Define mentor status state machine types and interfaces
epic-peer-mentor-pause-core-logic-task-001 — Define the TypeScript/Dart interfaces and enums for the mentor status state machine. This includes the MentorStatus enum (active, paused, inactive), StatusTransition type, and the MentorStatusRecord interface. Establish the valid transition matrix that enforces active→paused, paused→active, and active→inactive as the only legal state changes.
Acceptance Criteria
Technical Requirements
Implementation Notes
Use a `const Set<(MentorStatus, MentorStatus)>` (Dart record set) for `kValidTransitions` so `isValidTransition` is a O(1) set-contains check. Example: `const kValidTransitions = {(MentorStatus.active, MentorStatus.paused), (MentorStatus.paused, MentorStatus.active), (MentorStatus.active, MentorStatus.inactive)}`. Avoid if-else chains — the set approach is self-documenting and extensible. Use Dart's `sealed class` or `enum` with extension methods for `MentorStatus` to add helpers like `.isTerminal` (returns true for `inactive`).
Keep this file as pure-Dart domain logic with zero dependencies — it will be imported by both the Flutter app layer and the Supabase edge function layer.
Testing Requirements
Pure Dart unit tests (no widget pump needed). Test cases: (1) all 9 possible from/to combinations of the 3 status values — assert exactly 3 return true and 6 return false; (2) verify paused→inactive explicitly returns false; (3) verify active→active, paused→paused, inactive→inactive return false (self-transitions forbidden); (4) verify MentorStatusRecord can be constructed with all required fields; (5) verify StatusTransition serialises and deserialises correctly (toJson/fromJson if implemented). 100% branch coverage expected given the small surface area.
The status state machine must handle race conditions where two concurrent callers (e.g., a mentor self-pausing and a coordinator force-pausing simultaneously) attempt to update the same mentor's status. Without a concurrency guard, both writes could succeed, leaving the audit log in an inconsistent state.
Mitigation & Contingency
Mitigation: Use a Supabase RPC with a row-level lock (SELECT FOR UPDATE) inside a transaction so only one transition wins. Return a clear error to the losing caller. Test with concurrent requests in the integration test suite.
Contingency: If row-level locking proves unreliable in the Supabase environment, add an optimistic-locking version field to peer_mentors and have the service retry up to three times on version conflict before surfacing an error to the caller.
If the CertificationExpiryJob Edge Function fails silently (network timeout, Supabase cold start), HLF mentors with expired certifications could remain in active status and continue appearing on the chapter website, creating a compliance breach.
Mitigation & Contingency
Mitigation: Implement structured error logging inside the Edge Function, write a monitoring query that checks for mentors with expired certifications still in active status, and set up an alert if any are detected 30 minutes after the scheduled nightly run.
Contingency: Provide a coordinator-accessible manual trigger for the expiry check that can be invoked via the admin interface if the scheduled job is known to have failed. Document the manual recovery procedure for HLF coordinators.
pg_cron registration in Supabase requires superuser-level access that may not be available in all environments (local dev, staging, CI). If the cron job cannot be registered automatically, the Edge Function will never execute on schedule, breaking the HLF certification expiry workflow.
Mitigation & Contingency
Mitigation: Use Supabase's recommended pg_cron setup via the SQL editor migration script and document the exact commands. Validate cron registration in the staging environment as part of the epic's deployment checklist.
Contingency: If pg_cron is unavailable, switch to a Supabase scheduled Edge Function invocation via an external cron service (e.g., a GitHub Actions scheduled workflow calling the Edge Function endpoint with a service-role key) until the pg_cron approach is resolved.