key_mode_escalation
POST /v1/api-keys with mode: "live" from a test key. A live key branches telephony onto the live provider, so minting one from a sandbox credential would walk around the sandbox/production boundary CANON 122 rests on - the mode a key may issue is the mode it holds, never a field the caller supplies.
Problem shape
Every non-2xx response is an RFC 9457 application/problem+json body. The type URI below is stable and machine-matchable, so branch on the final path segment (the code) and treat the status as redundant confirmation. See the error-handling guide.
{
"type": "https://docs.vocapable.com/errors/key_mode_escalation",
"title": "…",
"status": 403,
"detail": "…",
"instance": "/v1/…"
}