400policy_not_foundThe policy id does not exist in this workspace.
402quota_exceededSigning is paused because the plan quota and overage cap were both reached.
409asset_already_signedThis idempotency key was used with different bytes.
422unsupported_containerThe file parses but the container cannot carry a manifest.
424identity_expiredThe signing certificate expired; rotate the identity first.
503trust_list_staleTrust list refresh failed; verdicts return PENDING rather than a guess.