Routing and ruling both good: 'procs in the chat windows but nothing in the alert box'
with zero exceptions — every failure stage was silent by design (Debug.WriteLine-only
preview catch, bare catch{} in RunAsync firing Completed regardless). A decode run that
starts but yields neither a frame nor an audio chunk left _clip != null with
_latestClipFrame == null, so RenderClipFrame returned null forever: the box stayed
transparent for the whole alert and the six-animation fallback (which only ran on
setup-time throws) never fired.
Fix: AlertOverlayLayer.Advance gives a started clip a NoFrameFallbackSeconds (1.0s)
grace — produce no frame AND no audio inside it and the clip is torn down, _elapsed
resets, and the SAME alert continues as the animation branch (never blank, never drained
early). Diagnostics stop the lying silence: BeginClip logs box id/path/size + setup
failures; AlertClipDecoder.RunAsync logs frame/chunk end-state and the exception it used
to swallow.
Good Dog test: SilentDecoder_FallsBackToTheAnimationAfterTheNoFrameGrace (transparent
inside grace, disposed past it, animation renders, drains to idle).
Reference: alert playback must degrade to its fallback on dead-air, never vanish —
same contract as every player/booth failure budget (e.g. OBS source fallbacks).
https://obsproject.com/forum/threads/source-visibility-fallback.187383/
Live test session proved the native alert box DID play (the alert ring was the
only source in the mix: micLevel/loopLevel 0.000 while peakMix went
0.375->0.733->0.891 after the sim injections) but the app crashed at
11:22:01.301 the moment a REAL message round-tripped through the poller:
System.ArgumentException: Must create DependencySource on same Thread as
the DependencyObject
at ...MS.Internal.Data.DataBindEngine.ProcessCrossThreadRequests()
OnMessageReceived ran RefreshAlertPreviews on the MTA poller thread and
stamped the WPF-bound VideoImageSource with a WriteableBitmap created there;
the binding engine's cross-thread re-bind killed the process. ChatOverlayLayer
already marshals this exact seam (Dispatcher.Invoke) - mirror it, guarded for
Application.Current null so the pure test seams still run inline.
Good Dog test:
AlertLayerVideoTests.OnMessageReceived_FromPollerThread_MarshalsPreviewWritesToTheUiThread
calls the seam from a raw MTA Thread while the RealApp loop runs, then asserts
on the UI thread that the preview bitmap's Dispatcher is the App's (red on the
old seam, green on the fix). WPF cross-thread rule recorded in MyMistakes.md.
Full suite 320/320, clean build 0 warnings, scope-check green.
TASK 43's alert box grows a real video celebration. Per-alert IAlertClipDecoder
(ffmpeg bgra + f32le pipes, real-time paced, disposed at drain) plays the shipped
Assets/alert-default.mp4 (stamped into the Asset table at startup) unless the
creator picks their own file — path reference only, never stored in the DB; the
six AlertRenderer animations stay the fallback. ~0.3s fade rides the alpha
envelope on straight-source copies (EOF freeze-frames then fades out); audio
forwards to a new AudioMixer alert ring (8s, 48k stereo) drained at unity — no
duck, creator ruling — scaled by volume × fade. An auto-composed marquee ticker
('Funder — Super Chat · $10.00', 140px/s) scrolls top-of-frame via a
FramePump._alertTicker seam through Render/CompositeLayers, mixed into the cache
signature (dynamic overlay, never baked). New Stream Alerts section in LeftPanel.
Derivative-work references (how OBS/Streamlabs alert boxes do per-alert video):
- https://support.streamlabs.com/hc/en-us/articles/217741147-Setting-Up-Your-Streamlabs-Alerts (custom image/video per alert type + variations)
- https://obsproject.com/kb/stream-tutorial-2-alerts (alert overlay as an on-screen zone)
- https://streamlabs.com/content-hub/widgets/alert-box (per-event alert playback)
Good Dog: AlertLayerVideoTests drives a fake IAlertClipDecoder through the whole
lifecycle in one pass (custom path wins, decoder spawns/disposes, fade envelope
0→127→255, audio volume×fade, ticker scrolls, EOF fade-drain to idle). It caught
the clip branch of Advance not clearing _current before AdvanceToNext — the layer
stayed IsPlaying after drain (MyMistakes post-mortem).
Full vstest 319/319; clean build 0 warnings; scope check green.
Replace the external StreamElements feed with NATIVE YouTube events per the creator's
2026-09-23 question.
Chat parity half:
- YouTubeChatService decodes ALL SIX liveChat/messages event types into
ChatMessage.Kind (superChat/superSticker/newSponsor/membershipGifting/
giftMembershipReceived/memberMilestoneChat) — the four formerly-empty overlay
rows are real now — and re-arms its one-shot poll on the server's
pollingIntervalMillis (streamList connection semantics; clamp 1000-6000ms,
maxResults=2000). ParsePage internal static seam + ChatPage record for
deterministic tests; optional HttpClient ctor seam kept; InjectSimulatedMessage
(TASK 41) preserved.
Alerts half (creator rulings: one celebration zone, six UNIQUE animations, no
menus/polls, sub mention = chat row only, NO viewer count):
- New SourceType.AlertBox 'Stream Alerts' (one per layout, CanAddAlerts gate
mirroring chat; idle = transparent).
- AlertRenderer: six distinct branded animations (SuperChat slide-up/shine/
count-up, SuperSticker scale-pop, NewMember drop-in/flash, MemberGift slide-left/
chip-fan, GiftReceived confetti, MemberMilestone rise/growth-bar), every card
drawing the 'made with LlamaCasty!' brand line.
- AlertOverlayLayer: true component (Commit-G pattern) — queue (cap 10, drop tail
never stall), 33ms UI ticker, cache-first RenderFrame + UpdatePreview,
Advance(double) as the deterministic test clock; ChatEventKind.None rows never
enqueue.
- Wired: resolver RenderAlertBox, _alertLayer ctor + dispose, LoadLayout previews,
Add menu item (Controls/LeftPanel.xaml), TestSessionViewModel sims tagged
(member->NewMember, superchat->SuperChat).
Good Dog ONE integration test: AlertLayerTests (RealApp STA, real WPF raster) —
ParsePage classifies all six kinds + cadence fields; None rows enqueue nothing;
six events play pairwise-distinct moving frames then drain to null.
Gate: clean build 0 warnings; full suite 316/317, the one failure
(LayerReorderPersistenceTests.RealMouseDrag) repros on the clean tree — the
known environmental class (real-mouse-drag no-ops with a game/fullscreen window
focused).
References (OBS/overlay ecosystem):
- streamList semantics: https://developers.google.com/youtube/v3/live/docs/liveChatMessages/streamList
- OBS alert-box pattern (designated celebration zone, idle transparent): creator-chosen model
gramps