Direct Selection: Shift-click deselects one anchor of a path selected whole

select.anchors in toggle and add mode now starts from all of a path's
anchors when the path is selected as a whole, as select.anchorsMany does.
Before, Shift-clicking an anchor of a fully selected path left only that
anchor selected.

Follow-up to #1237 / #1254.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/select.rs

@@ -340,12 +340,17 @@ fn anchors(s: &mut Session, p: &Value) -> Result<Value> {
         Some("toggle") => "toggle",
         Some(m) => return Err(bad(C, format!("unknown mode {m:?}"))),
     };
-    s.select(|_, sel| {
+    s.select(|d, sel| {
         if mode == "set" {
             sel.clear();
         }
+        // A path selected as a whole has every anchor selected: toggle and add start from them all.
+        let whole = sel.contains(id) && sel.partial(id).is_none();
         sel.add(id);
         let e = sel.anchors.entry(id).or_default();
+        if whole && let Some(path) = d.node(id).and_then(|n| n.path_data()) {
+            e.extend(path.anchors().map(|(s, i, _)| (s, i)));
+        }
         for r in refs {
             if mode == "toggle" && e.contains(&r) {
                 e.remove(&r);

crates/engine/src/tests.rs

@@ -1423,6 +1423,45 @@ fn direct_selection_moves_one_anchor() {
     assert_eq!(p.subpaths[0].anchors[1].p, vectorcraft_geom::Point::new(200.0, 100.0));
 }
 
+/// Follow-up to #1254: toggling or adding anchors of a path selected as a whole starts from all
+/// its anchors, so toggling one deselects it alone and adding one keeps them all.
+#[test]
+fn select_anchors_toggle_and_add_start_from_a_whole_path() {
+    let mut s = session();
+    let a = rect(&mut s, 100.0, 100.0, 100.0, 100.0);
+    let picked = |s: &Session| s.doc().unwrap().selection.partial(a).map(|set| set.iter().copied().collect::<Vec<_>>());
+    s.execute("select.set", &json!({"ids": [a.0]})).unwrap();
+    s.execute("select.anchors", &json!({"id": a.0, "anchors": [[0, 0]], "mode": "toggle"})).unwrap();
+    assert_eq!(picked(&s), Some(vec![(0, 1), (0, 2), (0, 3)]));
+    s.execute("select.set", &json!({"ids": [a.0]})).unwrap();
+    s.execute("select.anchors", &json!({"id": a.0, "anchors": [[0, 0]], "mode": "add"})).unwrap();
+    assert!(picked(&s).is_none_or(|v| v.len() == 4), "{:?}", picked(&s));
+    assert!(s.doc().unwrap().selection.contains(a));
+}
+
+/// Follow-up to #1254: Shift-clicking an anchor of a path selected as a whole (with the Selection
+/// tool) deselects that anchor and keeps the others, as in Illustrator.
+#[test]
+fn direct_selection_shift_click_deselects_one_anchor_of_a_whole_path() {
+    let mut s = session();
+    let a = rect(&mut s, 100.0, 100.0, 100.0, 100.0);
+    let v = ViewInfo::default();
+    s.execute("select.none", &json!({})).unwrap();
+    s.select_tool("selection", v).unwrap();
+    for kind in [PointerKind::Down, PointerKind::Up] {
+        s.pointer(&PointerEvent::new(kind, 150.0, 150.0), v).unwrap();
+    }
+    assert_eq!(s.doc().unwrap().selection.objects, vec![a]);
+    assert!(s.doc().unwrap().selection.partial(a).is_none(), "selected whole");
+    s.select_tool("directSelection", v).unwrap();
+    let shift = vectorcraft_tools::Mods { shift: true, ..Default::default() };
+    for kind in [PointerKind::Down, PointerKind::Up] {
+        s.pointer(&PointerEvent::new(kind, 100.0, 100.0).with_mods(shift), v).unwrap();
+    }
+    let sel = &s.doc().unwrap().selection;
+    assert_eq!(sel.partial(a).map(|set| set.iter().copied().collect::<Vec<_>>()), Some(vec![(0, 1), (0, 2), (0, 3)]));
+}
+
 /// Dragging a curved segment with Direct Selection bends it (its anchors stay), and dragging a
 /// straight one moves its two anchors, not the whole path; each is one undo step.
 #[test]