openslide · bgilbert · Apr 16, 2026 · Apr 15, 2026 · Apr 15, 2026 · Apr 15, 2026
diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
@@ -21,11 +21,11 @@ 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:
-          key: pre-commit|${{ env.pythonLocation }}|${{ hashFiles('.pre-commit-config.yaml') }}
-          path: ~/.cache/pre-commit
+          key: prek|${{ env.pythonLocation }}|${{ hashFiles('.pre-commit-config.yaml') }}
+          path: ~/.cache/prek
       - 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
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
@@ -1,3 +1,8 @@
+# priorities:
+# 0    - read-only
+# 1000 - mutually non-conflicting fixers
+# none - other fixers
+
 # exclude vendored files
 exclude: '^(api/|demo/openseadragon-scalebar\.js)'
 
@@ -6,51 +11,32 @@ repos:
     rev: v6.0.0
     hooks:
       - id: check-added-large-files
+        priority: 0
       - id: check-merge-conflict
+        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
       - id: trailing-whitespace
 
-  - repo: https://github.com/asottile/pyupgrade
-    rev: v3.21.2
-    hooks:
-      - id: pyupgrade
-        name: Modernize Python code
-        args: ["--py313-plus"]
-
-  - repo: https://github.com/PyCQA/isort
-    rev: 8.0.1
-    hooks:
-      - id: isort
-        name: Reorder Python imports with isort
-
-  - repo: https://github.com/psf/black
-    rev: 26.3.1
-    hooks:
-      - id: black
-        name: Format Python code with black
-
-  - repo: https://github.com/asottile/yesqa
-    rev: v1.5.0
-    hooks:
-      - id: yesqa
-        additional_dependencies: [flake8-bugbear, Flake8-pyproject]
-
-  - repo: https://github.com/PyCQA/flake8
-    rev: 7.3.0
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.15.10
     hooks:
-      - id: flake8
-        name: Lint Python code with flake8
-        additional_dependencies: [flake8-bugbear, Flake8-pyproject]
+      - id: ruff-check
+        types_or: [python, pyproject]
+        args: [--fix]
+      - id: ruff-format
 
   - repo: https://github.com/pre-commit/mirrors-mypy
     rev: v1.20.0
     hooks:
       - id: mypy
         name: Check Python types
+        priority: 0
         additional_dependencies:
           - boto3-stubs[s3]
           - types-Pillow
@@ -63,16 +49,20 @@ repos:
     hooks:
       - id: codespell
         name: Check spelling with codespell
+        priority: 0
 
   - repo: meta
     hooks:
       - id: check-hooks-apply
+        priority: 0
       - id: check-useless-excludes
+        priority: 0
 
   - repo: local
     hooks:
       - id: annotations
         name: Require "from __future__ import annotations"
+        priority: 0
         language: pygrep
         types: [python]
         # Allow files with import statement, or of less than two characters.

diff --git a/_testdata/testdata_fetch.py b/_testdata/testdata_fetch.py
@@ -64,7 +64,7 @@ def fetch_file(
                     sha.update(buf)
                 count += len(buf)
         if count != int(r.headers['Content-Length']):
-            raise OSError(f"Short read fetching {relpath}")
+            raise OSError(f'Short read fetching {relpath}')
         if expected_sha256 is not None and expected_sha256 != sha.hexdigest():
             raise OSError(f'Hash mismatch fetching {relpath}')
     except Exception:

diff --git a/_testdata/testdata_index.py b/_testdata/testdata_index.py
@@ -45,7 +45,7 @@
 )
 OPTIONAL_FIELDS = frozenset(('credit',))
 
-INDEX_TEMPLATE = '''<!doctype html>
+INDEX_TEMPLATE = """<!doctype html>
 <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css">
 <style type="text/css">
 table {
@@ -129,7 +129,7 @@
         extra.size|file_size_units, extra.description) }}
   {% endfor %}
 </table>
-'''  # noqa: E501
+"""
 
 
 class ValidationError(Exception):

diff --git a/demo/_synctiles.py b/demo/_synctiles.py
@@ -39,9 +39,6 @@
 from zipfile import ZipFile
 import zlib
 
-from PIL import ImageCms
-from PIL.Image import Image
-from PIL.ImageCms import ImageCmsProfile
 import boto3
 import openslide
 from openslide import (
@@ -52,6 +49,9 @@
     OpenSlideError,
 )
 from openslide.deepzoom import DeepZoomGenerator
+from PIL import ImageCms
+from PIL.Image import Image
+from PIL.ImageCms import ImageCmsProfile
 import requests
 
 if TYPE_CHECKING:
@@ -221,9 +221,7 @@ def _get_transform(image: AbstractSlide) -> Callable[[Image], None]:
         """Return a function that transforms an image to sRGB in place."""
         if image.color_profile is None:
             return lambda img: None
-        intent: int = ImageCms.getDefaultIntent(
-            image.color_profile
-        )  # type: ignore[no-untyped-call]
+        intent: int = ImageCms.getDefaultIntent(image.color_profile)  # type: ignore[no-untyped-call]
         transform = ImageCms.buildTransform(
             image.color_profile, SRGB_PROFILE, 'RGB', 'RGB', intent, 0
         )
@@ -344,8 +342,8 @@ def sync_image(
 
     def progress() -> None:
         print(
-            f"Tiling {slide_relpath} {associated_slug}: "
-            f"{count}/{total} tiles\r",
+            f'Tiling {slide_relpath} {associated_slug}: '
+            f'{count}/{total} tiles\r',
             end='',
         )
         sys.stdout.flush()
@@ -462,7 +460,7 @@ def sync_slide(
         # slide will be None if we can't read it
 
         # Enumerate existing keys
-        print(f"Enumerating keys for {slide_relpath}...")
+        print(f'Enumerating keys for {slide_relpath}...')
         key_md5sums = {}
         for obj in storage.bucket.objects.filter(
             Prefix=key_basepath.as_posix() + '/'
@@ -536,8 +534,8 @@ def do_tile(
     for name in metadata_key_name, properties_key_name:
         key_md5sums.pop(name, None)
     if key_md5sums:
-        to_delete = [k for k in key_md5sums]
-        print(f"Pruning {len(to_delete)} keys for {slide_relpath}...")
+        to_delete = list(key_md5sums)
+        print(f'Pruning {len(to_delete)} keys for {slide_relpath}...')
         while to_delete:
             cur_delete, to_delete = to_delete[0:1000], to_delete[1000:]
             delete_result = storage.bucket.delete_objects(
@@ -602,7 +600,7 @@ def start_retile(
     storage = S3Storage(bucket_name)
 
     # Set bucket configuration
-    print("Configuring bucket...")
+    print('Configuring bucket...')
     storage.bucket.Cors().put(
         CORSConfiguration={
             'CORSRules': [
@@ -615,7 +613,7 @@ def start_retile(
     )
 
     # Store static files
-    print("Storing static files...")
+    print('Storing static files...')
     for relpath, opts in BUCKET_STATIC.items():
         storage.object(relpath).put(
             Body=opts.get('data', '').encode(),
@@ -638,7 +636,7 @@ def start_retile(
         json.dump(context, ctxfile)
     with matrixfile:
         matrix: Matrix = {
-            "slide": sorted(slides.keys()),
+            'slide': sorted(slides.keys()),
         }
         json.dump(matrix, matrixfile)
 

diff --git a/docs/devguide/index.md b/docs/devguide/index.md
@@ -33,10 +33,10 @@ addressing feedback from code review, edit your existing commits with `git
 rebase -i` and update the branch with `git push -f`, rather than appending
 fixup commits to the branch.
 
-OpenSlide uses Git hooks and the [pre-commit][pre-commit] framework to
+OpenSlide uses Git hooks and the [prek][prek] framework to
 check coding style when you commit.  To configure the hooks, install
-pre-commit from your package manager or with `pip install pre-commit`, then
-run `pre-commit install` in your OpenSlide checkout.  The pre-commit checks
+prek from your package manager or with `pip install prek`, then
+run `prek install` in your OpenSlide checkout.  The pre-commit checks
 are also rerun as part of OpenSlide's CI.
 
 Please discuss your changes on the [openslide-users][users-subscribe]
@@ -52,7 +52,7 @@ license.  See the [submission form][submit-sample] for more details.
 
 [rjones]: https://people.redhat.com/~rjones/how-to-supply-code-to-open-source-projects/
 [rjones-splitting-commits]: https://people.redhat.com/~rjones/how-to-supply-code-to-open-source-projects/#split_patches
-[pre-commit]: https://pre-commit.com/
+[prek]: https://prek.j178.dev/
 [cc0]: https://creativecommons.org/publicdomain/zero/1.0/legalcode
 
 

diff --git a/pyproject.toml b/pyproject.toml
@@ -1,24 +1,23 @@
-[tool.black]
-line-length = 79
-skip-string-normalization = true
-target-version = ["py313", "py314"]
-
 # Ref: https://github.com/codespell-project/codespell#using-a-config-file
 [tool.codespell]
 check-hidden = true
 # ignore-regex = ""
 ignore-words-list = "subtile"
 
-# https://black.readthedocs.io/en/stable/guides/using_black_with_other_tools.html#flake8
-# requires Flake8-pyproject
-[tool.flake8]
-extend-ignore = ["E203"]
-
-[tool.isort]
-profile = "black"
-force_sort_within_sections = true
-
 [tool.mypy]
 namespace_packages = false
 python_version = "3.13"
 strict = true
+
+[tool.ruff]
+line-length = 79
+target-version = "py313"
+
+[tool.ruff.format]
+quote-style = "single"
+
+[tool.ruff.lint]
+extend-select = ["B", "C4", "FLY", "I", "RUF", "UP"]
+
+[tool.ruff.lint.isort]
+force-sort-within-sections = true