Two simultaneous TeamsISO processes contend over the NDI runtime, the same default sender names, and %APPDATA%\\TeamsISO\\config.json — observed during testing when launchers / shortcuts produced duplicate windows. Add a Local namespace per-user-keyed mutex (Local\\WildDragon.TeamsISO.SingleInstance.<username>) at startup; if a second instance can't claim it, broadcast a registered window message ('WildDragon.TeamsISO.BringToFront') and Shutdown(0). The running instance subscribes to that message via ComponentDispatcher.ThreadFilterMessage and surfaces its main window when received.
Per-user keying lets two different Windows users on the same machine each run their own TeamsISO. Mutex is released and disposed on OnExit.
Verified: Start-Process the exe twice in a row -> only one process remains, with the original window surfaced.
Adopts the design language from Dammyjay93/interface-design: warm Stone neutrals, accent orange (#EA580C), borders-only depth (no shadows), 8px spacing grid, all-caps section labels, mono typography for machine names and timecodes.
Themes/StoneTheme.xaml is the single source of truth for design tokens (color brushes, typography styles, spacing) plus restyled control templates (Button, TextBox, ComboBox, ComboBoxItem, CheckBox, DataGrid + DataGridColumnHeader / DataGridRow / DataGridCell, ScrollBar). MainWindow consumes the tokens and is laid out with a header (title + status pill), section-headed Settings sidebar (Output Format / NDI Network / Display), card-wrapped participant list, and a mono status footer.
Settings sidebar surfaces the new NDI group configuration (discovery + output) and a Hide-(Local) checkbox. The latter filters the user's own self-preview from the participants list at the MainViewModel layer (HideLocalSelf=true by default) so operators don't accidentally route their own preview as an ISO. Apply Changes round-trips both FrameProcessingSettings and NdiGroupSettings through the controller in one go.
- TeamsISO.App: hand-rolled net8.0-windows WPF csproj since the WPF
template isn't shipped on linux-arm64 .NET SDK; UI is a placeholder
for Phase C.
- TeamsISO.Engine.IntegrationTests: cross-platform xunit project with a
skipped scaffold fact tagged [Trait("requires", "ndi")] for Phase B.
- TeamsISO.Linux.slnf: solution filter for non-Windows CI that excludes
the WPF project (which can only build on Windows).
