Errors

Status	Meaning
400	Malformed request (missing/oversized field)
401	Missing or invalid API key
402	Subscription not active / quota exceeded
403	API key missing required scope, or CSRF failure on a browser route
404	Not found (including: exists, but not in your organization — never distinguished from truly-not-existing)
429	Rate limit exceeded for your plan
502	Engine-level failure — {"error": "engine_error", "category": "..."}. The category is the exception's class name only, never a raw message or stack trace.

A 502 is never silently reported as a semantic verdict — failure identity is always preserved.