pre-commit: switch to prek

The config should be backward-compatible to pre-commit, with warnings.

Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>

Author: bgilbert

.github/workflows/python.yml

@@ -28,14 +28,14 @@ jobs:
       with:
         python-version: '3.14'
     - name: Install dependencies
-      run: python -m pip install pre-commit
+      run: python -m pip install prek uv
     - name: Cache pre-commit environments
       uses: actions/cache@v5
       with:
-        path: ~/.cache/pre-commit
-        key: pre-commit|${{ env.pythonLocation }}|${{ hashFiles('.pre-commit-config.yaml') }}
+        path: ~/.cache/prek
+        key: prek|${{ env.pythonLocation }}|${{ hashFiles('.pre-commit-config.yaml') }}
     - name: Run pre-commit hooks
-      run: pre-commit run -a --show-diff-on-failure --color=always
+      run: prek run -a --show-diff-on-failure --color=always
     - name: Define artifact paths
       id: paths
       run: |

.pre-commit-config.yaml

@@ -1,3 +1,8 @@
+# priorities:
+# 0    - read-only
+# 1000 - mutually non-conflicting fixers
+# none - other fixers
+
 # exclude vendored files
 exclude: '^(COPYING\.LESSER|examples/deepzoom/static/.*\.js)$'
 
@@ -6,10 +11,15 @@ repos:
     rev: v6.0.0
     hooks:
       - id: check-added-large-files
+        priority: 0
       - id: check-merge-conflict
+        priority: 0
       - id: check-toml
+        priority: 0
       - id: check-vcs-permalinks
+        priority: 0
       - id: check-yaml
+        priority: 0
       - id: end-of-file-fixer
       - id: fix-byte-order-marker
       - id: mixed-line-ending
@@ -28,6 +38,7 @@ repos:
     hooks:
       - id: mypy
         name: Check Python types
+        priority: 0
         # Pillow is ignored in dependabot.yml
         additional_dependencies: [flask, openslide-bin, pillow >= 12.1.0, types-PyYAML, types-setuptools]
 
@@ -36,32 +47,38 @@ repos:
     hooks:
       - id: rstcheck
         name: Validate reStructuredText syntax
+        priority: 0
         additional_dependencies: [sphinx, toml]
 
   - repo: https://github.com/codespell-project/codespell
     rev: v2.4.2
     hooks:
       - id: codespell
         name: Check spelling with codespell
+        priority: 0
         additional_dependencies:
           - tomli  # Python < 3.11
 
   - repo: meta
     hooks:
       - id: check-hooks-apply
+        priority: 0
       - id: check-useless-excludes
+        priority: 0
 
   - repo: local
     hooks:
       - id: mkmaintainer
         name: Sync maintainer issue templates
+        priority: 1000
         entry: .github/maintainer/mkmaintainer.py
         files: .github/maintainer/
         language: python
         additional_dependencies: [PyYAML]
 
       - id: annotations
         name: Require "from __future__ import annotations"
+        priority: 0
         language: pygrep
         types: [python]
         # exclude config-like files