Build OrgSelectionScreen scaffold and layout
epic-organization-selection-ui-task-006 — Create the OrgSelectionScreen stateful widget with a single-action screen layout: app name/logo at top, a scrollable ListView of OrgCard widgets in the center, and a single primary CTA button at the bottom (disabled until selection is made). Use SingleActionScreenLayout pattern per cognitive accessibility rules — no secondary actions on this screen.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Manage the selected organization in local StatefulWidget state (`Organization? _selectedOrg`) — do not put transient UI selection state in Riverpod global state. Riverpod is used only to inject the OrgSelectionService. Use a Column with `Expanded` around the ListView to push the CTA button to the bottom without needing a Stack.
Wrap the entire Column in a SafeArea. For the CTA button, bind `onPressed: _selectedOrg != null ? _handleConfirm : null` — Flutter's ElevatedButton/AppButton renders as disabled automatically when onPressed is null, no custom disabled logic needed. The single-action layout rule from the workshop documentation (cognitive accessibility for NHF's stroke survivors) is critical: resist any temptation to add a 'skip' or 'back' link on this screen.
Testing Requirements
Widget tests with flutter_test: Test 1: render screen with empty org list, assert CTA button is disabled. Test 2: render screen with 3 mock orgs, assert 3 OrgCard widgets present. Test 3: tap first OrgCard, assert CTA button transitions to enabled state. Test 4: render on 375px width and 1024px width — assert no overflow RenderFlex errors.
Test 5: assert exactly one button widget with primary style is present (no secondary actions). Golden test: capture screenshot of screen with pre-selected org for visual regression baseline.
Flutter's Semantics system requires explicit configuration for custom card widgets — the default widget tree semantics may merge child nodes incorrectly, causing VoiceOver to announce partial or garbled text for each OrgCard. This is a critical failure for Blindeforbundet and violates the contractual WCAG 2.2 AA requirement.
Mitigation & Contingency
Mitigation: Wrap each OrgCard in a Semantics widget with an explicit label combining organization name and role label, set button role, and excludeSemantics: true on all child widgets to prevent double-announcement. Test on a physical iOS device with VoiceOver enabled before marking the epic complete.
Contingency: If automated semantics are insufficient, implement a dedicated AccessibilityLabel builder in the OrgCard that constructs the announcement string from OrgLabelsProvider output and passes it directly to the Semantics label field.
Organization logos must load before the screen is considered ready. If assets are fetched from a remote URL and network latency is high (a realistic scenario for rural NHF users), the screen may render with broken image placeholders, degrading the first-impression quality and potentially confusing screen reader users whose VoiceOver announcements would reference an empty image.
Mitigation & Contingency
Mitigation: Cache organization logos locally after first load using the org-branding-cache pattern. For the initial load, render a styled placeholder with the organization's initials and primary color while the logo loads asynchronously. Ensure the Semantics label is derived from the organization name, not the image asset, so screen reader announcements are never dependent on image load state.
Contingency: If caching implementation is out of scope for this epic, ship with initials-based placeholders as permanent fallbacks and defer logo loading to the org-branding-cache epic. The screen remains fully functional and accessible without logos.
The user story specifies that single-organization users bypass the selection screen and are routed directly into the app. If the bypass logic is implemented in the UI layer rather than in OrgSelectionService, it creates a tight coupling that breaks if the routing logic is ever reused or tested in isolation. It also creates a potential timing issue where the screen briefly renders before the bypass fires.
Mitigation & Contingency
Mitigation: Implement the single-org bypass entirely in OrgSelectionService.getPersistedSelection() or as a route guard — the screen should never be pushed onto the navigation stack for single-org users. The OrgSelectionScreen widget itself has no knowledge of this bypass.
Contingency: If the route guard approach is deferred to the routing epic, add a local guard in the OrgSelectionScreen's initState that calls OrgSelectionService, auto-selects if count is 1, and navigates forward before the first frame is painted, using a loading indicator to prevent the flash.