add test

.github/workflows/_test_langgraph.yml

@@ -56,3 +56,46 @@ jobs:
           # grep will exit non-zero if the target message isn't found,
           # and `set -e` above will cause the step to fail.
           echo "$STATUS" | grep 'nothing to commit, working tree clean'
+
+  build-strict-msgpack:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: libs/langgraph
+    name: "test strict msgpack #3.12"
+    steps:
+      - uses: actions/checkout@v6
+      - name: Set up Python 3.12
+        uses: astral-sh/setup-uv@v7
+        with:
+          python-version: "3.12"
+          enable-cache: true
+          cache-suffix: "test-langgraph-strict-msgpack"
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        if: ${{ !github.event.pull_request.head.repo.fork }}
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_RO_TOKEN }}
+
+      - name: Install dependencies
+        shell: bash
+        run: uv sync --frozen --group test --no-dev
+
+      - name: Run tests (strict msgpack)
+        shell: bash
+        env:
+          LANGGRAPH_STRICT_MSGPACK: "1"
+        run: make test_parallel
+
+      - name: Ensure the tests did not create any additional files
+        shell: bash
+        run: |
+          set -eu
+
+          STATUS="$(git status)"
+          echo "$STATUS"
+
+          # grep will exit non-zero if the target message isn't found,
+          # and `set -e` above will cause the step to fail.
+          echo "$STATUS" | grep 'nothing to commit, working tree clean'