fix(orchestrator): Apply refinements from code review

backend/tests/test_review_fix_vfs.py

@@ -0,0 +1,50 @@
+import pytest
+from ea_chatbot.utils.vfs import VFSHelper
+from ea_chatbot.graph.workers.data_analyst.mapping import prepare_worker_input
+from ea_chatbot.graph.state import AgentState
+
+def test_vfs_isolation_deep_copy():
+    """Verify that worker VFS is deep-copied from global state."""
+    global_vfs = {
+        "data.txt": {
+            "content": "original",
+            "metadata": {"tags": ["a"]}
+        }
+    }
+    state = AgentState(
+        checklist=[{"task": "test", "worker": "data_analyst"}],
+        current_step=0,
+        messages=[],
+        question="test",
+        analysis={},
+        next_action="",
+        iterations=0,
+        vfs=global_vfs,
+        plots=[],
+        dfs={}
+    )
+    
+    worker_input = prepare_worker_input(state)
+    worker_vfs = worker_input["vfs_state"]
+    
+    # Mutate worker VFS nested object
+    worker_vfs["data.txt"]["metadata"]["tags"].append("b")
+    
+    # Global VFS should remain unchanged
+    assert global_vfs["data.txt"]["metadata"]["tags"] == ["a"]
+
+def test_vfs_schema_normalization():
+    """Verify that VFSHelper handles inconsistent VFS entries."""
+    vfs = {
+        "raw.txt": "just a string", # Inconsistent with standard Dict[str, Any] entry
+        "valid.txt": {"content": "data", "metadata": {}}
+    }
+    helper = VFSHelper(vfs)
+    
+    # Should not crash during read
+    content, metadata = helper.read("raw.txt")
+    assert content == "just a string"
+    assert metadata == {}
+    
+    # Should not crash during list/other ops if they assume dict
+    assert "raw.txt" in helper.list()