Write done as a script
Theory: The four parts of a loop and the goal test build page. "Improve the error handling" cannot terminate a loop, because nothing can ever say it is finished. The goal must be phrased so that a program — not a person, not the model — returns true or false against it.
Workflow
- Extract the claim. Ask what the user wants true at the end, then restate it as verifiable facts: which command exits 0, which file exists, which string appears, which number crosses which threshold. If a part cannot be checked by a program, say so and negotiate it down to what can.
- Prefer checks that already exist. The test suite, the linter, the
build, the type checker. A goal test that shells out to
make testis better than one that reimplements it. - Write
goal-test.sh(or.pyif the checks are easier there) in the project root: runs every check, prints one line per check with pass/fail, exits 0 only when all pass. Keep it under ~40 lines; it must run in seconds and be safe to run repeatedly. - Run it now. It should fail before the work is done — a goal test that passes on the current state is testing nothing. Show the failing output.
- Offer the loop. If the user wants the agent driven until done, wrap it:
bash#!/usr/bin/env bash # goal-loop.sh — run a headless agent until the goal test passes or attempts run out. set -u MAX_ATTEMPTS=5 for i in $(seq 1 "$MAX_ATTEMPTS"); do FEEDBACK=$(./goal-test.sh 2>&1) && { echo "done in $i attempt(s)"; exit 0; } claude -p "Goal: <the goal>. The goal test currently fails with: $FEEDBACK Fix the code so the goal test passes." \ --permission-mode acceptEdits --output-format json > ".attempt-$i.json" done echo "goal test still failing after $MAX_ATTEMPTS attempts — falling back to a human" exit 1
Adjust the agent command to whatever CLI the user runs. Keep the three
brakes visible and named: the checker outside the model (goal-test.sh),
the stop rule (test passes), the budget (MAX_ATTEMPTS, plus a dollar cap
read from the JSON output if they want one).
Rules
- The checker never asks the model's opinion; self-review is not a checker.
- Feed the checker's output back verbatim — the failure text is the prompt.
- If the user cannot state done as a check, they do not have a loopable task yet; tell them that plainly and suggest an interactive session instead.
