Implement Expense Claim Status Repository
epic-expense-approval-workflow-coordinator-ui-task-003 — Create the ExpenseClaimStatusRepository managing the status lifecycle of expense claims (pending, under_review, approved, rejected, auto_approved). Support status transition queries, paginated pending-claim fetches filtered by coordinator chapter, and real-time status change subscriptions via Supabase.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 1 - 540 tasks
Can start after Tier 0 completes
Implementation Notes
Implement the transition guard as a static method on ClaimStatus or a dedicated ClaimStatusTransitionGuard class — this makes it independently testable. For Supabase Realtime, use `supabase.channel('claim_status_$claimId').on(PostgresChangeEvent.update, ...).subscribe()`. Ensure the StreamController is properly closed when the repository is disposed — expose a dispose() method and call it from the BLoC/provider's onClose/dispose lifecycle. For pagination, prefer keyset (cursor) pagination over offset if claims are frequently inserted to avoid page drift.
The Realtime subscription added here is the foundation for task-004, which will generalise it to the full approval queue.
Testing Requirements
Unit tests: test each valid and invalid status transition path in the transition guard. Mock Supabase and verify correct query parameters for paginated fetches (eq filters, range, order). Test Stream emits correctly from a mocked Realtime channel. Integration tests: insert a claim, subscribe to watchClaimStatus, update the status in a second connection, and assert the stream emits the new status within a timeout.
Test that page 2 of paginated results contains the correct items. Test RLS cross-chapter access is blocked. Use flutter_test with fake async for stream timing. Target 85%+ line coverage.
Maintaining multi-select state across paginated list pages is architecturally complex in Flutter with Riverpod/BLoC. If the selection state is stored in the widget tree rather than the state layer, page transitions and list redraws can silently clear selections, causing coordinators to lose their multi-select and re-enter it.
Mitigation & Contingency
Mitigation: Store the selected claim ID set in a dedicated Riverpod StateNotifier outside the paginated list widget tree. The paginated list reads selection state from this provider and does not own it. Selection persists independently of list scroll position or page loads.
Contingency: If cross-page selection proves prohibitively complex, limit bulk selection to the currently visible page (add a clear warning in the UI) and prioritise single-page bulk approval for the initial release.
If a coordinator has the queue open while another coordinator approves claims from the same queue (possible in large organisations with shared chapter coverage), the Realtime update may arrive out of order or be missed during a reconnect, leaving the first coordinator's view stale and allowing them to attempt to approve an already-actioned claim.
Mitigation & Contingency
Mitigation: The ApprovalWorkflowService's optimistic locking (from the foundation epic) will catch the concurrent edit at the database level. The CoordinatorReviewQueueScreen should handle the resulting ConcurrencyException by removing the claim from the local list and showing a brief snackbar: 'This claim was already actioned by another coordinator.'
Contingency: Add a queue staleness indicator (a subtle 'last updated X seconds ago' label) and a manual refresh button as a fallback for coordinators who notice inconsistencies.
The end-to-end test requirement that a peer mentor receives a push notification within 30 seconds of coordinator approval depends on FCM delivery latency, which is outside the application's control and can vary significantly in CI/CD environments.
Mitigation & Contingency
Mitigation: Structure end-to-end tests to verify notification intent (correct FCM payload dispatched, correct Realtime event emitted) rather than actual device delivery timing. Use test doubles for FCM delivery in automated tests and reserve real-device delivery tests for manual pre-release validation.
Contingency: If notification timing requirements must be validated in automation, instrument the ApprovalNotificationService with a test hook that records dispatch timestamps and assert against those rather than actual FCM callbacks.