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# Stream processing checkpointing and recovery hardening

> Hardened the durability of the stream processing pipeline: tuned checkpointing, explicit source-offset handling on restarts, and exactly-once view finalization.

We invested in the durability story for the Flink stream processor after observing missed views during deploys.

* Checkpointing intervals, tolerable failure counts and state backend settings were tuned and externalized as environment variables.
* The Kafka source offset behavior was made explicit so the first deployment after a restart resumes at the right position instead of skipping ahead to `latest`.
* View finalization logic was rewritten to ensure each session is emitted exactly once, even across operator failures and replays.
* Eliminates the class of incidents where views were not captured during Flink downtime or when the service came back up.