Fail-closed
When a control can't confirm an action is safe, it denies rather than allows.
category ▸ Governance
Fail-closed, in plain language.
A fail-closed control defaults to denial. If the system cannot positively establish that an action is authorized — a missing permission, an expired identity, an unreachable check — it refuses the action rather than letting it through. The opposite, fail-open, defaults to allowing the action when a check is uncertain or unavailable.
For security-critical decisions, fail-closed is the safe default: the cost of wrongly blocking a legitimate action is an annoyance; the cost of wrongly allowing a dangerous one can be a breach. The discipline of being explicit about which controls fail closed and which fail open is itself a sign of a mature governance design.
How Cortex implements it.
This term isn't abstract here — it maps to a real capability in the runtime. Here is exactly how Cortex enforces or relates to it.
Cortex's access and authorization controls fail closed: an expired agent identity cannot mint a token (403 IDENTITY_EXPIRED), an off-allow-list model is rejected (403 MODEL_NOT_ALLOWED), a restricted ontology field read is denied (403), and a high-injection tool input is blocked at the MCP Gateway.
Where blocking would harm availability rather than safety, Cortex is deliberately fail-open and says so: if reliability scoring is unavailable it does not block publish, and an unreachable ontology check during an action logs and proceeds. The choice is explicit, not accidental.
Keep building the vocabulary.
These terms sit next to this one in the governed-AI model — follow the thread to see how the controls connect.
Governance gate
A single decision point that allows, holds, or blocks a proposed agent action.
Agent IAM
Identity and access management that treats each AI agent as a governed enterprise identity.
Kill switch
An instant control that stops an agent or tool server from acting, immediately.
DLP
Data loss prevention — screening data in and out of tool calls to catch leakage and injection.
See Fail-closed enforced, not just defined.
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