Implement StatsSummaryCards row widget
epic-coordinator-statistics-dashboard-ui-task-002 — Build the StatsSummaryCards component displaying four tappable KPI cards: total activities, active peer mentors, hours contributed, and contacts reached. Each card shows a value, label, and trend indicator. Cards must be tappable for drill-down navigation, use design tokens for colors/typography, and include VoiceOver/TalkBack semantic labels. Support loading skeleton state.
Acceptance Criteria
Technical Requirements
Implementation Notes
Define a StatsSummaryData class with four KpiCardData fields. KpiCardData holds: int value, String label, TrendDirection trend (enum: up, down, neutral), and VoidCallback? onTap. Render the four cards using a Wrap widget with a runSpacing and spacing from the spacing token; set the breakpoint at 360 px using LayoutBuilder.
Each KpiCard renders a Card with InkWell for tap feedback. The trend indicator is a Row of an Icon (arrow_upward / arrow_downward / remove) and an optional percentage text, both using design token colors. For the loading skeleton, replace the value and trend widgets with a Container of width 60, height 20, and a shimmer animation from the shimmer package (already in pubspec) or a simple animated opacity. The Semantics label should be assembled as '${card.label}: ${card.value}, ${trend description}' — build this string in KpiCard so it is always consistent with the visual.
Testing Requirements
Widget tests using flutter_test. Test groups: rendering (all four cards visible with correct labels and formatted values, trend indicators match direction and color tokens), loading state (skeleton shown when isLoading=true, no values rendered, taps are no-ops), interaction (tapping each card invokes onCardTapped with the correct CardType), accessibility (each card Semantics node contains value + label + trend as a combined string), responsive (2×2 grid at 320 px width, single row at 375 px). Verify design token usage by asserting that no hardcoded Color values appear in the widget source (grep check in CI). Achieve ≥ 90 % line coverage.
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.