Cache the pnpm store between CI runs

The lockfile is not committed so the usual lockfile hash key does not work. Instead the store is snapshotted whenever a package.json changes or a week passes, and every run restores the most recent snapshot through a prefix restore key. pnpm still resolves the latest versions within the ranges; the cache only saves the tarball downloads. A composite action holds the setup so the four jobs share it.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

.github/actions/pnpm-install/action.yml

@@ -0,0 +1,36 @@
+name: Install dependencies
+description: Set up pnpm and Node.js, restore the pnpm store from the cache and run pnpm install
+
+inputs:
+  node-version:
+    description: Node.js version passed to actions/setup-node
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - uses: pnpm/action-setup@v6
+    - uses: actions/setup-node@v7
+      with:
+        node-version: ${{ inputs.node-version }}
+
+    # The lockfile is not committed, so the usual lockfile hash key does not
+    # apply. Instead a new store snapshot is saved whenever a package.json
+    # changes or a week passes, and every run restores the most recent one.
+    - id: store
+      shell: bash
+      run: |
+        echo "path=$(pnpm store path --silent)" >> "$GITHUB_OUTPUT"
+        echo "week=$(date -u +%G-%V)" >> "$GITHUB_OUTPUT"
+    - uses: actions/cache@v6
+      with:
+        path: ${{ steps.store.outputs.path }}
+        key: pnpm-store-${{ runner.os }}-${{ steps.store.outputs.week }}-${{ hashFiles('**/package.json', 'pnpm-workspace.yaml') }}
+        restore-keys: pnpm-store-${{ runner.os }}-
+
+    - shell: bash
+      run: pnpm i --no-frozen-lockfile
+    # Drop packages the restored store had but this install did not use, so
+    # the snapshot does not grow with every version bump.
+    - shell: bash
+      run: pnpm store prune

.github/workflows/node.js.yml

@@ -31,13 +31,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v7
-    - uses: pnpm/action-setup@v6
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v7
+    - name: Prepare and install
+      uses: ./.github/actions/pnpm-install
       with:
         node-version: ${{ matrix.node-version }}
-    - name: Prepare and install
-      run: pnpm i --no-frozen-lockfile
     - name: Use Factorio ${{ matrix.factorio-version }}
       run: wget -q -O factorio.tar.gz https://www.factorio.com/get-download/${{ matrix.factorio-version }}/headless/linux64 && tar -xf factorio.tar.gz && rm factorio.tar.gz
     - name: Run tests
@@ -78,12 +75,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v7
-    - uses: pnpm/action-setup@v6
-    - uses: actions/setup-node@v7
+    - name: Prepare and install
+      uses: ./.github/actions/pnpm-install
       with:
         node-version: ${{ env.NODE_VERSION }}
-    - name: Prepare and install
-      run: pnpm i --no-frozen-lockfile
     - name: Build
       run: pnpm run build
     - name: Test ${{ matrix.controller }} controller with ${{ matrix.host }} host
@@ -98,11 +93,9 @@ jobs:
     timeout-minutes: 5
     steps:
     - uses: actions/checkout@v7
-    - uses: pnpm/action-setup@v6
-    - uses: actions/setup-node@v7
+    - uses: ./.github/actions/pnpm-install
       with:
         node-version: ${{ env.NODE_VERSION }}
-    - run: pnpm i --no-frozen-lockfile
     - run: pnpm run lint
 
   build:
@@ -110,11 +103,9 @@ jobs:
     timeout-minutes: 5
     steps:
     - uses: actions/checkout@v7
-    - uses: pnpm/action-setup@v6
-    - uses: actions/setup-node@v7
+    - uses: ./.github/actions/pnpm-install
       with:
         node-version: ${{ env.NODE_VERSION }}
-    - run: pnpm i --no-frozen-lockfile
     - run: pnpm run build-mod
     # Upload build to artifacts
     - name: Upload build to artifacts