sandbox_session_limit_reached
The per-account in-browser session budget for the current window is spent. errors[] carries limit, window and resets_at, and Retry-After carries the wait, because waiting is the entire remedy.
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/sandbox_session_limit_reached",
"title": "…",
"status": 429,
"detail": "…",
"instance": "/v1/…"
}