The audio capture loop runs at ~50Hz publishing every buffer's peak via overwrite; the UI stats poll reads at 1Hz. With overwrite semantics the UI sees one of every ~50 audio frames per second — loud transients between reads were invisible to the VU meter.
New design: NdiReceiver maintains an atomic high-water mark, max-updated on each audio frame via CompareExchange CAS loop. IsoPipeline.GetStats now calls ConsumeAudioPeak() which atomically reads + resets to 0, so the next UI tick reflects the loudest sample seen in the next 1s window.
Added PeekAudioPeak() for non-consuming reads (e.g. external diagnostics dashboards that poll faster than the UI).
FakeNdiInterop gained a ReceiverAudioPeaks queue + CaptureAudioPeak override so tests can drive the audio path. 4 new tests in NdiReceiverTests cover: empty case, single-frame consume+reset, max-hold across 3 frames, no-frame leaves high-water mark untouched. 104 + 46 + 9 = 159/159 passing.
The DataGrid's per-row audio level bar (in the Live column) was inert because IsoHealthStats.PeakAudioLevel always returned 0.0. Engine work needed: capture NDI audio frames, compute peak amplitude, publish through the existing stats path.
Engine:
- AudioPeakComputer (new): max-abs computation across NDI's FLTP / FLT / PCM s16 sample formats. Pure managed code, fully unit-tested (14 cases — clamping behaviour, edge cases like short.MinValue overflow, totalSamples-vs-buffer mismatch defenses).
- INdiInterop.CaptureAudioPeak (new, default-implemented): polls one audio frame, returns peak in [0,1] or null on timeout. FakeNdiInterop inherits the no-op default; production NdiInteropPInvoke overrides with real FLTP decode through a sibling RecvCaptureV3Audio import + RecvFreeAudioV3.
- NdiNative: AudioFrameV3 struct + audio-only RecvCaptureV3 binding + FreeAudioV3.
- NdiReceiver: spins up a sibling audio-capture loop alongside the existing video loop on the same lifetime. Audio failures are caught + logged but never re-thrown (a misbehaving audio path must never tear down the live video pipeline). Latest peak published via Volatile<long> (BitConverter int64 bits) so UI reads are torn-free across threads.
- IsoPipeline.GetStats: surfaces NdiReceiver.LatestAudioPeak as IsoHealthStats.PeakAudioLevel.
UI:
- ParticipantViewModel.OnStatsTick already had the decay logic (max-of-new-or-decayed-old, 0.7 multiplier) waiting for real values. No UI changes needed.
Tests: 14 new + 141 existing = 155/155 passing. 0 warnings, 0 errors.
Four polish items + a test pass.
1. Inter Variable (rsms/inter v3.19, OFL) is bundled at Assets/Fonts/Inter.ttf (~800 KB) and registered as a WPF Resource. WildDragonTheme.xaml's Wd.Font.Sans now points at pack://application:,,,/Assets/Fonts/#Inter so the typography matches wilddragon.net regardless of whether the user has Inter installed system-wide. Falls back to Segoe UI Variable Display if the resource is missing.
2. 'Stop all ISOs' button at the right of the participants header. Bound to a new MainViewModel.StopAllIsosCommand that snapshots the enabled list, awaits DisableIsoAsync sequentially, and silently swallows per-pipeline failures (best-effort emergency stop). CanExecute gates on whether any ISO is currently enabled.
3. WindowStateStore service persists the main window's Left/Top/Width/Height/State to %LOCALAPPDATA%\\TeamsISO\\window.json on close and restores it on SourceInitialized. Multi-monitor friendly: a saved position with no corner inside any virtual screen is rejected so a disconnected monitor doesn't strand the window off-screen.
4. Two new unit tests cover FrameProcessor's drops + duplicates accounting. 76/76 unit tests pass (was 74).
