pyodide: preserve User-Agent header in httpx and httpx2 requests

.github/workflows/python-tests.yml

@@ -0,0 +1,49 @@
+name: Python Runtime Tests
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+concurrency:
+  group: python-tests-${{ github.event.pull_request.number || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  python-unit-tests:
+    name: Python Unit Tests (Python ${{ matrix.python-version }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ['3.12', '3.13']
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Run Python internal unit tests
+        run: |
+          python3 -m unittest discover -s src/pyodide/internal -p "test_*.py"
+
+      - name: Check git diff and whitespace hygiene
+        run: |
+          git diff --check
+
+  docker-tests:
+    name: Containerized Test Suite (Docker)
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Run tests inside Docker container
+        run: |
+          docker run --rm -v "$GITHUB_WORKSPACE":/workerd -w /workerd python:3.12-slim \
+            python3 -m unittest discover -s src/pyodide/internal -p "test_*.py"

.gitignore

@@ -25,6 +25,7 @@ MODULE.bazel.lock
 /.cache/
 
 /.bazel-cache
+/.context/
 /artifacts
 /.gitlab-ci-ca-file
 /.gitlab-ci-gitconfig

src/pyodide/BUILD.bazel

@@ -91,3 +91,17 @@ py_test(
     main = "internal/test_frozen_sdk.py",
     target_compatible_with = ["@platforms//os:linux"],
 )
+
+py_test(
+    name = "unit-test-entropy-patches",
+    srcs = [
+        "internal/test_entropy_patches.py",
+        "internal/topLevelEntropy/__init__.py",
+        "internal/topLevelEntropy/allow_entropy.py",
+        "internal/topLevelEntropy/entropy_import_context.py",
+        "internal/topLevelEntropy/entropy_import_context_packages.py",
+        "internal/topLevelEntropy/entropy_patches.py",
+        "internal/topLevelEntropy/import_patch_manager.py",
+    ],
+    main = "internal/test_entropy_patches.py",
+)

src/pyodide/internal/test_entropy_patches.py

@@ -0,0 +1,44 @@
+# Copyright (c) 2026 Cloudflare, Inc.
+# Licensed under the Apache 2.0 license found in the LICENSE file or at:
+#     https://opensource.org/licenses/Apache-2.0
+
+import sys
+import unittest
+from pathlib import Path
+from types import SimpleNamespace
+
+DIR = Path(__file__).parent
+sys.path.insert(0, str(DIR))
+
+from topLevelEntropy.import_patch_manager import patches
+import topLevelEntropy.entropy_import_context_packages  # noqa: F401
+
+
+class TestEntropyPatches(unittest.TestCase):
+    def test_httpx_user_agent_patch(self):
+        """Ensure httpx._transports.emscripten has HEADERS_TO_IGNORE cleared."""
+        self.assertIn("httpx._transports.emscripten", patches)
+        mock_httpx = SimpleNamespace(HEADERS_TO_IGNORE=("user-agent",))
+        with patches["httpx._transports.emscripten"].exec(mock_httpx):
+            pass
+        self.assertEqual(
+            mock_httpx.HEADERS_TO_IGNORE,
+            (),
+            "Expected HEADERS_TO_IGNORE to be cleared for httpx",
+        )
+
+    def test_httpx2_user_agent_patch(self):
+        """Ensure httpx2_jsfetch has HEADERS_TO_IGNORE cleared."""
+        self.assertIn("httpx2_jsfetch", patches)
+        mock_httpx2 = SimpleNamespace(HEADERS_TO_IGNORE=("user-agent",))
+        with patches["httpx2_jsfetch"].exec(mock_httpx2):
+            pass
+        self.assertEqual(
+            mock_httpx2.HEADERS_TO_IGNORE,
+            (),
+            "Expected HEADERS_TO_IGNORE to be cleared for httpx2_jsfetch",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()

src/pyodide/internal/topLevelEntropy/entropy_import_context_packages.py

@@ -190,3 +190,21 @@ def langchain_openai_chat_models_base_context(module):
             yield
     else:
         yield
+
+
+@register_exec_patch("httpx._transports.emscripten")
+@contextmanager
+def httpx_emscripten_context(module):
+    yield
+    # In browser environments, User-Agent is a forbidden request header and causes console warnings.
+    # In workerd, fetch() natively supports custom User-Agent headers without restriction.
+    module.HEADERS_TO_IGNORE = ()
+
+
+@register_exec_patch("httpx2_jsfetch")
+@contextmanager
+def httpx2_jsfetch_context(module):
+    yield
+    # In browser environments, User-Agent is a forbidden request header and causes console warnings.
+    # In workerd, fetch() natively supports custom User-Agent headers without restriction.
+    module.HEADERS_TO_IGNORE = ()