# Automatically lint and format code before commits
**URL:** https://meta.discourse.org/t/automatically-lint-and-format-code-before-commits/132947
**Category:** Developer Guides
**Tags:** how-to, code
**Created:** [November 8, 2019, 5:16pm UTC](https://meta.discourse.org/t/automatically-lint-and-format-code-before-commits/132947 "2019-11-08T17:16:11Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Discourse](https://meta.discourse.org/u/Discourse)
#### Post date: [November 8, 2019, 5:16pm UTC](https://meta.discourse.org/t/automatically-lint-and-format-code-before-commits/132947/1 "2019-11-08T17:16:12Z")
Discourse uses [lefthook](https://github.com/evilmartians/lefthook) for git hooks, and `bin/lint` as the main CLI entry point for running the same checks manually.
If you are working in a local clone, install the hooks once:
```sh
pnpm install
pnpm lefthook install
```
After that, staged files will be checked automatically on `git commit`.
## The main command: `bin/lint`
Use `bin/lint` when you want to run the repo’s configured linters yourself instead of waiting for the pre-commit hook.
Common examples:
```sh
bin/lint
bin/lint path/to/file.rb path/to/file.gjs
bin/lint --recent
bin/lint --staged
bin/lint --unstaged
bin/lint --wip
bin/lint --fix path/to/file.rb
bin/lint --fix --recent
bin/lint --fix
```
### What each mode does
- `bin/lint`: lint all supported files in the repository
- `bin/lint path/to/file ...`: lint only the given files
- `bin/lint --recent`: lint files changed in the last 50 commits, plus untracked files
- `bin/lint --staged`: lint only staged files
- `bin/lint --unstaged`: lint only unstaged files
- `bin/lint --wip`: lint staged files, unstaged files, and files changed since `main`
- `bin/lint --fix ...`: run the auto-fixers for the selected files
- `bin/lint --fix`: run all available auto-fixers across the repository
- `bin/lint --verbose`: print the underlying lefthook commands
When you pass explicit files, `bin/lint` filters them to supported lintable file types before invoking lefthook.
> ℹ Markdown documentation files are not currently part of `bin/lint`, so running `bin/lint path/to/doc.md` will report that there are no matching files to lint.
## What gets linted
The exact configuration lives in [`lefthook.yml`](https://github.com/discourse/discourse/blob/main/lefthook.yml). At the time of writing, `bin/lint` covers:
### Ruby
- `**/*.{rb,rake,thor}`
- Ruby scripts under `bin/**/*`
- `Gemfile`
Checks:
- `rubocop`
- `syntax_tree` (`stree check`)
### JavaScript, GJS, CSS, and SCSS formatting
- `app/assets/stylesheets/**/*.{css,scss}`
- `frontend/**/*.{js,gjs,scss,css,cjs,mjs}`
- matching plugin and theme asset files
Checks:
- `prettier`/`pprettier`
### JavaScript and GJS linting
- `frontend/**/*.{js,gjs}`
- matching plugin and theme JS files
Checks:
- `eslint` (with `eslint-plugin-ember`’s `template-*` rules covering the template portion of `.gjs` files)
### SCSS linting
- `app/assets/stylesheets/**/*.scss`
- matching plugin and theme SCSS files
Checks:
- `stylelint`
### YAML and locale checks
- `**/*.{yaml,yml}` except `config/database.yml`
- `**/{client,server}.en.yml`
Checks:
- `yaml-lint`
- `script/i18n_lint.rb`
### Type checking
When you run `bin/lint` with no file arguments, the full-repo lint also runs:
- `pnpm lint:types`
This is the Glint/TypeScript-style check for Discourse’s JavaScript type information.
> ℹ `bin/lint path/to/file` and the pre-commit hook do **not** run the full type check. Use plain `bin/lint` when you want the complete repo-wide lint pass.
## What can be auto-fixed
`bin/lint --fix` can automatically fix a lot of issues, but not all of them.
Auto-fix is configured for:
- `prettier --write`
- `eslint --fix`
- `stylelint --fix`
- `rubocop -A`
- `syntax_tree` (`stree write`)
In practice, that means `--fix` can reformat and rewrite:
- Ruby
- JavaScript / GJS
- CSS / SCSS
These checks are **not** auto-fixed by `bin/lint --fix`:
- YAML syntax validation
- i18n linting for `client.en.yml` / `server.en.yml`
- Glint/type checking
## Relationship to git hooks
The pre-commit hook uses the same lefthook configuration as `bin/lint`, but it runs only against staged files.
That means:
- a commit can fail because staged files do not pass linting
- `bin/lint --staged` is the closest manual equivalent to the pre-commit hook
- `bin/lint --fix --staged` is a good way to repair exactly what you are about to commit
## Practical workflow
For day-to-day development, these are the most useful commands:
```sh
# Before committing a couple of changed files
bin/lint --fix path/to/file1.rb path/to/file2.gjs
# Check exactly what the pre-commit hook will check
bin/lint --staged
# Clean up all current in-progress work
bin/lint --fix --wip
# Run the full repo lint suite, including type checks
bin/lint
```
* * *
This document is version controlled - suggest changes [on github](https://github.com/discourse/discourse/blob/main/docs/developer-guides/docs/03-code-internals/03-lint-and-format.md).
---
### Author:  [@sam](https://meta.discourse.org/u/sam)
#### Post date: [March 13, 2026, 6:34am UTC](https://meta.discourse.org/t/automatically-lint-and-format-code-before-commits/132947/2 "2026-03-13T06:34:52Z")
7 posts were split to a new topic: [Debugging linting on Discourse](https://meta.discourse.org/t/debugging-linting-on-discourse/398343)