Clove Learning asks you to repair reminders that repeat after timeouts. The fictional arrival rate is 2,400 reminders/minute, and the latest provider outage lasted 7 minutes. Deliver a delivery board, backlog estimate, notification model and checked recommendation. Cover duplicate scheduling, ambiguous provider acceptance and an opt-out after scheduling.
Clove Learning sends reminders through an external provider. Its scheduler can enqueue a reminder twice, and the provider can accept a send while its response is lost. Those failures look similar from the worker, but they occur at different boundaries. A unique local job ID doesn't prevent a provider from sending twice if every retry uses a new provider key.
Carry one notification identity from scheduling through delivery. Store the intended channel and recipient with that identity, respect preferences before sending, and use provider idempotency or a lookup when a timeout is ambiguous. A queue controls retries; it can't prove what an external provider did. Build the pipeline, size the backlog, and decide when to retry or reconcile an uncertain result.