Fix #2178: Pathfinder Unite groups disconnected islands for Ungroup

After Unite, split the result with draw2::components so each island (outer
contour plus its holes) becomes one group child instead of one compound path.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/engine/src/cmd/pathops.rs

@@ -300,6 +300,7 @@ fn shape_node_styled(d: &mut Document, path: PathData, style: &Style) -> Node {
     n
 }
 
+
 /// Whether `ids` are separate objects, as [`Document::remove_many`] and [`Document::insert_beside`]
 /// take them: each one is in the tree and listed once, and none lies inside another listed one.
 pub(crate) fn separate(d: &Document, ids: &[NodeId]) -> bool {
@@ -464,14 +465,29 @@ fn run_pf(s: &mut Session, op: PathfinderOp) -> Result<Value> {
             let r =
                 results.into_iter().find(|r| !r.path.is_empty()).ok_or_else(|| EngineError::Other(format!("{label} produced an empty result")))?;
             let style = styles.get(r.key as usize).ok_or_else(|| EngineError::Other(format!("{label}: lost track of a shape's style")))?;
-            let mut n = shape_node_styled(d, r.path, style);
-            n.name = match op {
-                // A subtraction keeps its surviving source's identity, even when unnamed.
+            let name = match op {
                 PathfinderOp::MinusFront => names.first().cloned().flatten(),
                 PathfinderOp::MinusBack => names.last().cloned().flatten(),
                 _ => names.into_iter().flatten().next(),
             };
-            n
+            let path = r.path;
+            if op == PathfinderOp::Unite {
+                let pieces = super::draw2::components(&path);
+                if pieces.len() > 1 {
+                    let children = pieces.into_iter().map(|p| Arc::new(shape_node_styled(d, p, style))).collect();
+                    let mut g = Node::group(d.alloc_id(), children);
+                    g.name = name;
+                    g
+                } else {
+                    let mut n = shape_node_styled(d, path, style);
+                    n.name = name;
+                    n
+                }
+            } else {
+                let mut n = shape_node_styled(d, path, style);
+                n.name = name;
+                n
+            }
         } else {
             let mut children = vec![];
             for r in results {

crates/engine/src/tests_pathops.rs

@@ -205,6 +205,49 @@ fn a_group_selected_alone_is_combined_member_by_member() {
     assert_eq!((bounds.x0, bounds.x1), (0.0, 10.0), "the back member less the front one");
 }
 
+/// #2178: Unite on separated shapes should group them so Object › Ungroup releases each piece.
+#[test]
+fn pathfinder_unite_non_overlapping_grouped_shapes_stay_ungroupable() {
+    let mut s = session();
+    let a = rect(&mut s, 0.0, 0.0, 20.0, 20.0);
+    let b = rect(&mut s, 30.0, 0.0, 20.0, 20.0);
+    s.execute("select.set", &json!({"ids": [a.0, b.0]})).unwrap();
+    let g = NodeId(s.execute("object.group", &json!({})).unwrap()["id"].as_u64().unwrap());
+    let layer = s.doc().unwrap().doc.parent_of(g).unwrap();
+    s.execute("object.pathfinder.unite", &json!({})).unwrap();
+    let result = s.doc().unwrap().selection.objects[0];
+    assert!(matches!(node(&s, result).kind, NodeKind::Group { .. }));
+    assert_eq!(node(&s, result).children().unwrap().len(), 2);
+    s.execute("object.ungroup", &json!({})).unwrap();
+    let d = &s.doc().unwrap().doc;
+    assert!(d.node(g).is_none());
+    assert_eq!(s.doc().unwrap().selection.len(), 2);
+    for id in &s.doc().unwrap().selection.objects {
+        assert_eq!(d.parent_of(*id), Some(layer));
+    }
+}
+
+/// #2178: each connected island stays one object; holes stay with their outer contour, not separate group children.
+#[test]
+fn pathfinder_unite_groups_disjoint_islands_not_subpaths_of_one_island() {
+    let mut s = session();
+    let outer = rect(&mut s, 0.0, 0.0, 40.0, 40.0);
+    let hole = rect(&mut s, 10.0, 10.0, 10.0, 10.0);
+    s.execute("select.set", &json!({"ids": [outer.0, hole.0]})).unwrap();
+    let ring = NodeId(s.execute("object.compoundPath.make", &json!({})).unwrap()["id"].as_u64().unwrap());
+    let separate = rect(&mut s, 60.0, 0.0, 20.0, 20.0);
+    s.execute("select.set", &json!({"ids": [ring.0, separate.0]})).unwrap();
+    s.execute("object.group", &json!({})).unwrap();
+    s.execute("object.pathfinder.unite", &json!({})).unwrap();
+    let result = s.doc().unwrap().selection.objects[0];
+    let g = node(&s, result);
+    assert!(matches!(g.kind, NodeKind::Group { .. }));
+    let kids = g.children().unwrap();
+    assert_eq!(kids.len(), 2);
+    let subpath_counts: Vec<usize> = kids.iter().map(|c| path_of(&s, c.id).0.subpaths.len()).collect();
+    assert_eq!(subpath_counts, [2, 1]);
+}
+
 #[test]
 fn unite_with_group() {
     let mut s = session();