Queue consumers need age-based alerts and idempotent sends to handle rate limits

A weekly digest pipeline can rely on a local token bucket placed before an idempotent send, backed by durable retries and a metric tracking the oldest queued work. Relying on queue depth alone is insufficient, since a consumer can appear healthy while missing the delivery window. The recommended approach is to record enqueue timestamps and alert when the oldest ready message exceeds the customer-facing delivery promise. Rate limiting decides when a request may start, while idempotency keys and durable state transitions prevent duplicate customer emails after timeouts. Teams should document the delivery window, normal drain rate, and maximum retry horizon in a runbook to set sensible thresholds.