fix(tools): expose active Python environment in workspace namespace

tests/test_tool_path_confinement.py

@@ -304,7 +304,7 @@ async def test_write_file_dispatch_rejects_empty_directory_like_workspace_path(m
         security_context=NO_TOOL_SECURITY_CONTEXT,
     )
     assert desc == "write_file: /workspace/papers"
-    assert "refusing to create an empty file at a directory-like path" in (
+    assert "content required; refusing to create an empty file" in (
         result.get("error") or ""
     )
     assert result.get("exit_code") == 1