callback_too_far_ahead
A requested callback time is beyond the booking horizon. detail names the horizon in days. Legacy callbacks use it as a not_before floor that calling rules may move later. Under exact_action_v2, a proposed time change is refused and requires fresh caller confirmation. Neither policy waives calling rules.
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/callback_too_far_ahead",
"title": "…",
"status": 409,
"detail": "…",
"instance": "/v1/…"
}