App.xaml.cs was 461 lines / 21KB and conflated four concerns: process-
level lifecycle (mutex / message pump filter / shutdown), engine bootstrap
(NDI runtime / IsoController / view model construction), crash handling
(three exception channels + log directory + dialog), and the background
update-checker kickoff.
Splits via partial-class into themed sibling files:
* App.xaml.cs (was 461L → now 219L) — class skeleton, fields, internal
property accessors, Win32 P/Invoke surface, OnStartup as a wiring
pipeline that calls the bootstrap steps in order, OnExit, CLI parser.
* App.Bootstrap.cs (250L, new) — linear startup steps:
TryAcquireSingleInstance, TryBootstrapNdiInterop, BootstrapEngine,
ConstructAndShowMainWindow, BootstrapControlSurfaceServices,
BootstrapTrayIcon, TryShowOnboarding, TryAutoLaunchTeams. Each
returns a signal (bool / window ref) when OnStartup needs it to
decide whether to continue.
* App.CrashHandlers.cs (93L, new) — OnAppDomainUnhandled,
OnDispatcherUnhandled, OnUnobservedTaskException, TryLogFatal,
TryShowCrashDialog, LogDirectory.
* App.UpdateCheckBootstrap.cs (42L, new) — StartBackgroundUpdateCheck
(24h-throttled, fire-and-forget).
OnStartup's body is now a 30-ish-line procedure that names each step,
which is what the original was trying to be. Comments inline the
"happened before, kept here for reason X" notes (theme.Apply before
window show; CLI args parsed before InitializeAsync). Behavior is
unchanged — Shutdown codes, error paths, and the side-effect order are
all preserved.
Build clean (0 warnings, 0 errors); 56 + 104 tests still pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
