Two real concerns from the code review on ab07297..b266623:
1. ActiveSpeaker removal poisoned the rename-window heuristic. ParticipantTracker.HandleRemoved appends to _recentlyRemoved keyed by MachineName alone; the next Participant Add on the same machine consulted that list with no kind discrimination, so an active-speaker disappearance immediately followed by a participant joining (very common: Teams renames its outputs as participants enter/leave) would cause the new participant to inherit the auto-mix's deterministic v5 GUID. New HandleAutoMixRemoved deliberately skips _recentlyRemoved — the auto-mix row's identity is already stable via the deterministic Id, so re-add restores it without the rename window.
2. IsoPipeline.State writes were not synchronized. Supervisor loop sets State on its own thread; UI thread reads from GetStats. Without volatility, the JIT could cache the field in a register and the UI would stay stuck on Receiving even after Error. Backing field is now an int read/written via Volatile.Read/Volatile.Write, matching the pattern already used for _liveReceiver / _liveSender / _liveProcessor.
Tests: 79/79 (was 78) — added ParticipantTrackerTests.ActiveSpeakerRemove_DoesNotPoisonRenameWindowForLaterParticipant which would have caught (1).
Four polish improvements aimed at production-floor usability.
1. Empty-state placeholder for the participants card. When Participants.Count == 0, the DataGrid is hidden in favor of a friendly 'Waiting for Teams' panel: faded dragon mark, headline, explainer, and a four-item checklist (Teams running? NDI broadcast on? Discovery group correct? Firewall clear?). New CountToVisibilityConverter (with optional 'empty' parameter to invert) drives both the placeholder and the DataGrid visibility from the same Participants.Count source.
2. Per-pipeline error / no-signal surfacing. IsoHealthStats grows an init-only State property populated from IsoPipeline.State. ParticipantViewModel.UpdateStats maps that to a StateLabel ('LIVE' / 'NO SIGNAL' / 'ERROR' / 'STARTING' / '—'). The ISO toggle button gains DataTriggers on StateLabel — coral-tinted '● ERROR' when the supervisor gives up, amber-tinted '● NO SIGNAL' when the slate threshold trips. Operators can see at a glance which pipelines are broken.
3. JetBrains Mono Variable v2.304 (OFL) bundled at Assets/Fonts/JetBrainsMono.ttf. Wd.Font.Mono now points at the embedded font so machine names, timecodes, and stat counters render in JetBrains Mono regardless of system fonts. Falls back to Cascadia Mono / Consolas if the resource is missing.
4. Tooltip pass over every interactive control in the settings panel (framerate / resolution / aspect / audio / discovery group / output group / hide-local checkbox / Apply button / per-row Output Name textbox / per-row ISO toggle). Operators learn affordances on hover instead of by trial and error.
Tests: 76/76 unit + 9/9 NDI integration green.
Six related polish items, all building on tonight's groundwork.
1. App icon: teamsiso.ico generated from dragon-mark.png at 7 sizes (16-256), wired as ApplicationIcon in the WPF csproj, MainWindow.Icon, AboutWindow.Icon, and ARPPRODUCTICON in the WiX MSI. Taskbar / window / Add-Remove-Programs all show the dragon mark now.
2. Running incoming FPS: ring buffer of last 30 frame timestamps in IsoPipeline; ComputeFps() returns moving-average rate. Surfaced on IsoHealthStats.IncomingFps and shown in the Source column of the participants DataGrid as 'WxH · 59.94 fps'. Resets cleanly on every supervisor restart.
3. Drops counter: FrameProcessor.Stats already aggregated FramesDropped (closest-frame strategy when the receiver outpaces the processor) and FramesDuplicated; just plumbed _liveProcessor through IsoPipeline so GetStats() can read them. Exposed in the Live column under the in/out counters as a coral-tinted 'drop N'.
4. Console --version flag: prints engine version (with embedded git SHA), .NET version, OS, NDI runtime banner, expected prefix, exit-code legend, plus a wilddragon.net link. Useful for support tickets.
5. About dialog: chromeless modal with the dragon mark + version / .NET / OS / NDI runtime fields and a link to wilddragon.net. Triggered by clicking the rail logo.
6. Teams launcher Stop toggle: TeamsLauncher gains IsRunning() and StopAll(). The rail's Teams button now toggles — if Teams is up, ask to close all Teams windows via WM_CLOSE; otherwise launch as before. Confirms before stopping so we don't kill the user's call mid-transition.
Tests: 74/74 unit + 9/9 NDI integration green throughout. MSI builds clean and now embeds the dragon icon for ARP.
Code review on d14a33a..bab29b0 turned up three real issues, fixed here.
1. EngineLogging.CreateDefault no longer mutates Serilog.Log.Logger. The static set was a belt-and-suspenders attempt to catch any code path that reaches for the singleton, but it doesn't matter (engine code uses ILogger<T>, never Serilog.Log.*) and it raced under xUnit's parallel test execution.
2. IsoPipeline stops holding a RawFrame reference for stats. The receiver-side TappedChannelWriter callback now snapshots only Width/Height into volatile ints — frame's pixel buffer is allowed to GC on its normal schedule and a late stats poll can never resurrect a dropped frame. (Today the buffer is fully managed so a use-after-free wasn't actually possible, but the snapshot pattern is the right ownership shape.)
3. App.xaml.cs's ComponentDispatcher.ThreadFilterMessage subscription now lives in a field and is unsubscribed in OnExit. Mutex release is gated on a new _ownsSingleInstanceMutex flag so the 'lost the race; shut down silently' path doesn't accidentally try to release a handle it never owned.
Plus a load-bearing comment in NdiInteropPInvoke.CreateFinder explaining why we free the UTF-8 group buffers right after the native call returns — same lifetime contract Phase B-2's CreateReceiver / CreateSender have always relied on; if it's wrong, those would fail too. The loopback discovery integration test would catch a regression.
Tests: 74/74 unit + 9/9 NDI integration green.
IsoPipeline now publishes refs to its currently-live NdiReceiver and NdiSender (set by RunInnerPipelineAsync, cleared on exit) so a stats poll from any thread can read FramesCaptured / FramesSent without entangling the pipeline's lifetime with its observer. The receiver's raw-frame channel is wrapped with a TappedChannelWriter so the most recent RawFrame is captured for source-resolution display, again without changing the receiver's contract.
IsoController.GetStats() drops the stub return-Empty and instead reads the live pipeline.GetStats() outside the gate so a slow stats read can't serialize the controller's other operations.
WPF: MainViewModel runs a 1 Hz DispatcherTimer that pulls stats for every participant view-model and pushes them via UpdateStats(). ParticipantViewModel grows three displayable properties — FramesIn, FramesOut, IncomingResolution — bound into the participants DataGrid as a new 'Live' column showing the down/up frame counts and the source resolution underneath the machine name.
Tests: 74/74 unit + 9/9 NDI integration green; the existing round-trip integration test exercises the new wiring at runtime (live receiver/sender refs are set, frames flow, channels close cleanly).
Adds an NdiGroupSettings record carrying optional comma-separated NDI group lists for the finder and the senders. Extends INdiInterop.CreateFinder / CreateSender with optional groups arguments and populates NDIlib_find_create_t.p_groups and NDIlib_send_create_t.p_groups via P/Invoke. IsoController reads the settings on construction, threads DiscoveryGroups into NdiDiscoveryService and OutputGroups into IsoPipelineConfig, and exposes SetGroupSettingsAsync for runtime updates (group changes apply on next process restart so live pipelines aren't orphaned).
This unblocks the 'transcoder' topology where Teams broadcasts NDI on a private group (e.g. teamsiso-input) and TeamsISO re-emits clean normalized streams on Public — keeping raw, wrong-framerate Teams sources off the production network.
EngineConfig schema is JSON-back-compat: existing config.json files (no NdiGroups field) deserialize with NdiGroups=null and load as NdiGroupSettings.Default. UI surface for these settings comes in a follow-up.
Tests: 72/72 passing (was 69) — added IsoController coverage that group settings are read from ConfigStore on startup, passed to the finder, threaded into per-pipeline config, and round-trip through SetGroupSettingsAsync/Save/Load.
