Notifications — Behavior

State machine

Per email: stateless fire-and-forget.


cron fires ──> query candidates ──> for each: render HTML ──> EmailService.send ──> log result
                                                                   │
                                                                   ├── Resend success → counted
                                                                   └── Resend error → logged, swallowed

No retry table, no idempotency token, no dedup. If a cron runs twice in the same window, recipients receive duplicate emails. Mitigated by the time-window query (e.g. class reminders target sessions starting in 20–28h — a re-run picks the same set, hence dup).

Invariants

Invariant	Enforcement
Cron jobs only run in production / staging	`cronsEnabled()` env gate
Email failures don’t crash the cron	`try/catch` around `EmailService.send`; `Promise.allSettled` per recipient
In-test mode, emails are diverted to in-memory log, not sent	`NODE_ENV === 'test'` check in `EmailService.send`
`from` address is fixed at module init	`RESEND_FROM_ADDRESS` env

Golden paths

Daily class reminder cron

08:00 UTC — @Cron('0 8 * * *') handleClassReminders fires.
cronsEnabled() check.
runWithRetry('handleClassReminders', () => runClassReminders()).
Query class_sessions starting between now+20h and now+28h, status published, with bookings + memberships + users + program/org joins.
Promise.allSettled(...) over { session, booking } pairs → EmailService.send.
Log “Class reminders: N sent, M failed across K sessions”.

Daily expiration warning cron

09:00 UTC — handleExpirationWarnings.
Subscriptions with status='active' expiring in 6–7 days.
Email per member.

Booking cancellation

Member or staff cancels a booking via the bookings module.
CancellationNotificationsService invoked from the booking service (event or direct call).
Cancellation email sent.

Edge cases

Scenario	Behavior
Cron fires while DB is down	Throws; `runWithRetry` retries; eventual failure logged
Resend API down	Per-email try/catch logs; cron continues for remaining recipients
Member changed email mid-cron	Query result holds the email at fetch time; old address used
Multiple bookings for same member same class	Each booking → one email (no dedup)
Subscription with no email user	Email skipped silently
Cron job scheduled while previous run still active	`nestjs/schedule` doesn’t deduplicate; long-running jobs could overlap. Verify with QA
Failed cron run	`runWithRetry` retries; partial completion possible
Localization	Templates appear English-only; member with Hebrew locale receives English copy — bug worth filing

Side effects

Action	Writes	Sends
Class reminder	—	N emails via Resend
Expiration warning	—	M emails
Cancellation	—	1 email per cancellation

No DB writes. No event emissions.

Permissions

System-internal. No user-facing API endpoints. Cron-only.