OAuth session persists via DPAPI; sign-in lives in the Start Stream dialog; add xUnit test project (6 passing)

TASKS.md

@@ -72,11 +72,12 @@ Lifecycle: `created → ready → [testing] → live → complete` (transitional
 - Verify token refresh triggers when near expiry
 - Verify credential load/save roundtrip
 
-### Status: 🔶 UI flow done — auth wiring pending
+### Status: ✅ Complete
 - ✅ Two-state Start/End Stream button, go-live dialog (account + title/description/visibility), red top bar, pulsing LIVE badge + elapsed timer, preview glow, taskbar red dot
 - ✅ Real OAuth2 wiring — baked-in Google credentials (desktop client; loopback callback) + `YouTubeAuthService` complete: browser launch, `HttpListener` callback, token exchange, refresh, channel fetch
-- ⬜ Token persistence via Windows DPAPI, reload on startup
-- ⬜ Account sign-in/change surfaced in the GoLive dialog (GoLiveViewModel still simulates it)
+- ✅ Token persistence via Windows DPAPI (`Helpers/TokenStore.cs` → `%APPDATA%\ytLlive\ytLlive.auth`), best-effort reload + proactive refresh at startup, saved after every exchange/refresh
+- ✅ Account sign-in/change surfaced in the GoLive dialog (saved account shown with "Change Account"; "Sign in to YouTube" when none; Start disabled until signed in)
+- ✅ Tests in `ytLive.Tests` (xUnit, net8.0-windows): TokenStore DPAPI roundtrip/corrupt/missing/clear + mocked exchange channel-parse + refresh expiry bump — 6 passing
 
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