Add structured logging to ReminderEvaluationService
epic-assignment-follow-up-reminders-services-task-003 — Integrate structured logging throughout ReminderEvaluationService. Log evaluation inputs (assignment ID, days since contact, thresholds), the computed result variant, and the no-contact-ever edge case separately. Use a consistent log schema that enables downstream observability and audit trails.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 2 - 518 tasks
Can start after Tier 1 completes
Implementation Notes
Use the project's existing logger abstraction (check `lib/core/logging/` or equivalent). If no abstraction exists, wrap the Dart `logging` package in a thin `AppLogger` class so log output can be redirected in tests. Define a private `_logEvaluation()` helper inside `ReminderEvaluationServiceImpl` that accepts the evaluation context as named parameters and formats the log map — this keeps the main `evaluate()` method readable. For the no-contact-ever case, emit at INFO (not DEBUG) because it represents an operationally significant state that coordinators may want to monitor.
Never log `OrgReminderThresholds` values in production builds as they reveal internal org configuration.
Testing Requirements
Unit tests should verify that: (1) a DEBUG log entry is emitted for each evaluate() call, (2) the no-contact-ever path emits the dedicated INFO event, (3) no PII fields appear in log output. Use a mock/fake logger that captures log entries as a list for assertion. Verify log entries are NOT emitted when the logger is set to WARN level.
The idempotency window (how long after a reminder is sent before another can be sent for the same assignment) is not explicitly specified. An incorrect window — too short, duplicate reminders appear; too long, a resolved and re-opened situation is not re-notified. This ambiguity could result in user-visible bugs post-launch.
Mitigation & Contingency
Mitigation: Before implementation, define the idempotency window explicitly with stakeholders: a reminder is suppressed if a same-type notification record exists with sent_at within the last (reminder_days - 1) days. Document this rule as a named constant in the service with a comment referencing the decision.
Contingency: If the window is wrong in production, it is a single constant change with a hotfix deployment. The notification_log table allows re-processing without data migration.
For organisations with thousands of open assignments (e.g., NHF with 1,400 chapters), the daily scheduler query over all open assignments could time out or consume excessive Supabase compute units, especially if the contact tracking query lacks proper indexing.
Mitigation & Contingency
Mitigation: Add a composite index on assignments(status, last_contact_date) before running performance tests. Use cursor-based pagination in the scheduler (query 500 rows at a time). Run a load test with 10,000 synthetic assignments as described in the feature documentation before merging.
Contingency: If the query is too slow for synchronous execution, move the evaluation to the Edge Function (cron trigger epic) and use Supabase's built-in parallelism. The service interface does not change, only the execution context.
If the push notification service fails (FCM outage, invalid device token) during dispatch, the in-app notification may already be persisted but the push is silently lost. Inconsistent state makes it impossible to report accurate delivery status.
Mitigation & Contingency
Mitigation: Implement push dispatch and in-app persistence as separate operations with independent error handling. Record delivery_status as 'pending', 'delivered', or 'failed' on the notification_log row. Retry failed push deliveries up to 3 times with exponential backoff.
Contingency: If FCM is consistently unavailable, the in-app notification is still visible to the user, providing a degraded but functional fallback. Alert on consecutive push failures via the cron trigger's error logging.