opportunity_won_locked
The sale's scope and value were accepted by the customer, so a stage, value or scope edit cannot move it. Open an amendment (POST …/amendments) or a follow-on opportunity (POST …/reopen with mode=new); the accepted sale and its history stay.
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/opportunity_won_locked",
"title": "…",
"status": 409,
"detail": "…",
"instance": "/v1/…"
}