Shard serialized server CI suites in PR workflow

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/pr.yml

@@ -79,8 +79,8 @@ jobs:
       - name: Typecheck
         run: pnpm -r typecheck
 
-      - name: Run tests
-        run: pnpm test:run
+      - name: Run general test suites
+        run: pnpm test:run:general
 
       - name: Verify release registry test coverage
         run: pnpm run test:release-registry
@@ -88,6 +88,49 @@ jobs:
       - name: Build
         run: pnpm build
 
+  verify_serialized_server:
+    name: Verify serialized server suites (${{ matrix.shard_label }})
+    needs: [policy]
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - shard_index: 0
+            shard_count: 4
+            shard_label: 1/4
+          - shard_index: 1
+            shard_count: 4
+            shard_label: 2/4
+          - shard_index: 2
+            shard_count: 4
+            shard_label: 3/4
+          - shard_index: 3
+            shard_count: 4
+            shard_label: 4/4
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9.15.4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Run serialized server test shard
+        run: pnpm test:run:serialized -- --shard-index ${{ matrix.shard_index }} --shard-count ${{ matrix.shard_count }}
+
   canary_dry_run:
     name: Canary Dry Run
     needs: [policy]