# HANDOFF — 2026-11-05 (TASK 21 — video file layer + its audio)

## State

- `main`; TASK 21 is complete. A video file added from the (+) menu decodes, composites into preview and
  stream, loops on toggle, and **plays its own soundtrack** (Mute + Level per layer, mixed into the
  desktop/game group so the desktop fader and the ducker apply). Removing it stops the decoder.
- Decoding is now ONE pipe: `Services/VideoClipPipe.cs` behind both `MediaVideoSource` (TASK 21) and
  `AlertClipDecoder` (TASK 47) — "a clip is a clip". Alert behaviour is unchanged and its tests stay green.
- Tests: `MediaSourceAcquisitionTests` (add → decoder starts, frames, loop, remove) and
  `MediaSourceAudioTests` (chunks, level scaling, mute, sound reaching the desktop meter). App build 0 warnings.

## Next action

- Next queued unit: TASK 49 (chat profanity filter). Day 3's TASK 32/33 resilience slices are still
  outstanding — 32·4 (fragmented MP4) is the smallest.
- Agreed next feature work (designed, not started): green/blue screen detection + keying through the clip
  pipe — suggest-only by default, an opt-in "Auto Green/Blue Screen" setting, alert clips included.
- Do not push absent a checkpoint request.

## Landmines

- `LayerReorderPersistenceTests.RealMouseDrag_OnTheLayerList_PersistsTheReorder` injects physical
  mouse input. Do not run it while the desktop is in use.
- Integration tests constructing `MainWindow` must set a temporary `LayoutPathOverride` and clear it in `finally`.
- Media sessions are keyed per **path**, not per layer: acquire through `EnsureMediaSession`, release
  through `ReleaseMediaIfUnused`, never `AcquireAsync` twice for one path. Level/mute are therefore
  per session too.
- Bundled FFmpeg stays outside the single-file exe (`ExcludeFromSingleFile="true"`).