Partner API circuit breaker no longer trips on lookups that miss

What We Fixed

• Looking up an ID that doesn’t exist no longer pauses your API token. Each API token has a circuit breaker that pauses it for five minutes after 20 consecutive failed requests. A 404 on a lookup used to count as one of those failures, so a single stale or wrong ID, requested repeatedly, could take every endpoint on the token offline. Not-found responses are now ignored by the breaker. Rejected writes and server errors still count. Requests turned away before they reach the endpoint — an invalid or expired token, an inactive subscription — are not counted either way.
• A paused token now tells you it is paused, not rate limited. The 429 response from the circuit breaker used to carry the same headers as a rate limit, which sent integrators chasing request volume when the real problem was a failing call. It now sends X-Throttle-Reason: circuit_breaker, a code of circuit_breaker_open, and names the request that was failing, for example POST /api/partner/notes returned 400. Regular rate-limit responses send X-Throttle-Reason: rate_limit.
• API request logs now record the response status, so our team can see a burst of 404s or 429s on a token and help you sooner.

See the Rate Limiting section of the Partner API reference for details on what counts toward the breaker.