Edit Points: a panic or another document leaves no stale point type

A command that panicked after changing the point type Edit Points remembers
left the new type in place, since the guard put back only the document and
selection. The guard now puts the remembered type back too. Shape ids repeat
across documents, so a change of active document forgets the remembered
type.

crates/engine/src/guard.rs

@@ -36,11 +36,13 @@ impl Session {
     /// Run command `id` (`f`) inside the guard.
     pub(crate) fn guarded(&mut self, id: &str, f: impl FnOnce(&mut Session) -> Result<Value>) -> Result<Value> {
         let before = self.active().map(|d| (d.uid, d.doc.clone(), d.selection.clone(), d.revision));
+        let vertex_kind = self.tool.vertex_kind.clone();
         let depth = self.depth;
         match catch_unwind(AssertUnwindSafe(|| f(self))) {
             Ok(r) => r,
             Err(payload) => {
                 self.depth = depth;
+                self.tool.vertex_kind = vertex_kind;
                 let msg = panic_message(payload.as_ref());
                 // Keep the document as it was before the command.
                 if let (Some((uid, doc, selection, revision)), Some(st)) = (before, self.active_mut())
@@ -91,6 +93,20 @@ mod tests {
         s.execute("shape.insert", &json!({"preset": "ellipse", "rect": [36, 236, 200, 400]})).unwrap();
     }
 
+    #[test]
+    fn a_panicking_command_keeps_the_remembered_point_type() {
+        let mut s = Session::new();
+        s.execute("file.new", &json!({})).unwrap();
+        let kept = Some((deckcraft_model::ShapeId(1), 0, 0, "straight".to_string()));
+        s.tool.vertex_kind = kept.clone();
+        let r = s.guarded("test.panic", |s| {
+            s.tool.vertex_kind = Some((deckcraft_model::ShapeId(1), 0, 0, "corner".to_string()));
+            panic!("boom");
+        });
+        assert!(r.is_err());
+        assert_eq!(s.tool.vertex_kind, kept);
+    }
+
     #[test]
     fn a_command_that_fails_after_editing_leaves_the_document_alone() {
         let mut s = Session::new();

crates/engine/src/lib.rs

@@ -561,16 +561,21 @@ impl Session {
         self.active_mut().ok_or(EngineError::NoDocument)
     }
     pub fn set_active(&mut self, i: usize) {
+        let was = self.active().map(|d| d.uid);
         if i < self.docs.len() {
             self.active = Some(i);
         }
+        self.forget_vertex_kind_unless(was);
     }
     pub fn add_document(&mut self, d: DocState) -> usize {
+        let was = self.active().map(|d| d.uid);
         self.docs.push(d);
         self.active = Some(self.docs.len() - 1);
+        self.forget_vertex_kind_unless(was);
         self.docs.len() - 1
     }
     pub fn close_document(&mut self, i: usize) {
+        let was = self.active().map(|d| d.uid);
         if i < self.docs.len() {
             let d = self.docs.remove(i);
             if let Some(dir) = &self.recovery_dir {
@@ -578,6 +583,14 @@ impl Session {
             }
             self.active = if self.docs.is_empty() { None } else { Some(i.min(self.docs.len() - 1)) };
         }
+        self.forget_vertex_kind_unless(was);
+    }
+    /// The point type Edit Points remembers names a shape of the active document, and another
+    /// document can have a shape with the same id: a change of active document forgets it.
+    fn forget_vertex_kind_unless(&mut self, was: Option<u64>) {
+        if self.active().map(|d| d.uid) != was {
+            self.tool.vertex_kind = None;
+        }
     }
     pub fn next_untitled(&mut self) -> String {
         self.untitled += 1;

crates/engine/src/tests.rs

@@ -2324,6 +2324,17 @@ fn edit_points_remembered_point_type_follows_undo_redo_and_its_shape() {
     drag(&mut s, ho6, to6, Mods::default());
     let (hi6, _, _) = handles_of(&s);
     assert!((hi6 - (v6 - Vec2::new(0.0, 40.0))).hypot() < 1e-3, "the other handle mirrors the dragged one: {hi6:?}");
+    // Another document can have a shape with the same id: a change of active document forgets the
+    // remembered type, and choosing the active document again keeps it.
+    s.execute("shape.pointType", &json!({"index": 0, "type": "corner"})).unwrap();
+    s.execute("file.new", &json!({})).unwrap();
+    assert_eq!(s.tool.vertex_kind, None);
+    s.tool.vertex_kind = Some((other, 0, 0, "corner".to_string()));
+    let new_doc = s.active_index().unwrap();
+    s.set_active(new_doc);
+    assert!(s.tool.vertex_kind.is_some());
+    s.set_active(0);
+    assert_eq!(s.tool.vertex_kind, None);
 }
 
 #[test]