workspace_reply_channel_mismatch
An email reply is edited through PATCH /v1/workspace/inbox/email-replies/{id}, not the text-reply route.
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/workspace_reply_channel_mismatch",
"title": "…",
"status": 409,
"detail": "…",
"instance": "/v1/…"
}