00The answer
A fail-closed review gate is a checkpoint where AI-written code merges only when a reviewer explicitly approves it: no verdict, an unparseable verdict, a missing reviewer, or a failed fetch all block the merge. For coding agents it means the failure mode is 'stops', never 'lets it through'. Turbo Rig's gate is fail-closed by construction.
01How the rig's gate fails closed
Every blockable condition blocks. An unparseable verdict text, a reviewer that never answered, a fetch that failed mid-review: each one ends in "no merge", never "merge and hope". A network outage is never a green check.
Deterministic checks run first: tests, type checks, lints. They cost $0, they cannot be sweet-talked, and they speak before any model does.
The verdict must be parseable: the reviewer ends with APPROVED or REVISE in a machine-readable form. Prose that never commits is not a verdict.
02Why fail-closed matters with agents
Agents generate plausible code at machine speed; the risk is not that they cannot write, it is that nothing in the loop is allowed to say stop. A gate that fails open turns every outage into a silent approval lane.
In the rig's audited week the gate issued 868 verdicts and sent 687 back (79.1%). That is what a working gate looks like: it says no, most of the time, and the merges that survive earned it. Every number is re-derived in the public dossier.