refactor(backend): update orchestrator endpoint and services

- endpoints/orchestrator.py: update orchestrator API endpoint
- services/agent_conversations.py: update agent conversations service
- services/orchestrator.py: update orchestrator service
- services/user_agent.py: update user agent service

server/src/app/services/agent_conversations.py

@@ -11,6 +11,7 @@ from app.models.agent_conversation import AgentConversation, AgentConversationMe
 from app.services.settings import SettingsService
 
 STATEFUL_CONTEXT_KEYS = (
+    "session_type",
     "entry_source",
     "request_context",
     "attachment_names",
@@ -37,10 +38,16 @@ class AgentConversationService:
 
         normalized_id = str(conversation_id or "").strip()
         normalized_user_id = str(user_id or "").strip() or None
+        incoming_session_type = str(context_json.get("session_type") or "").strip() or "expense"
         conversation = self.get_conversation(normalized_id) if normalized_id else None
         if conversation is not None and conversation.user_id != normalized_user_id:
             normalized_id = ""
             conversation = None
+        if conversation is not None:
+            existing_session_type = str((conversation.state_json or {}).get("session_type") or "").strip() or "expense"
+            if existing_session_type != incoming_session_type:
+                normalized_id = ""
+                conversation = None
 
         if conversation is None:
             conversation = AgentConversation(
@@ -117,6 +124,7 @@ class AgentConversationService:
         *,
         user_id: str | None,
         source: str | None = "user_message",
+        session_type: str | None = None,
     ) -> AgentConversation | None:
         self.prune_expired_conversations()
 
@@ -128,7 +136,16 @@ class AgentConversationService:
         if source:
             stmt = stmt.where(AgentConversation.source == source)
         stmt = stmt.order_by(AgentConversation.updated_at.desc(), AgentConversation.created_at.desc())
-        return self.db.scalar(stmt.limit(1))
+        conversations = list(self.db.scalars(stmt).all())
+        normalized_session_type = str(session_type or "").strip()
+        if not normalized_session_type:
+            return conversations[0] if conversations else None
+
+        for conversation in conversations:
+            current_session_type = str((conversation.state_json or {}).get("session_type") or "").strip() or "expense"
+            if current_session_type == normalized_session_type:
+                return conversation
+        return None
 
     def hydrate_context_json(
         self,
@@ -285,6 +302,7 @@ class AgentConversationService:
         *,
         user_id: str | None,
         source: str | None = "user_message",
+        session_type: str | None = None,
     ) -> int:
         normalized_user_id = str(user_id or "").strip()
         if not normalized_user_id:
@@ -294,6 +312,14 @@ class AgentConversationService:
         if source:
             stmt = stmt.where(AgentConversation.source == source)
         conversations = list(self.db.scalars(stmt).all())
+        normalized_session_type = str(session_type or "").strip()
+        if normalized_session_type:
+            conversations = [
+                conversation
+                for conversation in conversations
+                if (str((conversation.state_json or {}).get("session_type") or "").strip() or "expense")
+                == normalized_session_type
+            ]
         if not conversations:
             return 0
 
@@ -303,6 +329,33 @@ class AgentConversationService:
         self.db.commit()
         return len(conversations)
 
+    def delete_conversation(
+        self,
+        *,
+        conversation_id: str | None,
+        user_id: str | None = None,
+        source: str | None = "user_message",
+    ) -> int:
+        normalized_id = str(conversation_id or "").strip()
+        if not normalized_id:
+            return 0
+
+        conversation = self.get_conversation(normalized_id)
+        if conversation is None:
+            return 0
+
+        normalized_user_id = str(user_id or "").strip()
+        if normalized_user_id and str(conversation.user_id or "").strip() != normalized_user_id:
+            return 0
+
+        normalized_source = str(source or "").strip()
+        if normalized_source and str(conversation.source or "").strip() != normalized_source:
+            return 0
+
+        self.db.delete(conversation)
+        self.db.commit()
+        return 1
+
     def serialize_conversation(
         self,
         conversation: AgentConversation,