Optimize cache for pre-commit workflow

.github/workflows/pre-commit.yml

@@ -7,6 +7,7 @@ permissions: {}
 env:
   # Forks and Dependabot don't have access to secrets
   HAS_SECRETS: ${{ secrets.PRE_COMMIT != '' }}
+  UV_NO_SYNC: true
 
 jobs:
   pre-commit:
@@ -48,6 +49,10 @@ jobs:
           # Before upgrading uv version, make sure astral-sh/setup-uv knows its checksum.
           # See: https://github.com/astral-sh/setup-uv/issues/851#issuecomment-4282017837
           version: "0.11.18"
+          cache-suffix: dev-all
+          # Cache written by workflow triggered by pull_request is PR-scoped and almost useless.
+          # Disable saving here, it will be populated by `warm-cache.yml`.
+          save-cache: false
           cache-dependency-glob: |
             pyproject.toml
             uv.lock

.github/workflows/warm-cache.yml

@@ -0,0 +1,43 @@
+name: Warm Cache
+
+# Populates the `dev-all` uv cache at default-branch scope so that it could be used by
+# `pre-commit.yml` (it has `pull_request` trigger and can't write cache available across PRs)
+# and some others that use subset of dev dependencies.
+
+on:
+  push:
+    branches:
+      - master
+  schedule:
+    - cron: "0 4 * * *"
+  workflow_dispatch:
+
+permissions: {}
+
+jobs:
+  warm-cache:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+      - name: Set up Python
+        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        with:
+          python-version-file: ".python-version"
+      - name: Setup uv
+        id: setup-uv
+        uses: astral-sh/setup-uv@c771a70e6277c0a99b617c7a806ffedaca235ff9 # v9.0.0
+        with:
+          # Before upgrading uv version, make sure astral-sh/setup-uv knows its checksum.
+          # See: https://github.com/astral-sh/setup-uv/issues/851#issuecomment-4282017837
+          version: "0.11.18"
+          enable-cache: true
+          cache-suffix: dev-all
+          cache-dependency-glob: |
+            pyproject.toml
+            uv.lock
+      - name: Populate the cache
+        if: steps.setup-uv.outputs.cache-hit != 'true'
+        run: uv sync --locked --extra all