Every response tells you where you stand, so you never have to guess:
429 rate_limit_exceeded with a Retry-After header in seconds. Wait that long and carry on.
Separately, there’s a ceiling across all API traffic that protects the service as a whole. If Hypastack is shedding load you’ll see 503 server_busy, also with Retry-After. It’s rare, it’s not your fault, and retrying works. Those two, rate_limit_exceeded and server_busy, are the only failures worth retrying automatically. See Errors for the rest.