This PR contains the following updates:

Release Notes

v0.5.0

Compare Source

Released on 2026-08-27.

Highlights

Choose where hook toolchains come from

language_version now accepts a source preference alongside the version
request, letting you control where prek looks for a compatible toolchain when
it creates a hook environment. Use managed (the default) or system to choose
which source prek tries first while still allowing fallback and downloads. Use
only-managed or only-system to require one source.

For example, this local Ruff hook requires a Python 3.12 toolchain managed by
prek:

repos:
  - repo: local
    hooks:
      - id: ruff
        name: ruff
        language: python
        entry: ruff check
        additional_dependencies: [ruff]
        language_version:
          request: "3.12"
          preference: only-managed

With only-managed, prek reuses a compatible toolchain from its managed store
or downloads one when needed. It never falls back to Python from PATH, an OS
package manager, or a version manager, so toolchain selection does not depend on
the developer or CI machine's external environment.

Existing scalar values such as language_version: "3.12" continue to work. See
toolchain management and language_version
for the full source-selection behavior. (#​2613)

Breaking changes

The breaking changes in this release are mostly small cleanups, and most users should not be affected.

• Group names can no longer start with @. This prefix is now reserved for special group selectors such as the new @ungrouped selector. (#​2617)
• PREK_MAX_CONCURRENCY has been removed. Use PREK_CONCURRENT_HOOKS and PREK_CONCURRENT_BATCHES to control hook and per-hook batch concurrency separately. (#​2620)
• The top-level prek init-template-dir command has been removed. Use prek util init-template-dir, or prek init-templatedir for drop-in compatibility with pre-commit. (#​2623)
• prek auto-update has been removed. Use prek update, or prek autoupdate for drop-in compatibility with pre-commit. (#​2619)

Enhancements

• Add configurable toolchain source preferences (#​2613)
• Allow explicit language: python to opt out of fast-path hooks (#​2608)
• Group run and update options in CLI help (#​2629)
• Preserve terminal theme contrast for status labels (#​2592)
• Add @ungrouped group selector (#​2617)
• Retry uv installation with static musl binary (#​2600)
• Support {hook_repo} placeholder in hook entry (#​2602)

Bug fixes

• Expose the git work tree to hooks running outside the git root (#​2579)
• Isolate local hook environment installation (#​2615)
• Preserve hook config deserialization error locations (#​2573)
• Resolve hook log files from their config directory (#​2580)
• Track explicit config paths as absolute paths (#​2574)

Documentation

• Document prek run architecture (#​2630)
• Publish versioned documentation (#​2626)

Contributors

• @​jeromeheissler
• @​gurgeous
• @​j178

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