Implement Approval Status Notification Service
epic-expense-approval-workflow-coordinator-ui-task-006 — Create the ApprovalStatusNotificationService that triggers push notifications and in-app notifications to peer mentors when their claim status changes (approved, rejected, requires action). Integrate with FCM dispatcher and in-app notification repository, including localized message templates for each status transition.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 2 - 518 tasks
Can start after Tier 1 completes
Implementation Notes
Keep notification template strings in a dedicated NotificationTemplates class with a static method resolveTemplate(ClaimStatus, Locale, {String? justification}) → NotificationContent to make the template logic independently testable. For FCM dispatch, implement a thin FcmDispatcher interface with a SupabaseEdgeFunctionFcmDispatcher concrete implementation — this keeps the service testable without real FCM calls. Use Future.wait([sendPush(), createInApp()]) wrapped in a try/catch that captures partial failures independently, logs each, and rethrows only if both fail.
The workshop notes emphasise that peer mentors (likepersoner) have diverse digital skill levels — keep notification copy simple, action-oriented, and jargon-free in both languages.
Testing Requirements
Unit tests: mock FCM dispatcher and in-app notification repository. Verify that for each ClaimStatus, the correct template key is selected and the correct locale is applied. Test that FCM failure does not prevent in-app notification creation (and vice versa). Test missing FCM token path (push skipped, in-app created).
Test justification injection into the rejection template with and without justification text. Test Norwegian and English locale outputs for each status. Integration test: write a notification to the Supabase test notifications table and verify the row has the correct recipient_id, claim_id, and read=false. Use flutter_test.
Target 90%+ line coverage on template resolution and dispatch logic.
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.