# HANDOFF — 2026-09-26 (TASK 47 shipping crash + the "nothing in the box" void both fixed; 3 local commits, NOT pushed)

## Branch / Commit State

`main` — three local commits ahead of `origin/main` (= `ecb329e`), **NOT pushed** (awaiting the
creator's go / milestone signal):

1. `a11b15e` — **TASK 47** alert box video (built-in/custom clip + read-time fade + message
   ticker + unity audio) + `AlertLayerVideoTests` (fake decoder, 0 warnings, 319/319 green).
2. `7b940b6` — **crash fix**: AlertOverlayLayer marshals the chat-poller seam to the UI thread
   (regression test red pre-fix / green post-fix, both verified). Full suite 320/320.
3. *(uncommitted next — this session)* — **silent-decoder fallback + diagnostics** (see below),
   scope: `Services/AlertOverlayLayer.cs`, `Services/AlertClipDecoder.cs`,
   `ytLive.Tests/AlertLayerVideoTests.cs` + docs (task-47 addendum, `MyMistakes.md` lesson, this
   file). New Good Dog test green; build 0 warnings; full suite 321 with the **known env flake**
   (RealMouseDrag reorder failing while windows are up — passes with the desktop clean; unrelated
   to this change). `scope-check.sh` pending, then commit.

## ✅ Crash fixed (`7b940b6`)

The creator's first live session: test-tab alerts DID fire (11:21 startup.log: alert-clip audio in
the mix, `peakMix 0.375 → 0.891` with mic+loop at 0.000) but the app crashed at `11:22:01.301` on
the first REAL polled message: `Must create DependencySource on same Thread as the DependencyObject`
in `DataBindEngine.ProcessCrossThreadRequests`. `AlertOverlayLayer.OnMessageReceived` had no
UI-thread marshal (`ChatOverlayLayer` has one); it ran `RefreshAlertPreviews` → `UpdatePreview` on
the MTA poller thread and stamped `alertBox.VideoImageSource` (INPC + WPF-bound) with a
WriteableBitmap created there. Fix + Good Dog regression test
`OnMessageReceived_FromPollerThread_MarshalsPreviewWritesToTheUiThread` (red/green verified).
`MyMistakes.md`: every INPC-raising seam fed by the poller must marshal WPF-object writes.

## ⚠️ The "nothing in the alert box" void — diagnosed + fixed (this unit)

After the crash fix the creator reported: On-Air → test → **remove and re-add** the Stream Alerts
layer → TEST event → procs in the chat windows but **nothing in the alert box**. startup.log 11:44:
`peakMix 0.105` (no alert audio) vs 11:21's 0.375–0.891. No exception anywhere — every stage of the
clip path was silent by design (`UpdatePreview` catch = `Debug.WriteLine`-only; `RunAsync` bare
`catch { }` firing `Completed` regardless). Established the guaranteed-invisible fail: a decoder
whose `Start()` succeeds but yields **no frames AND no audio** leaves `_clip != null` with
`_latestClipFrame == null` → `RenderClipFrame` returns null forever → box transparent FOREVER; the
six-animation fallback only ran on setup-time throws. (Hunted & ruled out meanwhile: `LiveScene` is
never assigned — the encoder always renders `StagedScene` (MainViewModel.cs:323), so the re-added
box IS in the render graph; the bake invalidates per element on add; DB row
`c85b46ac-…` X=602 Y=26 680×200 healthy; pinned ffmpeg decodes the default clip to `scale=680:200`
rawvideo correctly to a file. Frame pacing silently off too: no probe → `frameDuration=0`.)

**Fix (uncommitted):** `AlertOverlayLayer.Advance` — a started clip that produced neither a frame
nor an audio chunk inside `NoFrameFallbackSeconds` (1.0 s) is torn down, `_elapsed` resets, and the
SAME alert continues as the six-animation render (never blank, never drained early).
Diagnostics: `BeginClip` logs box id / resolved path / size + setup failure; `AlertClipDecoder.RunAsync`
logs frame/chunk end-state + the swallowed exception. Good Dog test
`SilentDecoder_FallsBackToTheAnimationAfterTheNoFrameGrace`: transparent inside the grace →
decoder disposed past it → animation renders → drains to idle. `MyMistakes.md`: an alert that plays
is a promise — degrade on dead-air, and a `catch` hiding WHY output vanished is a lie.

## Follow-ups queued (NOT done in this unit)

- **TASK 3 item 20 persistence half** — canonical `RewardEvents` SQLite table +
  `superChatEvents.list` (30-day) backfill + session-report rollup (still in-memory only).
- TASK 3 item 16 (Text source); TASK 40 units A/C/D; TASK 32–36; TASK 12 master limiter — queued.
- If the alert box is STILL blank after this fix + relaunch: the new logs make the failure
  conclusive (look for `Alert clip start:` → `Alert clip decode failed` → `Alert clip end:`). The
  creator's Live scene also has a WebSource "Web Resource-0" bottom-right — confirm which element
  they watch when describing the "stream-alerts layer".
- The known pump stall (`render=full-render … totalMs=147`, ~6fps worst) is recorded as a
  pre-existing perf item, NOT part of this unit.

## Around the task (carried facts)

- RealMouseDrag tests no-op while a game/fullscreen window steals the mouse — **close fullscreen
  windows before full-suite runs**; passes in isolation.
- Test-env trap: saved OAuth session loads synchronously → force `vm.IsConnected` in signed-in tests.
- `subscriberCount` YPP slice 2 needs re-consent — do not merge with other units. `MARCOM.md`/
  `MONETIZATION.md` gitignored — never commit.
- API facts (TASK 44 + 45): liveChatId unavailable until broadcast live; `400 MISSING_REQUIRED_FIELD`
  from `liveChat/messages.insert` = wrong body shape (missing `snippet.type`).
- TASK 47 sticky facts: bgra from ffmpeg is opaque (alpha=255); audio pipe = carry-buffer loop;
  default clip = `%TEMP%\ytLive-alert-{id}.mp4`; decoder per-play; DB stays `user_version 10`.
- ChatOverlayLayer.OnMessageReceived marshals the poller seam; AlertOverlayLayer mirrors it; the
  no-frame fallback lives in Advance (has the 1 s grace + diagnostics).
- Every committed change needs a **close + relaunch** of the running app to be seen.

## Next step

1. Commit this unit with the declared scope
   `./scripts/scope-check.sh "Services/AlertOverlayLayer.cs" "Services/AlertClipDecoder.cs" "ytLive.Tests/AlertLayerVideoTests.cs"`.
2. Push the three local commits at the creator's go / milestone signal.
3. Creator to relaunch and re-run the repro (compare the 11:21 vs 11:44 behavior) — the new logs
   will say exactly what the decoder did.

## Critical working rules (unchanged, still binding)

- **Good Dog = ONE integration test per change.** Scope lock + `./scripts/scope-check.sh` before commit.
- Windows dotnet host for all WSL builds (`/mnt/c/Program Files/dotnet/dotnet.exe`, quoted paths).
- 0 warnings on real clean builds. One commit = fix + its memory (task doc, MyMistakes, handoff).
- No menus/polls with the creator; decisions asked once then held; do the work, then report.