Add date-range filter bar to recruitment dashboard
epic-membership-recruitment-coordinator-badge-task-005 — Integrate a DateRangeFilterBar widget into the coordinator recruitment dashboard allowing selection of preset ranges (last 7 days, last 30 days, last 90 days, custom). Dispatch filter events to the BLoC and reflect the active range in the UI. Reuse existing stats period filter patterns from 452-stats-period-filter-bar for design consistency.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 3 - 413 tasks
Can start after Tier 2 completes
Implementation Notes
Extend or copy the pattern from 452-stats-period-filter-bar rather than building from scratch — check if it can be parameterized to accept a different set of preset options. If it cannot, create DateRangeFilterBar as a new widget that follows the same visual and behavioral contract. Date computation for presets: use DateTime.now() minus Duration(days: N) at dispatch time, not at widget construction time, to ensure accuracy. Store the active DateRange in the BLoC state, not in widget state — this ensures the filter bar reflects state correctly after hot restart or screen pop.
For the custom range picker, use Flutter's built-in showDateRangePicker which handles accessibility and locale automatically.
Testing Requirements
Widget tests (flutter_test): (1) tapping each preset chip dispatches the correct DateRangeChanged event with the correct computed date range, (2) active chip reflects BLoC state — not internal widget state, (3) cancelling custom picker does not dispatch an event, (4) custom picker confirm dispatches correct start/end dates, (5) chips are scrollable without overflow on a 320px width constraint. Use MockBloc and verify add() calls.
BadgeCriteriaIntegration must reference specific badge definition IDs from the badge-definition-repository for recruitment badges. If those badge definitions have not been created in the database when this epic is implemented, the integration will silently fail to award badges.
Mitigation & Contingency
Mitigation: As the first task of this epic, create the four recruitment badge definitions (seed data migration) with known, stable IDs. BadgeCriteriaIntegration hardcodes these IDs as constants. Include an assertion in the integration tests that verifies the badge definition records exist in the test database.
Contingency: If the badge definitions system does not support seeding at migration time, store the badge definition IDs in a feature-flag-style config table and look them up at runtime, falling back to a no-op with a warning log if they are absent.
The coordinator dashboard aggregates referral stats across all peer mentors in an organisation. For large organisations (HLF has many peer mentors nationally), the aggregation query may be slow, causing the dashboard to feel unresponsive.
Mitigation & Contingency
Mitigation: Implement the aggregation as a Supabase database view or RPC that runs server-side with appropriate indexes on (mentor_id, org_id, created_at, event_type). Add a composite index on referral_events during the foundation epic's migration. Cache the result in the Riverpod provider with a 5-minute TTL.
Contingency: If query performance remains unacceptable at scale, materialise the aggregation in a nightly pg_cron job into a stats_cache table, and serve the dashboard from the cache with a 'last updated' timestamp shown to the coordinator.
The existing badge award service is implemented by the achievement-badges feature. If that feature's public API (BadgeAwardService interface) changes while this epic is in progress, the BadgeCriteriaIntegration will break at compile time or behave incorrectly at runtime.
Mitigation & Contingency
Mitigation: Confirm the BadgeAwardService interface is stable and document the exact method signatures this integration depends on. Write a narrow integration test that constructs the real BadgeAwardService against a test database to detect breaking changes immediately.
Contingency: If the badge service interface changes, adapt the BadgeCriteriaIntegration adapter class to match the new contract. The adapter pattern used here isolates the change to a single class.