Manage the CI Python interpreter with uv

.github/actions/setup-python/action.yml

@@ -13,18 +13,20 @@ inputs:
 runs:
   using: composite
   steps:
-    - uses: actions/setup-python@v5
-      with:
-        python-version: "${{ inputs.python-version }}"
-
-    # Install uv and enable its built-in cache. The cache key takes the
-    # platform, the uv version, and a hash of the files below into account.
+    # Install uv together with a uv-managed Python interpreter, and
+    # create and activate a virtual environment that is used by all
+    # subsequent steps (e.g. the `uv pip install` step below installs
+    # into it). Also enables uv's built-in cache. The cache key takes
+    # the platform, the uv version, and a hash of the files below
+    # into account.
     # See https://docs.astral.sh/uv/guides/integration/github/ for details.
     # NOTE: setup-uv publishes immutable releases only (no
     #       floating major tags), so we pin the full version
-    - name: Install uv
+    - name: Install uv and python
       uses: astral-sh/setup-uv@v9.0.0
       with:
+        python-version: "${{ inputs.python-version }}"
+        activate-environment: true
         enable-cache: true
         cache-suffix: "py${{ inputs.python-version }}"
         cache-dependency-glob: |
@@ -34,4 +36,4 @@ runs:
     - name: Install requirements
       if: ${{ inputs.requirements != '' }}
       shell: bash
-      run: uv pip install --verbose --system ${{ inputs.requirements }}
+      run: uv pip install --verbose ${{ inputs.requirements }}

docs/reference/changelog.md

@@ -31,6 +31,7 @@ Unreleased changes
 - pre-commit autoupdate ({gh-pr}`379`)
 - Fix the test suite's compatibility with the latest pytest release ({gh-pr}`384`)
 - Use the official `astral-sh/setup-uv` action to install and cache `uv` in CI ({gh-pr}`386`)
+- Let `uv` manage the Python interpreter and virtual environment in CI ({gh-pr}`393`)
 
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