enhance: include timestamps on history return (#583)

Author: Wendong-Fan

server/app/controller/chat/history_controller.py

@@ -3,7 +3,7 @@
 from fastapi_pagination.ext.sqlmodel import paginate
 from app.model.chat.chat_history import ChatHistoryOut, ChatHistoryIn, ChatHistory, ChatHistoryUpdate
 from fastapi_babel import _
-from sqlmodel import Session, select, desc
+from sqlmodel import Session, select, desc, case
 from app.component.auth import Auth, auth_must
 from app.component.database import session
 from utils import traceroot_wrapper as traceroot
@@ -38,7 +38,19 @@ def create_chat_history(data: ChatHistoryIn, session: Session = Depends(session)
 def list_chat_history(session: Session = Depends(session), auth: Auth = Depends(auth_must)) -> Page[ChatHistoryOut]:
     """List chat histories for current user."""
     user_id = auth.user.id
-    stmt = select(ChatHistory).where(ChatHistory.user_id == user_id).order_by(desc(ChatHistory.created_at))
+    
+    # Order by created_at descending, but fallback to id descending for old records without timestamps
+    # This ensures newer records with timestamps come first, followed by old records ordered by id
+    stmt = (
+        select(ChatHistory)
+        .where(ChatHistory.user_id == user_id)
+        .order_by(
+            desc(case((ChatHistory.created_at.is_(None), 0), else_=1)),  # Non-null created_at first
+            desc(ChatHistory.created_at),  # Then by created_at descending
+            desc(ChatHistory.id)  # Finally by id descending for records with same/null created_at
+        )
+    )
+    
     result = paginate(session, stmt)
     total = result.total if hasattr(result, 'total') else 0
     logger.debug("Chat histories listed", extra={"user_id": user_id, "total": total})

server/app/model/chat/chat_history.py

@@ -2,6 +2,7 @@
 from sqlmodel import Field, SmallInteger, Column, JSON, String
 from typing import Optional
 from enum import IntEnum
+from datetime import datetime
 from sqlalchemy_utils import ChoiceType
 from app.model.abstract.model import AbstractModel, DefaultTimes
 from pydantic import BaseModel, model_validator
@@ -13,6 +14,16 @@ class ChatStatus(IntEnum):
 
 
 class ChatHistory(AbstractModel, DefaultTimes, table=True):
+    """
+    Chat history model with timestamp tracking.
+    
+    Inherits from DefaultTimes which provides:
+    - created_at: timestamp when record is created (auto-populated)
+    - updated_at: timestamp when record is last modified (auto-updated)
+    - deleted_at: timestamp for soft deletion (nullable)
+    
+    For legacy records without timestamps, sorting falls back to id ordering.
+    """
     id: int = Field(default=None, primary_key=True)
     user_id: int = Field(index=True)
     task_id: str = Field(index=True, unique=True)
@@ -70,13 +81,22 @@ class ChatHistoryOut(BaseModel):
     summary: str | None = None
     tokens: int
     status: int
+    created_at: Optional[datetime] = None
+    updated_at: Optional[datetime] = None
 
     @model_validator(mode="after")
     def fill_project_id_from_task_id(self):
-        """fill by task_id when project_id is None"""
+        """Fill project_id from task_id when project_id is None"""
         if self.project_id is None:
             self.project_id = self.task_id
         return self
+    
+    @model_validator(mode="after") 
+    def handle_legacy_timestamps(self):
+        """Handle legacy records that might not have timestamp fields"""
+        # For old records without timestamps, we rely on database-level defaults
+        # The sorting in the controller will handle ordering appropriately
+        return self
 
 
 class ChatHistoryUpdate(BaseModel):