Definition
A verification gate is a control point that blocks promotion until required evidence has been produced and validated. Promotion might mean accepting an answer, merging code, deploying a model, sending a message, or granting an agent more authority.
The gate needs explicit admission criteria, trusted evidence inputs, a clear pass or fail outcome, and an audit record. It should fail closed when required evidence is missing or the verifier is unavailable, unless a separately authorized exception path applies.
Place enforcement at the transition being protected. A model instruction that says "do not deploy without tests" is guidance. A deployment service that rejects an unsigned verification record is a gate.
Distinguish it from nearby terms
A grader emits a judgment. A review informs a person. A verification gate enforces the admission decision. A guardrail is broader and may advise, detect, block, contain, or recover.
Check your understanding
An agent can edit the test, mark it passed, and set the deployment flag. The workflow contains a check, but not an independent gate because the producer controls the evidence and the transition.