Deep Link and Restoration

When handling deep links or state restoration, ensure predictable redirects and stable app states.

Links and Redirects

• Cold vs Warm Links: A cold link opens the app from closed; a warm link routes within an already running app. Both must reach the correct state.
• Auth Flow: Route unauthenticated requests for protected content to a login screen, passing a redirect target. On success, seamlessly navigate to that target.
• Redirect Loops: Prevent infinite cycles by maintaining clear auth-state boundaries and avoiding circular redirect dependencies.

State Restoration

• RestorationMixin: Use to persist UI state across app restarts. Combine with the router to maintain navigation history.
• Router Integration: Ensure deep links re-hydrate not just the destination, but also essential parent routes or dependencies required by that destination.

Testing

Build a risk-based matrix that can be replayed with the same fixture identity and expected destination:

• Verify both cold and warm entry, including a link received while another route, dialog, sheet, or loading overlay is visible.
• Exercise signed-out redirect and post-login continuation, then repeat after logout or account switch so a destination cannot reuse stale authorization or user data.
• Assert Back or Up behavior after direct entry and after the authentication detour.
• Deliver the same link more than once and verify one intended navigation or idempotent refresh rather than stacked destinations or duplicate side effects.
• Hold the destination API in a controlled slow, empty, error, or malformed state and verify loading, cancellation, retry, and fallback behavior without losing the pending destination.
• Detect multiple listener registration by counting receipt, parsing, navigation, and domain effects for one link.
• Assert proper fallback or error handling for invalid, expired, or unauthorized paths.

Use flutter-device-testing when OS delivery or lifecycle behavior must be proven on a target. Keep route assertions in the project's existing integration-test or semantic inspection layer instead of relying on launch-command success alone.