Implement role-based scope switching for coordinator vs org-admin
epic-coordinator-statistics-dashboard-ui-task-013 — Add a role scope toggle to CoordinatorStatsDashboardScreen that switches between coordinator-scoped data (own chapter only) and org-admin-scoped data (all chapters). Toggle visibility is controlled by the RoleAccessValidator. On scope switch, the BLoC dispatches a scope-changed event, clears cached data, and fetches org-wide stats. The toggle must have appropriate semantic labels for screen readers.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Store the current scope in the BLoC state, not in a local StatefulWidget. When processing StatsScopeChangedEvent, emit a CoordinatorStatsLoadingState immediately (clearing all previous data) then fire the scoped repository call. The repository method signature should accept a StatsScope parameter and construct the appropriate Supabase query: for coordinator scope, add a .eq('chapter_id', currentUser.chapterId) filter; for orgAdmin scope, omit the chapter filter and rely on RLS to allow the broader query. Avoid passing the raw role string to the query — use the strongly-typed StatsScope enum at the BLoC and repository boundaries.
RoleAccessValidator should be injected into the screen or BLoC (not accessed via a global singleton) to keep the component testable.
Testing Requirements
Write flutter_test widget tests and BLoC unit tests: (1) verify toggle is not rendered when user has coordinator role only, (2) verify toggle is rendered when user has org-admin role, (3) tap toggle and verify StatsScopeChangedEvent dispatched with correct scope, (4) verify BLoC clears cached data on scope change (state transitions through loading), (5) verify all sections re-render with scope-appropriate data, (6) verify Semantics label and hint update on scope change, (7) verify filters reset to defaults on scope change. Security test: verify Supabase RLS rejects org-wide queries for coordinator-role sessions (integration test against Supabase test environment).
PeerMentorStatsList must handle rosters of 40+ mentors efficiently. A naive ListView implementation that re-renders all rows on filter change may cause frame drops on mid-range devices, degrading the experience for coordinators managing large chapters.
Mitigation & Contingency
Mitigation: Use ListView.builder with const constructors for row widgets. Profile the list with Flutter DevTools on a release build against a 60-mentor dataset before submitting for review. Implement sort in the BLoC layer, not in the widget.
Contingency: If frame drops persist, introduce pagination (load 20 mentors, scroll to load more) and add a search filter to reduce visible row count in practice.
The ActivityTypeDonutChart must render org-configured activity type labels from the org-labels system. If the terminology provider is not available or returns stale labels, chart segments will display raw key strings instead of human-readable organisation-specific names, confusing coordinators.
Mitigation & Contingency
Mitigation: Always resolve labels through the OrganizationLabelsProvider before passing data to the donut chart widget. Implement a fallback that formats the raw key as a readable string (e.g., 'peer_support' → 'Peer Support') if the provider returns null.
Contingency: If the org-labels system is unavailable, display the formatted fallback label and log a warning. Do not block chart rendering on label resolution — render with fallbacks immediately.
fl_chart widgets do not natively expose semantic labels for individual bars and donut segments. Without explicit Semantics wrappers, VoiceOver and TalkBack users will receive no meaningful chart information, failing accessibility requirements critical for Blindeforbundet and NHF deployments.
Mitigation & Contingency
Mitigation: Wrap each fl_chart widget in a Semantics widget with a descriptive label summarising the chart data. Implement the data table fallback toggle from the start, not as an afterthought. Validate with VoiceOver on iOS and TalkBack on Android during development.
Contingency: If fl_chart's rendering pipeline prevents semantic overlay from working reliably, replace chart widgets with a custom Canvas-based implementation that has full semantic control, or use a different charting library with better accessibility support.
The period filter state must be preserved when navigating away from the dashboard (e.g., drilling into a mentor's detail screen and pressing back). If the BLoC is re-created on navigation, the filter resets to default, forcing coordinators to re-select their period every time they drill down, degrading operational workflow efficiency.
Mitigation & Contingency
Mitigation: Provide the StatsBloc at a route level above the dashboard screen using a BlocProvider scoped to the statistics navigation shell, not inside the screen widget itself. Verify persistence with a widget integration test that navigates away and back.
Contingency: If route-level scoping is not achievable within the current navigation architecture, persist the last-used filter to a local session store and restore it on screen re-entry.