feat(ci): implement sharding for unit test performance

.github/actions/calculate-shard-matrix/action.yaml

@@ -0,0 +1,22 @@
+name: "Calculate Shard Matrix"
+description: "Calculates the dynamic test shard matrix and shard total"
+outputs:
+  shard_matrix:
+    description: "JSON array of shard indices"
+    value: ${{ steps.set-matrix.outputs.shard_matrix }}
+  shard_total:
+    description: "Total number of shards"
+    value: ${{ steps.set-matrix.outputs.shard_total }}
+runs:
+  using: "composite"
+  steps:
+    - name: Calculate Matrix
+      id: set-matrix
+      shell: bash
+      env:
+        RUN_TESTS_MODE: CALCULATE_SHARD_MATRIX
+        BUILD_TYPE: presubmit
+        TEST_TYPE: units
+        GIT_DIFF_ARG: "HEAD^1"
+      run: |
+        bash ci/run_conditional_tests.sh --strict

.github/actions/check-shard-status/action.yaml

@@ -0,0 +1,31 @@
+name: "Check Shard Status"
+description: "Checks if all unit test shards passed for a given Node version"
+inputs:
+  node-version:
+    required: true
+    description: "Node version to check"
+runs:
+  using: "composite"
+  steps:
+    - name: Check shard status
+      uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+      with:
+        script: |
+          const { data: { jobs } } = await github.rest.actions.listJobsForWorkflowRun({
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            run_id: context.runId,
+          });
+          const nodeVersion = '${{ inputs.node-version }}';
+          const shardJobs = jobs.filter(j => j.name.includes(`units (Node ${nodeVersion},`));
+          if (shardJobs.length === 0) {
+            core.setFailed(`No shard jobs found for Node ${nodeVersion}`);
+            return;
+          }
+          const failed = shardJobs.filter(j => j.conclusion !== 'success');
+          if (failed.length > 0) {
+            const failedLinks = failed.map(j => `- ${j.name}: ${j.html_url}`).join('\n');
+            core.setFailed(`${failed.length} shards failed for Node ${nodeVersion}:\n${failedLinks}`);
+          } else {
+            core.info(`All shards passed for Node ${nodeVersion}`);
+          }

.github/actions/run-unit-tests/action.yaml

@@ -0,0 +1,34 @@
+name: "Run Unit Test Shard"
+description: "Sets up Node.js, pnpm, and runs a unit test shard"
+inputs:
+  node-version:
+    required: true
+    description: "Node.js version to test"
+  shard-total:
+    required: true
+    description: "Total number of shards"
+  shard-index:
+    required: true
+    description: "0-based shard index"
+runs:
+  using: "composite"
+  steps:
+    - name: Use Node.js ${{ inputs.node-version }}
+      uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6.5.0
+      with:
+        node-version: ${{ inputs.node-version }}
+    - uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4
+      with:
+        version: ^10.0.0
+    - run: node --version
+      shell: bash
+    - name: Run unit tests
+      shell: bash
+      run: bash ci/run_conditional_tests.sh --strict
+      env:
+        RUN_TESTS_MODE: RUN_UNIT_TESTS
+        BUILD_TYPE: presubmit
+        TEST_TYPE: units
+        SHARD_TOTAL: ${{ inputs.shard-total }}
+        SHARD_INDEX: ${{ inputs.shard-index }}
+        GIT_DIFF_ARG: HEAD^1

.github/workflows/presubmit.yaml

@@ -5,29 +5,37 @@ on:
   pull_request:
 name: presubmit
 jobs:
+  setup:
+    runs-on: ubuntu-latest
+    outputs:
+      shard-matrix: ${{ steps.set-matrix.outputs.shard_matrix }}
+      shard-total: ${{ steps.set-matrix.outputs.shard_total }}
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
+        with:
+          fetch-depth: 2
+          persist-credentials: false
+      - id: set-matrix
+        uses: ./.github/actions/calculate-shard-matrix
   units:
+    needs: setup
+    name: units (Node ${{ matrix.node-version }}, Shard ${{ matrix.shard-index }})
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         node-version: [22, 24, 26]
+        shard-index: ${{ fromJSON(needs.setup.outputs.shard-matrix) }}
     steps:
       - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
         with:
-          fetch-depth: 300
+          fetch-depth: 2
           persist-credentials: false
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6.5.0
+      - uses: ./.github/actions/run-unit-tests
         with:
           node-version: ${{ matrix.node-version }}
-      - uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4
-        with:
-          version: ^10.0.0
-      - run: node --version
-      - run: ci/run_conditional_tests.sh
-        name: Run unit tests
-        env:
-          BUILD_TYPE: presubmit
-          TEST_TYPE: units
+          shard-total: ${{ needs.setup.outputs.shard-total }}
+          shard-index: ${{ matrix.shard-index }}
   lint:
     runs-on: ubuntu-latest
     continue-on-error: true
@@ -43,3 +51,22 @@ jobs:
       - run: npm install
       - run: npm run lint
         name: Run monorepo linter
+
+  # Consolidate shards into jobs representing aggregate status to simplify branch protection requirements
+  units-status:
+    name: units (${{ matrix.node-version }})
+    needs: units
+    runs-on: ubuntu-latest
+    if: always()
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [22, 24, 26]
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
+        with:
+          persist-credentials: false
+      - name: Check shard status
+        uses: ./.github/actions/check-shard-status
+        with:
+          node-version: ${{ matrix.node-version }}

.github/workflows/windows-presubmit.yaml

@@ -5,27 +5,53 @@ on:
   pull_request:
 name: presubmit-windows
 jobs:
+  setup:
+    runs-on: ubuntu-latest
+    outputs:
+      shard-matrix: ${{ steps.set-matrix.outputs.shard_matrix }}
+      shard-total: ${{ steps.set-matrix.outputs.shard_total }}
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
+        with:
+          fetch-depth: 2
+          persist-credentials: false
+      - id: set-matrix
+        uses: ./.github/actions/calculate-shard-matrix
   units:
+    needs: setup
+    name: units (Node ${{ matrix.node-version }}, Shard ${{ matrix.shard-index }})
     runs-on: windows-latest
     strategy:
+      fail-fast: false
       matrix:
         node-version: [22, 24, 26]
+        shard-index: ${{ fromJSON(needs.setup.outputs.shard-matrix) }}
     steps:
       - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
         with:
-          fetch-depth: 300
+          fetch-depth: 2
           persist-credentials: false
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6.5.0
+      - uses: ./.github/actions/run-unit-tests
         with:
           node-version: ${{ matrix.node-version }}
-      - uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4
+          shard-total: ${{ needs.setup.outputs.shard-total }}
+          shard-index: ${{ matrix.shard-index }}
+
+  # Dummy jobs to satisfy branch protection requirements for each node version
+  units-status:
+    name: units (${{ matrix.node-version }})
+    needs: units
+    runs-on: ubuntu-latest
+    if: always()
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [22, 24, 26]
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
         with:
-          version: ^10.0.0
-      - run: node --version
-      - run: bash ci/run_conditional_tests.sh
-        name: Run windows unit tests
-        shell: bash
-        env:
-          BUILD_TYPE: presubmit
-          TEST_TYPE: units
+          persist-credentials: false
+      - name: Check shard status
+        uses: ./.github/actions/check-shard-status
+        with:
+          node-version: ${{ matrix.node-version }}

.pnpmfile.cjs

@@ -0,0 +1,25 @@
+module.exports = {
+  hooks: {
+    readPackage(pkg, context) {
+      // Override yargs for Node >= 24 to prevent ESM scope require errors
+      if (pkg.dependencies && pkg.dependencies.yargs) {
+        mutateYargs(pkg.dependencies, pkg.name, 'dependencies', context);
+      }
+      if (pkg.devDependencies && pkg.devDependencies.yargs) {
+        mutateYargs(pkg.devDependencies, pkg.name, 'devDependencies', context);
+      }
+      return pkg;
+    }
+  }
+};
+
+function mutateYargs(deps, pkgName, depType, context) {
+  const nodeVersion = process.version;
+  const majorVersion = parseInt(nodeVersion.replace('v', '').split('.')[0], 10);
+
+  if (majorVersion >= 24) {
+    console.log(`[pnpmfile] Node.js version is ${nodeVersion} (>= 24). Overriding yargs to 18.0.0 in ${pkgName}`);
+    deps.yargs = '18.0.0';
+  }
+}
+