“Formatting is off here” and “there’s a leftover console log” are review comments a machine should be making, not a person. pre-commit runs a fixed set of checks every time you commit.

Install 

  brew install pre-commit
pip install pre-commit

Install the hooks from the project root:

  pre-commit install

They now run on every git commit.

The config file

.pre-commit-config.yaml at the project root:

  repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v4.6.0
    hooks:
      - id: trailing-whitespace
      - id: end-of-file-fixer
      - id: check-yaml
      - id: check-json
      - id: check-merge-conflict
      - id: check-added-large-files
        args: ["--maxkb=1000"]

  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.6.9
    hooks:
      - id: ruff
        args: [--fix]
      - id: ruff-format

  - repo: https://github.com/gitleaks/gitleaks
    rev: v8.19.2
    hooks:
      - id: gitleaks

gitleaks stops API keys and tokens from slipping into a commit. Since a pushed secret is effectively unrecoverable, that hook alone justifies adopting this.

Commands

CommandAction
pre-commit runRun against staged files
pre-commit run --all-filesRun against the whole repo (once, at adoption)
pre-commit autoupdateBump hook versions
pre-commit run <hook-id>Run a single hook
git commit --no-verifySkip the hooks (emergencies only)

Rolling it out

  1. Run --all-files first and put the result in its own commit. Mixing formatting with behaviour changes makes review impossible.
  2. Add that commit’s hash to .git-blame-ignore-revs so blame stays useful.
      echo "<formatting-commit-hash>" >> .git-blame-ignore-revs
git config blame.ignoreRevsFile .git-blame-ignore-revs
  3. Tell the team to run pre-commit install once. Hooks are not applied automatically by cloning; everyone installs them.
  4. Run the same checks in CI so commits from people who skipped step 3 still get caught.
  # part of .github/workflows/lint.yml
- uses: pre-commit/action@v3.0.1

When it gets slow

  • Move heavy hooks (type checking, tests) to pre-push or CI.
      pre-commit install --hook-type pre-push
  • Narrow the scope with files: and exclude:.

Next

With the code tidy, on to talking to the outside world → Network & APIs

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Last updated 19 Aug 2026, 00:00 UTC. history