A fast, general linter

One file configures it

The .alint.yml at the root of that workspace, and what alint check and alint fix printed for it.

version: 1
extends:
  - alint://bundled/oss-baseline@v1
  - alint://bundled/rust@v1
  - alint://bundled/ci/github-actions@v1
  - alint://bundled/hygiene/no-tracked-artifacts@v1

rules:
  - id: crates-use-edition-2024
    kind: toml_path_equals
    paths: "crates/*/Cargo.toml"
    path: "$.package.edition"
    equals: "2024"
    level: error

version: 1
extends:
  - alint://bundled/oss-baseline@v1
  - alint://bundled/rust@v1
  - alint://bundled/ci/github-actions@v1
  - alint://bundled/hygiene/no-tracked-artifacts@v1

rules:
  - id: crates-use-edition-2024
    kind: toml_path_equals
    paths: "crates/*/Cargo.toml"
    path: "$.package.edition"
    equals: "2024"
    level: error

.env  ✗  error    hygiene-no-env-files              Environment files containing real values must not be              committed. Use `.env.example` (or similar) for shared              non-secret defaults. ⋯ 2 more findings crates/cli/src/ParseArgs.rs  ✗  error    rust-sources-snake-case   fixable              Rust module filenames must be snake_case. ⋯ 2 more findings Summary (6 violations):  ✗ 3 errors   ⚠︎ 3 warnings  34 passing · 6 failing · 2 auto-fixable   → run `alint fix` to resolve 2 fixable violations.

.env  ✗  error    hygiene-no-env-files              Environment files              containing real values              must not be committed. Use              `.env.example` (or              similar) for shared              non-secret defaults. ⋯ 2 more findings crates/cli/src/ParseArgs.rs  ✗  error    rust-sources-snake-case   fixable              Rust module filenames must              be snake_case. ⋯ 2 more findings Summary (6 violations):  ✗ 3 errors   ⚠︎ 3 warnings  34 passing · 6 failing · 2 auto-fixable   → run `alint fix` to resolve 2 fixable violations.

alint groups what it finds by file, names the rule behind each finding and ends with a summary. The exit code fails CI on errors.

error [rust-sources-snake-case]:  ✓ renamed crates/cli/src/ParseArgs.rs -> crates/cli/src/parse_args.rs warning [rust-sources-final-newline]:  ✓ appended final newline to crates/core/src/lib.rs ⋯ 4 more findings

error [rust-sources-snake-case]:  ✓ renamed crates/cli/src/ParseArgs.rs    -> crates/cli/src/parse_args.rs warning [rust-sources-final-newline]:  ✓ appended final newline to    crates/core/src/lib.rs ⋯ 4 more findings

alint fix renamed the module and added the missing newline. There are 26 kinds of fix, from renames to license headers; the other 4 findings here need a person.

Where these rules live now

No code linter checks rules like these. Today they live in one of three places, and each one has a gap:

• in a reviewer's head, where they slip when that reviewer is busy or away;
• in CONTRIBUTING.md, where nothing fails when a pull request ignores them;
• in check scripts, where each one walks the tree its own way and prints its own output. Kubernetes had 50 of them in hack/ in May 2026.

#!/usr/bin/env bash
set -euo pipefail
fail=0
for d in packages/*/; do
  if [ ! -f "${d}README.md" ]; then
    echo "missing: ${d}README.md" >&2
    fail=1
  fi
done
exit $fail

missing: packages/emails/README.mdmissing: packages/web/README.md

- id: package-readme
  kind: for_each_dir
  select: "packages/*"
  require:
    - kind: file_exists
      paths: "{path}/README.md"
      message: "{path} has no README.md"
  level: error

packages/emails  ✗  error    package-readme              packages/emails has no README.md packages/web  ✗  error    package-readme              packages/web has no README.md

packages/emails  ✗  error    package-readme              packages/emails has no              README.md packages/web  ✗  error    package-readme              packages/web has no              README.md

The rule finds the same two packages. It also runs in the same walk as every other rule, reports under its own name in any of alint's 8 output formats, shows up in your editor and keeps checking when someone adds a package.

Turn it on without fixing everything first

alint baseline

Records the findings you have today. Point the config's baseline: field at the file, and CI fails only on new findings while the old ones get fixed as you go.

alint check --changed

Checks only files with changes you haven't staged yet, new or edited, which keeps a local run short. In a pull request, --base origin/main checks every file the pull request touches.

alint init

Writes a starter .alint.yml for the languages and tools it finds.

alint suggest

Looks for problems already in your tree and proposes the rules that would catch them.

How the baseline works, and what --changed still checks across the whole tree.

Runs where you work

The same rules give the same findings in CI, pre-commit, your editor and your coding agent. This is the misnamed module from the workspace, in two of alint's 8 output formats.

- uses: asamarts/alint@10d1c0a2bafd0bd316dbad9fe63ea5e1e3761c71 # v0.20.0

::error title=rust-sources-snake-case,file=crates/cli/src/ParseArgs.rs::Rust module filenames must be snake_case.

{  "rule_id": "rust-sources-snake-case",  "severity": "error",  "file": "crates/cli/src/ParseArgs.rs",  "agent_instruction": "error: Rust module filenames must be snake_case. To resolve: edit crates/cli/src/ParseArgs.rs (or run `alint fix --only rust-sources-snake-case` to apply the auto-fix).",  "fix_command": [    "fix",    "--only",    "rust-sources-snake-case"  ]}

For a coding agent. Each finding comes with an instruction and, where one exists, the command that fixes it. Above is one finding from the report, cut to the fields an agent acts on. How agents use it.

On real repositories

The reference configs cover 30 open-source repositories, written to test alint on real trees; the projects don't use alint. Three things the configs found:

1. flutter/flutter oss-no-bidi-controls

   U+202C, an invisible bidi control, hides in 5 Markdown files, probably pasted in with contributor names.

2. facebook/react react-package-repository-directory-matches

   react-refresh sets repository.directory to packages/react, copied from a sibling package, so npm links to the wrong folder.

3. NixOS/nixpkgs hygiene-no-ruby-bundler-cache

   Two packages commit Ruby's bundler cache, .bundle/, which none of nixpkgs' CI checks looks for.

All 30 reference configs, each with what it checks, what stays outside alint and, where a run found something, what it found.