engine: keep a one-frame run a sequence when replacing footage

crates/engine/src/cmd/file_more.rs

@@ -884,12 +884,28 @@ fn replace_footage(s: &mut Session, p: &Value) -> Result<Value> {
         Some(ItemKind::Footage(f)) if f.kind == FootageKind::Sequence => (true, true, f.alphabetical),
         _ => (false, false, false),
     };
+    // Only `sequence` decides whether the item keeps its kind; `alphabetical` is a sequence
+    // modifier, not a request to make one.
+    let inherited = b_p(p, "sequence").is_none();
     let mut opts = SequenceOptions::from_params(p);
-    if b_p(p, "sequence").is_none() && b_p(p, "alphabetical").is_none() {
-        (opts.sequence, opts.folders, opts.alphabetical) = previous;
+    if inherited {
+        (opts.sequence, opts.folders) = (previous.0, previous.1);
+        if previous.0 && b_p(p, "alphabetical").is_none() {
+            opts.alphabetical = previous.2;
+        }
     }
     let src = crate::sequence::source_of(s.services.as_ref(), &path, opts);
-    let f = crate::sequence::probe(importer.as_ref(), &src, s.sequence_rate()).map_err(|e| EngineError::Other(format!("{path}: {e}")))?;
+    let mut f = crate::sequence::probe(importer.as_ref(), &src, s.sequence_rate()).map_err(|e| EngineError::Other(format!("{path}: {e}")))?;
+    // A single-file source comes back as a still; an inherited sequence kind keeps it a
+    // one-frame sequence, so a later default replacement still brings numbered runs (#2073).
+    if inherited && previous.0 && matches!(src, crate::sequence::Source::File(_)) && f.kind == FootageKind::Still {
+        f.kind = FootageKind::Sequence;
+        f.sequence = vec![f.path.clone()];
+        f.alphabetical = opts.alphabetical;
+        f.frame_rate = s.sequence_rate();
+        f.native_rate = None;
+        f.sync_sequence_duration();
+    }
     let name = src.name();
     // Replacing a missing file relinks the other missing files that moved with it (as After Effects
     // does when you locate one).

crates/engine/src/tests/sequence.rs

@@ -194,12 +194,36 @@ fn replace_footage_keeps_a_still_a_still() {
     s.execute("file.replaceFootage", json!({"path": at(&dir, "shot_0004.png"), "sequence": null})).unwrap();
     let (name, f) = footage(&s, &item);
     assert_eq!((name.as_str(), f.kind), ("shot_0004.png", FootageKind::Still));
+    // Alphabetical is a sequence modifier, not a request to make one.
+    s.execute("file.replaceFootage", json!({"path": at(&dir, "shot_0004.png"), "alphabetical": true})).unwrap();
+    let (name, f) = footage(&s, &item);
+    assert_eq!((name.as_str(), f.kind), ("shot_0004.png", FootageKind::Still));
     // Asking for the run still brings it.
     s.execute("file.replaceFootage", json!({"path": at(&dir, "shot_0004.png"), "sequence": true})).unwrap();
     let (name, f) = footage(&s, &item);
     assert_eq!((name.as_str(), f.kind, f.sequence.len()), ("shot_[0001-0005].png", FootageKind::Sequence, 4));
 }
 
+#[test]
+fn replace_footage_keeps_a_one_frame_run_a_sequence() {
+    let dir = folder(&["shot_0001.png", "shot_0002.png", "solo_0007.png", "cover.png"]);
+    let mut s = session();
+    let item = s.execute("file.import", json!({"paths": [at(&dir, "shot_0001.png")], "sequence": true})).unwrap()["items"][0].clone();
+    s.state.project_selection = vec![ItemId(item.as_u64().unwrap())];
+    // A numbered file with no other frame in its run is still the replacement for a sequence.
+    s.execute("file.replaceFootage", json!({"path": at(&dir, "solo_0007.png")})).unwrap();
+    let (name, f) = footage(&s, &item);
+    assert_eq!((name.as_str(), f.kind, f.sequence.len()), ("solo_0007.png", FootageKind::Sequence, 1));
+    // A single-file source keeps the sequence kind too.
+    s.execute("file.replaceFootage", json!({"path": at(&dir, "cover.png")})).unwrap();
+    let (name, f) = footage(&s, &item);
+    assert_eq!((name.as_str(), f.kind, f.sequence.len()), ("cover.png", FootageKind::Sequence, 1));
+    // An explicit `sequence: false` still asks for one frame.
+    s.execute("file.replaceFootage", json!({"path": at(&dir, "cover.png"), "sequence": false})).unwrap();
+    let (_, f) = footage(&s, &item);
+    assert_eq!((f.kind, f.sequence.len()), (FootageKind::Still, 0));
+}
+
 #[test]
 fn replace_footage_and_reload_keep_sequences() {
     let dir = folder(&RUN);