Preserve authored projection content and contextual canvas selection

crates/oa-core/src/language.rs

@@ -340,6 +340,18 @@ pub(crate) fn diagnostic(source: &str, error: Error) -> Diagnostic {
         },
     }
 }
+pub(crate) fn diagnostic_with_issue(
+    source: &str,
+    error: Error,
+    issue: Option<validation::Issue>,
+) -> Diagnostic {
+    let mut result = diagnostic(source, error);
+    if let Some(issue) = issue {
+        result.object_id = issue.element;
+        result.field = issue.field;
+    }
+    result
+}
 fn reserved(word: &str) -> bool {
     crate::reserved_alias(word)
         || declaration_kind(word).is_some()
@@ -622,6 +634,7 @@ fn parse_document(source: &str, limits: ParseLimits) -> Result<ParsedDocument, V
     if tokens.get(1).is_some_and(|t| t.text(source) == "2") {
         return v2_source::parse(source, tokens, limits);
     }
+    let mut migration_issue = None;
     Parser {
         source,
         tokens,
@@ -629,8 +642,8 @@ fn parse_document(source: &str, limits: ParseLimits) -> Result<ParsedDocument, V
         value_depth: 0,
         limits,
     }
-    .document()
-    .map_err(|e| vec![diagnostic(source, e)])
+    .document(&mut migration_issue)
+    .map_err(|e| vec![diagnostic_with_issue(source, e, migration_issue)])
 }
 fn offset_for(source: &str, line: usize, column: usize) -> usize {
     let mut offset = 0;
@@ -1449,7 +1462,10 @@ impl Parser<'_> {
             },
         }
     }
-    fn document(&mut self) -> Result<ParsedDocument, Error> {
+    fn document(
+        &mut self,
+        migration_issue: &mut Option<validation::Issue>,
+    ) -> Result<ParsedDocument, Error> {
         let unit = self.unit(true, false)?;
         let header = unit.header.expect("entry header");
         let mut aliases = BTreeMap::from([(header.project.alias.clone(), header.project.id)]);
@@ -1476,9 +1492,14 @@ impl Parser<'_> {
                     .map(|(key, span)| ((d.id, key.clone()), span.start)),
             );
         }
-        let decoded =
-            resolve_declarations(header.project, &unit.declarations, &aliases, self.limits)
-                .map_err(|(_, error)| error)?;
+        let decoded = resolve_declarations(
+            header.project,
+            &unit.declarations,
+            &aliases,
+            self.limits,
+            migration_issue,
+        )
+        .map_err(|(_, error)| error)?;
         Ok(ParsedDocument {
             project: decoded.project,
             migration: decoded.migration,
@@ -1682,6 +1703,7 @@ pub(crate) fn resolve_declarations(
     declarations: &[Declaration],
     aliases: &BTreeMap<String, Id>,
     limits: ParseLimits,
+    migration_issue: &mut Option<validation::Issue>,
 ) -> Result<crate::persistence::DecodeResult, (usize, Error)> {
     let legacy = project.schema_version == 3;
     let mut legacy_elements = serde_json::Map::new();
@@ -1989,6 +2011,38 @@ pub(crate) fn resolve_declarations(
             crate::persistence::migrate_v6(project, limits)
         })
         .map_err(|error| {
+            // These frozen admission checks formerly ran in final validation.
+            // Keep their diagnostic code and reference location after moving
+            // them before schema normalization.
+            if let crate::persistence::FileError::Model { issues, .. } = &error
+                && let Some(issue) = issues.first()
+                && let Some(code) = match issue.code.as_str() {
+                    "diagram_layer" => Some("diagram_layer"),
+                    "view_options" => Some("view_options"),
+                    _ => None,
+                }
+            {
+                let index = issue
+                    .element
+                    .and_then(|id| declarations.iter().position(|d| d.id == id))
+                    .unwrap_or(usize::MAX);
+                let offset = declarations.get(index).map_or(0, |d| {
+                    issue
+                        .field
+                        .as_ref()
+                        .and_then(|field| d.field_spans.get(field))
+                        .map_or(d.offset, |span| span.start)
+                });
+                *migration_issue = Some(issue.clone());
+                return (
+                    index,
+                    Error {
+                        code,
+                        offset,
+                        message: issue.message.clone(),
+                    },
+                );
+            }
             (
                 usize::MAX,
                 Error {

crates/oa-core/src/migration_v4.rs

@@ -69,8 +69,8 @@ impl Project4 {
         }
         crate::persistence::check_pre6_relations(self.relations.values())?;
         crate::persistence::check_pre6_elements(self.elements.values())?;
-        Ok(Project {
-            schema_version: SCHEMA_VERSION,
+        let mut project = Project {
+            schema_version: self.schema_version,
             id: self.id,
             alias: self.alias,
             name: self.name,
@@ -84,7 +84,11 @@ impl Project4 {
                 .into_iter()
                 .map(|(id, trace)| (id, trace.into()))
                 .collect(),
-        })
+        };
+        // Schema3's adapter also enters here, without calling `finish`.
+        crate::persistence::check_pre7_diagram_admission(&project)?;
+        project.schema_version = SCHEMA_VERSION;
+        Ok(project)
     }
 }
 
@@ -104,6 +108,8 @@ pub(crate) fn review_defaults(project: &Project, report: &mut MigrationReport) {
 }
 
 pub(crate) fn finish(mut project: Project, limits: ParseLimits) -> Result<DecodeResult, FileError> {
+    // Source4 enters here directly rather than through `Project4`.
+    crate::persistence::check_pre7_diagram_admission(&project)?;
     crate::persistence::check_pre6_relations(project.relations.values())?;
     crate::persistence::check_pre6_elements(project.elements.values())?;
     project.schema_version = SCHEMA_VERSION;

crates/oa-core/src/persistence.rs

@@ -341,6 +341,50 @@ pub(crate) fn check_pre6_baseline(baseline: &SemanticBaseline) -> Result<(), Fil
     }
     Ok(())
 }
+/// Frozen sources 3–6 admit opposite-layer placements and visibility references
+/// only in Traceability. Check before migration discards the advertised version;
+/// current ordinary projections may retain these records as latent presentation.
+pub(crate) fn check_pre7_diagram_admission(project: &Project) -> Result<(), FileError> {
+    let mut issues = Vec::new();
+    for diagram in project.diagrams.values() {
+        let option_issues = if diagram.projection == ProjectionKind::Traceability {
+            crate::view_options::validate_options_cross_layer(project, &diagram.view_options)
+        } else {
+            crate::view_options::validate_options(project, diagram.layer, &diagram.view_options)
+        };
+        for issue in option_issues {
+            validation::error(
+                &mut issues,
+                diagram.id,
+                "view_options",
+                issue.field,
+                issue.message,
+            );
+        }
+        for node in diagram.nodes.values() {
+            if !project.elements.get(&node.element).is_some_and(|element| {
+                diagram.projection == ProjectionKind::Traceability
+                    || element.layer() == diagram.layer
+            }) {
+                validation::error(
+                    &mut issues,
+                    node.id,
+                    "diagram_layer",
+                    "element",
+                    "Diagram nodes reference existing elements in the selected layer.",
+                );
+            }
+        }
+    }
+    if let Some(issue) = issues.into_iter().next() {
+        return Err(FileError::Model {
+            message: issue.message.clone(),
+            issues: vec![issue],
+        });
+    }
+    Ok(())
+}
+
 pub(crate) fn migrate_v5(
     mut project: Project,
     limits: crate::language::ParseLimits,
@@ -348,6 +392,7 @@ pub(crate) fn migrate_v5(
     if project.schema_version != 5 {
         return Err(FileError::Invalid("Expected schema_version 5.".into()));
     }
+    check_pre7_diagram_admission(&project)?;
     check_pre6_relations(project.relations.values())?;
     check_pre6_elements(project.elements.values())?;
     for baseline in project
@@ -420,6 +465,7 @@ pub(crate) fn migrate_v6(
     if project.schema_version != 6 {
         return Err(FileError::Invalid("Expected schema_version 6.".into()));
     }
+    check_pre7_diagram_admission(&project)?;
     reject_source7_fields(&serde_json::to_value(&project)?).map_err(FileError::Invalid)?;
     limits.check_model(&project).map_err(FileError::Limit)?;
     project.schema_version = SCHEMA_VERSION;

crates/oa-core/src/projection.rs

@@ -85,6 +85,7 @@ pub(crate) fn parents(p: &Project, d: &Diagram) -> BTreeMap<Id, Option<Id>> {
         .filter(|n| {
             p.elements.get(&n.element).is_some_and(|e| {
                 e.kind() != Kind::Port
+                    && (d.projection == ProjectionKind::Traceability || e.layer() == d.layer)
                     && d.projection.includes(e.kind())
                     && d.projection
                         .state_machine()

crates/oa-core/src/session.rs

@@ -589,6 +589,17 @@ fn apply_command(
                 .map(|d| d.id)
                 .ok_or_else(missing)?;
             if source != *diagram {
+                let destination = &p.diagrams[diagram];
+                let element = p.diagrams[&source].nodes[node].element;
+                if destination.projection != ProjectionKind::Traceability
+                    && p.elements
+                        .get(&element)
+                        .is_none_or(|e| e.layer() != destination.layer)
+                {
+                    return Err(ModelError(
+                        "Move the placement to a view in its layer or a traceability view.".into(),
+                    ));
+                }
                 let placement = p
                     .diagrams
                     .get_mut(&source)

crates/oa-core/src/source_project.rs

@@ -573,16 +573,26 @@ fn compile_once(
             span,
         }),
     };
-    let decoded =
-        language::resolve_declarations(header.project, &declarations, &aliases, limits.model)
-            .map_err(|(index, error)| {
-                let path = declaration_paths.get(index).unwrap_or(&bundle.entry);
-                vec![SourceDiagnostic {
-                    path: path.clone(),
-                    diagnostic: language::diagnostic(&bundle.files[path], error),
-                    related: Vec::new(),
-                }]
-            })?;
+    let mut migration_issue = None;
+    let decoded = language::resolve_declarations(
+        header.project,
+        &declarations,
+        &aliases,
+        limits.model,
+        &mut migration_issue,
+    )
+    .map_err(|(index, error)| {
+        let path = declaration_paths.get(index).unwrap_or(&bundle.entry);
+        vec![SourceDiagnostic {
+            path: path.clone(),
+            diagnostic: language::diagnostic_with_issue(
+                &bundle.files[path],
+                error,
+                migration_issue,
+            ),
+            related: Vec::new(),
+        }]
+    })?;
     let diagnostics = model_diagnostics(bundle, &index, &decoded.project);
     let errors: Vec<_> = diagnostics
         .iter()

crates/oa-core/src/validation.rs

@@ -620,11 +620,14 @@ pub fn validate(p: &Project) -> Vec<Issue> {
         text(&mut out, d.id, "name", &d.name);
         text(&mut out, d.id, "description", &d.description);
         crate::scenario_layout::validate_diagram(p, d, &mut out);
-        let option_issues = if d.projection == ProjectionKind::Traceability {
-            crate::view_options::validate_options_cross_layer(p, &d.view_options)
-        } else {
-            crate::view_options::validate_options(p, d.layer, &d.view_options)
-        };
+        // Ordinary projections are reversible filters over the same authored view.
+        // Retain opposite-layer visibility choices when leaving Traceability.
+        let option_issues =
+            if d.projection.state_machine().is_none() && d.projection.scenario().is_none() {
+                crate::view_options::validate_options_cross_layer(p, &d.view_options)
+            } else {
+                crate::view_options::validate_options(p, d.layer, &d.view_options)
+            };
         for issue in option_issues {
             error(&mut out, d.id, "view_options", issue.field, issue.message);
         }
@@ -798,8 +801,10 @@ pub fn validate(p: &Project) -> Vec<Issue> {
                 );
             }
             match p.elements.get(&n.element) {
-                Some(e) if d.projection == ProjectionKind::Traceability || e.layer() == d.layer => {
-                }
+                Some(e)
+                    if (d.projection.state_machine().is_none()
+                        && d.projection.scenario().is_none())
+                        || e.layer() == d.layer => {}
                 _ => error(
                     &mut out,
                     n.id,

crates/oa-core/src/view_options.rs

@@ -218,7 +218,9 @@ pub fn validate_options(p: &Project, layer: Layer, options: &ViewOptions) -> Vec
     validate_options_in(p, Some(layer), options)
 }
 
-/// Traceability views admit references from either architecture layer.
+/// Ordinary saved views retain references from either architecture layer so
+/// projection changes preserve authored visibility choices. Projection decides
+/// which layer is visible; typed State/Scenario views use layer-scoped validation.
 pub fn validate_options_cross_layer(p: &Project, options: &ViewOptions) -> Vec<OptionError> {
     validate_options_in(p, None, options)
 }

crates/oa-core/tests/legacy_diagram_admission.rs

@@ -0,0 +1,203 @@
+//! Current latent presentation must not broaden frozen source/JSON admission.
+use oa_core::{view_options::*, *};
+
+fn legacy_json(project: &Project, version: u32) -> Vec<u8> {
+    let mut value = serde_json::to_value(project).unwrap();
+    value["schema_version"] = version.into();
+    for diagram in value["diagrams"].as_object_mut().unwrap().values_mut() {
+        let fields = diagram.as_object_mut().unwrap();
+        fields.remove("layout");
+        if version < 6 {
+            fields.remove("view_options");
+        }
+    }
+    serde_json::to_vec(&value).unwrap()
+}
+
+fn model_issue(error: persistence::FileError) -> validation::Issue {
+    match error {
+        persistence::FileError::Model { mut issues, .. } => issues.remove(0),
+        other => panic!("Expected a located model issue, got {other:?}"),
+    }
+}
+
+#[test]
+fn frozen_3_through_6_reject_cross_layer_nodes_but_keep_mixed_traceability() {
+    for version in 3..=6 {
+        let source = format!(
+            "arcadia {version}; project compat \"Compatibility\" {{\n\
+             sa_function work \"Counterpart\" {{}}\n\
+             diagram view \"OA concern\" {{ layer Oa; projection Traceability; }}\n\
+             node occurrence {{ diagram @view; element @work; }}\n}}"
+        );
+        let mixed = language::parse(&source).unwrap();
+        assert_eq!(
+            persistence::decode(&legacy_json(&mixed, version)).unwrap(),
+            mixed
+        );
+
+        let ordinary = source.replace("projection Traceability", "projection Overview");
+        let same_layer = ordinary.replace("layer Oa", "layer Sa");
+        let ordinary_project = language::parse(&same_layer).unwrap();
+        assert_eq!(
+            persistence::decode(&legacy_json(&ordinary_project, version)).unwrap(),
+            ordinary_project
+        );
+        let errors = language::parse(&ordinary).unwrap_err();
+        // Source3 already reported migration errors with the offending location.
+        let code = if version == 3 {
+            "migration_error"
+        } else {
+            "diagram_layer"
+        };
+        assert!(
+            errors.iter().any(|error| error.code == code
+                && error.line == 4
+                && error.message.contains("selected layer")),
+            "{version}: {errors:?}"
+        );
+
+        let mut latent = mixed.clone();
+        let diagram = latent.diagrams.values_mut().next().unwrap();
+        diagram.projection = ProjectionKind::Overview;
+        let node = diagram.nodes.values().next().unwrap().id;
+        if version >= 4 {
+            let diagnostic = errors
+                .iter()
+                .find(|error| error.code == "diagram_layer")
+                .unwrap();
+            assert_eq!(diagnostic.object_id, Some(node));
+            assert_eq!(diagnostic.field.as_deref(), Some("element"));
+            let bundle = source_project::SourceBundle {
+                entry: "model.arcadia".into(),
+                files: std::collections::BTreeMap::from([("model.arcadia".into(), ordinary)]),
+            };
+            let errors =
+                source_project::compile_bundle(&bundle, source_project::ProjectLimits::default())
+                    .unwrap_err();
+            let diagnostic = &errors
+                .iter()
+                .find(|error| error.diagnostic.code == "diagram_layer")
+                .unwrap()
+                .diagnostic;
+            assert_eq!(diagnostic.object_id, Some(node));
+            assert_eq!(diagnostic.field.as_deref(), Some("element"));
+        }
+        let issue = model_issue(persistence::decode(&legacy_json(&latent, version)).unwrap_err());
+        assert_eq!(issue.code, "diagram_layer");
+        assert_eq!(issue.element, Some(node));
+        assert_eq!(issue.field.as_deref(), Some("element"));
+        // The exact same record is valid under the current presentation contract.
+        assert_eq!(language::parse(&language::format(&latent)).unwrap(), latent);
+        assert_eq!(
+            persistence::decode(&serde_json::to_vec(&latent).unwrap()).unwrap(),
+            latent
+        );
+        let mut dangling = mixed;
+        dangling
+            .diagrams
+            .values_mut()
+            .next()
+            .unwrap()
+            .nodes
+            .values_mut()
+            .next()
+            .unwrap()
+            .element = Id::new_v4();
+        let issue = model_issue(persistence::decode(&legacy_json(&dangling, version)).unwrap_err());
+        assert_eq!(issue.code, "diagram_layer");
+        assert_eq!(issue.element, Some(node));
+        assert_eq!(issue.field.as_deref(), Some("element"));
+    }
+}
+
+#[test]
+fn frozen_6_checks_every_layer_sensitive_saved_selector_before_upgrade() {
+    let mut project = Project::empty();
+    let a = project
+        .add_element(Kind::Activity, Layer::Oa, "A", None)
+        .unwrap();
+    let b = project
+        .add_element(Kind::Activity, Layer::Oa, "B", None)
+        .unwrap();
+    let edge = project.relate(RelationKind::Interaction, "Interaction", a, b);
+    let category = project
+        .add_element(Kind::ExchangeCategory, Layer::Oa, "Work category", None)
+        .unwrap();
+    let participant_category = project
+        .add_element(
+            Kind::ExchangeCategory,
+            Layer::Oa,
+            "Participant category",
+            None,
+        )
+        .unwrap();
+    *project
+        .elements
+        .get_mut(&participant_category)
+        .unwrap()
+        .shared_mut()
+        .unwrap() = SharedBody::ExchangeCategory {
+        family: ExchangeFamily::Participant,
+        exchanges: vec![],
+    };
+    let context = project
+        .add_element(Kind::Process, Layer::Oa, "Process", None)
+        .unwrap();
+    let diagram = project.ensure_diagram(Layer::Sa);
+    for (field, options) in [
+        (
+            "hidden_edges",
+            ViewOptions {
+                hidden_edges: vec![edge],
+                ..Default::default()
+            },
+        ),
+        (
+            "work_categories",
+            ViewOptions {
+                work_categories: CategorySelection::Any(vec![category]),
+                ..Default::default()
+            },
+        ),
+        (
+            "participant_categories",
+            ViewOptions {
+                participant_categories: CategorySelection::Any(vec![participant_category]),
+                ..Default::default()
+            },
+        ),
+        (
+            "work_contexts",
+            ViewOptions {
+                work_contexts: ContextSelection::Any(vec![context]),
+                ..Default::default()
+            },
+        ),
+    ] {
+        project.diagrams.get_mut(&diagram).unwrap().view_options = options;
+        let issue = model_issue(persistence::decode(&legacy_json(&project, 6)).unwrap_err());
+        assert_eq!(issue.code, "view_options");
+        assert_eq!(issue.element, Some(diagram));
+        assert_eq!(issue.field.as_deref(), Some(field));
+        let current_source = language::format(&project);
+        assert_eq!(language::parse(&current_source).unwrap(), project);
+        let source6 = current_source.replacen("arcadia 7;", "arcadia 6;", 1);
+        let errors = language::parse(&source6).unwrap_err();
+        let diagnostic = errors
+            .iter()
+            .find(|error| error.code == "view_options")
+            .unwrap();
+        assert_eq!(diagnostic.object_id, Some(diagram));
+        assert_eq!(diagnostic.field.as_deref(), Some(field));
+
+        project.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Traceability;
+        assert_eq!(
+            persistence::decode(&legacy_json(&project, 6)).unwrap(),
+            project
+        );
+        let source6 = language::format(&project).replacen("arcadia 7;", "arcadia 6;", 1);
+        assert_eq!(language::parse(&source6).unwrap(), project);
+        project.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Overview;
+    }
+}

crates/oa-core/tests/projection_switching.rs

@@ -0,0 +1,156 @@
+use oa_core::{source_project::*, view_options::*, *};
+
+fn fixture(layer: Layer) -> (Project, Id, Id, Id, Id) {
+    let mut p = Project::empty();
+    let oa = p
+        .add_element(Kind::Activity, Layer::Oa, "Assess alarm", None)
+        .unwrap();
+    let oa2 = p
+        .add_element(Kind::Activity, Layer::Oa, "Respond", None)
+        .unwrap();
+    let sa = p
+        .add_element(Kind::Function, Layer::Sa, "Assess alarm", None)
+        .unwrap();
+    let edge = p.relate(RelationKind::Interaction, "Alarm", oa, oa2);
+    let category = p
+        .add_element(Kind::ExchangeCategory, Layer::Oa, "Alarm data", None)
+        .unwrap();
+    *p.elements.get_mut(&category).unwrap().shared_mut().unwrap() = SharedBody::ExchangeCategory {
+        family: ExchangeFamily::Work,
+        exchanges: vec![edge],
+    };
+    let context = p
+        .add_element(Kind::Process, Layer::Oa, "Alarm handling", None)
+        .unwrap();
+    let d = p.ensure_diagram(layer);
+    p.diagrams.get_mut(&d).unwrap().projection = ProjectionKind::Traceability;
+    for (i, element) in [oa, oa2, sa].into_iter().enumerate() {
+        p.place(
+            d,
+            element,
+            Position {
+                x: 300. * i as f32,
+                y: 40.,
+            },
+        );
+    }
+    p.diagrams.get_mut(&d).unwrap().view_options = ViewOptions {
+        hidden_edges: vec![edge],
+        work_categories: CategorySelection::Any(vec![category]),
+        work_contexts: ContextSelection::Any(vec![context]),
+        ..Default::default()
+    };
+    validate_candidate(&p).unwrap();
+    (p, d, oa, sa, category)
+}
+
+#[test]
+fn projection_switching_preserves_complete_model_history_and_all_serializations() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (baseline, diagram, _, _, _) = fixture(layer);
+        for projection in [
+            ProjectionKind::Overview,
+            ProjectionKind::Decomposition,
+            ProjectionKind::Allocation,
+            ProjectionKind::FunctionalDataflow,
+            ProjectionKind::Capabilities,
+        ] {
+            let mut expected = baseline.clone();
+            expected.diagrams.get_mut(&diagram).unwrap().projection = projection;
+            let mut session = Session::new(baseline.clone());
+            session
+                .execute(Command::EditDiagram(
+                    diagram,
+                    expected.diagrams[&diagram].clone(),
+                ))
+                .unwrap();
+            assert_eq!(session.project(), &expected);
+            let view = projection::project_view(session.project(), diagram);
+            assert!(
+                view.nodes
+                    .iter()
+                    .all(|n| expected.elements[&n.element].layer() == layer)
+            );
+            assert_eq!(
+                view,
+                projection::project_view_with_index(&expected, diagram, &ViewIndex::new(&expected))
+            );
+            let source = language::format(&expected);
+            assert_eq!(language::parse(&source).unwrap(), expected);
+            assert_eq!(
+                persistence::decode(&serde_json::to_vec(&expected).unwrap()).unwrap(),
+                expected
+            );
+            let bundle = format_bundle(&expected);
+            assert_eq!(
+                compile_bundle(&bundle, ProjectLimits::default())
+                    .unwrap()
+                    .decoded
+                    .project,
+                expected
+            );
+            session.undo();
+            assert_eq!(session.project(), &baseline);
+            assert!(!session.can_undo());
+            session.redo();
+            assert_eq!(session.project(), &expected);
+            session
+                .execute(Command::EditDiagram(
+                    diagram,
+                    baseline.diagrams[&diagram].clone(),
+                ))
+                .unwrap();
+            assert_eq!(session.project(), &baseline);
+            assert_eq!(
+                projection::project_view(session.project(), diagram),
+                projection::project_view(&baseline, diagram)
+            );
+        }
+    }
+}
+
+#[test]
+fn projection_switching_does_not_admit_missing_elements_or_invalid_filter_kinds() {
+    let (mut p, d, oa, _, category) = fixture(Layer::Sa);
+    p.diagrams.get_mut(&d).unwrap().projection = ProjectionKind::Allocation;
+    validate_candidate(&p).unwrap();
+    let valid = p.clone();
+    let node = p.diagrams[&d]
+        .nodes
+        .values()
+        .find(|n| n.element == oa)
+        .unwrap()
+        .id;
+    p.diagrams
+        .get_mut(&d)
+        .unwrap()
+        .nodes
+        .get_mut(&node)
+        .unwrap()
+        .element = Id::new_v4();
+    assert!(validate_candidate(&p).is_err());
+    p = valid.clone();
+    p.diagrams.get_mut(&d).unwrap().view_options.work_categories = CategorySelection::Any(vec![oa]);
+    assert!(validate_candidate(&p).is_err());
+    p = valid;
+    p.elements.remove(&category);
+    assert!(validate_candidate(&p).is_err());
+}
+
+#[test]
+fn projection_switching_keeps_typed_state_membership_strict() {
+    let (mut p, d, _, _, _) = fixture(Layer::Sa);
+    let system = p
+        .add_element(Kind::System, Layer::Sa, "System", None)
+        .unwrap();
+    let machine = p
+        .add_element(Kind::StateMachine, Layer::Sa, "Modes", Some(system))
+        .unwrap();
+    p.diagrams.get_mut(&d).unwrap().projection = ProjectionKind::StateMachine { machine };
+    assert!(
+        validation::validate(&p)
+            .iter()
+            .any(|i| i.code == "state_diagram_member")
+    );
+    assert!(validate_candidate(&p).is_err());
+}

crates/oa-core/tests/source6_view_contract.rs

@@ -67,7 +67,18 @@ fn source6_traceability_default_keeps_both_layers_and_indexed_projection_matches
             .any(|e| e.id == interaction)
     );
     p.diagrams.get_mut(&d).unwrap().projection = ProjectionKind::Overview;
-    assert!(validate_candidate(&p).is_err());
+    validate_candidate(&p).unwrap();
+    let ordinary = projection::project_view_with_index(&p, d, &index);
+    assert!(
+        ordinary
+            .nodes
+            .iter()
+            .all(|n| p.elements[&n.element].layer() == Layer::Oa)
+    );
+    assert!(ordinary.edges.iter().any(|e| e.id == interaction));
+    assert!(!ordinary.edges.iter().any(|e| e.id == fe));
+    assert_eq!(p.diagrams[&d].nodes.len(), 4);
+    assert_eq!(p.diagrams[&d].view_options.hidden_edges, vec![fe]);
     p.diagrams.get_mut(&d).unwrap().projection = ProjectionKind::Traceability;
     p.diagrams.get_mut(&d).unwrap().view_options.relation_kinds = RelationKinds::Only(vec![]);
     assert!(