Function shouldCacheResponse

internal/agent/idempotency_guard.go:131–136

shouldCacheResponse decides whether finalize should Complete (cache the response) or Release the claim. Pulled out as a pure function so the policy can be unit-tested without standing up the full HTTP + DB stack. Rule: cache on 2xx/3xx always; cache on 4xx/5xx ONLY if the handler signalled that an

(statusCode int, sideEffectCommitted bool)

// upstream send accepted, or the loopback DB rows landed). Otherwise
// Release so the caller can retry with the same key.
func shouldCacheResponse(statusCode int, sideEffectCommitted bool) bool {
	if statusCode < 400 {
		return true
	}
	return sideEffectCommitted
}

// markSideEffectCommitted is called by handlers immediately after an
// irreversible action succeeds (an upstream SMTP/SES accept, a