Build ActivityWizardStepSemantics step-transition announcer
epic-screen-reader-support-complex-widgets-task-003 — Implement the ActivityWizardStepSemantics component's step-transition announcement logic. On each wizard step change, post a live region announcement describing the new step name and its ordinal position (e.g., 'Step 2 of 5: Select date'). Use the LiveRegionAnnouncer dependency and expose the current step progress as a semantic progress value via Flutter's Semantics widget.
Acceptance Criteria
Technical Requirements
Implementation Notes
Use a BLoC listener (BlocListener
Store step labels in the localisation arb file, keyed as activity_wizard_step_contact, activity_wizard_step_date, etc. Inject LiveRegionAnnouncer through Riverpod so it can be mocked in tests without difficulty.
Testing Requirements
Unit tests: verify that given a step transition from step 1→2 in a 5-step wizard, the announcer produces 'Step 2 of 5: Select date'. Verify no announcement fires when step index is unchanged. Widget tests: use flutter_test SemanticsController to capture semantic announcements; assert progressValue is 0.4 on step 2 of 5. Verify LiveRegionAnnouncer is called exactly once per step transition.
Integration test: simulate a full 5-step wizard flow programmatically and assert all 5 transition announcements fire in the correct order. Localisation test: switch locale to Norwegian and verify announcement format. Accessibility audit: run Flutter's built-in semanticsChecker on the wizard page. Coverage target: 85% for announcer logic.
Flutter does not natively enforce a focus trap within a bottom sheet or modal dialog in the semantic tree — VoiceOver and TalkBack can navigate outside the sheet to background content. Implementing a reliable focus trap requires overriding the semantic tree, which may conflict with the existing modal helper infrastructure in the app and require changes to shared components beyond this feature's scope.
Mitigation & Contingency
Mitigation: Prototype the focus trap on the first modal sheet implementation before building the remaining sheets. Evaluate Flutter's ExcludeSemantics and BlockSemantics widgets as the trap mechanism, and coordinate with the team owning the shared modal helpers to agree on a non-breaking integration point before writing production code.
Contingency: If a complete semantic focus trap cannot be implemented without breaking existing modal patterns, implement a partial solution using FocusScope with autofocus on the modal's first element and a prominent 'Return to main content' semantic action, documenting the deviation from WCAG 2.4.3 with a scheduled remediation item.
The activity wizard uses BLoC state management and the UI rebuilds the entire step widget subtree on transition. If the semantic tree is traversed by VoiceOver before the build cycle settles, focus may land on a stale or partially rendered step, causing the wrong step label or progress value to be announced. This is particularly problematic for blind users who cannot visually verify the announcement against the screen.
Mitigation & Contingency
Mitigation: Coordinate ActivityWizardStepSemantics with FocusManagementService (from the core services epic) to delay focus placement until the post-build callback confirms the new step's semantic tree is complete. Write integration tests using the AccessibilityTestHarness that assert the full announcement sequence across all five wizard steps.
Contingency: If post-build focus delay is insufficient due to async BLoC emission timing, add an explicit semantic notification barrier in the wizard cubit that emits a 'step ready' event only after the new widget tree has been marked as built, decoupling the announcement trigger from the raw state transition.
Automated WCAG contrast ratio checking on widget tree snapshots may produce false positives for gradient backgrounds, dark-mode overrides, or design token overrides that are resolved at runtime but appear as unresolvable colours at static analysis time. Excessive false positives would erode team trust in the CI gate, leading to suppression rules that also mask real violations.
Mitigation & Contingency
Mitigation: Scope the WCAGComplianceChecker to check only solid-colour backgrounds in the first iteration, explicitly excluding gradients from contrast checks with documented rationale. Design the check output to distinguish 'undetermined' (gradient/unknown) from 'fail' (solid colour below threshold) so the team can take targeted action on genuine failures only.
Contingency: If false positive rates exceed 20% of reported violations during initial CI runs, switch the CI gate from a hard build failure to a warning annotation on the pull request, combined with a mandatory manual review step, until the checker's rule set has been tuned to match actual design token values.