prek

Use this skill when the user wants to set up or run Git hooks with

prek

prek

is a Rust reimplementation of

pre-commit

. Its main job is to run hooks that check code and repository files before commit or on demand: formatters, linters, validators, security checks, and custom project checks.

Start with the public docs

Use the LLM-oriented index first:

llms.txt

Per that file, prefer explicit markdown docs when you need details:

What prek is for

Use

prek

to:

run hooks that check source code and repo contents
install Git hook shims such as
```
pre-commit
```
,
```
pre-push
```
, and
```
commit-msg
```
run the same hook ecosystem used by
```
pre-commit
```
manage hook runtimes and toolchains for supported languages
validate configs, update pinned hook revisions, and inspect configured hooks

Typical jobs for hooks run by

prek

formatting and linting code
validating YAML, JSON, TOML, XML, and similar files
preventing merge-conflict markers, private keys, oversized files, and bad line endings

Authoring configs

For new configs, prefer

prek.toml

Important repo types:

remote repo: normal hook repository such as

https://github.com/astral-sh/ruff-pre-commit

```
repo = "local"
```
: hooks defined in the current repository

repo = "meta"

: config-checking hooks like

check-hooks-apply

check-useless-excludes

, and

identity

```
repo = "builtin"
```
:
```
prek
```
's offline Rust-native hooks

Minimal examples:

toml

[[repos]]
repo = "https://github.com/astral-sh/ruff-pre-commit"
rev = "v0.14.3"
hooks = [
  { id = "ruff" },
  { id = "ruff-format" },
]

toml

[[repos]]
repo = "local"
hooks = [
  {
    id = "cargo-fmt",
    name = "cargo fmt",
    language = "system",
    entry = "cargo fmt --",
    files = "\\.rs$",
  },
]

toml

[[repos]]
repo = "builtin"
hooks = [
  { id = "trailing-whitespace" },
  { id = "check-yaml" },
]

These examples use TOML 1.1 multiline inline tables. Use

[[repos.hooks]]

array-of-tables if an editor or parser in the toolchain does not support that syntax yet, or when a hook has many fields such as

env

pass_filenames = false

, or

priority

Filtering patterns:

regex is the most portable choice:
```
files = "\\.rs$"
```
```
prek
```
also supports globs:
```
files = { glob = "src/**/*.rs" }
```

use glob lists for multiple roots:

exclude = { glob = ["target/**", "dist/**"] }

Scheduling:

smaller
```
priority
```
values run earlier
hooks with the same
```
priority
```
can run concurrently
top-level
```
priorities
```
can declare configuration-local aliases for numeric priorities
hook
```
priority
```
accepts either a non-negative integer or a declared alias
```
priority
```
is evaluated within one config file, not across workspace projects

Useful

prek

-specific hook/config fields when editing TOML:

```
env
```
for per-hook environment variables
```
priorities
```
for readable, reusable priority aliases
```
priority
```
for hook ordering and concurrency
```
minimum_prek_version
```
for gating newer config features
```
orphan = true
```
to isolate a nested workspace project from parent configs

Default workflow

When adopting

prek

in a repository:

Check whether the repo already has

.pre-commit-config.yaml

.pre-commit-config.yml

If it does, usually keep that config and switch the commands from
```
pre-commit
```
to
```
prek
```
.
If migrating from
```
pre-commit
```
, reinstall the Git shims with
```
prek install -f
```
.
If it does not, prefer creating
```
prek.toml
```
for a fresh setup.
Install
```
prek
```
.
Validate the config with
```
prek validate-config
```
.
Install the Git shims and prepare hook environments with
```
prek install --prepare-hooks
```
.
Run everything once with
```
prek run --all-files
```
.
For monorepos, consider nested configs,
```
.prekignore
```
, and
```
orphan: true
```
.

If the user explicitly wants maximum upstream portability, stay with

.pre-commit-config.yaml

and avoid

prek

-only keys.

Install and run

Common install methods:

```
uv tool install prek
```
```
brew install prek
```
```
mise use prek
```
```
cargo binstall prek
```
```
cargo install --locked prek
```

Command guide

```
prek install
```
: install Git hook shims into the repo's effective hooks directory
```
prek prepare-hooks
```
: prepare hook environments without installing Git shims
```
prek install --prepare-hooks
```
: install shims and prepare environments in one step
```
prek run
```
: run hooks for the current staged file selection
```
prek run --all-files
```
: run hooks across the whole repository
```
prek run <hook-id>
```
: run only one hook
```
prek list
```
: list discovered hooks and projects

prek validate-config

: validate

prek.toml

.pre-commit-config.yaml

```
prek auto-update
```
: update pinned hook revisions
```
prek util yaml-to-toml
```
: convert an existing YAML config to
```
prek.toml
```
```
prek util identify <path>
```
: inspect file tags when
```
types
```
,
```
types_or
```
, or
```
exclude_types
```
do not match as expected

Useful quality-of-life commands and options mentioned in the docs:

```
prek run --dry-run
```
```
prek run --directory <dir>
```
```
prek run --last-commit
```
```
prek run --skip <hook-or-project>
```
```
prek -C <dir> ...
```

For debugging:

```
prek run -vvv
```
```
PREK_NO_FAST_PATH=1 prek run
```
: compare builtin fast-path behavior against the standard execution path
Check the Environment Variable Reference for
```
PREK_*
```
controls such as
```
PREK_HOME
```
,
```
PREK_SKIP
```
, and concurrency limits.

Built-in hook guidance

prek

has two important builtin paths:

automatic fast path for supported hooks from

https://github.com/pre-commit/pre-commit-hooks

explicit
```
repo: builtin
```
for offline, zero-setup built-in hooks

Reach for

repo: builtin

when speed, no-network setup, or minimal bootstrapping matters more than upstream

pre-commit

compatibility.

Builtin hooks called out by the docs include:

```
trailing-whitespace
```
```
check-added-large-files
```
```
check-case-conflict
```
```
check-illegal-windows-names
```
```
end-of-file-fixer
```
```
file-contents-sorter
```
```
fix-byte-order-marker
```
```
check-json
```
```
check-json5
```
```
pretty-format-json
```
```
check-toml
```
```
check-vcs-permalinks
```
```
check-yaml
```
```
check-xml
```
```
mixed-line-ending
```
```
check-symlinks
```
```
destroyed-symlinks
```
```
check-merge-conflict
```
```
detect-private-key
```
```
no-commit-to-branch
```
```
check-shebang-scripts-are-executable
```
```
check-executables-have-shebangs
```

Practical guidance for agents

Prefer
```
prek.toml
```
for new setups.
Prefer existing
```
.pre-commit-config.yaml
```
for migrations unless the user asks for TOML.
Reach for workspace mode in monorepos instead of forcing one giant root-only config.
Consider
```
repo: builtin
```
when offline or zero-setup hooks are useful.
If the repo already uses
```
pre-commit-hooks
```
, remember that
```
prek
```
can use built-in Rust implementations for some common hooks.
Start with a small default hook set, then add language-specific hooks the project already uses.
Use
```
prek util yaml-to-toml
```
instead of hand-converting YAML when migrating.
Before promising parity for a specific hook language, verify it in Language Support.

prek

NPX Install

Tags

SKILL.md Content

prek

Start with the public docs

What prek is for

Authoring configs

Default workflow

Install and run

Command guide

Built-in hook guidance

Practical guidance for agents