# HANDOFF — 2026-09-26 (TASK 47 shipping crash fixed; 2 local commits, NOT pushed)

## Branch / Commit State

`main` — two local commits ahead of `origin/main` (= `2c9af94`... actually `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, 318/319 with the
   known env flake → final full run 319/319 green).
2. *(uncommitted next)* — **the 2026-09-26 live-crash fix** (see below), scope = 3 files + docs:
   `Services/AlertOverlayLayer.cs`, `ytLive.Tests/AlertLayerVideoTests.cs`, plus docs
   (`TASKS/task-47-alert-videos.md` addendum, `MyMistakes.md` lesson, this file). Full suite
   **320/320** green, alert tests 3/3, `scope-check.sh` passed.

## ⚠️ The live crash + fix (this unit)

The creator ran the shipped build in a test session: **test-tab alerts DID fire** (button
commands run on the UI thread — startup.log `11:21:53` shows the sims and alert-clip audio in the
live mix: `micLevel=0.000 loopLevel=0.000` yet `peakMix 0.375 → 0.733 → 0.891`, which can only be
the alert ring; the default clip is materialized at `%TEMP%\ytLive-alert-941785b0-….mp4`, the
video pipe verified against the pinned ffmpeg), but the app **crashed at `11:22:01.301`** — the
first REAL message that round-tripped through the chat poller:

    System.ArgumentException: Must create DependencySource on same Thread as the DependencyObject.
    at ...MS.Internal.Data.DataBindEngine.ProcessCrossThreadRequests()

Root cause: `AlertOverlayLayer.OnMessageReceived` had NO UI-thread marshal while
`ChatOverlayLayer.OnMessageReceived` has one. A polled message ran `RefreshAlertPreviews` →
`UpdatePreview` on the MTA poller thread and stamped `alertBox.VideoImageSource` (INPC-raised +
WPF-bound) with a WriteableBitmap created there → binding engine cross-thread re-bind → crash.
Fix: marshal the whole ingest via `Application.Current.Dispatcher.Invoke` (null-guarded so pure
seams still run inline). Good Dog regression test
`AlertLayerVideoTests.OnMessageReceived_FromPollerThread_MarshalsPreviewWritesToTheUiThread`
(calls the seam from a raw MTA `Thread`, returns to the message loop, asserts on the UI thread
that `VideoImageSource.Dispatcher` is the App's dispatcher — **red pre-fix, green post-fix,
verified both ways**). Rule written into `MyMistakes.md`: every INPC-raising seam fed by the chat
poller must marshal WPF-object writes to the UI thread.

## 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 — all
  queued unchanged.
- If the creator still reports "nothing in the box" after this fix (their Live scene's "Stream
  Alerts" AlertBox is at 612,45 680×200; there is also a WebSource "Web Resource-0" bottom-right —
  confirm which element they're watching), investigate the video-render path live — but note all
  evidence (audio in the mix, materialized clip, verified pipe) says the native box played.

## Around the task (carried facts)

- RealMouseDrag tests no-op while a game/fullscreen window steals the mouse (POE 2 seen
  2026-09-22) — **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. `$99/yr` Polar
  must become one-time before launch. `MARCOM.md`/`MONETIZATION.md` gitignored — never commit.
- **API facts (TASK 44 + 45):** liveChatId unavailable before the broadcast is live (poll until
  active); `400 MISSING_REQUIRED_FIELD` from `liveChat/messages.insert` = wrong body shape
  (missing `snippet.type`), NOT auth/scope.
- **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, never the refcounted
  `MediaVideoSourceManager`. DB stays `user_version 10` — TASK 47's Source columns are additive
  guarded ALTERs. Recipe in `MyMistakes.md`.
- ChatOverlayLayer.OnMessageReceived marshals the poller seam; AlertOverlayLayer now mirrors it.
- Every committed change needs a **close + relaunch** of the running app to be seen.

## Next step

1. Commit the crash fix (declared scope + same-commit docs), then run
   `./scripts/scope-check.sh "Services/AlertOverlayLayer.cs" "ytLive.Tests/AlertLayerVideoTests.cs"`.
2. Full clean build (0 warnings, Windows dotnet host) + full vstest **320/320**.
3. Push `a11b15e` + the fix commit at the creator's go / milestone signal.
4. Creator to relaunch and re-run the test-tab alerts (one of each) + post a real chat message —
   the crash is fixed; then confirm which visual element they call the "web-alert box".

## 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 (verify only, never incremental). One runtime model.
- No menus/polls with the creator; decisions asked once then held; do the work, then report.