ci: add import profiler check across monorepo

.github/workflows/import-profiler.yml

@@ -0,0 +1,39 @@
+name: import-profiler
+
+on:
+  pull_request:
+    branches:
+      - main
+      - preview
+  # Trigger workflow on GitHub merge queue events
+  merge_group:
+    types: [checks_requested]
+
+permissions:
+  contents: read
+
+jobs:
+  import-profile:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v6
+      with:
+        fetch-depth: 2
+    - name: Setup Python
+      uses: actions/setup-python@v6
+      with:
+        python-version: "3.15"
+        allow-prereleases: true
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run import profiler
+      env:
+        BUILD_TYPE: presubmit
+        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        TEST_TYPE: import_profile
+        PY_VERSION: "3.15"
+      run: |
+        ci/run_conditional_tests.sh

packages/gapic-generator/gapic/templates/noxfile.py.j2

@@ -86,6 +86,7 @@ nox.options.sessions = [
     "lint_setup_py",
     "blacken",
     "docs",
+    "import_profile",
 ]
 
 # Error if a python version is missing
@@ -641,4 +642,16 @@ def core_deps_from_source(session, protobuf_implementation):
             "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
         },
     )
+
+
+@nox.session(python="3.15")
+def import_profile(session):
+    """Ensure import times remain below defined thresholds."""
+    session.install(".")
+    profiler_script = os.path.join(CURRENT_DIRECTORY.parent.parent, "scripts", "import_profiler", "profiler.py")
+    {% if api.naming.module_namespace %}
+    session.run("python", profiler_script, "--module", "{{ api.naming.module_namespace[0] }}", "--iterations", "10")
+    {% else %}
+    session.run("python", profiler_script, "--module", "{{ api.naming.versioned_module_name }}", "--iterations", "10")
+    {% endif %}
 {% endblock %}