Define ProxyActivity domain models and interfaces
epic-coordinator-proxy-registration-core-task-001 — Create the core Dart data models for proxy activity records, including ProxyActivityRecord with dual attribution fields (acting_coordinator_id, attributed_mentor_id), ProxyActivityStatus enum, and the ProxyActivityRequest/ProxyActivityResult value objects used throughout the registration flow.
Acceptance Criteria
Technical Requirements
Implementation Notes
Use Dart 3 sealed classes for ProxyActivityResult and ProxyRegistrationError to get compile-time exhaustiveness checking. Consider using the freezed package if it is already a project dependency, as it provides copyWith, equality, and serialisation boilerplate for free; if freezed is not in use, implement manually. Place the abstract ProxyActivityRepository interface in the domain layer (not in the data layer) to maintain dependency inversion — the Supabase implementation will live in lib/data/repositories/ and depend on this interface. Use DateTime.toUtc() consistently in toJson to avoid timezone ambiguity when persisting to Supabase.
Document the dual attribution pattern in a brief code comment: actingCoordinatorId is who submitted the record (for accountability), attributedMentorId is whose activity it represents (for reporting).
Testing Requirements
Write unit tests using flutter_test covering: ProxyActivityRecord.toJson produces correct snake_case keys matching Supabase column names; ProxyActivityRecord.fromJson correctly deserialises a sample Supabase row map; copyWith produces a new instance with only the specified fields changed; ProxyActivityStatus.displayLabel returns non-empty string for all enum values; sealed class switch statements on ProxyActivityResult and ProxyRegistrationError compile without default case (exhaustiveness check). No mocking required — these are pure data model tests. All tests should run in under 1 second total.
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.