Integration test: selection screen end-to-end with cache

Mock the Supabase client at the SupabaseClient constructor level by overriding the supabaseClientProvider in ProviderScope. Return pre-built List> from the mocked from() query chain. To count network calls without real HTTP, track invocations on the mock's from() method. For the cache-hit test, boot the provider graph, trigger one fetch, then recreate only the widget subtree (not the ProviderScope) so the cache state is preserved.

For mutation-then-refetch, call the service mutation on the ProviderContainer, then rebuild the selection screen widget and verify the mock was called a second time. For wizard propagation, wrap ActivityTypeSelectionScreen inside a minimal RegistrationWizardOrchestrator stub that reads the selected ActivityType from shared Riverpod state and conditionally renders downstream steps.

Flutter integration tests using flutter_test with testWidgets(). Use a real ProviderContainer or ProviderScope booting the full production provider graph, overriding only the Supabase client with a mocktail Mock. Count Supabase mock invocations using verify().called(n). For wizard propagation tests, navigate the full wizard flow using tester.tap() and tester.pumpAndSettle().

Assert presence/absence of downstream wizard widgets using find.byType(). Tests must be runnable with flutter test — no dependency on a running device or emulator beyond what flutter_test provides.