UPDATED, or VALID for a dry run.

The request, or a single write's item, is invalid. Nothing was saved.

Missing or invalid token. The older error shape. On the agent management endpoints a 413 BODY_TOO_LARGE is decided before the token is checked.

The Service User does not have full access (application/json, from the shared authentication layer), or the token is a corporate central repository token (application/problem+json, EPHEMERAL_SERVICE_USER_READ_ONLY). Corporate tokens get full access on a child tenant whatever their Service User may do on the corporate tenant, so agent writes refuse them, dry runs included, until that is fixed for every API. Reads still work.

AGENT_NOT_FOUND: no agent with that id or name(extension).

A conflict with stored configuration, a seat limit, an ambiguous identifier, or a caller ID the agent may not use. Nothing was saved.

BODY_TOO_LARGE: the request's Content-Length header is over 10 MiB, so it was refused before the body was parsed or the token checked. A chunked body without a Content-Length is not counted. May lack the Link header.

WRITE_IN_PROGRESS: another agent write is running on this tenant. Agent writes run one at a time and are not queued. Nothing was saved. Retry after a short wait; parallel writes only produce more 429s.

SETTINGS_BUSY: another settings save, from the web interface or another API, held the tenant's settings lock for too long. Nothing was saved. Retry.