The typecheck.
The fastest honest signal a codebase gives: does it compile. This gate asks on every single run.
What the check reads
The check runs npx tsc --noEmit against the repo, on every run in a TypeScript project; plain-JS projects get an honest skip, never a false NO-GO. A project counts as TypeScript when a tsconfig.json exists and TypeScript is actually a dependency. The compiler checks the whole project without writing output. On failure the report keeps the last twenty-five lines of compiler output, so the actual error lands in the record instead of scrolling away.
Why AI-built code ships this
AI edits at machine speed across many files, and speed leaves stale references: a prop renamed in one component but not in its callers, a helper whose signature changed under a consumer that never got the memo. The dev server can paper over it and the page still loads, right up until the one path that touches the broken reference runs in front of a user.
Why it blocks
Blocks. A change that does not compile does not ship. There is no judgement call to make here, which is exactly why the machine owns this one outright.
In the proof record
A pass line, or a fail line followed by the tail of the real compiler output so the first error is readable in the record itself.
✓ Typecheck (tsc --noEmit) — TypeScript compiled with no type errors. ✗ Typecheck (tsc --noEmit) — tsc reported type errors — fix them before shipping.
Honest limits
It proves the types line up, nothing more. A program can typecheck and still do the wrong thing, and code typed as any passes without a word. Whether the change behaves is what the human verification walk after deploy is for.
Want every change gated like this before it ships?
The same gate runs in every engagement, and each piece of work ends on a plain go or no-go, in writing. The gate itself is open source, so you can read exactly what we run.
The other 6 gates
The whole method, from the controlled zone to the proof record: the methodology.