Event-Driven Notification Platform · View 16 of 26 · 4 · Runtime

Timing, Scheduling and Digests

Six ways a notification can be timed, and the one due-work stream they all converge on.

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Decisions

Timing state is durable in Temporal and Kafka, never an in-process timer — a pod restart during a two-day delay loses nothing
Every lane converges on the same notif.due stream, so the dispatcher has one code path regardless of how the work became due
About 85 percent of traffic takes the immediate lane and never touches Temporal, which is what keeps Temporal off the critical path

Digest behaviour

Session windows per recipient in Flink, default one hour, tenant-configurable
A P0 item arriving inside a digest window takes the breakout lane and sends on its own — the red cell is what happens if that lane is missing
The digest records which notification ids it absorbed, so each still has an individual answer

Risk

Quiet hours across timezones create a synchronised release at the window boundary — a thundering herd of deferred sends
Mitigated by jittering the release across the first 15 minutes of the window, which must be load-tested before go-live

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