File size: 4,080 Bytes
549e098 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | #!/usr/bin/env bash
# Minimal runnable Loop Engineering reference: a test-repair loop.
#
# Runs a deterministic check command, and while it fails, hands the evidence
# to an agent CLI for a narrow fix, then re-runs the check. Demonstrates the
# Loop Contract with no dependencies beyond bash, coreutils, and your agent CLI.
#
# Objective : make CHECK_CMD pass
# Trigger : manual bootstrap (run this script)
# Intake : failing check output
# Workspace : current directory (run it inside a branch or worktree)
# Delegation : AGENT_CMD receives the evidence as a prompt
# Verification : CHECK_CMD exit code, judged by the script, not the agent
# State : PROGRESS_FILE survives across iterations and runs
# Budget : MAX_ITERATIONS
# Escalation : exits non-zero with a reason when evidence stops changing
# Exit : check passes, budget exhausted, or repeated failure
#
# Usage:
# CHECK_CMD="pytest -x" AGENT_CMD="claude -p" ./test-repair-loop.sh
# CHECK_CMD="npm test" AGENT_CMD="codex exec" ./test-repair-loop.sh
#
# Exit codes: 0 check passes, 1 budget exhausted, 2 no new evidence, 3 usage.
set -u
CHECK_CMD="${CHECK_CMD:-${1:-}}"
AGENT_CMD="${AGENT_CMD:-${2:-}}"
MAX_ITERATIONS="${MAX_ITERATIONS:-5}"
PROGRESS_FILE="${PROGRESS_FILE:-LOOP_PROGRESS.md}"
EVIDENCE_LINES="${EVIDENCE_LINES:-80}"
if [ -z "$CHECK_CMD" ] || [ -z "$AGENT_CMD" ]; then
echo "Usage: CHECK_CMD='pytest -x' AGENT_CMD='claude -p' $0" >&2
echo " or: $0 'pytest -x' 'claude -p'" >&2
exit 3
fi
# AGENT_CMD is split on whitespace; the prompt is passed as one final argument.
read -r -a agent_argv <<< "$AGENT_CMD"
failure_digest() {
# Stable fingerprint of the failure so we can tell when evidence stops changing.
if command -v shasum >/dev/null 2>&1; then shasum | cut -d' ' -f1; else cksum | cut -d' ' -f1; fi
}
record() {
printf '%s\n' "$1" >> "$PROGRESS_FILE"
}
if [ ! -f "$PROGRESS_FILE" ]; then
record "# Loop progress"
record ""
record "- Objective: make \`$CHECK_CMD\` pass."
fi
record ""
record "## Run started $(date -u '+%Y-%m-%d %H:%M:%S UTC')"
record ""
record "- Check command: \`$CHECK_CMD\`"
record "- Budget: $MAX_ITERATIONS iterations"
previous_digest=""
iteration=0
while [ "$iteration" -lt "$MAX_ITERATIONS" ]; do
iteration=$((iteration + 1))
echo "[loop] iteration $iteration/$MAX_ITERATIONS: running check..." >&2
check_output="$(bash -c "$CHECK_CMD" 2>&1)"
check_status=$?
if [ "$check_status" -eq 0 ]; then
echo "[loop] check passed." >&2
record "- Iteration $iteration: check passed. Loop complete."
exit 0
fi
evidence="$(printf '%s\n' "$check_output" | tail -n "$EVIDENCE_LINES")"
digest="$(printf '%s' "$evidence" | failure_digest)"
if [ "$digest" = "$previous_digest" ]; then
echo "[loop] same failure twice with no new evidence; escalating to a human." >&2
record "- Iteration $iteration: identical failure repeated (digest $digest). Escalated."
exit 2
fi
previous_digest="$digest"
record "- Iteration $iteration: check failed (exit $check_status, digest $digest). Delegating fix."
prompt="You are one iteration inside an automated test-repair loop.
Objective: make this command pass: $CHECK_CMD
Read $PROGRESS_FILE for what previous iterations already tried.
Latest failing output (last $EVIDENCE_LINES lines):
---
$evidence
---
Rules:
- Fix only the cause of this failure. Do not expand scope.
- Do not modify or delete tests to make them pass unless the test itself is provably wrong.
- Do not add dependencies, change CI config, or touch unrelated files.
- After editing, append one line to $PROGRESS_FILE describing what you changed and why.
- The loop re-runs the check itself; an external gate decides completion, not you."
"${agent_argv[@]}" "$prompt"
agent_status=$?
record "- Iteration $iteration: agent exited with status $agent_status."
done
echo "[loop] budget of $MAX_ITERATIONS iterations exhausted; escalating to a human." >&2
record "- Budget exhausted after $MAX_ITERATIONS iterations. Escalated."
exit 1
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