Include Python patch version in CI cache keys (#315)

* Include Python patch version in CI cache keys

The venv and pre-commit caches hold virtualenvs whose python symlink
points at /opt/hostedtoolcache/Python/<patch>/... When the hosted
toolcache bumps patch versions (e.g. 3.13.12 -> 3.13.13), the symlink
dangles and every entry point fails with "required file not found".
Keying on steps.python.outputs.python-version invalidates the cache on
any patch bump.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Deduplicate cache-key generation via YAML anchor

Pulls the "Generate cache keys" step into a &cache-keys-step anchor so
all six jobs share one definition. Cache keys become short single-line
references and a future toolcache bump or hash location change touches
only the anchor.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Use YAML scalar anchors for cache keys instead of a shared step

Anchors the venv and pre-commit cache key strings directly. Folded
scalar line breaks sit inside ${{ ... }} expressions so they vanish at
evaluation time. Drops the helper step and the $GITHUB_OUTPUT
roundtrip.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: agners

.github/workflows/ci.yaml

@@ -41,9 +41,10 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: venv
-          key: >
-            ${{ runner.os }}-venv-${{ matrix.python-version }}-
-            ${{ hashFiles('pyproject.toml') }}
+          key: &venv-key >-
+            ${{ runner.os }}-venv-${{
+            steps.python.outputs.python-version }}-${{
+            hashFiles('pyproject.toml') }}
       - name: Create Python virtual environment
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -57,9 +58,10 @@ jobs:
         with:
           path: ${{ env.PRE_COMMIT_CACHE }}
           lookup-only: true
-          key: >
-            ${{ runner.os }}-pre-commit-${{ matrix.python-version }}-
-            ${{ hashFiles('.pre-commit-config.yaml') }}
+          key: &pre-commit-key >-
+            ${{ runner.os }}-pre-commit-${{
+            steps.python.outputs.python-version }}-${{
+            hashFiles('.pre-commit-config.yaml') }}
           restore-keys: |
             ${{ runner.os }}-pre-commit-
       - name: Install pre-commit dependencies
@@ -88,9 +90,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: venv
-          key: >
-            ${{ runner.os }}-venv-${{ matrix.python-version }}-
-            ${{ hashFiles('pyproject.toml') }}
+          key: *venv-key
       - name: Fail job if Python cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -101,9 +101,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: ${{ env.PRE_COMMIT_CACHE }}
-          key: >
-            ${{ runner.os }}-pre-commit-${{ matrix.python-version }}-
-            ${{ hashFiles('.pre-commit-config.yaml') }}
+          key: *pre-commit-key
       - name: Fail job if cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -137,9 +135,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: venv
-          key: >
-            ${{ runner.os }}-venv-${{ matrix.python-version }}-
-            ${{ hashFiles('pyproject.toml') }}
+          key: *venv-key
       - name: Fail job if Python cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -150,9 +146,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: ${{ env.PRE_COMMIT_CACHE }}
-          key: >
-            ${{ runner.os }}-pre-commit-${{ matrix.python-version }}-
-            ${{ hashFiles('.pre-commit-config.yaml') }}
+          key: *pre-commit-key
       - name: Fail job if cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -186,9 +180,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: venv
-          key: >
-            ${{ runner.os }}-venv-${{ matrix.python-version }}-
-            ${{ hashFiles('pyproject.toml') }}
+          key: *venv-key
       - name: Fail job if Python cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -199,9 +191,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: ${{ env.PRE_COMMIT_CACHE }}
-          key: >
-            ${{ runner.os }}-pre-commit-${{ matrix.python-version }}-
-            ${{ hashFiles('.pre-commit-config.yaml') }}
+          key: *pre-commit-key
       - name: Fail job if cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -278,9 +268,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: venv
-          key: >
-            ${{ runner.os }}-venv-${{ matrix.python-version }}-
-            ${{ hashFiles('pyproject.toml') }}
+          key: *venv-key
       - name: Fail job if Python cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
@@ -330,9 +318,7 @@ jobs:
         uses: actions/cache@v5.0.5
         with:
           path: venv
-          key: >
-            ${{ runner.os }}-venv-${{ env.DEFAULT_PYTHON }}-
-            ${{ hashFiles('pyproject.toml') }}
+          key: *venv-key
       - name: Fail job if Python cache restore failed
         if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |