Implement export readiness status display in export screen
epic-bufdir-report-export-user-interface-task-011 — Add an ExportReadinessBanner widget at the top of BufdirExportScreen that computes and displays overall export readiness based on: (1) whether a valid scope is selected, (2) whether a valid period is selected, (3) whether the preview loaded without blocking errors, and (4) whether any unmapped activity warnings are present. Use green/amber/red status icons from the contrast-safe colour palette. The banner must announce status changes via a live region so screen reader users hear readiness updates without manually navigating.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 4 - 323 tasks
Can start after Tier 3 completes
Implementation Notes
Implement ExportReadinessBanner as a pure function of ExportReadinessStatus — compute the status in a dedicated pure function (computeReadiness(scope, period, previewState, warningCount)) that is unit-testable independently of Flutter. Observe state via a MultiRepositoryProvider or a combined Riverpod provider that merges exportScopeProvider, exportPeriodProvider, and ExportPreviewCubit state. Avoid direct BlocBuilder nesting; prefer BlocSelector targeting only the relevant state fields. Use SemanticsService.announce() as a fallback for older Flutter versions if the liveRegion approach does not fire reliably during CI tests.
Testing Requirements
Widget tests covering all four status combinations: (1) red when scope null, (2) red when period null, (3) red when preview has blocking error, (4) amber when preview not yet fetched, (5) amber when unmapped warnings present, (6) green when all conditions satisfied. Semantics test: verify liveRegion is true and label text matches expected string for each status. Accessibility test: run flutter_test semanticsEnabled tests and confirm no contrast violations with design token colours.
The preview panel requires a round-trip to the edge function to compute aggregated counts. If this call takes 5–15 seconds for large scopes, users may assume the app has frozen and navigate away, potentially triggering duplicate preview requests or leaving the export in an undefined state.
Mitigation & Contingency
Mitigation: Show an immediate skeleton loading state on the preview panel as soon as the period and scope are confirmed, with named stage labels (e.g. 'Querying activities…', 'Computing totals…') streamed from the edge function's progress events. Set a clear user-visible timeout with a retry option. Pre-warm the edge function with a lightweight ping when the scope selector is opened.
Contingency: If preview latency consistently exceeds 10 seconds for large scopes, cache the preview payload in local BLoC state and allow the coordinator to proceed to confirmation without re-fetching if scope and period have not changed since the last preview.
The export preview panel contains dynamic content (warning badges, loading skeletons, aggregated counts) that must be announced correctly by VoiceOver and TalkBack. Incorrect semantics annotations could make the preview unreadable for blind coordinators, violating the project's WCAG 2.2 AA accessibility mandate.
Mitigation & Contingency
Mitigation: Implement semantic annotations using Flutter's Semantics widget with explicit labels for all dynamic content. Use live region announcements for loading state transitions. Schedule a dedicated accessibility review session with a screen reader user (Blindeforbundet has relevant expertise) before marking the epic complete.
Contingency: If the preview panel cannot be made fully screen-reader-accessible in time for launch, ship a simplified text-only summary mode activated by a toggle at the top of the preview panel, which renders all data as a single readable paragraph with no interactive badges.