Implement MentorStatusBLoC event handlers
epic-peer-mentor-pause-ui-state-task-008 — Implement the BLoC event handlers for PauseMentorEvent and ReactivateMentorEvent. Each handler emits Loading, calls MentorStatusService, then emits Success or Error. Error handling must distinguish network failures from invalid state transitions and surface a human-readable message via the error state. Inject MentorStatusService via constructor.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 1 - 540 tasks
Can start after Tier 0 completes
Implementation Notes
Use flutter_bloc 8.x on
Emit order matters: always emit Loading before the await, otherwise the UI may miss the loading state if the service responds synchronously in tests. Use isClosed guard before emitting after async operations: if (!isClosed) emit(...).
Testing Requirements
Unit tests with bloc_test package: use blocTest
Test network failure: expect MentorStatusError with isInvalidTransition == false. Mock MentorStatusService using Mockito or Mocktail. Assert BLoC closes without error after all tests.
PauseConfirmationDialog must meet WCAG 2.2 AA focus trap requirements: when the dialog opens, focus must move to the first interactive element; when it closes, focus must return to the triggering toggle. Flutter's default showDialog does not always guarantee correct focus restoration on Android, which could trap screen-reader users.
Mitigation & Contingency
Mitigation: Use a custom modal implementation wrapping Flutter's Dialog with explicit FocusScope management and test with TalkBack on Android and VoiceOver on iOS during development, not just in final QA. Reference the accessible-modal-sheet pattern already used elsewhere in the codebase.
Contingency: If full WCAG focus management cannot be achieved within the sprint, ship the feature with a documented accessibility defect and schedule a dedicated accessibility remediation task. Communicate the known gap to the accessibility stakeholder at HLF/NHF.
If the user taps the PauseReactivateToggle rapidly before the BLoC emits a loading state, multiple PauseMentorEvents could be added to the BLoC stream, resulting in duplicate service calls and inconsistent UI state (toggle flickering between states).
Mitigation & Contingency
Mitigation: Disable the toggle widget immediately on first tap by emitting MentorStatusLoading synchronously before the async service call begins. Use BLoC's event transformer with droppable() to discard subsequent events while a transition is in progress.
Contingency: If BLoC event deduplication is not sufficient, add a debounce at the widget level (300 ms) and a server-side idempotency check in MentorStatusService that no-ops if the requested transition is already in progress.
PauseStatusBanner must conditionally render the reactivate shortcut only for users with coordinator permission. If the permission check relies on a stale role state in the Riverpod provider, a peer mentor could briefly see a reactivate action they are not authorised to use, which could cause a confusing permission-denied error if tapped.
Mitigation & Contingency
Mitigation: Source the permission check directly from the role-resolution Riverpod provider (which is kept in sync with Supabase auth) rather than from local component state. Add a widget test asserting the shortcut is absent when the user role is peer_mentor.
Contingency: If the shortcut is accidentally shown to an unauthorised user, the underlying MentorStatusService enforces role validation server-side, so the worst outcome is a visible error message rather than an actual unauthorised state change.