Paste this prompt into Claude Code before bed: a Builder-Checker harness that fixes bugs overnight
Arindam_1729 · x · 2026-11-02
Arindam shared a complete "night harness" prompt for Claude Code (Opus 5.5): paste it before bed and two agents keep building and fixing while you sleep.
Key design:
- Builder/Checker split: the Builder writes minimal changes and never edits tests; the Checker starts with fresh context, runs the full test suite, and even writes one extra test to break the change. Only the Checker can mark a step green.
- Loop rules: BUILD → CHECK → FIX, max 4 different fixes per step, then mark BLOCKED and move on.
- Guardrails: new branch only, no push to main, no new packages, deploys, migrations or paid APIs without approval; must paste real test output, never claim a run happened.
- Memory: repeated failures get written into HARNESS.md as a general rule; at 7:00 it reports in 10 lines max with a 3-line diff summary.
The accompanying graphic includes the full copy-paste prompt plus a three-file setup (HARNESS.md, tests.md, night-log.md).
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