Error codes

Error codes

A rejected call returns a machine code so a client can react without parsing prose:

• unauthorized — no or invalid token.
• forbidden — authenticated, but not allowed.
• not_found — no such entry or resource.
• invalid — validation failed; a per-field { code, message } map says which.
• precondition_required — a version was needed and not supplied.
• precondition_failed — the version was stale; re-read and retry.
• rate_limited — slow down and retry later.

The same shape is returned over HTTP and over MCP.