Implement duplicate detection UX in registration screen
epic-coordinator-proxy-registration-core-task-010 — When ActivityAttributionValidator returns a duplicate warning (same mentor, overlapping time window), display a non-blocking warning dialog inside ProxyRegistrationScreen presenting the conflicting record's date, time, and coordinator name. Allow the coordinator to dismiss and proceed (override) or cancel. Record override decisions in the audit event payload.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Model the duplicate warning as a distinct cubit state (ProxyRegistrationDuplicateWarning) that carries the ConflictingActivityRecord. In the BlocListener, show the dialog via showDialog() when this state is received. Pass 'proceed' / 'cancel' results back to the cubit via explicit cubit methods (cubit.confirmOverride() / cubit.cancelOverride()) — avoid passing BuildContext into the cubit. Use WillPopScope or PopScope (Flutter 3.14+) on the dialog to ensure back-press is treated as cancel.
The override flag should be stored in the cubit's pending submission data so it is included automatically when confirmOverride() re-dispatches the service call.
Testing Requirements
Unit-test the cubit: verify DuplicateWarning state is emitted when validator returns conflict, verify override payload is set when user confirms, verify clean cancellation resets state to Idle without service call. Widget-test: stub cubit to emit DuplicateWarning state and assert dialog appears with correct conflict data; simulate Cancel tap and assert no service call; simulate Proceed tap and assert service called with overrideDuplicate: true. Test back-button dismissal behaves as Cancel. Test that non-duplicate path never shows dialog.
The 2-hour window duplicate detection logic requires querying existing proxy records with compound key matching (mentor + date + activity type within time range). If the query is too broad it produces false positives that frustrate coordinators; if too narrow it misses genuine duplicates that corrupt Bufdir data.
Mitigation & Contingency
Mitigation: Define the duplicate detection window as a configurable parameter from the start. Prototype the Supabase query with representative data covering edge cases (midnight boundaries, different activity types same day, same activity type different mentors) before finalising the implementation.
Contingency: If the detection produces excessive false positives in UAT, allow coordinators to explicitly acknowledge and bypass the duplicate warning with a reason field, preserving safety while reducing friction.
If the proxy registration form does not clearly distinguish between the acting coordinator and the attributed mentor, coordinators may submit records attributing activities to themselves, causing inaccurate Bufdir reporting and potential funding issues.
Mitigation & Contingency
Mitigation: Conduct UAT with at least one real coordinator via TestFlight before release. Use distinct visual treatment (different card colours, explicit 'Registering on behalf of:' label) and require the confirmation screen to show both identities prominently.
Contingency: Add a mandatory confirmation checkbox on the confirmation screen that explicitly names the attributed mentor, preventing accidental self-attribution from slipping through.
Coordinators with multi-chapter access must select an active chapter context before the mentor list is filtered correctly. If chapter scope resolution fails or is bypassed, cross-org proxy registrations could occur, violating data isolation between chapters.
Mitigation & Contingency
Mitigation: Reuse the existing active-chapter-state and hierarchy-service components established by the org hierarchy feature. Add a guard that blocks entry to the proxy flow if no chapter context is active, prompting chapter selection first.
Contingency: If the chapter resolution service is unavailable, default to the most restrictive scope (no mentors visible) and surface a clear error message rather than showing an unfiltered mentor list.