Implement configurable re-mask timeout for EncryptedFieldDisplay
epic-contact-detail-and-edit-supporting-ui-task-010 — Add a configurable re-mask timer to EncryptedFieldDisplay. After decryption, start a countdown (default 30 seconds, configurable via sensitive-field-configuration component 616). On timeout, re-mask the field and announce the re-masking to screen readers via live region. Cancel the timer if the widget is disposed before timeout.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 4 - 323 tasks
Can start after Tier 3 completes
Implementation Notes
Add `Timer? _remaskTimer` as a private field in _EncryptedFieldDisplayState. In _onDecryptionSuccess(), after setting state, call `_remaskTimer?.cancel(); _remaskTimer = Timer(widget.configuration?.remaskTimeout ?? const Duration(seconds: 30), _onRemask);`.
In _onRemask(): `_remaskTimer?.cancel(); _remaskTimer = null; setState(() { _isRevealed = false; _plaintextValue = null; }); SemanticsService.announce(...)`. In dispose(): `_remaskTimer?.cancel(); _remaskTimer = null; super.dispose();`. For AppLifecycleObserver: mix in WidgetsBindingObserver, register in initState via WidgetsBinding.instance.addObserver(this), and override didChangeAppLifecycleState: if state == AppLifecycleState.paused && _isRevealed → call _onRemask(). Remove the observer in dispose() with WidgetsBinding.instance.removeObserver(this).
The SensitiveFieldConfiguration class should be a simple immutable Dart class with a remaskTimeout Duration field — it can be a stub for now if component 616 is not yet implemented, with the widget accepting `SensitiveFieldConfiguration? configuration` as an optional named parameter.
Testing Requirements
Widget tests using fake_async (test/widgets/encrypted_field_display_timer_test.dart): (1) reveal field with timeout of 5 seconds → advance fake timer by 5 seconds → assert field is in masked state and plaintext is absent; (2) reveal field → manually re-mask via unlock icon → advance fake timer beyond 5 seconds → assert no double setState or error; (3) reveal field → dispose widget before timer fires → assert no 'setState called after dispose' error (use FlutterError listener); (4) reveal field → re-reveal before timeout → assert timer restarts (advance to original deadline, assert still revealed, then advance to new deadline, assert masked); (5) reveal field with null SensitiveFieldConfiguration → assert default 30-second timer is used. Use FakeAsync.elapse for all timer-related assertions.
The encrypted-field-display confirmation dialog adds interaction steps that may frustrate coordinators who access sensitive fields frequently, leading to requests to bypass the flow or skip read-receipt logging, which would violate Blindeforbundet's compliance requirements.
Mitigation & Contingency
Mitigation: Design the confirmation dialog to be as minimal as possible (one clear sentence, single confirm action) and ensure it does not reappear for the same field within a single screen session. Validate the UX with Blindeforbundet coordinators during the TestFlight pilot before finalising.
Contingency: If coordinators raise strong objections, escalate to Blindeforbundet's data protection officer to determine whether a lighter confirmation pattern (e.g., biometric confirmation instead of dialog) satisfies their compliance obligation.
The activity-history-list infinite scroll requires paginated Supabase queries. Contacts with hundreds of activities (e.g., an HLF peer mentor with 380 annual registrations) could cause slow page loads or memory pressure on older devices if pagination boundaries are set too large.
Mitigation & Contingency
Mitigation: Use a page size of 20 records with cursor-based pagination. Implement list item recycling using Flutter's ListView.builder. Benchmark memory usage with 400+ item simulation on a low-end test device before TestFlight release.
Contingency: If performance degrades on older devices, reduce page size to 10 and add a time-window filter (last 30 days, last 6 months, all) so the default view loads a manageable record count for most coordinators.
The cognitive load rule engine (from the Cognitive Accessibility feature) mandates no more than 7 fields per screen section. If a contact model has more than 7 editable fields, the edit-contact-screen layout must be split into sections, adding complexity not accounted for in the initial scope.
Mitigation & Contingency
Mitigation: Audit the full contact field list from all four organisations before implementation. Group fields into logical sections (personal info, contact details, affiliation) so no single section exceeds 7 fields. Use the cognitive-load-rule-engine component if it is already delivered by the Cognitive Accessibility feature.
Contingency: If the rule-engine component is not yet available, implement a simple manual section layout with accordion-style expansion for less-frequently edited fields to stay within the 7-field guideline without blocking delivery.