Code linting

Check or fix Python with Ruff and JavaScript/TypeScript with Biome. Use repository commands and configuration before these defaults. Read project instructions, pyproject.toml, and biome.json; preserve configured rules and line width.

Check and fix

Use the project virtual environment (./venv/bin/ruff or ./env/bin/ruff) and installed JavaScript tooling. For mixed projects, check both languages unless the task selects one. Adapt src/ to the actual source directory.

Task	Python	JavaScript/TypeScript
Check	ruff check .	npx @biomejs/biome check src/
Format check	ruff format --check .	Included in Biome check
Fix lint	ruff check --fix .	npx @biomejs/biome check --write src/
Format	ruff format .	npx @biomejs/biome format --write src/

If configured, use make lint or make lint-fix. Check first; apply fixes only within the requested work. Review git diff, undo incorrect fixes, then rerun lint and format checks. Do not change rules, install new tooling, or expand cleanup scope merely to get a pass.

For remaining issues: F401 means remove or use the import; I001 needs import sorting; E501 needs shorter lines within existing settings. Biome noVar uses let/const, useConst marks unchanged bindings, and noDoubleEquals uses strict equality where semantics allow.

Report commands, exit status, and actionable rule/file:line diagnostics. Keep full logs available; summarize passing checks. Remove only temporary files created for this run, preserving useful failure logs.

Recovery and optional modes

• Ruff missing: check the project virtual environment. Installation options are pip install ruff or pipx run ruff check .; install only within authorized dependency work.
• Biome missing: check package dependencies before npx execution; do not let a read-only check download tooling unexpectedly.
• Config missing: verify project root before running defaults.
• Strict warnings, format-only, or rule exceptions: use only when requested; do not weaken repository requirements.

Reference loading table

Signal	Reference
Ruff rules, configuration, versions, or F401/E711/B006/UP errors	references/ruff-rules-reference.md
Biome rules, configuration, ESLint migration, or noVar/useConst/noDoubleEquals	references/biome-rules-reference.md
Lint versus format CI failure	Relevant tool reference above