conversation history

app/models.py

@@ -21,6 +21,12 @@ class GraphState(TypedDict):
     metadata_filters: Optional[Dict[str, Any]]
     metadata: Dict[str, Any]
 
+class Message(BaseModel):
+    """Single message in conversation history"""
+    role: str  # 'user', 'assistant', or 'system'
+    content: str
+    id: Optional[str] = None
+
 class ChatUIInput(BaseModel):
     """Input model for text-only ChatUI requests"""
     text: str  # Legacy: full concatenated prompt (for backward compatibility)