# HANDOFF — Session State

## Branch / Commit State

**`main`**, working through TASK 21 (media source). Local commits ahead of
`origin/main` (not yet pushed — user pushes at agreed checkpoints):
- `a1d9751` — docs: ffmpeg decode-contract verification recipe + WSL CLR boundary
- `8f49010` — TASK 21 Increment B: FFmpeg rawvideo video decoder -> VideoFrame
- `f89b9f9` — docs: default-device audio assumption (README + startup log)
- `e8ff4df` — TASK 22: global audio sync offset (positive delay at the mixer out)

Prior milestones pushed through `origin/main`: TASK 31 (`3bf053a..670fe3a`), plus
the full refactor series (Commit F `3107f92`, Commit G `85893ea`).

## What's In Flight

**TASK 21 (media source) — slice 1 step 3 shipped (the session-manager + interface); next open work is the VM wire-in (slice 1 step 4).**

Increment A (the `Source` model: `MediaSourceType`, `SourceType.MediaSource`,
`MediaPath`/`MediaIsLooping`/`MediaVolume`/`MediaPlaybackState` + LayoutStore
persistence) and Increment B (the decoder `MediaVideoSource`) shipped earlier.

This session:
- Refactored `Services/MediaVideoSource.cs` onto the new
  `Services/IMediaFrameSource.cs` (`Key`, `FrameAvailable`, `Completed`,
  `StartAsync`/`StopAsync`; `Start`→`StartAsync`, `FrameReady`→`FrameAvailable`)
  — behavior preserved, `MediaVideoSourceTests` updated and passing.
- Added `Services/MediaVideoSourceManager.cs` — app-wide decode-session
  ownership refcounted by `MediaPath`, `Func<string, IMediaFrameSource?>` factory
  seam, `AcquireAsync`/`ReleaseAsync`/`ReleaseAllAsync`/`GetLatestFrame`, frames
  coalesced onto the UI dispatcher onto one shared `WriteableBitmap` per file,
  `MediaFailed` + `PreviewBitmapChanged`. Structural mirror of `ScreenCaptureManager`.
- Added `ytLive.Tests/MediaVideoSourceManagerTests.cs` (5 unit + 1 integration:
  single shared bitmap, coalesce-to-latest). **Verified: all 10 media tests pass
  (5 manager + 3 reader + 1 decoder integration + 1), build 0 warnings.**

Slice 1 step 4 (wire-in) shipped: `_mediaManager` wired in the core ctor
(`path => new MediaVideoSource(path, 1920, 1080, new FfmpegLocator(), new FfmpegDecodeProcess())`,
dispatched preview), `OnMediaPreviewBitmapChanged` sets `VideoImageSource` on every
`IsMediaSource` with a matching `MediaPath`, a `Source { IsMediaSource, MediaPath }`
case in `ResolveOutputFrame` feeds `_mediaManager.GetLatestFrame`, `Source.DisplaySource`
routes `VideoImageSource` for `MediaSource`, and the manager is disposed on shutdown.
Lives in the new `ViewModels/MainViewModel.Media.cs` partial. **Verified: 14/14
media + DisplaySource tests pass, build 0 warnings.**

Next (slice 1 step 4's remaining open end): no session acquisition yet — nothing
`AcquireAsync`s a media path, so no frames flow until the UI picker (a later slice)
starts a session on add and releases on remove.

Slice 2a shipped: the native-FPS **probe seam** (not yet wired into pacing).
`Services/FfmpegFrameRateParser.cs` (pure — prefers `avg_frame_rate=` then
`r_frame_rate=`, rational `N`/`N/M`, unknown→null), `Services/FrameRateProbe.cs`
(`IFrameRateProbe` + `FfmpegFrameRateProbe` — derives sibling `ffprobe.exe` from
the located ffmpeg dir, reuses the `IDecodeProcess` seam for the ffprobe
subprocess text, null if ffprobe absent), and `FfmpegLocator.ProbeFileName`
(`ffprobe.exe`) + conditional extraction alongside ffmpeg.exe. Tests:
`ytLive.Tests/FfmpegFrameRateParserTests.cs` (6 pure units + 1 probe integration
via fake locator/process); `FfmpegLocatorTests` still green — 15/15 pass, build
0 warnings. Slice 2b shipped too: `MediaVideoSource` now takes optional
`IFrameRateProbe?` + `Func<TimeSpan,CancellationToken,Task>? delay` seams,
probes FPS once in `RunAsync`, and paces each emitted frame by 1/fps (unknown/
absent probe → no pacing). New test `MediaVideoSource_PacesFramesByProbedFps`
(fake probe + recording delay, one delay per frame ≈1ms). Media tests 5/5,
build 0 warnings.

Next (slice 3): loop control (restart decode on `Completed` when `MediaIsLooping`).

**Landmine:** a stale `testhost` can lock `ytLive.Tests`'s `ytLive.dll` and break
`dotnet build` of the test project — kill it first (`cmd.exe /c "taskkill /PID N /F"`)
on MSB3027. Full-suite vstest hangs headless (RealAppHost/WASAPI) — only filtered
pure tests run in WSL; user verifies the GUI suites on native Windows PowerShell
(which may also hang if WASAPI startup blocks — pre-existing, not this change).

## Next

1. Commit slice 2b (this unit): native-FPS pacing in `MediaVideoSource` + pacing test + docs.
2. Slice 3: loop control (restart decode on `Completed` when `MediaIsLooping`).
3. Slice 3: loop control (restart decode on `Completed` when `MediaIsLooping`).
4. UI picker slice: acquire/release media sessions on add/remove (the remaining slice-1-step-4 open end).
5. Await user push checkpoint for the pending TASK 22/21 commits.

## The directive (2026-08-31, user)

Rewrite the project into functional components to aid AI retrieval —
`Services/ChatOverlayLayer.cs` / `SceneGraph.cs` style (owner-state extraction),
not line-count chasing. Audio assumption is now an explicit contract (README
"Audio Assumption"): the app uses system defaults, never fights Windows device
locking, and does not debug user audio issues — OS's problem, not ours.