Build Unit Assignment Repository
epic-organizational-hierarchy-management-admin-portal-task-002 — Implement the Supabase-backed repository for unit assignment CRUD operations. Include methods for fetching assignments by user, by unit, setting primary unit, and batch assignment updates. Integrate with the hierarchy cache for read operations and ensure proper RLS policy compliance for data isolation.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 1 - 540 tasks
Can start after Tier 0 completes
Implementation Notes
Define a `UnitAssignmentRepository` abstract class and a `SupabaseUnitAssignmentRepository` concrete implementation. Inject `HierarchyCache` via constructor for cache-aside reads. For `setPrimaryUnit`, use a Supabase RPC (PostgreSQL function) to perform the unset+set atomically rather than two sequential client calls — this avoids race conditions. For `batchUpdateAssignments`, use a Supabase upsert with `onConflict` handling.
Map Supabase `PostgrestException` error codes to typed Dart exceptions in a private `_mapError()` helper. Register the repository as a Riverpod `Provider
Testing Requirements
Unit tests with MockSupabaseClient to cover all 5 repository methods. Integration tests (optional, run in CI against a local Supabase instance) covering RLS: verify that a user from org A cannot read org B's assignments. Test setPrimaryUnit atomicity: inject a fault between the unset and set operations and verify rollback. Test batchUpdateAssignments with 0, 1, and 10 assignments.
Test typed exception mapping from Supabase error codes (403 → PermissionDeniedException, 404 → AssignmentNotFoundException).
If the AccessScopeService and the Supabase RLS policies use different logic to determine accessible units, a coordinator could see data in the client that RLS blocks server-side, causing confusing empty states, or worse, RLS could block data the scope service declares accessible.
Mitigation & Contingency
Mitigation: Define the canonical scope computation in a single Supabase Postgres function shared by both the RLS policies and the RPC endpoint called by AccessScopeService. The client-side service calls this RPC rather than reimplementing the logic, ensuring a single source of truth.
Contingency: Add integration tests that execute the same access decision through both the RLS policy path and the AccessScopeService path and assert identical results. Use these as regression guards in the CI pipeline.
When a user switches active chapter via the ChapterSwitcher, widgets that are already built may not receive the context-change event if they subscribe incorrectly to the ActiveChapterState BLoC, leading to stale data being displayed under the new chapter context.
Mitigation & Contingency
Mitigation: Use Riverpod's ref.watch on the active chapter provider at the root of each scoped data subtree rather than at individual leaf widgets. Trigger a global data refresh by invalidating all scoped providers when the chapter changes.
Contingency: Add an app-level chapter-change listener that forces a full navigation stack reset to the home screen on chapter switch, guaranteeing all widgets rebuild from scratch with the new context. Accept the UX cost of navigation reset for correctness.
Non-technical organization administrators may find the hierarchy management interface too complex for the structural changes they need to make frequently (e.g., chapter renaming, coordinator reassignment), leading to low adoption and continued reliance on manual processes.
Mitigation & Contingency
Mitigation: Conduct usability testing with at least one NHF administrator before finalizing the admin portal screen layout. Prioritize the most common operations (rename, reparent, add child) as primary actions in the UI. Include inline help text and confirmation dialogs with plain-language descriptions of consequences.
Contingency: Provide a simplified 'quick edit' mode that exposes only the three most common operations (rename, deactivate, add child) and hides advanced structural operations behind an 'Advanced' toggle.