Document repository interfaces and RLS policy contracts
epic-certificate-expiry-notifications-data-foundation-task-014 — Produce developer-facing documentation for all four components in this epic: the CertificationExpiryRepository interface contract with method signatures and threshold semantics, the NotificationRecordRepository interface with deduplication guarantees, the FcmPushNotificationSender public API with error types and retry behavior, and the expiry RLS policy with its scope, affected tables, and admin override instructions. Include a dependency diagram showing how higher-tier epics consume these interfaces.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 3 - 413 tasks
Can start after Tier 2 completes
Implementation Notes
Write the primary documentation as dartdoc comments directly on the abstract classes / interfaces so that IDE tooling surfaces it inline. Supplement with a single docs/certificate-expiry-data-foundation.md file that provides the narrative overview, the dependency diagram, and the RLS policy section (which is SQL, not Dart, and does not belong in dartdoc). For the dependency diagram, a Mermaid flowchart is preferred because it renders natively in GitHub and most documentation sites. The RLS policy section should include the verbatim SQL of the CREATE POLICY statement alongside a plain-English explanation of each clause.
For the admin override section, document both the Supabase Dashboard UI path and the equivalent SQL (ALTER POLICY / DROP POLICY) so that it is actionable in both contexts.
Testing Requirements
No automated tests required for documentation itself. However, before merge, a peer review checklist must confirm: (1) every public method in each documented interface exists in the actual source code with a matching signature, (2) the RLS policy SQL snippet matches the policy deployed in the Supabase project, (3) the dependency diagram accurately reflects current task dependencies, and (4) dartdoc generates without errors or warnings when run against the annotated files.
The RLS policy predicate that checks certification_expiry_date and suppression_status on every coordinator list query could cause full table scans at scale, degrading response time for coordinator contact list screens across all chapters.
Mitigation & Contingency
Mitigation: Add a partial index on (certification_expiry_date, suppression_status) filtered to active mentors. Benchmark the policy predicate against a representative data set (500+ mentors) during development using EXPLAIN ANALYZE on Supabase staging.
Contingency: If the index does not resolve the performance issue, introduce a computed boolean column is_publicly_visible that is updated by the mentor_visibility_suppressor service and indexed separately, shifting the predicate cost to write time rather than read time.
FCM device tokens become invalid when users reinstall the app or switch devices. If the token management strategy does not handle token refresh reliably, notification delivery will silently fail for a significant portion of the user base without surfacing errors.
Mitigation & Contingency
Mitigation: Implement the FCM token refresh callback in the Flutter client to upsert the latest token to Supabase on every app launch. Store token with a last_refreshed_at timestamp. The FCM sender should handle UNREGISTERED error codes by deleting stale tokens.
Contingency: If token staleness becomes widespread, add a token health check that forces re-registration during the expiry check edge function run by querying mentors whose token was last refreshed more than 30 days ago and triggering a silent push to prompt re-registration.
The certification expiry and notification record tables may have column naming or constraint conflicts with existing tables in the peer mentor status and certification management features, causing migration failures in shared Supabase environments.
Mitigation & Contingency
Mitigation: Audit existing table schemas for user_roles, certifications, and notification tables before writing migrations. Prefix new columns with expiry_ to avoid collisions. Run migrations against a clean Supabase branch environment before merging.
Contingency: If a conflict is found post-merge, apply ALTER TABLE migrations to rename conflicting columns and issue a hotfix migration. Communicate schema changes to all dependent feature teams via a shared migration changelog.