request(&app, first);
+    assert!(Opened::new(&app, valid.clone(), 1).is_some());
+    let current = app.scenario_context().unwrap();
+    for captured in [
+        Context {
+            document: Id::new_v4(),
+            ..current
+        },
+        Context {
+            scenario: Id::new_v4(),
+            ..current
+        },
+        Context {
+            representation: Representation::Saved { diagram: view },
+            ..current
+        },
+        Context {
+            visit: Id::new_v4(),
+            ..current
+        },
+        Context {
+            revision: current.revision + 1,
+            ..current
+        },
+        Context {
+            epoch: current.epoch + 1,
+            ..current
+        },
+    ] {
+        let mut stale = valid.clone();
+        stale.scenario = Some(Box::new(captured));
+        assert!(Opened::new(&app, stale, 2).is_none());
+    }
+    let mut wrong = valid.clone();
+    wrong.object = second;
+    assert!(Opened::new(&app, wrong, 2).is_none());
+    assert!(app.project().contains(hidden));
+    assert!(!app.multiselect_target_visible(&Target::ScenarioObject(hidden)));
+    assert!(Opened::new(&app, request(&app, hidden), 2).is_none());
+    let mut wrong = valid.clone();
+    wrong.placement = Some(Id::new_v4());
+    assert!(Opened::new(&app, wrong, 2).is_none());
+    let mut wrong = valid.clone();
+    wrong.canvas = Some(route_edit::Context {
+        document: current.document,
+        diagram: view,
+        revision: current.revision,
+        epoch: current.epoch,
+    });
+    assert!(Opened::new(&app, wrong, 2).is_none());
+    let mut wrong = valid.clone();
+    wrong.process = Some(Box::new(crate::behavior::topology::Context {
+        document: current.document,
+        owner: current.scenario,
+        revision: current.revision,
+        epoch: current.epoch,
+    }));
+    assert!(Opened::new(&app, wrong, 2).is_none());
+    let mut wrong = valid.clone();
+    wrong.selection_target = Some(Box::new(Target::Edge(first)));
+    assert!(Opened::new(&app, wrong, 2).is_none());
+    let mut wrong = valid;
+    wrong.scenario = None;
+    assert!(Opened::new(&app, wrong, 2).is_none());
+}
+
+#[test]
+fn scenario_menu_rejects_saved_visit_roundtrip_even_with_equal_generic_snapshot() {
+    let (mut app, [first, second, _], _, [a, b]) = fixture();
+    let switch = |app: &mut App, diagram| {
+        let context = app.scenario_context().unwrap();
+        send(
+            app,
+            Message::ScenarioCanvas(CanvasEvent::Representation(
+                context,
+                Representation::Saved { diagram },
+            )),
+        );
+    };
+    switch(&mut app, a);
+    choose(&mut app, first, Choice::Replace);
+    choose(&mut app, second, Choice::Add);
+    let opened = Opened::new(&app, request(&app, first), 1).unwrap();
+    let old_context = app.scenario_context().unwrap();
+    let before = app.document.snapshot();
+    let selected = app.diagram_selection.take().unwrap();
+    switch(&mut app, b);
+    assert!(!opened.valid(&app));
+    switch(&mut app, a);
+    assert_ne!(app.scenario_context().unwrap().visit, old_context.visit);
+    // Restore the same shared selection and epoch deliberately. Only the full
+    // Scenario visit may distinguish the old request from this returned view.
+    app.canvas_epoch = old_context.epoch;
+    app.diagram_selection = Some(selected);
+    app.selected = second;
+    assert_eq!(app.multiselect_snapshot(), opened.scenario_selection);
+    assert!(!opened.valid(&app));
+    assert!(Opened::new(&app, opened.request.clone(), 2).is_none());
+    assert!(std::sync::Arc::ptr_eq(&before, &app.document.snapshot()));
+}
+
+#[test]
+fn scenario_group_menus_capture_set_and_never_expose_partial_model_actions() {
+    let (mut app, [first, second, third], _, _) = fixture();
+    choose(&mut app, first, Choice::Replace);
+    choose(&mut app, second, Choice::Add);
+    let before = app.document.snapshot();
+    let capture = actions_request(&app, Point::ORIGIN);
+    assert_eq!(capture.object, second);
+    assert_eq!(
+        capture.selection_target.as_deref(),
+        Some(&Target::ScenarioObject(second))
+    );
+    assert_eq!(capture.scenario.as_deref().copied(), app.scenario_context());
+    assert!(capture.canvas.is_none() && capture.process.is_none() && capture.placement.is_none());
+
+    for target in [first, third] {
+        let captured_request = request(&app, target);
+        send(&mut app, Message::Menu(Event::Open(captured_request)));
+        let snapshot = app.multiselect_snapshot().unwrap();
+        let menu = popup(&app).unwrap();
+        assert!(
+            menu.entries
+                .iter()
+                .any(|e| matches!(e, Entry::Title(label) if label == "2 selected"))
+        );
+        let mut enabled = 0;
+        let mut removals = 0;
+        for entry in menu.entries {
+            match entry {
+                Entry::Action {
+                    label,
+                    message: Some(Message::Menu(Event::Invoke(_, message))),
+                    ..
+                } => {
+                    if let Message::ScenarioRemoval(event) = &*message {
+                        let crate::app::scenario_removal::Event::Begin {
+                            context,
+                            snapshot: captured,
+                        } = &**event
+                        else {
+                            panic!("Group menu must capture a fresh removal review");
+                        };
+                        assert_eq!(label, "Remove selected from Scenario…");
+                        assert_eq!(Some(*context), app.scenario_context());
+                        assert_eq!(captured.as_ref(), &snapshot);
+                        removals += 1;
+                        continue;
+                    }
+                    let Message::ScenarioCanvas(CanvasEvent::Selection(event)) = *message else {
+                        panic!("Scenario group menu exposed a singleton model action");
+                    };
+                    assert_eq!(event.context, app.scenario_context().unwrap());
+                    assert_eq!(event.snapshot, snapshot);
+                    let selection::Intent::Choose(actual_target, choice) = event.intent else {
+                        panic!("Unexpected group selection intent");
+                    };
+                    assert_eq!(actual_target, Target::ScenarioObject(target));
+                    assert!(matches!(
+                        (label.as_str(), choice),
+                        ("Add to selection", Choice::Add)
+                            | ("Remove from selection", Choice::Remove)
+                            | ("Inspect this element", Choice::Inspect)
+                            | ("Select only this element", Choice::Replace)
+                    ));
+                    enabled += 1;
+                }
+                Entry::Action {
+                    label,
+                    message: None,
+                    ..
+                } => {
+                    assert!(!label.contains("Hide"));
+                }
+                Entry::Action {
+                    message: Some(_), ..
+                } => panic!("Uncaptured menu action"),
+                _ => {}
+            }
+        }
+        assert_eq!(enabled, if target == first { 3 } else { 2 });
+        assert_eq!(removals, 1, "One captured whole-selection removal action");
+        assert_eq!(
+            app.diagram_selection.as_ref().unwrap().targets(),
+            &[
+                Target::ScenarioObject(first),
+                Target::ScenarioObject(second)
+            ]
+        );
+        assert_eq!(app.selected, second);
+    }
+    let selected_request = request(&app, first);
+    send(&mut app, Message::Menu(Event::Open(selected_request)));
+    let inspect = action(&app, "Inspect this element");
+    send(&mut app, inspect);
+    assert_eq!(app.selected, first);
+    assert_eq!(
+        app.diagram_selection.as_ref().unwrap().targets(),
+        &[
+            Target::ScenarioObject(first),
+            Target::ScenarioObject(second)
+        ]
+    );
+    let remove_request = request(&app, second);
+    send(&mut app, Message::Menu(Event::Open(remove_request)));
+    let remove = action(&app, "Remove from selection");
+    send(&mut app, remove);
+    assert_eq!(
+        app.diagram_selection.as_ref().unwrap().targets(),
+        &[Target::ScenarioObject(first)]
+    );
+    assert!(std::sync::Arc::ptr_eq(&before, &app.document.snapshot()));
+    assert_eq!(app.source_workspace.bundle(), before.bundle);
+}
+
+#[test]
+fn scenario_menu_snapshot_rejects_selection_aba_and_singleton_actions_stay_available() {
+    let (mut app, [first, second, _], _, _) = fixture();
+    choose(&mut app, first, Choice::Replace);
+    let captured = request(&app, first);
+    send(&mut app, Message::Menu(Event::Open(captured)));
+    let _ = action(&app, "Properties");
+    let _ = action(&app, "Delete from model…");
+    let opened = app.model_menu.take().unwrap();
+    let context = app.scenario_context();
+    // Isolate generation admission from the adapter's additional epoch defense.
+    let selected = app.diagram_selection.as_mut().unwrap();
+    selected.add(Target::ScenarioObject(second), |_| true);
+    selected.remove(&Target::ScenarioObject(second));
+    assert_eq!(app.scenario_context(), context);
+    assert_eq!(app.selected, first);
+    assert!(!opened.valid(&app));
+}

crates/oa-desktop/src/removal_effects.rs

@@ -0,0 +1,230 @@
+//! Definition-level Process/FunctionalChain effects of a complete removal candidate.
+//! Stored record differences and unchanged interpretation modes do not establish
+//! unchanged caller behavior. This bounded analysis does not expand reuse trees.
+use oa_core::topology_context::TopologyIndex;
+use oa_core::{Id, Kind, OccurrenceBody, Project, RelationKind, SharedBody};
+use std::collections::{BTreeMap, BTreeSet};
+
+#[derive(Debug)]
+pub(crate) struct DerivedEffects {
+    pub(crate) interpretation: Vec<InterpretationChange>,
+    /// Definitions whose records or authored topology changed, including deleted
+    /// definitions. Values identify surviving direct and transitive callers in
+    /// either project, even if their own stored records or modes did not change.
+    pub(crate) affected_uses: BTreeMap<Id, BTreeSet<Id>>,
+}
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct InterpretationChange {
+    pub(crate) owner: Id,
+    pub(crate) before: Interpretation,
+    pub(crate) after: Interpretation,
+    pub(crate) callers: BTreeSet<Id>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct Interpretation {
+    /// None means explicit; Some includes the empty legacy order.
+    pub(crate) local_order: Option<Vec<Id>>,
+    /// Definition-level implicit order used within contextual expansion. This
+    /// does not claim complete expanded connectivity or boundary analysis.
+    pub(crate) expanded_order: Option<Vec<Id>>,
+    pub(crate) contextual_analysis: bool,
+}
+
+fn exchange(project: &Project, id: Id) -> bool {
+    matches!(
+        project.elements.get(&id).and_then(|e| e.shared()),
+        Some(SharedBody::Occurrence {
+            body: OccurrenceBody::Exchange { .. },
+            ..
+        })
+    )
+}
+
+fn interpretations(project: &Project) -> BTreeMap<Id, Interpretation> {
+    let index = TopologyIndex::new(project);
+    // This is exactly TopologyIndex::with_cache_capacity's relation ownership
+    // rule. Its link_definitions is private; do not expand repeated reuse trees
+    // just to answer this finite definition-level question.
+    let linked: BTreeSet<_> = project
+        .relations
+        .values()
+        .filter_map(|relation| {
+            relation.contextual_owner().or_else(|| {
+                (relation.kind() == RelationKind::SequenceLink)
+                    .then(|| {
+                        project
+                            .elements
+                            .get(&relation.source())
+                            .and_then(|e| e.parent)
+                    })
+                    .flatten()
+            })
+        })
+        .collect();
+    project
+        .elements
+        .values()
+        .filter(|e| matches!(e.kind(), Kind::Process | Kind::FunctionalChain))
+        .map(|e| {
+            let steps = e.steps().expect("Sequence definitions have ordered steps");
+            // All-exchange steps exclude every non-exchange explicit marker, so only
+            // local SequenceLinks remain to test (the desktop discriminator).
+            // legacy_order alone loses the explicit-versus-empty distinction.
+            let local_order = (!project.relations.values().any(|relation| {
+                relation.kind() == RelationKind::SequenceLink
+                    && project
+                        .elements
+                        .get(&relation.source())
+                        .and_then(|element| element.parent)
+                        == Some(e.id)
+                    && project
+                        .elements
+                        .get(&relation.target())
+                        .and_then(|element| element.parent)
+                        == Some(e.id)
+            }) && steps.iter().all(|id| exchange(project, *id)))
+            .then(|| steps.clone());
+            let children = index.contributions(e.id);
+            // Mirrors topology_context/analysis.rs Builder::expand's legacy-order
+            // discriminator: all indexed contributions (including unlisted ones),
+            // and neither SequenceLink nor ContextualLink definitions. Tests retain
+            // literal discriminators where this intentionally differs from desktop.
+            let expanded_order = (!linked.contains(&e.id)
+                && children.iter().all(|id| exchange(project, *id)))
+            .then_some(children);
+            (
+                e.id,
+                Interpretation {
+                    local_order,
+                    expanded_order,
+                    contextual_analysis: index.has_contextual_links(e.id),
+                },
+            )
+        })
+        .collect()
+}
+
+fn caller_edges(project: &Project, edges: &mut BTreeMap<Id, BTreeSet<Id>>) {
+    for element in project.elements.values() {
+        if let (
+            Some(parent),
+            Some(SharedBody::Occurrence {
+                body:
+                    OccurrenceBody::SequenceReference {
+                        sequence: Some(sequence),
+                    },
+                ..
+            }),
+        ) = (element.parent, element.shared())
+        {
+            edges.entry(*sequence).or_default().insert(parent);
+        }
+    }
+}
+
+fn callers(
+    owner: Id,
+    edges: &BTreeMap<Id, BTreeSet<Id>>,
+    surviving: &BTreeMap<Id, Interpretation>,
+) -> BTreeSet<Id> {
+    let mut seen = BTreeSet::from([owner]);
+    let mut pending = vec![owner];
+    while let Some(sequence) = pending.pop() {
+        for &caller in edges.get(&sequence).into_iter().flatten() {
+            if seen.insert(caller) {
+                pending.push(caller);
+            }
+        }
+    }
+    seen.remove(&owner);
+    seen.retain(|id| surviving.contains_key(id));
+    seen
+}
+
+fn definition_owner(project: &Project, id: Id) -> Option<Id> {
+    let owner = if let Some(element) = project.elements.get(&id) {
+        if matches!(element.kind(), Kind::Process | Kind::FunctionalChain) {
+            Some(id)
+        } else {
+            element.parent.filter(|_| {
+                matches!(
+                    element.shared(),
+                    Some(SharedBody::Occurrence {
+                        body: OccurrenceBody::Action { .. }
+                            | OccurrenceBody::Exchange { .. }
+                            | OccurrenceBody::Control { .. }
+                            | OccurrenceBody::SequenceReference { .. },
+                        ..
+                    })
+                )
+            })
+        }
+    } else {
+        project.relations.get(&id).and_then(|relation| {
+            relation.contextual_owner().or_else(|| {
+                (relation.kind() == RelationKind::SequenceLink)
+                    .then(|| {
+                        project
+                            .elements
+                            .get(&relation.source())
+                            .and_then(|e| e.parent)
+                    })
+                    .flatten()
+            })
+        })
+    }?;
+    project
+        .elements
+        .get(&owner)
+        .filter(|e| matches!(e.kind(), Kind::Process | Kind::FunctionalChain))
+        .map(|_| owner)
+}
+
+/// Analyze the actual accepted before/after projects and their complete record
+/// differences. Both graphs participate: deleting a definition can clear its
+/// surviving reference records, but must not erase their previous dependency.
+pub(crate) fn analyze(
+    project: &Project,
+    candidate: &Project,
+    removed: &BTreeSet<Id>,
+    changed: &BTreeSet<Id>,
+) -> DerivedEffects {
+    let before = interpretations(project);
+    let after = interpretations(candidate);
+    let mut edges = BTreeMap::new();
+    caller_edges(project, &mut edges);
+    caller_edges(candidate, &mut edges);
+    let affected_owners: BTreeSet<_> = removed
+        .iter()
+        .chain(changed)
+        .flat_map(|&id| {
+            [
+                definition_owner(project, id),
+                definition_owner(candidate, id),
+            ]
+            .into_iter()
+            .flatten()
+        })
+        .collect();
+    let affected_uses = affected_owners
+        .into_iter()
+        .map(|owner| (owner, callers(owner, &edges, &after)))
+        .collect();
+    let interpretation = after
+        .iter()
+        .filter_map(|(&owner, next)| {
+            let previous = before.get(&owner)?;
+            (previous != next).then(|| InterpretationChange {
+                owner,
+                before: previous.clone(),
+                after: next.clone(),
+                callers: callers(owner, &edges, &after),
+            })
+        })
+        .collect();
+    DerivedEffects {
+        interpretation,
+        affected_uses,
+    }
+}

crates/oa-desktop/src/removal_input.rs

@@ -0,0 +1,132 @@
+//! Transient pointer ownership shared by the canvas and its App adapter.
+//!
+//! Iced queues messages until the entire native event batch has reached widgets.
+//! A later press must therefore revoke an earlier removal packet synchronously,
+//! without relying on the ordering of two queued application messages.
+use std::sync::{
+    Arc,
+    atomic::{AtomicU64, Ordering},
+};
+
+#[derive(Clone, Default)]
+pub(crate) struct Lifetime(Arc<AtomicU64>);
+
+impl Lifetime {
+    /// Keep a retained canvas's private gesture ownership visible to App even
+    /// when its update returns early or emits no application message.
+    pub(crate) fn sync(&self, lease: &mut Option<Lease>, busy: bool) {
+        if !busy
+            || lease
+                .as_ref()
+                .is_some_and(|lease| !Arc::ptr_eq(&self.0, &lease.lifetime.0))
+        {
+            *lease = None;
+        }
+        if busy && lease.is_none() {
+            *lease = self.acquire();
+        }
+    }
+
+    pub(crate) fn observe(&self, event: &iced::widget::canvas::Event) {
+        use iced::{keyboard, mouse, widget::canvas, window};
+        let boundary = matches!(
+            event,
+            canvas::Event::Window(window::Event::Unfocused | window::Event::Resized(_))
+                | canvas::Event::Mouse(
+                    mouse::Event::ButtonPressed(_)
+                        | mouse::Event::WheelScrolled { .. }
+                        | mouse::Event::CursorLeft
+                )
+        ) || matches!(event, canvas::Event::Keyboard(keyboard::Event::KeyPressed { key, .. })
+            if *key != keyboard::Key::Named(keyboard::key::Named::Delete));
+        if boundary {
+            self.revoke_idle();
+        }
+    }
+
+    /// Even generations are idle; odd generations belong to one live gesture.
+    pub(crate) fn idle(&self) -> Option<u64> {
+        let generation = self.0.load(Ordering::SeqCst);
+        generation.is_multiple_of(2).then_some(generation)
+    }
+
+    /// Retire an idle packet at a native input boundary (including the
+    /// viewport's synthetic Unfocused event when it takes camera ownership).
+    pub(crate) fn revoke_idle(&self) {
+        if let Some(generation) = self.idle() {
+            // Keep overflow terminal and unavailable rather than reusing zero.
+            let next = generation.saturating_add(2);
+            let _ = self
+                .0
+                .compare_exchange(generation, next, Ordering::SeqCst, Ordering::SeqCst);
+        }
+    }
+
+    pub(crate) fn acquire(&self) -> Option<Lease> {
+        let generation = self.idle()?;
+        let active = generation.checked_add(1)?;
+        self.0
+            .compare_exchange(generation, active, Ordering::SeqCst, Ordering::SeqCst)
+            .ok()?;
+        Some(Lease {
+            lifetime: self.clone(),
+            active,
+        })
+    }
+}
+
+pub(crate) struct Lease {
+    lifetime: Lifetime,
+    active: u64,
+}
+
+impl Drop for Lease {
+    fn drop(&mut self) {
+        // A terminal odd generation stays unavailable on overflow. No stale
+        // packet can become valid again through counter wraparound.
+        if let Some(next) = self.active.checked_add(1) {
+            let _ = self.lifetime.0.compare_exchange(
+                self.active,
+                next,
+                Ordering::SeqCst,
+                Ordering::SeqCst,
+            );
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn removal_input_lease_revokes_idle_capture_and_drop_never_reuses_it() {
+        let lifetime = Lifetime::default();
+        let captured = lifetime.idle().unwrap();
+        let clone = lifetime.clone();
+        let lease = clone.acquire().unwrap();
+        assert!(lifetime.idle().is_none());
+        assert!(lifetime.acquire().is_none());
+        drop(lease);
+        assert!(lifetime.idle().is_some());
+        assert_ne!(lifetime.idle(), Some(captured));
+        let after_drop = lifetime.idle();
+        lifetime.revoke_idle();
+        assert_ne!(lifetime.idle(), after_drop);
+    }
+
+    #[test]
+    fn removal_input_saturation_and_replaced_owner_cannot_reuse_a_packet() {
+        let terminal = Lifetime(Arc::new(AtomicU64::new(u64::MAX - 1)));
+        terminal.revoke_idle();
+        assert!(terminal.idle().is_none() && terminal.acquire().is_none());
+        let original = Lifetime::default();
+        let replacement = Lifetime::default();
+        let captured = original.idle();
+        let mut lease = original.acquire();
+        replacement.sync(&mut lease, true);
+        assert_ne!(original.idle(), captured);
+        assert!(replacement.idle().is_none());
+        drop(lease);
+        assert!(replacement.idle().is_some());
+    }
+}

crates/oa-desktop/src/views.rs

@@ -326,6 +326,27 @@ pub fn view(app: &App) -> View<'_, Message> {
         );
     }
     if let Some(target) = app.delete_target.as_ref().filter(|_| app.delete_pending) {
+        if target.saved.is_some() {
+            return modal_width(
+                root,
+                crate::app::saved_removal::view::view(app, target),
+                700.,
+            );
+        }
+        if target.process.is_some() {
+            return modal_width(
+                root,
+                crate::app::process_removal::view::view(app, target),
+                700.,
+            );
+        }
+        if target.scenario.is_some() {
+            return modal_width(
+                root,
+                crate::app::scenario_removal::view::view(app, target),
+                650.,
+            );
+        }
         return modal(
             root,
             column![
@@ -468,6 +489,7 @@ fn diagram(app: &App) -> View<'_, Message> {
     .align_y(iced::Center);
     let canvas: View<'_, Message> = if let Some(id) = app.active_diagram {
         let program = DiagramCanvas {
+            removal_input: &app.saved_removal_input,
             selection: app.diagram_selection.as_ref(),
             allocation: Some(app.allocation_capability()),
             project: app.project(),
@@ -660,17 +682,25 @@ fn diagram(app: &App) -> View<'_, Message> {
                     )),
                 ));
             }
+            selection_controls = selection_controls.push(
+                button(text("Delete from model…").size(12))
+                    .padding([6, 8])
+                    .on_press_maybe(
+                        crate::app::saved_removal::begin(app)
+                            .filter(|_| app.saved_removal_enabled()),
+                    ),
+            );
             selection_controls = selection_controls
                 .push(action(
-                    "Clear selection",
+                    "Clear",
                     Message::DiagramSelection(crate::app::multiselect::Event::Clear(
                         snapshot.context(),
                     )),
                 ))
                 .push(
                     label(format!(
-                        "Properties edit only {}",
-                        short(app.project().named(app.selected), 36)
+                        "Edit only {}",
+                        short(app.project().named(app.selected), 12)
                     ))
                     .wrapping(widget::text::Wrapping::None),
                 );

docs/language.rst

@@ -2279,6 +2279,28 @@ transition row, uses confirmed relation deletion for either key. States and
 referenced Activity/Function definitions remain. Hidden or collapsed rows are
 not keyboard deletion targets.
 
+For a group in a saved architecture or state view, plain Delete retains its
+placement-only Hide meaning; a mixture containing ports, edges or state rows
+MUST refuse Hide rather than silently delete model objects. Explicit group
+model deletion, including focused Shift+Delete, resolves each exact visible
+placement to its semantic element, each port to that port, each stored edge to
+its relation or trace, and each state row to its maintained relation. Navigation
+groupings and inferred edges are not semantic deletion subjects. Every original
+typed member MUST be admitted before redundant semantic subjects or cascade
+commands are reduced. A selected ancestor does not make a hidden or invalid
+member admissible. Existing project validity constraints, including placement
+uniqueness within a diagram, remain in force.
+
+Saved-view aggregate review distinguishes selected visual targets, unique
+semantic subjects, actual deleted records and changed surviving records. Model
+deletion affects all placements of deleted elements in all views. A trace does
+not cause deletion of its counterpart endpoints; an explicitly selected
+counterpart remains an independent deletion subject. Removing a state action
+row deletes its maintained relation, not the referenced Activity or Function.
+The combined candidate and source update MUST form one atomic transaction;
+neither partial primary-only deletion nor intermediate singleton history is
+permitted.
+
 Process and scenario projections have no independent occurrence placements.
 Delete and Shift+Delete request confirmed removal of the selected occurrence,
 participant or maintained link. A link's endpoints and outbound reusable
@@ -2292,6 +2314,26 @@ A qualified selection inside an expanded reusable process MUST NOT silently
 delete the outer reference or shared definition item. The editor directs the
 user to open the definition or explicitly select the outer reference.
 
+For a group of local Process or FunctionalChain contributions and maintained
+links, removal MUST admit every original typed selection member before reducing
+overlapping cascade commands. A selected link already removed by a selected
+occurrence's cascade remains a selected effect in the review. A mixed local and
+qualified selection MUST refuse as a whole, without a primary-only fallback.
+A locally owned ContextualLink is distinct from a read-only relation displayed
+inside a reused definition; its explicit owner governs removal even when both
+endpoint paths are qualified.
+
+The aggregate review MUST identify actual deleted records, changed surviving
+records, and affected caller definitions. Removing the last explicit topology
+marker can restore an exchange-only sequence's implicit ordered meaning;
+removing an interior exchange from a legacy order changes adjacent pairs.
+These consequences MUST be explicit before confirmation. Reused topology and
+entry/exit connections can also change without an interpretation-mode switch
+or new stored relation. Caller-definition counts MUST NOT be presented as
+counts of reference instances. Empty or incomplete surviving sequences retain
+their ordinary diagnostics; deletion MUST NOT invent replacement controls or
+links to conceal such consequences.
+
 Confirmation identifies the captured object and removal effect. Cancel and
 Escape preserve model, source and history. A confirmation token belongs to one
 dialog; changes to its document, revision, owner or selected identity invalidate

harness/DECISIONS.md

@@ -498,101 +498,3 @@ editing remains separate from semantic reconnect. The [decision and evidence
 map](edge-attachments-20260922.md) records alternatives, lifecycle rules,
 independent falsifiers, evaluators and the Process/Scenario applicability limits.
 This is branch-specific work; it does not establish an integrated release.
-
-## Retain released routing after independent corpus comparison — 2026-09-25
-
-Issue #32's [fixed comparison](experiments/routing-independent-20260925/results.md)
-rejects adoption of target-join J and bounded-lane L at this checkpoint. Optimized
-timings pass the declared screen, but a fixed edge-ID permutation worsens shared
-runs under both candidates; workshop label conflicts also increase. L's large
-workshop overlap improvement does not establish native traceability. Keep released
-`715036e` routing for the separate explicit Arrange-reset candidate. Preserve the
-experiments and stop tuning this corpus. Reconsider adoption only with meaningful
-named trace-task improvements, no newly ambiguous task, and appropriate runtime
-evidence. This is a branch-specific decision, not a completed Arrange feature or
-integrated release; the linked record retains rejected alternatives and limits.
-
-
-## Placement must respect derived ports and mandatory exits — 2026-09-25
-
-Branch-specific issue32 research, not an integrated release. The bounded
-[placement comparison](experiments/connection-layout-reference-20260925/results.md)
-shows that a node/label layout followed by independent port selection and routing
-is not a faithful transfer of a port-constrained engine result. Automatic ports
-change sides/slots after positions move even though authored anchors stay exact.
-The sparse reference's20-unit gap cannot contain the released router's18-unit
-port lead plus12-unit obstacle clearance. The sole endpoint pair is rejected
-before path search; increasing search work would not repair that placement.
-
-Keep both candidates experimental. A future candidate needs explicit final-port
-and mandatory-lead compatibility checks, compound/undirected semantics, and the
-existing preservation/native trace gates. Raw engine paths avoiding uninflated
-node interiors do not prove compatibility with our inflated obstacles and leads.
-Do not silently shorten those leads, move authored anchors, or persist external
-generated bends to make a comparison pass. Revisit engine integration only with
-a faithful geometry interface and observed usability benefit.
-
-## Lead compatibility does not establish layout quality — 2026-09-25
-
-The [bounded separation experiment](experiments/placement-clearance-20260925/results.md)
-at07405126 fixes the exact sparse mandatory-lead conflict by moving eight nodes
-down11 units. It removes NoClearPath and node penetration while preserving model
-records, anchors and repeated-call stability. Existing route-control output is
-byte-identical to released routing. However crossings20→22, shared length666→761
-and label/stroke intersections0→1 prevent a general readability improvement
-claim. Keep this flat-only repair isolated; do not connect it to production
-Arrange or increase its rounds to tune away the result. Use actual endpoint
-compatibility as a necessary placement constraint in a future initial coordinate
-assignment with connection ordering and corridor/label space. Compound geometry,
-automatic side changes and native tracing remain separate required evidence.
-This is branch-specific experimental evidence, not an integrated capability.
-
-## Keep cyclic groups coherent before assigning global ranks — 2026-09-25
-
-The [SCC placement experiment](experiments/scc-placement-20260925/results.md)
-at `2426d286` supports condensation of sibling-subtree cycles as a useful
-structural step. Independent reconstruction finds four ten-node components in
-the sparse case. Compact blocks remove the old layered prototype's shared top
-corridor: raw pairwise sharing falls from 40,522 to 32, with fewer crossings and
-less area than that prototype. The released router is unchanged. The full
-comparison includes original and Arrange-reset controls; this is not a universal
-improvement across all measures or scenes.
-
-Preserve effective geometry at the placement-transfer boundary. An old
-projected size can depend on children that subsequently move inward; retaining
-the old authored size then loses an explicitly requested minimum. The corrected
-example importer makes one conditional simultaneous minimum restoration and
-still demands exact final projection. All 14 frozen cases now complete; the
-13 prior successful outputs remain exactly unchanged, with conservation,
-roundtrip and ten-call checks recorded. This is an experimental transfer
-contract, not a production command or history integration.
-
-Do not adopt the whole candidate yet. The two-container case still ignores
-external-neighbor order within each parent and is worse than the old layered
-zero-sharing witness. Sparse residual label conflicts, folded route retracing,
-bipartite sharing and area tradeoffs remain distinct issues. The next bounded
-comparison should preserve coherent SCC ranks while using actual cross-boundary
-neighbors to order siblings. Treat label association separately from route
-sharing, preserve the full quality vector, and retain native tracing as a later
-acceptance gate. No global gap or routing-penalty sweep follows from this result.
-
-## Incoming boundary order is useful but not sufficient — 2026-09-25
-
-The [boundary-order comparison](experiments/boundary-order-20260925/results.md)
-at3e21c1bc preserves SCC blocks/ranks and orders same-rank child blocks using
-incoming external source centers. Dependency components provide deterministic
-propagation; cycles use one simultaneous snapshot. It fixes the declared
-simple two-container tracing witness (sharing164→0) and three-parent chain,
-while preserving all ten flat Projects/metrics exactly. All20 candidates pass
-independent full-Project conservation. Native saved-Project inspection confirms
-the simple trace improvement without establishing a native planner integration.
-
-Retain the mechanism experimentally. Folded workshop sharing726.5→1077.5,
-expanded crossing6→7, and anchored/local-SCC label intersections prevent
-unconditional adoption. Native anchored labels remain readable while their
-backgrounds interrupt the parent border: geometric collision counts require
-severity and ownership interpretation, not silent removal. Full member displacement
-must be checked in f64 before final f32 rounding; checking only a rounded delta
-misses large-origin errors. No further parameter sweep or release change is
-justified by this checkpoint. Production selection, label handling and integration
-remain open; the user requested a stop after publication.

harness/STATE.md

@@ -25,13 +25,7 @@ the current code includes that one-line correction. The original compile failed
 before running tests. The first combined compile at `897d9f04` subsequently
 found a missing `text_editor` import in the Allocation Text Apply regression;
 the current source includes that one-line correction too. Both failures remain
-recorded in the source handoff. The subsequent full test run at `8ddfadf4`
-failed the mounted State picker fixture: added selection controls invalidated
-its canvas-relative clicks. Source successor `a9cd364eacbbffa0693bab05b5a2b65f9d105535`
-measures an identified fixed-height picker slot and checks Escape capture,
-retaining the exact preservation/reopen/Place/Undo assertions. The source
-handoff links the preserved failed and interrupted attempts. Corrected combined
-Windows execution and package acceptance remain pending.
+recorded in the source handoff. Corrected combined execution remains pending.
 
 Live build, final-source and publication results belong in
 [issue37](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/37).

harness/auto-layout-investigation-20260925.md

@@ -1,160 +0,0 @@
-# Automatic layout investigation
-
-Issue [32](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/32)
-owns scope, ownership, milestones and integration status. This is an experiment
-record above released `715036e132677dd2bc2fb37ed316d93dc9987aec`, not an accepted
-replacement layout contract or a completed fix. User-owned requirements remain
-in `PROJECT_GOAL.md` and the issue.
-
-The [first executed experiment](experiments/auto-layout-20260925/results-01.md)
-records nine Windows fixtures at `e7deea70`: hierarchy/label improvements,
-repeat stability, and two shared-connector regressions. The candidate remains
-experimental; successful execution is not acceptance of a replacement command.
-
-The [target-join experiment](experiments/auto-layout-20260925/results-j.md)
-isolates a routing score correction with fixed Projects/nodes/ports/endpoints.
-Its 185 regression checks pass, but an original-scene overlap regression and
-additional bipartite T contacts prevent a general readability acceptance.
-
-The [completed scoring/lane comparison](experiments/auto-layout-20260925/results-lanes.md)
-records J/P/PL/L and closes this fixture-tuning experiment. L passes 188 selected
-checks and strict core Clippy, but residual ambiguity and a runtime cost signal
-require broader, independently selected evidence before production adoption.
-
-The [frozen independent corpus comparison](experiments/routing-independent-20260925/results.md)
-passes its optimized timing screen but exposes additional ID-order and label
-tradeoffs. Retain released routing for the separate route-reset work; J/L remain
-experiments without native traceability acceptance. Its complete inputs, raw
-receipts, corrected evaluator and independent reviews are recorded together.
-
-## Question and existing evidence
-
-Can explicit Auto-layout produce a readable arrangement that accounts for
-connections and their labels, including removal of stale bends, while preserving
-semantic endpoints, containment/allocation, source parity and reversible editing?
-
-The current `session::layout` sizes the containment forest, sorts roots using
-directed edges and alias tie breaks, places four roots per row, and translates
-authored route points only when both actual endpoints move equally. Its authored
-route preservation is deliberate and tested in `tests/release_routing.rs` and
-`tests/state_diagrams.rs`; the user's requested automatic bend replacement needs
-an explicit amendment, not a silently weakened test.
-
-The [source map](experiments/auto-layout-20260925/source-evaluator-map.md)
-identifies the actual callers and preserved input/source/API contracts. The
-[primary-source research](experiments/auto-layout-20260925/research.md) compares
-Sirius/Capella workflows, ELK and reuse of the existing Rust router. The
-[candidate critique](experiments/auto-layout-20260925/candidate-critique.md)
-records unresolved design gaps before any production choice.
-
-The existing `routing` module already supplies bounded deterministic orthogonal
-search, node/header obstacles, fixed semantic port endpoints, crossing/shared-run
-costs and automatic label collision search. Automatic elbows are derived, not
-persisted. The investigation should reuse this capability unless experiments
-show a concrete reason to replace it. Process topology rendering is a different
-path; its reported overlapping routes do not alone prove an Auto-layout defect.
-
-## Candidate decisions, not yet accepted
-
-Compare these materially different choices against visible route/label quality,
-semantic conservation, predictable user control, runtime/dependency cost,
-determinism, model size and maintainability:
-
-1. Retain node arrangement and only reset effective visible route/label constraints.
-   This is a useful control, but cannot by itself optimize poor node ordering.
-2. Use a hierarchy-aware layered node arrangement and the existing router, with
-   label-aware spacing and bounded crossing-reduction sweeps. Explicit Auto-layout
-   can replace effective visible pins/label offsets; ordinary drag keeps its
-   existing preservation rules. This is a candidate, not a chosen implementation.
-3. Adopt a mature external layout engine, accounting for ports, labels, nested
-   containers, runtime packaging and coordinate conversion. Evidence must justify
-   the integration/dependency cost over reusing the current router.
-
-Open contract questions include hidden/folded routes, authored attachment and port
-anchors, undirected and cyclic graphs, nested cross-boundary edges, repeated
-layout stability, and the observable treatment of exhausted search/poor results.
-No option may change semantic endpoints, ownership, allocation, expressions,
-relation kind or source identity to improve a drawing. Other views must remain
-unchanged, and one Undo on clean input must recover the complete pre-layout
-project. Existing application behavior applies an unrelated pending property
-draft first; that separate Apply is not silently folded into Layout's history.
-
-The initial experiment retains the current command as the baseline and compares
-reset-only with a layered prototype isolated under `examples/auto_layout_probe`.
-Neither prototype changes production behavior. Effective reset eligibility must
-come from the pre-layout projection and actual endpoint identities; merely being
-drawn does not make a promoted route's dormant metadata eligible. Explicit label
-reset means both fraction and offset, while semantic text and endpoint/port
-attachments remain fixed. Production adoption remains conditional on the
-critic's hierarchy, stability, direction, measurement and global-work checks.
-
-The first [probe recipe](experiments/auto-layout-20260925/probe-notes.md) covers
-nine small SA FunctionalDataflow fixtures. Its [independent source review](
-experiments/auto-layout-20260925/probe-review.md) found no blocker to that finite
-diagnostic run and lists important evaluator limitations. After that review,
-the parent inspected the added ten-call prototype stability loop and formatted
-the examples; the loop reports every differing/error result without a quality
-pass. No production file was changed. The experiment intentionally does not
-establish folded/filtered, State, Allocation, source-bundle or native acceptance.
-
-## Evaluator before implementation
-
-Use independently specified small graphs and real project views. Separate proper
-crossings, collinear shared runs, obstacle collisions, label/card collisions,
-label/label collisions, routing warnings, bends, length and occupied area. A low
-crossing count alone can hide coincident edges or enormous drawings. Exempt only
-explicitly documented intentional containment and common endpoint geometry;
-never discard a failure because it is inconvenient to the proposed algorithm.
-
-Compare the current command and the reset-only control before choosing a design.
-Include a chain longer than the current four-column row, diamond/bipartite cases,
-nested cross-boundary exchanges, stale authored detours/labels, fixed ports,
-cycles/self-loops and disconnected components. Check deterministic repeat calls,
-idempotence, model/source round trips and complete Undo/Redo. A probe is evidence
-about its named fixtures, not universal graph quality or native usability.
-
-Actual representative Windows workflows, including meaningful window/zoom sizes,
-selection and saved reopen, follow an implemented candidate. Linux remains
-excluded by the current user instruction. The separately published State label
-candidate in issue36 is not silently treated as integrated into this base.
-
-
-## Placement/reference compatibility checkpoint
-
-The [fixed external placement comparison](experiments/connection-layout-reference-20260925/results.md)
-tests the old native prototype and elkjs0.12.0 positions through the released
-router on the same independent corpus. Mixed placement metrics improve, but
-automatic ports differ from the engine's assumptions; the sparse candidate
-violates mandatory port-exit clearance and falls back before path search.
-Both workshop reference cases reject an unsupported undirected edge. Neither
-candidate is adopted. The next interface must account for final automatic
-ports and mandatory leads, not only node/label boxes. All results remain
-branch-specific; Gitea holds publication and integration status.
-
-The follow-up [mandatory-lead separation experiment](experiments/placement-clearance-20260925/results.md)
-supplies that necessary check using the router's actual endpoint choices. One
-bounded flat repair removes the sparse hard routing failure, but worsens crossing,
-shared-run and label/stroke measures. Preserve the compatibility result without
-adopting this repair as Arrange. Initial connection ordering and reserved routing/
-label space, with compound handling, remain the next planner questions; more
-repair iterations or router penalty tuning are not supported by this evidence.
-
-The [coherent cyclic-group experiment](experiments/scc-placement-20260925/results.md)
-then isolates the old native candidate's rank-stretching problem. Sparse sharing
-falls from 40,522 to 32 with unchanged released routing. A corrected importer
-preserves requested effective container minima after child movement; all 14
-frozen cases complete and the 13 previously successful results remain exact.
-This is useful structural evidence, not an Arrange replacement. Cross-boundary
-child ordering, local label conflicts and folded backtracking remain explicit
-witnesses. Source, failed/successful runs, conservation and independent reviews
-are linked from the result. Gitea remains authoritative for live ownership and
-publication status; no integrated checkpoint or release change is implied.
-
-The [incoming boundary-order experiment](experiments/boundary-order-20260925/results.md)
-resolves the exact simple two-container tracing defect and preserves all flat
-SCC results. Twenty supported cases retain model/anchor/block invariants, but
-workshop sharing/crossing and label tradeoffs remain. Saved-Project native
-inspection confirms the simple benefit and limits the severity interpretation
-of anchored label intersections. This is a published research checkpoint, not
-an integrated Arrange replacement. Gitea records handoff and the user-requested
-pause; no further experiment is authorized during that pause.

harness/experiments/auto-layout-20260925/candidate-critique.md

@@ -1,38 +0,0 @@
-# #32 candidate critique — 2026-09-25
-
-Read-only adversarial review of `harness/auto-layout-investigation-20260925.md` in the715036e-based isolated checkout, against the source/evaluator map. This critiques candidate choices; no implementation, execution or acceptance is claimed.
-
-## Recommendation
-
-Use the existing explicit **Command::Layout / Auto-layout / Arrange elements** operation for the new automatic behavior. The user specifically asks that operation to replace bends and consider labels/intersections. A second command/UI choice would preserve the obsolete behavior as a competing default without demonstrated need. Deliberately amend its documented contract and focused preservation tests, retain exact Undo, and retain existing ordinary drag/Arrange-next-drag contracts. A new command becomes warranted only if concrete compatibility/user workflows require both automatic policies, not merely because a test currently asserts old behavior.
-
-Prefer comparing candidate1 reset-only against candidate2 layered siblings plus the existing router. No external engine is justified yet. The existing router already creates derived elbows, so reset does not require writing every solver corner as a persisted hard pin. Keep generated corners derived initially; the saved node placement plus remaining explicit attachments determines their repeatable reconstruction.
-
-Recommended explicit Layout route contract: identify eligible visible, non-promoted edges from the **pre-layout projection**, remove their stored waypoints and label override (fraction and offset together), retain source/target attachments and node port anchors. Retain unrelated/hidden/promoted route records with existing equal-delta endpoint-owner translation. Do not call broad Reset routing if that also clears attachments. Preserve stable route-list order and remove an emptied record only under an explicit canonical no-metadata rule. Layout-generated record churn is not progress.
-
-## Blocking design gaps before accepting candidate2
-
-1. **Eligibility must be frozen once.** Visible edges, semantic endpoint-owner placements and promoted endpoints are different sets. Compute the reset set before node movement using projection visibility plus actual owner identity, not “every stored edge” or endpoints merely present in `d.nodes`. A filtered/hidden edge can retain a valid route; a folded edge may be drawn from an ancestor while its own route is suspended. Recomputing eligibility mid-layout risks erasing metadata when visibility/promotion changes. Small experiment: parallel visible/filtered edges, one folded child endpoint, and one both-endpoints-fold-to-same-anchor edge, all with distinctive pins/labels/attachments. Require only declared reset members to change, and retained pins to translate only through the existing owner-delta rule. Unfold/unfilter must reveal the retained custom route.
-
-2. **Two forests are needed conceptually, not two model hierarchies.** The authored projection-parent forest includes folded descendants; the rendered topology may omit them. Reordering only rendered nodes can leave hidden children outside resized parents or leave future expand geometry broken. Conversely, expanding all hidden content for outer layout wastes space and ignores the actual view. Decide visible sibling arrangement versus hidden subtree placement/reservation explicitly. Lift each rendered inter-subtree edge to the relevant direct children at its lowest common ancestor; do not flatten every edge to roots (loses nested ordering) or count the same edge at every depth as independent demand. Small experiment: nested A/B children with crossed exchanges, folded A, external sibling C and a State entry/exit boundary. Check containment/header/port-footer rules before and after expand, with semantic parents/allocations exact.
-
-3. **Idempotence will fail if spacing compounds current sizes.** Current measure uses each authored `node.size` as a lower bound. If label clearance expands a container and the next call adds the same margin again, repeated Arrange grows indefinitely. Label spacing based on previous routed bounds can similarly oscillate. Decide whether current sizes are immutable minima, or may shrink; the latter exceeds today's behavior and needs justification. Compute desired padding from content minima with `max`, not repeated addition to an already padded size. Small experiment: ten consecutive calls on nested long-label/parallel-edge fixtures, comparing full Projects after first vs second and sizes after tenth; repeat after Save/reparse. A two-call-only test can miss alternating period-two layouts.
-
-4. **Cycle/direction policy is not settled by “stable sweeps”.** Some projected edges are undirected; direction may be semantic or merely an endpoint representation. Use directed topology where justified, deterministic SCC treatment for cycles, and explicit undirected ordering inputs. Do not arbitrarily make a Capability/Traceability edge's serialized orientation a mandatory rank. Freeze alias/identity tie rules; crossing sweeps require a stable acceptance tie-break to avoid ping-pong. Small experiment: directed diamond+return, reversed undirected endpoint records, self-loop, parallel/reversed edges and disconnected isolates. Permute input records; independently require identical output for identical IDs and stable quality under UUID changes (not necessarily identical coordinates under reidentification).
-
-5. **Label reset and label-aware spacing need different evidence.** Clearing authored overrides is a reasonable explicit-auto interpretation but must be announced, since issue32 says “take into account” labels, not explicitly erase them. Retain semantic text/typed references; only the target view's override changes. A stale far-away label is a concrete reset fixture; an intentionally constrained attachment/label case tests whether residual collisions are honestly reported. Base715 label widths are scalar estimates, and State title/multiline geometry is known inaccurate without36. Do not tune spacing to claim accurate measured-State acceptance on715. First isolate ordinary/association labels; use conservative declared bounds for experiments, then rerun State B/W/U once36 integrates. Font-free core/API parity forbids quietly using desktop-only font results inside Command::Layout.
-
-6. **Bounded sweeps do not alone bound runtime.** Each complete route evaluation invokes previous-edge interactions, node obstacles and label comparisons; repeated per-sibling trial routing can multiply this cost by nodes×sweeps. Lifting topology naively can multiply edges×depth. Define global deterministic work budgets for candidate ordering/scoring, not just a fixed iteration count, and retain the best valid candidate on exhaustion. Route only a bounded number of whole candidates; cheap crossing surrogates can rank candidates but final acceptance must inspect actual geometry. Small experiment: a fixed family increasing sibling count/edge density/nesting, recording candidate count, comparison/work counters and wall time; include no-edge/isolate cases so they do not pay quadratic routing costs. No hard latency threshold should be fabricated from one machine.
-
-## Input/source/API contract checks
-
-- Clean whole-view Layout should create one reversible model/source transaction. `app.rs` applies a pending property draft before executing Layout, potentially as a separate transaction; do not accidentally promise one Undo reverses both an unrelated draft Apply and Layout. Use a clean-input one-step Undo oracle and a separate valid/invalid pending-draft admission test. Keep diagram UUID remapping, stale selection handling and disabled/pending form policy.
-- `prepare_command`/Document/source bundle/REST dry-run must produce the same Project for the same inputs without GUI fonts, caches or selection. A frontend-only rearrangement would fail this. Roundtrip the stored record representation, check unrelated source files/comments remain exact, and recover the exact old source/model with Undo—not merely visually similar positions.
-- Keep Allocation Arrange-next-drag, ordinary group translation, semantic ports, reconnect, Hide/show, collapse flags and other diagrams unchanged. A route reset belongs only to explicit Layout. A failed candidate must not clear history or leave a partially reset diagram.
-- Native validation later needs visible controls, Fit/export agreement, actual label containment and route readability, plus Save/reopen/Undo. Do not extend the implementation merely to expose a new State Auto-layout control before a demonstrated workflow need; shared State initialization still needs regression coverage.
-
-## Smallest discriminating experiment set
-
-Freeze six hand-built cases before implementation: (A) stale dogleg+far label with fixed attachments, (B) two-container reversed sibling connections with a known zero-crossing witness, (C) nested folded/filtered route-conservation sentinel, (D) cycle/self-loop/parallel/undirected variants, (E) long ordinary/association labels with feasible compact clearance, (F) dense bounded stress. Compare existing Layout, reset-only, and a layered prototype on the same independent vector: invalid overlap/penetration, label collisions, proper crossings, positive collinear overlap, turns, path length/stretch, area and routing warnings. Include ten-call idempotence, exact other-view/semantic conservation, source roundtrip and Undo/Redo.
-
-Candidate2 earns selection only if it materially improves at least B/E over reset-only without regressing the hard invariants or bounded workload. A tie favors the smaller candidate. A nonplanar or contradictory-fixed-port fixture may retain crossings; zero-crossing-by-overlap, giant detours, hidden edges or clipped labels is not a solution. Failure on a named fixture should revise the exact layer/policy implicated, not trigger an automatic wholesale engine dependency.

harness/experiments/auto-layout-20260925/compare_probe.py

@@ -1,56 +0,0 @@
-"""Compare fixed Project/node/port/endpoint geometry and report routing changes.
-
-Usage: python compare_probe.py OLD_JSONL NEW_JSONL NEW_OUTPUT_JSON
-No layout-quality pass is inferred from equal inputs or successful execution.
-"""
-from pathlib import Path
-import hashlib
-import json
-import sys
-
-old_path, new_path, out = map(Path, sys.argv[1:])
-def read(path):
-    rows = [json.loads(line) for line in path.read_text(encoding='utf-8').splitlines()]
-    return {row['fixture']: row for row in rows if 'fixture' in row}
-old, new = read(old_path), read(new_path)
-assert old.keys() == new.keys()
-def variants(row):
-    yield 'before', row['before_project'], row['before']
-    yield 'baseline', row['after_project'], row['after']
-    for name in ['reset_only_control', 'experimental_candidate', 'manual_planar_order_witness']:
-        if row[name] is not None:
-            yield name, row[name]['project'], row[name]['metrics']
-def endpoints(metrics):
-    return {e['id']: [e['points'][0], e['points'][-1]] for e in metrics['routed_edges']}
-keys = ['proper_crossings', 'pairwise_collinear_shared_length',
-        'nonterminal_pairwise_shared_length', 'unrelated_node_collisions',
-        'unrelated_edge_node_penetrations', 'label_node_collisions',
-        'label_label_collisions', 'unrelated_label_stroke_intersections',
-        'warning_count', 'route_bends', 'route_length', 'drawing_area']
-results = []
-for name in old:
-    lhs, rhs = list(variants(old[name])), list(variants(new[name]))
-    assert len(lhs) == len(rhs)
-    for (variant, op, om), (other, np, nm) in zip(lhs, rhs):
-        assert variant == other
-        fixed = {'project':op == np, 'nodes':om['projected_nodes'] == nm['projected_nodes'],
-                 'ports':om['projected_ports'] == nm['projected_ports'],
-                 'route_endpoints':endpoints(om) == endpoints(nm)}
-        results.append({'fixture':name, 'variant':variant, 'fixed_geometry':fixed,
-            'metrics':{key:{'old':om[key], 'new':nm[key]} for key in keys},
-            'new_point_contacts':nm.get('point_contacts'),
-            'new_point_contact_details':nm.get('point_contact_details')})
-summary = {'old_sha256':hashlib.sha256(old_path.read_bytes()).hexdigest(),
-           'new_sha256':hashlib.sha256(new_path.read_bytes()).hexdigest(),
-           'all_projects_nodes_ports_endpoints_exact':all(all(r['fixed_geometry'].values()) for r in results),
-           'scope':'Fixed-geometry comparison; quality vector retained, no aggregate quality pass.',
-           'results':results}
-with out.open('x',encoding='utf-8') as f:
-    json.dump(summary,f,indent=2)
-    f.write('\n')
-print(json.dumps({k:v for k,v in summary.items() if k != 'results'}))
-for row in results:
-    if row['variant'] == 'experimental_candidate':
-        print(json.dumps({'fixture':row['fixture'], 'fixed_geometry':row['fixed_geometry'],
-            'changed_metrics':{k:v for k,v in row['metrics'].items() if v['old'] != v['new']},
-            'point_contacts':row['new_point_contacts']}))

harness/experiments/auto-layout-20260925/lanes-results-audit.md

@@ -1,46 +0,0 @@
-# L results and four-way routing experiment audit
-
-Recommendation: stop tuning these fixtures. L is a useful experimental witness that route alternatives affect sharing, but its small layered benefit and material runtime signal do not presently justify its per-leg preprocessing as a production default. Keep J as the simpler independently motivated scoring correction candidate; decide L only against frozen independent scenes and route-only timing. No production/native acceptance claimed.
-
-## Verified final L result
-
-Primary J06 pin `08656b18bf8934cf264469cf68fc6dea97c15cbb`; L11 pin `e8ec6dbb3160f62476a5557f14605f68959f65fe`. Both recorded offline dev/gnullvm probe commands exit0, source unchanged, failure null. Verified receipt log hashes. Separate raw-output traversal confirms all37 Projects, projected nodes/ports and per-edge endpoint records exactly equal. All nine candidate supported/repeat-input/idempotence/ten-call/JSON-and-single-source-roundtrip results remain true, with unchanged conservation and baseline history checks. Candidate Command/Undo integration remains absent.
-
-J→L changed scalar rows only:
-
-- Original bipartite raw sharing872→724, nonterminal800→652.
-- Layered bipartite raw187→176, nonterminal115→104; drawing area175960→165360.
-- Original two-container raw/nonterminal54→12.
-- Two-container baseline and reset raw/nonterminal18→12 each.
-
-The other32 rows are unchanged in recorded scalar quality metrics. No changed point-contact, proper-crossing, length, bend, warning or collision counts in J→L. Independently comparing full candidate metric objects confirms all nine L layered metrics exactly equal PL, not merely the headline totals. Remaining layered bipartite104 nonterminal shared units still prohibit a solved-traceability claim.
-
-Test10 receipts record135+7+13+18+2+13=188 passed,0 failed/ignored, exit0, unchanged source. J02 and L10 command argv and entire recorded environment dictionaries compare equal. Their routing_geometry test summary elapsed4.30s versus16.43s (~3.82 times, +12.13s); parent reports no concurrent agent compiler. This is a material cost signal, not a controlled routing benchmark: suite runtime includes varied tests and scheduling effects, with no repeated route-only timing. It must not be dismissed by quoting cargo compilation time or presented as an established scaling law.
-
-Verified37 L schematic image hashes/lengths and manifest input hash. Native/glyph rendering was not exercised. Strict Clippy12 was active when assigned and is outside this audit; no outcome inferred.
-
-## Four-way conclusion
-
-All numbers below are raw pairwise shared length; inspect the preceding audits for contacts/area/turn tradeoffs.
-
-| Scene/variant | J | P | P+L | L |
-|---|---:|---:|---:|---:|
-| Layered bipartite |187|187|176|176|
-| Original bipartite |872|730|724|724|
-| Baseline/reset bipartite |276|276|72|276|
-| Original two-container |54|6|12|12|
-| Baseline/reset two-container |18|18|12|12|
-
-P has no layered benefit. P+L's baseline bipartite72 means only common terminal sharing remains, but proper crossings rise0→1, length+24 and area+19392; L alone does not produce that tradeoff. The strongest ordinary two-container sharing result is P6, at an extra bend,12 length units and one T contact. Neither the coefficient nor lanes dominates all vectors. J diamond's isolated improvement remains valid but does not erase its original bipartite regression.
-
-Next scope should be finite and specified before inspecting outcomes: one realistic nested/folded scene, one mixed fan-in/out with a fixed edge-ID permutation, and one modest sparse scene measured by route-only timing and warning/budget counts. Preserve endpoint/model constraints and evaluate traceability, collisions, bends/length/area jointly. Do not silently extend unsupported layered folded behavior into an acceptance claim. Set practical timing and readability criteria before repeating improvement. If L does not show proportionate independent benefit, omit it; avoid adding configuration/architecture solely to retain every experiment. The explicit Layout reset policy and ordinary input/Undo/Save lifecycle are still separate implementation work.
-
-## Evidence identities
-
-J06 output `f9ac7c1320b1cf026259bfcaf13a39e968ae317463712d8dc793375d9a4a541f`.
-L11 output `64232f580600b7a874a6f4ceb128a6188fd5ff72655bc6b93d824ebed27ffb7d`.
-L11 result.json `feee84c2fde115c22ea865033ff2d136da2aace1f1c8a7423c8add11358366a8`.
-L comparison JSON `e1e23e6c2a50cd384457bb061d5b70a740f586f42767164fad9703ecbb4096a8`.
-L contact audit JSON `6f6cc674c27d3f43001fe1751ef3b09332caa9ddca396759f5525f811cbe1aaf`.
-
-Read-only audit of completed records; no build/probe/helper rerun, source edit or publication. Earlier independent J/P/PL source/results notes retain grid-axis, subdivision-score, capped retained coordinates versus unbounded preprocessing, stable-edge-order and approximate-label limitations.

harness/experiments/auto-layout-20260925/lanes-source-review.md

@@ -1,20 +0,0 @@
-# Bounded L lane-candidate source review
-
-Reviewed routing.rs SHA256 `af5995af10c8e3b30c5c6fb776a2ac2678eeef59dd58eb0cdb3d5c62cd153f1b` before parent formatting. Static inspection only; no builds or source edits. No blocking implementation finding for the finite nine-fixture P+L / J+L probe comparison.
-
-The code retains all sorted base obstacle coordinates and adds at most64 unique extras EACH axis (128 total), filters nonfinite generated values, deduplicates before ranking, then ranks distance from the start/end axis interval, distance from its midpoint, and numeric value. Final lists return to coordinate order. It derives perpendicular offsets only from nondegenerate settled other-edge segments. The current edge's earlier legs/source stub still contribute occupied scoring but do not generate lanes. Fast/grid receive the identical per-leg RoutingSpace; obstacles, endpoints, authored pins, terminal joins and fallback remain unchanged.
-
-Three new tests cover80 retained base coordinates plus64 extras per axis, previous-segment reorder/duplication invariance, nearest-interval/midpoint selection and nonfinite rejection, and direct calls to fast/grid sharing the same parallel-lane witness. The latter expects min(direct cost,272) and supports both coefficients. No test success is inferred before execution.
-
-Test-scope caveat sent to parent: the existing `unspecified_continuation_keeps_intermediate_leg_choice` test deliberately hardcodes baseline coefficient0.12, path choice and cost255.52. At P3, the shared penalty caps80 and the alternative is cheaper; a whole private suite at P3 can fail that baseline-policy assertion. Preserve the result honestly; restore0.12 for baseline-suite claims or explicitly distinguish experimental tests. This does not block a diagnostic P+L probe.
-
-Limits relevant to interpreting results:
-
--64 bounds retained coordinates, not scan/sort work. Every endpoint-pair/leg constructs candidates from all previous segments; this preprocessing is outside the search-step budget. No large-scene performance guarantee.
-- Added coordinates can make the grid exceed65536 cells even when its original grid fit. Existing exhaustion warning/fallback is the evidence to inspect, not something to suppress.
-- Grid scoring is coordinate-subdivision-sensitive: strict-interior crossing tests can miss contacts at inserted grid vertices, and per-segment capped overlap charges can change with subdivision. Therefore a grid result can change due to scoring partition as well as newly offered parallel lanes. Keep independent contact/shared-interval metrics authoritative for quality observations.
-- Rank uses one axis and does not filter segment extent on the other; remote lanes can consume the cap. This deterministic heuristic is not proof of optimal lane coverage. The router still uses a feasible fast path before grid, two-axis rather than signed-direction search state, stable sequential edge order, and local hard-pin legs.
-
-Required experiment interpretation: compare P+L to P and J+L to J with exact Project/node/port/endpoints, all quality metrics and warning counts. Retain label collisions, T/bend contacts, length/turn/area regressions; fewer shared units alone is not acceptance. No broad production or native readability conclusion follows from this finite source review.
-
-Current formatted routing SHA256: 3a8af7a44f8f32bd9fb94dddd9184fafcf64c93c510025169c62958566bbaedf. Reread formatted lane construction: filtering/ranking/cap semantics agree with reviewed candidate. No mechanical original-byte whitespace comparison claimed. Parent plans exactly the three lane-filtered private tests for P+L, then restores0.12 for the full baseline suite; that appropriately separates the baseline-policy assertion noted above.