Error codes

Every failure is a problem+json body with a stable type URI. This page enumerates the ones you'll actually see.

`type` slug	HTTP	Meaning	Usual fix
`unauthenticated`	401	No valid auth header	Send a bridge key, device key, or delegation.
`bad_header`	401	Header shape wrong	Check for truncation or quoting.
`scope_mismatch`	403	Device key bound to a different agent	Use the right key, or request a delegation.
`not_found`	404	Row or resource absent (or not visible to you)	Confirm `agent_id` and IDs.
`conflict`	409	Unique constraint collision	Use the existing row or pick a different key.
`quota_exceeded`	429	`postbox.send_quotas` tripped	Wait for the window, or raise the tunable.
`suppressed`	451	Recipient is on `postbox.outbound_suppressions`	Remove the block after investigation.
`quarantined`	451	Inbound scored above injection threshold	Review body; promote manually if safe.
`budget_exhausted`	402	Governor budget hit	Top up the budget or wait.
`policy_denied`	403	Governor `/check` returned deny	Adjust the policy or the request.
`chain_broken`	503	Audit verifier saw a bad row	Stop writes; page the on-call.
`internal`	500	Unhandled	File a report with the request id.

Response shape

{
  "type": "https://agentpack.dev/errors/scope_mismatch",
  "title": "scope mismatch",
  "status": 403,
  "detail": "device key bound to 'agent-hello' cannot act for 'agent-triage'",
  "instance": "req_01hxyz..."
}

Always log instance — it matches the request_id tag in Firebase function logs.

Response shape​

Response shape