A full region answers 503, and an account at its limit 429

No room for a sandbox, a fork, a restart, a wake, a build or a volume, no_capacity, is now 503 Service Unavailable with Retry-After: 1. The account at a limit on what runs at once, quota_exceeded or no_credit_running_limit, is now 429 Too Many Requests with Retry-After: 5. All three were 409 Conflict, which a client that retries only 5xx and 429 gave up on. Such a client now retries them with no change. The body is the same, so code that reads error.code keeps working. In the SDKs' next release the error's class follows the status: no_capacity is a ServiceUnavailableError, and the two limits are a RateLimitError, not a ConflictError. The SDKs still wait them out on create, wake and restart, and return them at once elsewhere, as before. See errors.