Repeated Mistake Question Explained
This worked Harness Engineering practice question tests Feedback and Hooks. Try the answer first, then review why D is the best choice.
Short answer
The correct answer is D. Add a check that compares the page prices with the source file.
The rule exists and the agent broke it twice, so the instruction alone is not enough. Reading the prices yourself is a check you do by hand. Turn it into code: a script that reads the prices from the source file and fails when the page shows a different or missing number. OpenAI's team calls this promoting the rule into code when documentation falls short. Once the check exists, a Stop hook can run it each time the agent finishes. The correct answer is D. Add a check that compares the page prices with the source file
The Question
Your AGENTS.md already says "Do not change prices unless asked." Twice this week the agent still changed the coffee price during an unrelated edit. Both times you noticed by reading the page and corrected it in chat. What should you do now?
Why D is correct
The rule exists and the agent broke it twice, so the instruction alone is not enough. Reading the prices yourself is a check you do by hand. Turn it into code: a script that reads the prices from the source file and fails when the page shows a different or missing number. OpenAI's team calls this promoting the rule into code when documentation falls short. Once the check exists, a Stop hook can run it each time the agent finishes. The correct answer is D. Add a check that compares the page prices with the source file
Why the other options are wrong
Chat corrections do not survive the session. The third correction leaves the project exactly as able to repeat the mistake as the first two did.
Capitals make the same rule louder, and the agent already missed that rule twice. A check reports the changed price even when the agent misses the rule.
The mistake came from an edit touching text near the price, which any model can do. The project lacked a check, not a better model.
Key idea: Feedback and Hooks
Every question here is a situation you meet with Claude Code or Codex: the agent gets something wrong, and you choose what to change. The best answer is usually a file, a check, or a hook that stops the mistake from repeating, not a louder prompt. If you miss a question, read the explanation and note which part of the harness it uses: the AGENTS.md map, a skill, a check, a visitor check, a hook, or a handoff note.
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