DeduplicationQueueScreen detail view with comparison panel
epic-duplicate-activity-detection-ui-task-010 — Implement the detail view accessible from DeduplicationQueueScreen list items. The detail view must render the DuplicateComparisonPanel for coordinator-level side-by-side review and expose coordinator-level resolution actions (Merge, Dismiss as Non-Duplicate, Mark Reviewed) by invoking DuplicateResolutionHandler.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Route this screen as /deduplication/detail/:pairId using GoRouter or the project's existing routing solution, accepting pairId as a path parameter — this doubles as the deep-link entry point required by task-011. Fetch the full pair details inside the screen's BLoC/Cubit initiation rather than passing the full object via route arguments, so deep links (which only have a pairId) also work. Model resolution state as a sealed class: Idle, Loading(action), Success(action), Failure(action, error), AlreadyResolved. The DuplicateComparisonPanel should be a stateless widget that receives two Activity objects and an optional Set
Implement field diffing as a pure utility function comparing field-by-field. Use a confirmation dialog (showDialog) only for the destructive 'Dismiss' action to reduce friction on 'Merge' and 'Mark Reviewed'. Ensure all three buttons share a single isLoading flag to prevent concurrent action submissions.
Testing Requirements
Unit tests must cover DeduplicationDetailBloc/Cubit: initial loading state, loaded state with pair data, each resolution action transitioning through loading → success/failure, and the already-resolved state. Widget tests must verify: DuplicateComparisonPanel renders both activities' fields; diff highlights appear on fields with different values; resolution buttons are disabled during loading; success snackbar appears and back-navigation is triggered on merge success; error snackbar appears on API failure with buttons re-enabled; AlreadyResolvedNotice is shown when pair status is already resolved. Integration test must mock DuplicateResolutionHandler and assert correct method is called with the correct pairId for each action.
The merge resolution path requires identifying which fields from the draft differ from the existing record, applying those differences to the existing record, and cancelling the draft — all as an atomic operation. Partial failures (e.g., update succeeds but draft cancellation fails) could leave the system in an inconsistent state.
Mitigation & Contingency
Mitigation: Implement the merge path as a Supabase RPC transaction that updates the existing record and soft-deletes the draft in a single atomic call. The DuplicateResolutionHandler should never attempt field-level merge at the application layer.
Contingency: If the atomic RPC approach proves too complex for the initial release, simplify the merge path to: mark existing record as the canonical record and cancel the new submission without field merging, displaying a message to the user to manually verify the existing record's fields. Log a follow-up ticket for full field-merge in a later sprint.
The DuplicateWarningBottomSheet must intercept the activity wizard's save action without disrupting the wizard's existing navigation stack. If the bottom sheet is implemented as a separate route rather than an overlay, back navigation could break the wizard's step state.
Mitigation & Contingency
Mitigation: Use a `showModalBottomSheet` overlay pattern so the bottom sheet sits above the wizard route without pushing a new route onto the Navigator stack. The wizard's CuBit/BLoC retains all draft state while the sheet is visible. Test this integration with the existing activity-registration-cubit before merging.
Contingency: If the overlay approach causes Z-order or focus issues with the wizard's keyboard-aware layout, route the duplicate check result back to the wizard as a state event (DuplicateDetected), and let the wizard render a local inline warning banner instead of a bottom sheet.
The bottom sheet and comparison panel involve complex layouts with multiple interactive elements. Screen reader users (particularly relevant for Blindeforbundet) may struggle with the side-by-side comparison layout if semantics are not carefully ordered.
Mitigation & Contingency
Mitigation: Design the comparison panel with a single-column semantic order (read record A fully, then record B fully) regardless of visual layout. Use Flutter's `Semantics` widget with `sortKey` to enforce correct traversal order. Test with TalkBack and VoiceOver against the WCAG 2.2 AA reading order criteria.
Contingency: If side-by-side layout cannot achieve acceptable screen reader ordering, switch to a stacked tab layout (Tab A / Tab B) for the comparison panel that is semantically simple even if less visually immediate for sighted users.