Take photos removed by Synchronize Folder out of their stacks

Found while testing crates/engine/src/sync.rs:851 (SyncStep::Remove; compare mark_deleted in crates/engine/src/cmd/library.rs:168)

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

crates/engine/src/sync.rs

@@ -845,13 +845,12 @@ impl SyncCommit {
                 }
             }
             SyncStep::Remove(gone) => {
-                let ops: Vec<Op> = gone
-                    .iter()
-                    .filter(|id| s.catalog.photo(**id).is_some_and(|p| p.in_library()))
-                    .map(|id| Op::SetDeleted { id: *id, deleted: true })
-                    .collect();
+                let ids: Vec<PhotoId> = gone.into_iter().filter(|id| s.catalog.photo(*id).is_some_and(|p| p.in_library())).collect();
+                let mut ops: Vec<Op> = ids.iter().map(|id| Op::SetDeleted { id: *id, deleted: true }).collect();
                 let n = ops.len();
                 if n > 0 {
+                    // Like `photo.delete`, take them out of their stacks.
+                    ops.extend(s.catalog.remove_from_stacks_ops(&ids));
                     match s.commit("Remove Missing Photos", Op::Batch { ops }) {
                         Ok(()) => report.removed += n,
                         Err(e) => report.failed.push((String::new(), e.to_string())),

crates/engine/src/tests_sync.rs

@@ -739,3 +739,21 @@ fn a_cancelled_scan_does_not_check_the_cached_probes_against_the_disk() {
     let new = out.candidates.iter().find(|c| c.name == "new.png").expect("new.png is a candidate");
     assert!(new.error.is_some(), "the cached probe was used after ✕: {new:?}");
 }
+
+#[test]
+fn removing_missing_photos_takes_them_out_of_their_stacks() {
+    let dir = Scratch::new("remove-stacked");
+    let mut s = library(&dir);
+    let id = |s: &Session, name: &str| s.catalog.photos().find(|p| p.file_name == name).unwrap().id;
+    let (a, b) = (id(&s, "a.png"), id(&s, "b.png"));
+    let group = s.catalog.group_ops(a, &[b], true).unwrap();
+    s.catalog.apply(group).unwrap();
+    assert!(s.catalog.stack_of(b).is_some());
+    std::fs::remove_file(dir.path("trip/day1/b.png")).unwrap();
+    let r = s.execute("folder.synchronize", &json!({"path": dir.path("trip"), "removeMissing": true})).unwrap();
+    assert_eq!(r["removed"].as_u64(), Some(1), "{r}");
+    assert!(s.catalog.photo(b).unwrap().deleted);
+    assert!(s.catalog.stack_of(b).is_none(), "like photo.delete, a removed photo leaves its stack: {:?}", s.catalog.stack_of(b));
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert!(s.catalog.stack_of(b).is_some(), "one undo step puts b back in its stack");
+}