Supabase Contact Chapter Adapter

This is a medium-complexity infrastructure component that sits at the foundation of the data layer, meaning several higher-level components — including the Contact Chapter Repository and Cross-Chapter Activity Query — cannot be built or tested without it. It should be prioritized early in the sprint schedule to unblock dependent work. Development requires familiarity with Supabase PostgREST query syntax, RLS policy configuration, and domain-to-database serialization patterns. Testing should include both unit tests with mocked Supabase responses and integration tests against a staging Supabase instance to verify RLS filtering behaves correctly under different auth contexts.

Since this adapter has no dependencies of its own, it can be developed independently in parallel with other foundational work.

This adapter wraps the Supabase client for the contact_chapters table, providing six discrete interfaces: insert, delete, selectByContact, selectByChapter, countByContact, and joinActivities. It handles serialization of ContactChapter domain objects to and from Map row format. The joinActivities interface is the most complex — it must perform a Supabase embedded resource join between contact_chapters and activities, returning raw row maps for the Cross-Chapter Activity Query to consume. RLS policy compliance is handled automatically via the authenticated Supabase client; the adapter must ensure the correct auth context is propagated on every call.

Error handling must map Supabase PostgrestException codes to typed domain exceptions rather than surfacing raw database errors upstream. Runs in both mobile and backend contexts, so the Supabase client instance must be injected rather than instantiated directly.