Footage: a file that can't be read is tried again once it changes, not on every look

A footage file the automatic reload couldn't read (still being written, or
one the importer doesn't read) kept its old stamp, so every two-second look
saw it as changed and probed it again. It now keeps its new stamp and is
tried again once it changes again (when the other app finishes writing it).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/engine/src/footage_reload.rs

@@ -184,8 +184,8 @@ fn forget(s: &mut Session, paths: &BTreeSet<String>) {
 /// time is only remembered; one whose stamp moved is reloaded: the items reading it get their
 /// size and duration from it again and its pixels are read again. A file that can't be stamped
 /// right now (an app saving by delete and rename) keeps its last stamp, and one that can't be
-/// read yet (still being written) keeps its old stamp so the next scan tries again; missing
-/// files are left to the footage check. Returns `{files, reloaded}`.
+/// read (still being written) is tried again once it changes again; missing files are left to
+/// the footage check. Returns `{files, reloaded}`.
 pub fn apply_stamps(s: &mut Session, now: Vec<(String, Option<Stamp>)>) -> crate::Result<Value> {
     let before = std::mem::take(&mut s.footage_stamps);
     let mut changed = BTreeSet::new();
@@ -209,10 +209,9 @@ pub fn apply_stamps(s: &mut Session, now: Vec<(String, Option<Stamp>)>) -> crate
     }
     let ids: Vec<ItemId> = s.project.items.values().filter(|i| matches!(&i.kind, ItemKind::Footage(f) if changed.contains(&f.path))).map(|i| i.id).collect();
     let (reloaded, failed) = if ids.is_empty() { (0, BTreeSet::new()) } else { reload(s, &ids, false)? };
+    // Not readable (still being written, or not a file the importer reads): its new stamp is kept,
+    // so it is tried again once it changes again, not on every look.
     for p in &failed {
-        if let Some(old) = before.get(p) {
-            s.footage_stamps.insert(p.clone(), *old);
-        }
         changed.remove(p);
     }
     if changed.is_empty() {

docs/preferences.md

@@ -114,7 +114,7 @@ Commands (CLI, MCP, control channel):
   size and modification time with what they were, and reloads what another app saved: a
   Photoshop file edited in PhotoCraft or Photoshop shows its new pixels without File ▸ Reload
   Footage. It is not an undo step and doesn't modify the project; a layer item stays on its layer
-  (found again by name), and a file still being written is tried again on the next check.
+  (found again by name), and a file that can't be read yet (still being written) is tried again once it changes again.
   `footage.reloadChanged` runs the same check once (CLI, agents)
 - `import.unlabeledAlpha`: alpha of TGA / TIFF / movie footage (Ask opens Interpret Footage;
   Guess takes premultiplied for movies, straight for stills)