Configuration Reference

This page documents the configuration keys that prek understands.

Global config file

prek reads an optional user-level global config from:

• Linux and macOS: ~/.config/prek/prek.toml (or $XDG_CONFIG_HOME/prek/prek.toml when XDG_CONFIG_HOME is set)
• Windows: %APPDATA%\prek\prek.toml

This file stores user-level prek settings and does not define project hooks.

Global auto_update.cooldown_days

Default cooldown for prek auto-update.

• Type: integer days, 0 to 255
• Default: 0
• CLI override: prek auto-update --cooldown-days <DAYS>

[auto_update]
cooldown_days = 7

The age is computed from the tag creation timestamp for annotated tags, or from the tagged commit timestamp for lightweight tags. A value of 0 disables the cooldown check.

Project configs can also set auto_update.cooldown_days. The effective precedence is:

1. prek auto-update --cooldown-days <DAYS>
2. project config
3. user-level global config
4. default 0

Top-level keys

auto_update.cooldown_days

Project default cooldown for prek auto-update.

• Type: integer days, 0 to 255
• Default: inherited from the user-level global config, or 0
• CLI override: prek auto-update --cooldown-days <DAYS>

=== "prek.toml"

```toml
[auto_update]
cooldown_days = 7
```

=== ".pre-commit-config.yaml"

```yaml
auto_update:
  cooldown_days: 7
```

In workspace mode, this setting is scoped to the project config file that defines it. It applies only to that project and is not inherited by nested projects. Sub-projects use their own auto_update setting, then the user-level global config, then the default. If two projects use the same repo URL with different cooldown settings, prek auto-update fetches the repo once but evaluates each project with its own cooldown.

repos (required)

A list of hook repositories.

Each entry is one of:

• a remote repository (typically a git URL)
• repo: local for hooks defined directly in your repository
• repo: meta for built-in meta hooks
• repo: builtin for prek's built-in fast hooks

See Repo entries.

<a id="top-level-files"></a>

files

Global include regex applied before hook-level filtering.

• Type: regex string (default, pre-commit compatible) or a prek-only glob pattern mapping
• Default: no global include filter

This is usually used to narrow down the universe of files in large repositories.

!!! note "What path is matched? (workspace + nested projects)"

`files` (and `exclude`) are matched against the file path **relative to the project root** — i.e. the directory containing the configuration file.

- For the root project, this is the workspace root.
- For a nested project, this is the nested project directory.

Example (workspace mode):

- Root project config: `./.pre-commit-config.yaml`
- Nested project config: `./nested/.pre-commit-config.yaml`

For a file at `nested/excluded_by_project`:

- Root project sees the path as `nested/excluded_by_project`
- Nested project sees the path as `excluded_by_project`

This matters most for anchored patterns like `^...$`.

!!! tip "Regex matching"

When `files` / `exclude` are regex strings, they are matched with *search* semantics (the pattern can match anywhere in the path).
Use `^` to anchor at the beginning and `$` at the end.

`prek` uses the Rust [`fancy-regex`](https://github.com/fancy-regex/fancy-regex) engine.
Most typical patterns are portable to upstream `pre-commit`, but very advanced regex features may differ from Python’s `re`.

!!! note "prek-only globs"

In addition to regex strings, `prek` supports glob patterns via:

- `files: { glob: "..." }` (single glob)
- `files: { glob: ["...", "..."] }` (glob list)

This is a `prek` extension. Upstream `pre-commit` expects regex strings here.

For more information on the glob syntax, refer to the [globset documentation](https://docs.rs/globset/latest/globset/#syntax).

Examples:

=== "prek.toml"

```toml
# Regex (portable to pre-commit)
files = "\\.rs$"

# Glob (prek-only)
files = { glob = "src/**/*.rs" }

# Glob list (prek-only; matches if any glob matches)
files = { glob = ["src/**/*.rs", "crates/**/src/**/*.rs"] }
```

=== ".pre-commit-config.yaml"

```yaml
# Regex (portable to pre-commit)
files: "\\.rs$"

# Glob (prek-only)
files:
  glob: "src/**/*.rs"

# Glob list (prek-only; matches if any glob matches)
files:
  glob:
    - "src/**/*.rs"
    - "crates/**/src/**/*.rs"
```

<a id="top-level-exclude"></a>

exclude

Global exclude regex applied before hook-level filtering.

• Type: regex string (default, pre-commit compatible) or a prek-only glob pattern mapping
• Default: no global exclude filter

exclude is useful for generated folders, vendored code, or build outputs.

!!! note "What path is matched?"

Same as [`files`](#top-level-files): the pattern is evaluated against the file path **relative to the project root** (the directory containing the config).

!!! note "prek-only globs"

Like `files`, `exclude` supports `glob` (single glob or glob list) as a `prek` extension.
For glob syntax details, see the [globset documentation](https://docs.rs/globset/latest/globset/#syntax).

Examples:

=== "prek.toml"

```toml
# Regex (portable to pre-commit)
exclude = "^target/"

# Glob (prek-only)
exclude = { glob = "target/**" }

# Glob list (prek-only)
exclude = { glob = ["target/**", "dist/**"] }
```

=== ".pre-commit-config.yaml"

```yaml
# Regex (portable to pre-commit)
exclude: "^target/"

# Glob (prek-only)
exclude:
  glob: "target/**"

# Glob list (prek-only)
exclude:
  glob:
    - "target/**"
    - "dist/**"
```

Verbose regex example (useful for long allow/deny lists):

=== "prek.toml"

```toml
# `(?x)` enables "verbose" regex mode (whitespace and newlines are ignored).
exclude = """(?x)^(
  docs/|
  vendor/|
  target/
)"""
```

=== ".pre-commit-config.yaml"

```yaml
# `(?x)` enables "verbose" regex mode (whitespace and newlines are ignored).
exclude: |
  (?x)^(
    docs/|
    vendor/|
    target/
  )
```

fail_fast

Stop the run after the first failing hook.

• Type: boolean
• Default: false

This is a global default; individual hooks can also set fail_fast.

default_language_version

Map a language name to the default language_version used by hooks of that language.

• Type: map
• Default: none (hooks fall back to language_version: default)

Example:

=== "prek.toml"

```toml
default_language_version.python = "3.12"
default_language_version.node = "20"
```

=== ".pre-commit-config.yaml"

```yaml
default_language_version:
  python: "3.12"
  node: "20"
```

prek treats language_version as a version request (often a semver-like selector) and may install toolchains automatically. See Difference from pre-commit.

default_stages

Default stages used when a hook does not specify its own.

• Type: list of stage names
• Default: all stages

Allowed values:

• manual
• commit-msg
• post-checkout
• post-commit
• post-merge
• post-rewrite
• pre-commit
• pre-merge-commit
• pre-push
• pre-rebase
• prepare-commit-msg

default_install_hook_types

Default Git shim name(s) installed by prek install when you don’t pass --hook-type.

• Type: list of --hook-type values
• Default: [pre-commit]

This controls which Git shims are installed (for example pre-commit vs pre-push). It is separate from a hook’s stages, which controls when a particular hook is eligible to run.

Allowed values:

• pre-commit
• pre-push
• commit-msg
• prepare-commit-msg
• post-checkout
• post-commit
• post-merge
• post-rewrite
• pre-merge-commit
• pre-rebase

minimum_prek_version

<a id="prek-only-minimum-prek-version-config"></a>

!!! note "prek-only"

This key is a `prek` extension. Upstream `pre-commit` uses `minimum_pre_commit_version`, which `prek` intentionally ignores.

Require a minimum prek version for this config.

• Type: string (version)
• Default: unset

If the installed prek is older than the configured minimum, prek exits with an error.

Example:

=== "prek.toml"

```toml
minimum_prek_version = "0.2.0"
```

=== ".pre-commit-config.yaml"

```yaml
minimum_prek_version: "0.2.0"
```

orphan

<a id="prek-only-orphan"></a>

!!! note "prek-only"

`orphan` is a `prek` workspace-mode feature and is not recognized by upstream `pre-commit`.

Workspace-mode setting to isolate a nested project from parent configs.

• Type: boolean
• Default: false

When orphan: true, files under this project directory are handled only by this project’s config and are not “seen” by parent projects.

Example:

=== "prek.toml"

```toml
orphan = true

[[repos]]
repo = "https://github.com/astral-sh/ruff-pre-commit"
rev = "v0.8.4"
hooks = [{ id = "ruff" }]
```

=== ".pre-commit-config.yaml"

```yaml
orphan: true
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.4
    hooks:
      - id: ruff
```

See Workspace Mode - File Processing Behavior for details.

Repo entries

Each item under repos: is a mapping that always contains a repo: key.

Remote repository

Use this for hooks distributed in a separate repository.

Required keys:

• repo: repository location (commonly an https git URL)
• rev: version to use (tag, branch, or commit SHA)
• hooks: list of hook selections

Remote hook definitions live inside the hook repository itself in the .pre-commit-hooks.yaml manifest (at the repo root). Your config only selects hooks by id and optionally overrides options. See Authoring Hooks if you maintain a hook repository.

repo

Where to fetch hooks from.

In most configs this is a git URL. prek also recognizes special values documented separately: local, meta, and builtin.

rev

The revision to use for the remote repository.

Use a tag or commit SHA for repeatable results. If you use a moving target (like a branch name), runs may change over time.

hooks

The list of hooks to enable from that repository.

Each item must at least specify id. You can also add hook-level options (filters, args, stages, etc.) to customize behavior.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "https://github.com/astral-sh/ruff-pre-commit"
rev = "v0.8.4"
hooks = [{ id = "ruff", args = ["--fix"] }]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.4
    hooks:
      - id: ruff
        args: [--fix]
```

Notes:

• For reproducibility, prefer immutable pins (tags or commit SHAs).
• prek auto-update can help update rev values.

repo: local

Define hooks inline inside your repository.

Keys:

• repo: must be local
• hooks: list of local hook definitions (see Local hook definition)

Example:

=== "prek.toml"

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

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: cargo-fmt
        name: cargo fmt
        language: system
        entry: cargo fmt
        files: "\\.rs$"
```

repo: meta

Use pre-commit-style meta hooks that validate and debug your configuration.

prek supports the following meta hook ids:

• check-hooks-apply
• check-useless-excludes
• identity

Restrictions:

• id is required.
• entry is not allowed.
• language (if set) must be system.

You may still configure normal hook options such as files, exclude, stages, etc.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "meta"
hooks = [{ id = "check-useless-excludes" }]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: meta
    hooks:
      - id: check-useless-excludes
```

repo: builtin

<a id="prek-only-repo-builtin"></a>

!!! note "prek-only"

`repo: builtin` is specific to `prek` and is not compatible with upstream `pre-commit`.

Use prek’s built-in fast hooks (offline, zero setup).

Restrictions:

• id is required.
• entry is not allowed.
• language (if set) must be system.

Example:

=== "prek.toml"

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

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: builtin
    hooks:
      - id: trailing-whitespace
      - id: check-yaml
```

For the list of available built-in hooks and the “automatic fast path” behavior, see Built-in Fast Hooks.

Hook entries

Hook items under repos[*].hooks have slightly different shapes depending on the repo type.

Remote hook selection

For a remote repo, the hook entry must include:

• id (required): selects the hook from the repository

All other hook keys are optional overrides (for example args, files, exclude, stages, …).

!!! note "Advanced overrides"

`prek` also supports overriding `name`, `entry`, and `language` for remote hooks.
This can be useful for experimentation, but it may reduce portability to the original `pre-commit`.

Local hook definition

For repo: local, the hook entry is a full definition and must include:

• id (required): stable identifier used by prek run <id> and selectors
• name (required): label shown in output
• entry (required): command to execute
• language (required): how prek sets up and runs the hook

Builtin/meta hook selection

For repo: builtin and repo: meta, the hook entry must include id. You can optionally provide name and normal hook options (filters, stages, etc), but not entry.

Common hook options

These keys can appear on hooks (remote/local/builtin/meta), subject to the restrictions above.

id

The stable identifier of the hook.

• For remote hooks, this must match a hook id defined by the remote repository.
• For local hooks, you choose it.

id is also used for CLI selection (for example prek run <id> and PREK_SKIP).

!!! note "Hook ids containing :"

If your hook id contains `:` (for example `id: lint:ruff`), `prek run lint:ruff`
will not select that hook. `prek` interprets `lint:ruff` as the selector
`<project-path>:<hook-id>`, with project `lint` and hook `ruff`.
To select the hook id `lint:ruff`, add a leading `:` and run
`prek run :lint:ruff`.

name

Human-friendly label shown in output.

• Required for repo: local hooks.
• Optional as an override for remote/meta/builtin hooks.

entry

The command line to execute for the hook.

• Required for repo: local hooks.
• Optional override for remote hooks.
• Not allowed for repo: meta and repo: builtin.

If pass_filenames: true, prek appends matching filenames to this command when running.

shell

<a id="prek-only-shell"></a>

!!! note "prek-only"

`shell` is a `prek` extension and may not be recognized by upstream `pre-commit`.

Run entry through a predefined shell adapter.

• Type: one of sh, bash, pwsh, powershell, cmd
• Default: null (run entry directly without a shell)

When shell is omitted, prek preserves the default no-shell behavior: it parses entry into argv, invokes the command directly, and appends args and matching filenames as process arguments.

When shell is set, entry is treated as source for that shell. prek writes the source to a temporary script file, runs it with the selected shell adapter, and passes hook args followed by matching filenames as script arguments.

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "test-all",
    name = "test-all",
    language = "system",
    entry = """
    uv run --python=3.10 --isolated pytest
    uv run --python=3.11 --isolated pytest
    """,
    shell = "bash",
    pass_filenames = false,
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: test-all
        name: test-all
        language: system
        entry: |
          uv run --python=3.10 --isolated pytest
          uv run --python=3.11 --isolated pytest
        shell: bash
        pass_filenames: false
```

??? note "Unsupported languages"

`shell` is rejected for language backends that do not run `entry` through
the shell-aware entry resolver, and for `repo: meta` and `repo: builtin`
hooks.

| Language | Why `shell` is unsupported |
| -- | -- |
| `docker`, `docker_image` | `entry` participates in container image or entrypoint selection instead of direct host process execution. |
| `dart` | Dart package config injection requires `entry` to resolve to a direct `dart` command. |
| `fail` | `entry` is the failure message body. |
| `julia`, `rust` | `entry` participates in install/runtime package resolution and is split before execution. |
| `pygrep` | `entry` is the regex pattern. |
| `conda`, `coursier`, `perl`, `r` | The language backend is not implemented yet. |

language

How prek should run the hook (and whether it should create a managed environment).

• Required for repo: local hooks.
• Optional override for remote hooks.
• Not allowed (except as system) for repo: meta and repo: builtin.

Common values include system, python, node, rust, golang, ruby, and docker.

See Language Support for per-language behavior, supported values, and language_version details.

!!! note "Language name aliases"

For compatibility with upstream `pre-commit`, the following legacy language names are also accepted:

- `unsupported` is treated as `system`
- `unsupported_script` is treated as `script`

alias

An alternate identifier for selecting the hook from the CLI.

If set, you can run the hook via either prek run <id> or prek run <alias>.

args

Extra arguments appended to the hook’s entry.

• Type: list of strings

Example:

=== "prek.toml"

```toml
hooks = [{ id = "ruff", args = ["--fix"] }]
```

=== ".pre-commit-config.yaml"

```yaml
hooks:
  - id: ruff
    args: [--fix]
```

env

<a id="prek-only-env"></a>

!!! note "prek-only"

`env` is a `prek` extension and may not be recognized by upstream `pre-commit`.

Extra runtime environment variables for the hook process.

• Type: map of string to string

Values override the existing process environment (including variables such as PATH). They are applied when the hook runs, not when prek installs or prepares the hook environment.

For remote hooks, env may also be set by the hook author in .pre-commit-hooks.yaml. Values from the project configuration are merged with manifest values and override duplicate keys.

For docker / docker_image hooks, these variables are passed into the container rather than being applied to the container runtime command.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "cargo-doc",
    name = "cargo doc",
    language = "system",
    entry = "cargo doc --all-features --workspace --no-deps",
    env = { RUSTDOCFLAGS = "-Dwarnings" },
    pass_filenames = false,
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: cargo-doc
        name: cargo doc
        language: system
        entry: cargo doc --all-features --workspace --no-deps
        env:
          RUSTDOCFLAGS: -Dwarnings
        pass_filenames: false
```

files / exclude

Filters applied to candidate filenames.

• files selects which files are eligible for the hook.
• exclude removes files matched by files.

If you use both global and hook-level filters, the effective behavior is “global filter first, then hook filter”.

By default (and for compatibility with upstream pre-commit), these are regex strings. As a prek extension, you can also specify globs using glob or a glob list.

See Top-level files and Top-level exclude for syntax notes and examples.

types / types_or / exclude_types

File-type filters based on identify tags.

!!! tip

Use [`prek util identify <path>`](cli.md#prek-util-identify) to see how prek tags a file when you’re troubleshooting `types` filters.

Compared to regex-only filtering (files / exclude), tag-based filtering is often easier and more robust:

• tags can match by file extension and by shebang (for extensionless scripts)
• you can easily exclude things like symlinks or binary files

Common tags include:

• file, text, binary, symlink, executable

• language-ish tags such as python, rust, javascript, yaml, toml, ...

• types: all listed tags must match (logical AND)

• types_or: at least one listed tag must match (logical OR)

• exclude_types: tags that disqualify a file

How these combine:

• files / exclude, types, and types_or are combined with AND.
• Tags within types are combined with AND.
• Tags within types_or are combined with OR.

Defaults:

• types: [file] (matches all files)
• types_or: []
• exclude_types: []

These filters are applied in addition to regex filtering.

Examples:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  # AND: must be under `src/` AND have the `python` tag
  {
    id = "lint-py",
    name = "Lint (py)",
    language = "system",
    entry = "python -m ruff check",
    files = "^src/",
    types = ["python"],
    exclude_types = ["symlink"]
  },

  # OR: match any of the listed tags under `web/`
  {
    id = "lint-web",
    name = "Lint (web)",
    language = "system",
    entry = "npm run lint",
    files = "^web/",
    types_or = ["javascript", "jsx", "ts", "tsx"]
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: lint-py
        name: Lint (py)
        language: system
        entry: python -m ruff check
        files: ^src/
        types: [python]
        exclude_types: [symlink]

      - id: lint-web
        name: Lint (web)
        language: system
        entry: npm run lint
        files: ^web/
        types_or: [javascript, jsx, ts, tsx]
```

If you need to match a path pattern that doesn’t align with a hook’s default types (common when reusing an existing hook in a nonstandard way), override it back to “all files” and use files:

=== "prek.toml"

```toml
[[repos]]
repo = "meta"
hooks = [
  {
    id = "check-hooks-apply",
    types = ["file"],
    files = "\\.(yaml|yml|myext)$"
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: meta
    hooks:
      - id: check-hooks-apply
        types: [file]
        files: \.(yaml|yml|myext)$
```

always_run

Run the hook even when no files match.

• Type: boolean
• Default: false

This is commonly used for hooks that check repository-wide state (for example, running a test suite) rather than operating on specific files.

pass_filenames

Controls whether prek appends the matching filenames to the command line.

• Type: boolean or positive integer
• Default: true which passes all matching filenames

Set pass_filenames: false for hooks that don’t accept file arguments (or that discover files themselves).

Set pass_filenames: n (a positive integer) to limit each invocation to at most n filenames. When there are more matching files than n, prek splits them across multiple invocations. Those invocations may run concurrently unless require_serial: true is set. This is useful for tools that can only process a limited number of files at once.

Prek will automatically limit the number of filenames to ensure command lines don’t exceed the OS limit, even when pass_filenames: true.

!!! note "prek-only"

`pass_filenames: n` with a positive integer is a `prek` extension. Upstream `pre-commit` only accepts a boolean value.

stages

Declare which stages a hook is eligible to run in.

• Type: list of stage names
• Default: all stages

Allowed values:

• manual
• commit-msg
• post-checkout
• post-commit
• post-merge
• post-rewrite
• pre-commit
• pre-merge-commit
• pre-push
• pre-rebase
• prepare-commit-msg

When you run prek run --hook-stage <stage>, only hooks configured for that stage are considered.

require_serial

Force a hook to run without parallel invocations (one in-flight process for that hook at a time).

• Type: boolean
• Default: false

This is useful for tools that use global caches/locks or otherwise can’t handle concurrent execution.

priority

<a id="prek-only-priority"></a>

!!! note "prek-only"

`priority` controls `prek`'s scheduler and does not exist in upstream `pre-commit`.

Each hook can set an explicit priority (a non-negative integer) that controls when it runs and with which hooks it may execute in parallel.

Scope:

• priority is evaluated within a single configuration file and is compared across all hooks in that file, even if they appear under different repos: entries.
• priority does not coordinate across different config files. In workspace mode, each project’s config file is scheduled independently.

Hooks run in ascending priority order: lower priority values run earlier. Hooks that share the same priority value run concurrently, subject to the global concurrency limit.

When priority is omitted, prek assigns an implicit value based on hook order to preserve sequential behavior.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "format",
    name = "Format",
    language = "system",
    entry = "python3 -m ruff format",
    always_run = true,
    priority = 0,
  },
  {
    id = "lint",
    name = "Lint",
    language = "system",
    entry = "python3 -m ruff check",
    always_run = true,
    priority = 10,
  },
  {
    id = "tests",
    name = "Tests",
    language = "system",
    entry = "just test",
    always_run = true,
    priority = 20,
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: format
        name: Format
        language: system
        entry: python3 -m ruff format
        always_run: true
        priority: 0

      - id: lint
        name: Lint
        language: system
        entry: python3 -m ruff check
        always_run: true
        priority: 10

      - id: tests
        name: Tests
        language: system
        entry: just test
        always_run: true
        priority: 20
```

!!! danger "Parallel hooks modifying files"

If two hooks run in the same priority group and both mutate the same files (or depend on shared state), results are undefined.
Use separate priorities to avoid overlap.

!!! note "Hooks modifying files without a non-zero exit code"

If a hook modifies files without emitting a non-zero exit code (e.g. `ruff format`), the priority group as a whole will fail.
It is not possible for prek to attribute the failure to a specific hook in the group which modified files.
Use separate priorities for clearer failure attribution.

!!! note "require_serial is different"

`require_serial: true` prevents concurrent invocations of the *same hook*.
It does not prevent other hooks from running alongside it; use a unique `priority` if you need exclusivity.

fail_fast

Hook-level fail-fast behavior.

• Type: boolean
• Default: false

If true, a failure in this hook stops the run immediately.

verbose

Print hook output even when the hook succeeds.

• Type: boolean
• Default: false

log_file

Write hook output to a file when the hook fails (and also when verbose: true).

• Type: string path

description

Free-form description shown in listings / metadata.

• Type: string

language_version

Choose the language/toolchain version request for this hook.

• Type: string
• Default: default

If not set, prek may use default_language_version for the hook’s language.

!!! note "prek-only"

`language_version` is treated as a **version request**, not a single pinned value. For languages that use semver requests, you can specify ranges (for example `^1.2`, `>=1.5, <2.0`).

Special values:

- `default`: use the language’s default resolution logic.
- `system`: require a system-installed toolchain (no downloads).

Language-specific behavior:

- Python: passed to the Python resolver (for example `python3`, `python3.12`, or a specific interpreter name). May trigger toolchain download.
- Node: passed to the Node resolver (for example `20`, `18.19.0`). May trigger toolchain download.
- Go: uses Go version strings such as `1.22.1` (downloaded if missing).
- Rust: supports rustup toolchains such as `stable`, `beta`, `nightly`, or versioned toolchains.
- Other languages: parsed as a semver request and matched against the installed toolchain version.

Examples:

=== "prek.toml"

    ```toml
    hooks = [
      { id = "ruff", language = "python", language_version = "3.12" },
      { id = "eslint", language = "node", language_version = "20" },
      { id = "cargo-fmt", language = "rust", language_version = "stable" },
      { id = "my-tool", language = "system", language_version = "system" },
    ]
    ```

=== ".pre-commit-config.yaml"

    ```yaml
    hooks:
      - id: ruff
        language: python
        language_version: "3.12"

      - id: eslint
        language: node
        language_version: "20"

      - id: cargo-fmt
        language: rust
        language_version: stable

      - id: my-tool
        language: system
        language_version: system
    ```

additional_dependencies

Extra dependencies for hooks that run inside a managed environment (for example Python or Node hooks).

• Type: list of strings

If you set this for a language that doesn’t support dependency installation, prek fails with a configuration error.

minimum_prek_version

<a id="prek-only-minimum-prek-version-hook"></a>

!!! note "prek-only"

This is a `prek`-specific requirement gate. Upstream `pre-commit` does not have a hook-level minimum version key.

Require a minimum prek version for this specific hook.

• Type: string (version)
• Default: unset

For process environment controls, see the Environment Variable Reference.