Reliability: retries, idempotency, backpressure
The failure-handling stack assembled: timeouts inside retries inside breakers, idempotent handlers, bounded work.
Reliability: retries, idempotency, backpressure
The stack from module 20 returns, assembled: timeout inside retry (with exponential backoff and jitter) inside a circuit breaker, all wrapped around operations that are idempotent — because a retry after an ambiguous failure is indistinguishable from a duplicate delivery, and the handler must make duplicates harmless (the checkpoint of module 20, now load-bearing).
Backpressure closes the loop: an unbounded queue is a slow-motion crash — it
converts "we are overloaded" into "we are overloaded and out of memory,
and every latency SLO is dead." A bounded queue with an explicit admission
decision (reject fast, return 429-style responses, let callers decide) keeps
the system honest. The capstone's Submit returns false over capacity:
that is the whole production posture in one boolean.
Failure injection is the teaching method here: the platform is graded by a deterministic schedule of duplicate deliveries and over-capacity submits, so every acceptance/rejection/executed count is a contract you can reason about — the same way you reason about a load test before black Friday.