Add exact Process selection and atomic column-slot group reorder

Preserve the full-desktop-1 captured source. Qualified previews inspect their exact subject read-only; group movement preserves source order and other columns. Native acceptance and strict-lint payload-size corrections follow separately.

crates/oa-desktop/src/app.rs

@@ -268,6 +268,7 @@ mod direct_scenario_tests {
 #[cfg(test)]
 mod behavior_lifecycle_tests;
 mod process_canvas;
+mod process_multiselect;
 mod state_diagram;
 #[cfg(test)]
 mod state_diagram_tests;
@@ -818,6 +819,9 @@ impl App {
                 .map(|n| n.id);
         }
         self.draft = Draft::from_project(self.project(), self.selected);
+        if self.process_preview_primary().is_some() {
+            self.draft = None;
+        }
         if self.exact_strings
             && let Some(d) = &mut self.draft
         {
@@ -1294,6 +1298,7 @@ impl App {
         ])
     }
     pub fn update(&mut self, message: Message) -> Task<Message> {
+        let preview_read_only = self.process_preview_primary().is_some();
         let selection_boundary = self.multiselect_boundary();
         // Reject delayed gestures before they can retire newer input ownership.
         if let Message::DiagramSelection(event)
@@ -1326,6 +1331,52 @@ impl App {
             // or allocation ownership before its edit is refused.
             return Task::none();
         }
+        if let Message::TopologyCanvas(event) = &message {
+            use crate::behavior::topology::CanvasEvent;
+            if !matches!(
+                event,
+                CanvasEvent::Camera(..) | CanvasEvent::Scrolled(..) | CanvasEvent::Viewport(..)
+            ) && self.topology_context() != Some(event.context())
+            {
+                return Task::none();
+            }
+            if matches!(
+                event,
+                CanvasEvent::Select(..)
+                    | CanvasEvent::SelectQualified(..)
+                    | CanvasEvent::Remove(..)
+                    | CanvasEvent::Reorder { .. }
+                    | CanvasEvent::Reconnect { .. }
+            ) && self
+                .multiselect_snapshot()
+                .is_some_and(|s| s.targets().len() > 1)
+            {
+                return Task::none();
+            }
+        }
+        if self.process_order_noop(&message) {
+            return Task::none();
+        }
+        if self.process_preview_primary().is_some()
+            && matches!(
+                &message,
+                Message::Field(..)
+                    | Message::FieldText(..)
+                    | Message::FieldShape(..)
+                    | Message::FieldAppend(..)
+                    | Message::FieldValuePath(..)
+                    | Message::FieldVariant(..)
+                    | Message::FieldArray(..)
+                    | Message::ElementKind(_)
+                    | Message::RelationKind(_)
+                    | Message::Apply
+                    | Message::Delete
+                    | Message::DiagramRemove(_)
+            )
+        {
+            self.status = "Open the referenced definition to edit its contents.".into();
+            return Task::none();
+        }
         // Captured Text commands validate their origin before they can
         // invalidate that same origin or pass into existing command handlers.
         if let Message::TextWorkspace(event) = message {
@@ -1420,6 +1471,9 @@ impl App {
         {
             self.reconcile_multiselect();
         }
+        if preview_read_only && self.process_preview_primary().is_none() && self.draft.is_none() {
+            self.refresh_draft();
+        }
         task
     }
     fn behavior_control(&mut self, intent: behavior::canvas_workspace::Intent) -> Task<Message> {
@@ -2333,6 +2387,9 @@ impl App {
                         self.route_context()
                     };
                 }
+                if request.process.is_some() {
+                    request.process = self.topology_context();
+                }
                 self.model_menu = crate::model_menu::Opened::new(self, request, self.menu_sequence);
             }
             Message::Menu(crate::model_menu::Event::Close) => {
@@ -2362,7 +2419,10 @@ impl App {
                         "Apply or revert pending edits before using modeling actions.".into();
                     return Task::none();
                 }
-                if matches!(*action, Message::DiagramSelection(_)) {
+                if matches!(*action, Message::DiagramSelection(_))
+                    || (menu.request.process.is_some()
+                        && matches!(*action, Message::TopologyCanvas(_)))
+                {
                     return self.update(*action);
                 }
                 self.select(menu.request.object);
@@ -3215,7 +3275,11 @@ impl App {
                     .multiselect_snapshot()
                     .is_some_and(|s| s.targets().len() > 1)
                 {
-                    self.status = "Group model-deletion review is not available yet. Select one element or use Hide selected.".into();
+                    self.status = if self.topology_context().is_some() {
+                        "Group removal needs an aggregate review. Select one contribution to remove it individually."
+                    } else {
+                        "Group model-deletion review is not available yet. Select one element or use Hide selected."
+                    }.into();
                     return Task::none();
                 }
                 if self.selected != self.project().id && self.apply() {