Our verifier was buggier than the code it verified

The most dangerous bug in a verification pipeline isn't a false pass. It's a false fail.

We know because we shipped one.

Refactyl migrates codebases — Vue 2 to Vue 3, JS to TS, Pages Router to App Router — and the whole pitch is that a compiler gate decides what ships, not vibes. This is the story of the gate itself being wrong: valid Vue 3 output, rejected by our own verifier, on a live migration. The conversion was correct. The code checking it was not.

If you build anything with a validation step — CI, linters, schema checks, LLM output filters — the failure taxonomy here applies to you.

The symptom