prek/docs/builtin.md

Built-in Fast Hooks

Prek includes fast, Rust-native implementations of popular hooks for speed and low overhead. When a matching hook from a popular repository (for example, pre-commit/pre-commit-hooks) is detected, prek can run an internal implementation instead of spawning external interpreters.

Built-in hooks are activated when the repo field in your configuration exactly matches a supported repository URL, regardless of the rev field. For example:

repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks  # Enables fast path
    rev: v4.5.0  # This is ignored for fast path detection
    hooks:
      - id: trailing-whitespace

!!! note Even when all hooks in a repository are supported as built-in hooks, the repository will still be cloned and the environment will still be created as usual. Only the hook execution itself is replaced with the built-in implementation when running the hook. This may change in the future to skip cloning and environment setup when all hooks are built-in.

Currently, only https://github.com/pre-commit/pre-commit-hooks is supported. More popular repositories may be added over time.

Currently implemented hooks

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

• trailing-whitespace (Trim trailing whitespace)
• check-added-large-files (Prevent committing large files)
• end-of-file-fixer (Ensure newline at EOF)
• fix-byte-order-marker (Remove UTF-8 byte order marker)
• check-json (Validate JSON files)
• check-toml (Validate TOML files)
• check-yaml (Validate YAML files)
• check-xml (Validate XML files)
• mixed-line-ending (Normalize or check line endings)
• check-symlinks (Check for broken symlinks)
• check-merge-conflict (Check for merge conflicts)
• detect-private-key (Detect private keys)
• no-commit-to-branch (Prevent committing to protected branches)
• check-executables-have-shebangs (Ensures that (non-binary) executables have a shebang)

Notes:

• check-yaml fast path does not yet support the --unsafe flag; for those cases, fast path is skipped automatically.
• Fast-path detection currently matches only the repository URL (e.g., https://github.com/pre-commit/pre-commit-hooks) and does not take the rev into account.

Disabling the fast path

If you need to compare with the original behavior or encounter differences:

PREK_NO_FAST_PATH=1 prek run

This forces prek to fall back to the standard execution path.