riverpod-stream-provider-auth-transition-oscillation

Riverpod StreamProvider Auth Transition Oscillation

Problem

After successful login and redirect, the main screen (home feed, dashboard, etc.) is permanently stuck on a loading indicator. The auth redirect works correctly (URL shows /home/0), but the screen never renders data. This is NOT a rapid rebuild issue — the widget builds a few times then settles on a loading state.

Context / Trigger Conditions

Symptoms:

• Screen stuck on loading spinner after successful login redirect
• URL bar / GoRouter shows correct path (e.g., /home/0)
• Data provider (e.g., homeFeedProvider) has data if checked directly
• No error messages — just permanent loading
• May show brief flash of content before reverting to loading

Architecture that triggers this:

1. A StreamProvider that watches router.routerDelegate for location changes
2. This stream parses routes into a RouteContext with a type field (home, explore, etc.)
3. Downstream providers gate on routeContext.type == RouteType.home and return AsyncValue.loading() when the type doesn't match
4. The widget watches the downstream provider and shows loading indicator

The oscillation pattern:

Auth state changes → Router redirects to /home/0
  → routerDelegate emits /home/0 ✓
  → routerDelegate emits /welcome/login (stale!) ✗
  → routerDelegate emits /home/0 ✓
  → routerDelegate emits /welcome/* (stale!) ✗
  ...oscillates for several frames

Why it happens: GoRouter's routerDelegate listener fires for EVERY location change during transitions, including intermediate/stale states. During post-login, the router processes multiple pending navigations (pop welcome screen, push home screen) and the delegate emits each intermediate state. A sync StreamController propagates these instantly.

Log signature:

CTX derive: type=RouteType.home npub=null index=0
CTX derive: type=RouteType.welcome npub=null index=null   ← stale!
CTX derive: type=RouteType.home npub=null index=0