Explain captured removal impact and exercise rendered confirmation buttons

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

@@ -47,6 +47,27 @@ fn placement(app: &App) -> Option<Id> {
 /// The derived canvases remove semantic occurrences, not reusable definitions.
 /// Kept beside target capture so confirmation rendering uses the same meaning.
 pub(crate) fn explanation(app: &App, object: Id) -> &'static str {
+    if app
+        .project()
+        .diagrams
+        .values()
+        .any(|diagram| diagram.nodes.contains_key(&object))
+    {
+        return "Remove only this diagram placement. The model element and its placements in other diagrams remain. Undo restores this placement.";
+    }
+    if app
+        .project()
+        .relations
+        .get(&object)
+        .is_some_and(|relation| {
+            matches!(
+                relation.kind(),
+                RelationKind::StateAction | RelationKind::StateTransition
+            )
+        })
+    {
+        return "Remove this state relation. Its states and referenced activities or functions remain. Undo restores the relation.";
+    }
     if app
         .project()
         .relations

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

@@ -331,8 +331,8 @@ async fn mounted_shift_delete_captures_target_cancel_escape_and_confirmation_rep
     let target = f.app.delete_target.as_ref().unwrap();
     assert_eq!(target.snapshot.request.object, f.object);
     let stale_token = target.snapshot.token;
-    let task = f.app.update(Message::CancelDelete);
-    mounted.perform(&mut f.app, task).await;
+    let cancel = mounted.geometry(&f.app).bounds("delete-cancel").center();
+    mounted.click(&mut f.app, cancel).await;
     let task = f.app.update(Message::ConfirmDelete(stale_token));
     mounted.perform(&mut f.app, task).await;
     assert_eq!(f.app.document.bundle(), &before.bundle);
@@ -345,8 +345,9 @@ async fn mounted_shift_delete_captures_target_cancel_escape_and_confirmation_rep
         f.app.delete_pending,
         "old dialog must not accept a new confirmation"
     );
-    let task = f.app.update(Message::ConfirmDelete(token));
-    mounted.perform(&mut f.app, task).await;
+    assert_eq!(f.app.delete_target.as_ref().unwrap().snapshot.token, token);
+    let confirm = mounted.geometry(&f.app).bounds("delete-confirm").center();
+    mounted.click(&mut f.app, confirm).await;
     assert!(!f.app.project().contains(f.object));
     assert!(f.app.project().contains(f.other));
     consistent(&f.app);

crates/oa-desktop/src/views.rs

@@ -344,7 +344,31 @@ pub fn view(app: &App) -> View<'_, Message> {
         );
     }
     if let Some(target) = app.delete_target.as_ref().filter(|_| app.delete_pending) {
-        return modal(root,column![text("Delete from model?").size(21),text(format!("{} and its owned elements will be removed. Incident relationships, occurrences and view placements are updated together. Counterparts in the other layer remain.",p.named(target.snapshot.request.object))).size(13),label("Undo restores the complete change. Use Hide for diagram-only removal."),row![action("Cancel",Message::CancelDelete),button("Delete from model").style(button::danger).padding(10).on_press(Message::ConfirmDelete(target.snapshot.token))].spacing(10)].spacing(16).into());
+        return modal(
+            root,
+            column![
+                text("Delete from model?").size(21),
+                text(p.named(target.snapshot.request.object)).size(16),
+                text(crate::app::diagram_removal::explanation(
+                    app,
+                    target.snapshot.request.object
+                ))
+                .size(13),
+                row![
+                    widget::container(action("Cancel", Message::CancelDelete)).id("delete-cancel"),
+                    widget::container(
+                        button("Delete from model")
+                            .style(button::danger)
+                            .padding(10)
+                            .on_press(Message::ConfirmDelete(target.snapshot.token))
+                    )
+                    .id("delete-confirm")
+                ]
+                .spacing(10)
+            ]
+            .spacing(16)
+            .into(),
+        );
     }
     if app.pending.is_some() {
         return modal(root,column![text("Keep your changes?").size(21),text("Save the model and pending edits before continuing. Invalid drafts stay available for correction.").size(13),row![action("Cancel",Message::Cancel),action("Discard changes",Message::Discard),button("Save & continue").padding(10).on_press(Message::SaveAndContinue)].spacing(8)].spacing(16).into());