Add pre-commit config

.github/workflows/format.yml

@@ -0,0 +1,69 @@
+name: pre-commit (PR only on changed files)
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+permissions:
+  contents: read
+
+jobs:
+  detect_changes:
+    runs-on: ubuntu-latest
+    outputs:
+      changed: ${{ steps.changed_files.outputs.changed }}
+
+    steps:
+      - name: Checkout full history
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Detect changed files
+        id: changed_files
+        env:
+          BASE_REF: ${{ github.base_ref }}
+        run: |
+          git fetch origin "$BASE_REF"
+          CHANGED_FILES=$(git diff --name-only --diff-filter=d "origin/$BASE_REF...HEAD")
+
+          delimiter="changed_$(openssl rand -hex 16)"
+          {
+            echo "changed<<$delimiter"
+            echo "$CHANGED_FILES"
+            echo "$delimiter"
+          } >> "$GITHUB_OUTPUT"
+
+      - name: Show changed files
+        env:
+          CHANGED_FILES: ${{ steps.changed_files.outputs.changed }}
+        run: |
+          echo "Changed files:"
+          echo "$CHANGED_FILES"
+
+  precommit:
+    needs: detect_changes
+    runs-on: ubuntu-latest
+    if: ${{ needs.detect_changes.outputs.changed != '' }}
+
+    steps:
+      - name: Checkout PR branch
+        uses: actions/checkout@v6
+        with:
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+
+      - name: Install pre-commit
+        run: pip install pre-commit
+
+      - name: Run pre-commit (CI check-only stage) on changed files
+        env:
+          CHANGED_FILES: ${{ needs.detect_changes.outputs.changed }}
+        run: |
+          mapfile -t files <<< "$CHANGED_FILES"
+          pre-commit run --hook-stage manual --files "${files[@]}" --show-diff-on-failure

.pre-commit-config.yaml

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+default_stages: [pre-commit]
+
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v6.0.0
+    hooks:
+      - id: check-added-large-files
+        stages: [pre-commit, manual]
+      - id: check-yaml
+        stages: [pre-commit, manual]
+      - id: check-toml
+        stages: [pre-commit, manual]
+      - id: check-merge-conflict
+        stages: [pre-commit, manual]
+      - id: name-tests-test
+        args: [--pytest-test-first]
+        stages: [pre-commit, manual]
+      - id: check-json
+        stages: [pre-commit, manual]
+      # In CI a fixer fails by modifying the file; --show-diff-on-failure prints the change
+      - id: end-of-file-fixer
+        stages: [pre-commit, manual]
+      - id: trailing-whitespace
+        stages: [pre-commit, manual]
+
+  - repo: https://github.com/tox-dev/pyproject-fmt
+    rev: v2.19.0
+    hooks:
+      - id: pyproject-fmt
+        stages: [pre-commit, manual]
+
+  - repo: https://github.com/abravalheri/validate-pyproject
+    rev: v0.25
+    hooks:
+      - id: validate-pyproject
+        stages: [pre-commit, manual]
+
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.15.6
+    hooks:
+      - id: ruff-check
+        name: ruff-check (fix)
+        args: [--fix]
+        stages: [pre-commit]
+      - id: ruff-format
+        name: ruff-format (write)
+        stages: [pre-commit]
+      - id: ruff-check
+        name: ruff-check (ci)
+        args: [--no-fix, --output-format=github]
+        stages: [manual]
+      - id: ruff-format
+        name: ruff-format (ci)
+        args: [--check, --diff]
+        stages: [manual]

pyproject.toml

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+[tool.ruff]
+# TODO: @C-Achard "py310" once requires-python is ">=3.10" (CI update PR); main still tests 3.9
+target-version = "py39"
+line-length = 120
+format.docstring-code-format = true
+lint.select = [
+  "ANN",
+  "ARG",
+  "B",
+  "C4",
+  "D",
+  "DTZ",
+  "E",
+  "ERA",
+  "F",
+  "I",
+  "N",
+  "PIE",
+  "RET",
+  "RUF",
+  "SIM",
+  "UP",
+]
+lint.ignore = [
+  "ANN401",
+  "B007",
+  "D100",
+  "D101",
+  "D102",
+  "D104",
+  "D106",
+  "D107",
+  "D202",
+  "E741",
+  "N803",
+  "N806",
+]
+lint.per-file-ignores."__init__.py" = [ "E402", "F401" ]
+lint.per-file-ignores."tests/**" = [ "D" ]
+lint.pydocstyle.convention = "google"