feat(workers): Define WorkerState for the Data Analyst subgraph

backend/src/ea_chatbot/graph/workers/data_analyst/state.py

@@ -0,0 +1,28 @@
+from typing import TypedDict, List, Dict, Any, Optional
+from langchain_core.messages import BaseMessage
+
+class WorkerState(TypedDict):
+    """Internal state for the Data Analyst worker subgraph."""
+    
+    # Internal worker conversation (not bubbled up to global unless summary)
+    messages: List[BaseMessage]
+    
+    # The specific sub-task assigned by the Orchestrator
+    task: str
+    
+    # Generated code and execution context
+    code: Optional[str]
+    output: Optional[str]
+    error: Optional[str]
+    
+    # Number of internal retry attempts
+    iterations: int
+    
+    # Temporary storage for analysis results
+    plots: List[Any]
+    
+    # Isolated/Snapshot view of the VFS
+    vfs_state: Dict[str, Any]
+    
+    # The final summary or result to return to the Orchestrator
+    result: Optional[str]

backend/tests/test_data_analyst_state.py

@@ -0,0 +1,17 @@
+from typing import get_type_hints, List
+from langchain_core.messages import BaseMessage
+from ea_chatbot.graph.workers.data_analyst.state import WorkerState
+
+def test_data_analyst_worker_state():
+    """Verify that DataAnalyst WorkerState has the required fields."""
+    hints = get_type_hints(WorkerState)
+    
+    assert "messages" in hints
+    assert "task" in hints
+    assert hints["task"] == str
+    
+    assert "code" in hints
+    assert "output" in hints
+    assert "error" in hints
+    assert "iterations" in hints
+    assert hints["iterations"] == int