Davy7/25/2026, 2:52:10 AM

#180 — cancel a running single-song separation:
- Thread `cancel: &AtomicBool` into `inference::separate_streaming`, checked at
  the top of each chunk iteration; on cancel it returns
  `SeparationError::Cancelled` without finalizing writers, so no partial stem
  set or cache entry is promoted (aborted runs restart from chunk 0).
- Add a per-song cancel registry (song_hash -> Arc<AtomicBool>) to
  SeparationState; jobs register on start and remove on exit on both paths.
- New `cancel_separation(song_id)` command — a no-op success when the song is
  not currently separating.
- Batch cancel now flags the in-flight song via `batch_current_song` so it
  stops mid-song instead of after the current track.
- Cancelled jobs emit a `separation-cancelled` event and reset the row to idle
  — never `separation-error`, and no error toast.
- UI: an x affordance beside the inline spinner on the running SongListItem
  row and on the single-song global progress bar.

#181 — surface cache hits: `cache_hit` was already populated end-to-end but
never shown. On a `separation-complete` event with cache_hit=true, show a
lightweight "Using cached separation" toast. Downgrade sets cache_hit=false so
the explicit downgrade action does not raise the cue.

i18n: add library.cancelSeparation and library.usingCachedSeparation to en and
zh-CN.

Tests: inference-level cancellation (pre-set flag and mid-run), cancel-registry
unit tests, and frontend tests for the cancel affordance, the cancelled event
reducer, and the cache-hit toast.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Parent037a6e6