feat(api): Synchronize history and summary from DB in chat stream

backend/src/ea_chatbot/api/routers/agent.py

@@ -7,10 +7,12 @@ from ea_chatbot.api.utils import convert_to_json_compatible
 from ea_chatbot.graph.workflow import app
 from ea_chatbot.graph.checkpoint import get_checkpointer
 from ea_chatbot.history.models import User as UserDB, Conversation
+from ea_chatbot.history.utils import map_db_messages_to_langchain
 from ea_chatbot.api.schemas import ChatRequest
 import io
 import base64
 from langchain_core.runnables.config import RunnableConfig
+from langchain_core.messages import BaseMessage
 
 router = APIRouter(prefix="/chat", tags=["agent"])
 
@@ -18,14 +20,15 @@ async def stream_agent_events(
     message: str, 
     thread_id: str, 
     user_id: str,
-    summary: str
+    summary: str,
+    messages: List[BaseMessage] = []
 ) -> AsyncGenerator[str, None]:
     """
     Generator that invokes the LangGraph agent and yields SSE formatted events.
     Persists assistant responses and plots to the database.
     """
     initial_state = {
-        "messages": [], 
+        "messages": messages, 
         "question": message,
         "summary": summary,
         "analysis": None,
@@ -149,8 +152,16 @@ async def chat_stream(
             raise HTTPException(status_code=404, detail="Conversation not found")
         if conv.user_id != current_user.id:
             raise HTTPException(status_code=403, detail="Not authorized to access this conversation")
+        
+        # Load existing summary from DB if not provided in request
+        db_summary = conv.summary or ""
 
-    # Save user message immediately
+    # Load last 10 messages for context (BEFORE saving the current user message)
+    # This ensures we don't include the current message twice if the graph reduces it.
+    db_messages = history_manager.get_messages_by_window(request.thread_id, window_size=10)
+    lc_messages = map_db_messages_to_langchain(db_messages)
+
+    # Save user message immediately to DB
     history_manager.add_message(request.thread_id, "user", request.message)
 
     return StreamingResponse(
@@ -158,7 +169,8 @@ async def chat_stream(
             request.message, 
             request.thread_id, 
             current_user.id,
-            request.summary or ""
+            db_summary,
+            lc_messages
         ),
         media_type="text/event-stream"
     )