Verification tooling for AI agents.
AI coding agents report work as finished when it isn’t — and they do it fluently enough that you can’t tell by reading. A plausible narration and verified work look identical at the moment you read them. The cost arrives later.
This is not fabrication. The agent’s account is its honest best guess. The problem is that nothing sits between its fluency and your trust. I build the layer that goes there, and release it openly.
Rules and drop-in configs that stop coding agents from reporting work as finished when it isn’t — and from quietly doing something other than what you asked. Includes a model-specific failure taxonomy and verification gates shaped to match each one, for Claude Code and Codex.
Each model fails in its own characteristic shape, and the shapes are stable. Knowing which one you are dealing with tells you where to put the check.
| Model | Characteristic failure |
|---|---|
| Claude | Overstates. Reaches for the more dramatic reading; defaults to plausible values instead of checking live state. |
| Codex | Overengineers while losing the thread. Elaborate, internally correct, drifted from the request. |
| Gemini | Agreeable past the point of usefulness. |
| Open-weight | Drift out of format under pressure. |
Derived from running several frontier models daily on production work and keeping written records: 92 structured session receipts across four months, each logging five to seven distinct failures with the correction that followed. One practitioner’s observation, not a benchmark — benchmarks measure success rates, not failure shapes.
Because a verifier only catches the failures it is shaped to look for. A gate that hunts overstatement passes an overengineering agent every time — every claim it made was true. A gate that compares work against the original request misses an overstating agent entirely — the described work is exactly right and simply does not exist.
Neither gate is broken. They answer different questions, and only one is the question that matters for a given agent. A single reviewer pointed at everything has a shape whether or not anyone chose one, and is blind to everything outside it.
A receipt the agent quotes is an assertion. Only what the checker re-derives is evidence. If a gate reads back what the caller handed it, the caller can shape the receipt to pass and the gate does nothing. Gates must go to source themselves.
Two corollaries: the verifier should usually be a different model than the one being verified, since a model auditing its own work brings its own blind spot to the audit. And a cheap model can hold a shape-matched gate — matching the shape matters more than the checker’s raw capability.