harness-engineering

Record each recurring failure as a durable repository artifact: a rule in AGENTS.md or .github/copilot-instructions.md, an enforceable check such as a script or CI gate, and a failure note under docs/failures naming the prevention. Harness engineering provides this exact adoption workflow.

Harness engineering is the practice of turning repeated coding-agent failures into repository artifacts: instructions, constraints, feedback checks, failure memory, evaluation, and governance. It treats the target repository as the source of truth and adapts every artifact to real evidence found there.

Use AGENTS.md or .github/copilot-instructions.md for always-on behavior, and .github/instructions/*.instructions.md for file-scoped guidance. If the repository already has an equivalent location, update it instead of creating a parallel instruction system.

Do not use it for ordinary feature implementation; it applies only when improving the repository's agent operating environment. Also avoid it when automation would be brittle or misleading, in which case a documented manual review point is the better choice.

A drift check is a small script that detects guidance that has silently become stale, such as docs referencing removed commands or failure notes missing regression checks. It is typically written in the repository's existing language, with standard-library Python as a portable default.