Add ARIA labels and semantic roles across all map components
epic-geographic-peer-mentor-map-ui-accessibility-task-012 — Conduct a full semantic annotation pass across all six map UI components: MapViewScreen, MapMarkerWidget, MentorInfoPopup, MapFilterPanel, ViewToggleButton, and MentorListFallback. Ensure every interactive element has an explicit semanticsLabel, correct SemanticsRole, and that focus management is correct on open/close of popups and bottom sheets. Run Flutter semantics tree dump and verify no unlabelled interactive nodes remain.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Start by running flutter test --plain-name 'semantics' with SemanticsHandle to enumerate all current annotations, then work component by component. For modals and bottom sheets, use FocusTrap widget (available in Flutter 3.x) or implement manually with FocusScope. Label dynamic content using string interpolation directly in Semantics: Semantics(label: '${mentor.name}, ${availabilityLabel}, tap to view details'). For toggle buttons use Semantics(toggled: isToggled, label: 'List view').
Do not rely on child widget text as the semantic label for complex interactive widgets — always provide an explicit label. For the map canvas ExcludeSemantics wrapping (from task-011), ensure the exclusion is applied here too for consistency. Document the full semantics annotation pattern in a brief inline comment per component so future contributors know why Semantics wrappers exist.
Testing Requirements
Write widget tests for each of the six components using tester.getSemantics() and expect(semantics, ...) matchers to assert labels, roles, and actions. Use expectLater(tester, meetsGuideline(labeledTapTargetGuideline)) and meetsGuideline(iOSTapTargetGuideline) in all six component tests. Write a focused semantics tree snapshot test that dumps the tree for MapViewScreen and asserts no null-label interactive nodes exist. Test focus trap in MentorInfoPopup: open popup, send tab key events, assert focus does not leave the popup subtree.
Test focus restoration on close.
Flutter's map canvas (flutter_map) does not natively support semantic focus traversal for screen readers, meaning map markers may be entirely invisible to VoiceOver/TalkBack users. If the accessible list fallback is not treated as a first-class view, screen reader users will have no access to the feature.
Mitigation & Contingency
Mitigation: From sprint 1, treat mentor-list-fallback as a fully featured primary view, not an afterthought. Implement and test it in parallel with the map canvas. Make the view-toggle-button keyboard focusable and announced on every screen state. Conduct VoiceOver testing on device before submitting each PR touching UI components.
Contingency: If map canvas accessibility cannot be achieved for marker focus traversal, make the view-toggle-button the default focus target on screen load for VoiceOver users (detected via screen-reader-detection-service) so they are immediately directed to the list fallback without needing to discover the toggle.
The mentor-info-popup must occupy no more than 40% of visible map area on small screens. On devices with screen heights under 667px (iPhone SE), overlapping with the filter panel or obscuring most of the map could severely degrade usability.
Mitigation & Contingency
Mitigation: Implement the popup as a bottom sheet capped at 40% of screen height with a ScrollView for overflow content. Test on iPhone SE (375x667pt) and the smallest commonly used Android form factor in the device lab. Define max-height as a percentage constant in location-privacy-config or design tokens.
Contingency: If the popup cannot fit all required fields within 40% height on smallest targets, truncate assigned contact count and certification badge to icons-only in the compact view, with a 'View Profile' button always visible at the bottom of the popup regardless of scroll position.
Filter state must remain perfectly synchronised between the map view and the list fallback. If the filter panel emits state that is not consumed identically by both views, coordinators switching between views will see inconsistent mentor sets, eroding trust in the feature.
Mitigation & Contingency
Mitigation: Store active filter criteria in a single shared Riverpod provider owned by the map-view-screen and consumed by both map-marker-widget (via mentor-location-service) and mentor-list-fallback. Write integration tests that apply a filter, switch views, and assert identical mentor counts in both views.
Contingency: If filter sync proves brittle, simplify to a single filter state object passed explicitly as a constructor argument to both views on each rebuild, eliminating indirect state sharing.