fix(browser): isolate Browser Use Python environment

contributors/emails/DELTA31TECH@live.com

@@ -0,0 +1,2 @@
+d31tcjg
+# PR #84143

tests/tools/test_browser_use_cli.py

@@ -663,6 +663,27 @@ def test_code_piped_on_stdin(self, tmp_path, monkeypatch):
         assert 'got:print("hi")' in result["output"]
         assert "session" not in result
 
+    def test_python_runtime_vars_are_stripped(self, tmp_path, monkeypatch):
+        """Hermes' Python environment must not contaminate uvx/browser-use.
+
+        The Desktop launcher puts Hermes' Python 3.11 site-packages on
+        PYTHONPATH; browser-use currently runs under Python 3.12, so inheriting
+        that path can load ABI-incompatible extension modules.
+        """
+        cli = _fake_cli(
+            tmp_path,
+            'cat > /dev/null\nprintf "pythonpath_set:[%s]\\npythonhome_set:[%s]\\n" "${PYTHONPATH+x}" "${PYTHONHOME+x}"\n',
+        )
+        monkeypatch.setattr(bu_cli, "_find_cli", lambda: [cli])
+        monkeypatch.setenv("PYTHONPATH", "/hermes/python3.11/site-packages")
+        monkeypatch.setenv("PYTHONHOME", "/hermes/python3.11")
+
+        result = json.loads(bu_cli.browser_exec("print(1)"))
+
+        assert result["success"] is True
+        assert "pythonpath_set:[]" in result["output"]
+        assert "pythonhome_set:[]" in result["output"]
+
     def test_session_sets_bu_name(self, tmp_path, monkeypatch):
         cli = _fake_cli(tmp_path, 'cat > /dev/null\necho "bu:$BU_NAME"\n')
         monkeypatch.setattr(bu_cli, "_find_cli", lambda: [cli])

tools/browser_use_cli.py

@@ -51,9 +51,19 @@ def _blocked_url_in_code(code: str) -> Optional[str]:
 
 
 def _base_subprocess_env() -> dict:
+    """Return a credential-scrubbed, Python-runtime-neutral CLI environment.
+
+    Browser Use may run under a different Python version than Hermes (notably
+    uvx selecting Python 3.12 while Desktop embeds Python 3.11). Inheriting
+    PYTHONPATH or PYTHONHOME can make that isolated runtime import Hermes'
+    ABI-specific packages instead of its own dependencies.
+    """
     from tools.browser_tool import _build_browser_env
 
-    return _build_browser_env()
+    env = _build_browser_env()
+    env.pop("PYTHONPATH", None)
+    env.pop("PYTHONHOME", None)
+    return env
 
 
 def _read_browser_cfg() -> dict: