加入会话管理和助手管理

2025-04-30 02:23:00 +08:00 · 2025-04-30 02:23:00 +08:00 · 7df10e82be
commit 7df10e82be
parent 194282e029
11 changed files with 1232 additions and 351 deletions
--- a/backend/app/api/v1/api.py
+++ b/backend/app/api/v1/api.py
@ -1,15 +1,12 @@
-# File: backend/app/api/v1/api.py
+# File: backend/app/api/v1/api.py (更新)
 # Description: 聚合 v1 版本的所有 API 路由

 from fastapi import APIRouter
-from app.api.v1.endpoints import chat # 导入聊天路由
+from app.api.v1.endpoints import chat, assistants, sessions # 导入新路由

-# 创建 v1 版本的总路由
 api_router = APIRouter()

-# 将聊天路由包含到 v1 总路由中，并添加前缀
-api_router.include_router(chat.router, prefix="/chat", tags=["chat"])
+api_router.include_router(chat.router, prefix="/chat", tags=["Chat"])
+api_router.include_router(assistants.router, prefix="/assistants", tags=["Assistants"]) # 添加助手路由
+api_router.include_router(sessions.router, prefix="/sessions", tags=["Sessions"]) # 添加会话路由

-# --- 如果有其他路由，也在这里 include ---
-# from app.api.v1.endpoints import workflow
-# api_router.include_router(workflow.router, prefix="/workflow", tags=["workflow"])
--- a/backend/app/api/v1/endpoints/assistants.py
+++ b/backend/app/api/v1/endpoints/assistants.py
@ -0,0 +1,66 @@
+# File: backend/app/api/v1/endpoints/assistants.py (新建)
+# Description: 助手的 API 路由
+
+from fastapi import APIRouter, HTTPException, Depends, status
+from typing import List
+from app.models.pydantic_models import AssistantRead, AssistantCreate, AssistantUpdate
+from app.services.assistant_service import assistant_service_instance, AssistantService
+
+router = APIRouter()
+
+# --- 依赖注入 AssistantService ---
+def get_assistant_service() -> AssistantService:
+    return assistant_service_instance
+
+@router.post("/", response_model=AssistantRead, status_code=status.HTTP_201_CREATED)
+async def create_new_assistant(
+    assistant_data: AssistantCreate,
+    service: AssistantService = Depends(get_assistant_service)
+):
+    """创建新助手"""
+    return service.create_assistant(assistant_data)
+
+@router.get("/", response_model=List[AssistantRead])
+async def read_all_assistants(
+    service: AssistantService = Depends(get_assistant_service)
+):
+    """获取所有助手列表"""
+    return service.get_assistants()
+
+@router.get("/{assistant_id}", response_model=AssistantRead)
+async def read_assistant_by_id(
+    assistant_id: str,
+    service: AssistantService = Depends(get_assistant_service)
+):
+    """根据 ID 获取特定助手"""
+    assistant = service.get_assistant(assistant_id)
+    if not assistant:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的助手")
+    return assistant
+
+@router.put("/{assistant_id}", response_model=AssistantRead)
+async def update_existing_assistant(
+    assistant_id: str,
+    assistant_data: AssistantUpdate,
+    service: AssistantService = Depends(get_assistant_service)
+):
+    """更新指定 ID 的助手"""
+    updated_assistant = service.update_assistant(assistant_id, assistant_data)
+    if not updated_assistant:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的助手")
+    return updated_assistant
+
+@router.delete("/{assistant_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_existing_assistant(
+    assistant_id: str,
+    service: AssistantService = Depends(get_assistant_service)
+):
+    """删除指定 ID 的助手"""
+    deleted = service.delete_assistant(assistant_id)
+    if not deleted:
+        # 根据服务层逻辑判断是找不到还是不允许删除
+        assistant = service.get_assistant(assistant_id)
+        if assistant and assistant_id == 'asst-default':
+             raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="不允许删除默认助手")
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的助手")
+    # 成功删除，不返回内容
--- a/backend/app/api/v1/endpoints/chat.py
+++ b/backend/app/api/v1/endpoints/chat.py
@ -1,41 +1,68 @@
 # File: backend/app/api/v1/endpoints/chat.py (更新)
-# Description: 聊天功能的 API 路由 (使用 ChatService)
+# Description: 聊天功能的 API 路由 (使用更新后的 ChatService)

-from fastapi import APIRouter, HTTPException, Depends
-from app.models.pydantic_models import ChatRequest, ChatResponse
-# 导入 ChatService 实例
+from fastapi import APIRouter, HTTPException, Depends, status
+from app.models.pydantic_models import ChatRequest, ChatResponse, SessionCreateRequest
 from app.services.chat_service import chat_service_instance, ChatService
+from app.services.session_service import session_service_instance, SessionService # 导入 SessionService

 router = APIRouter()

-# --- (可选) 使用 FastAPI 的依赖注入来获取 ChatService 实例 ---
-# 这样更符合 FastAPI 的风格，方便测试和替换实现
-# async def get_chat_service() -> ChatService:
-#     return chat_service_instance
+# --- 依赖注入 ---
+def get_chat_service() -> ChatService:
+    return chat_service_instance
+
+def get_session_service() -> SessionService:
+    return session_service_instance

@router.post("/", response_model=ChatResponse)
 async def handle_chat_message(
    request: ChatRequest,
-    # chat_service: ChatService = Depends(get_chat_service) # 使用依赖注入
+    chat_service: ChatService = Depends(get_chat_service),
+    session_service: SessionService = Depends(get_session_service) # 注入 SessionService
 ):
-  """
-  处理用户发送的聊天消息，并使用 LangChain 获取 AI 回复
-  """
-  user_message = request.message
-  # session_id = request.session_id # 如果 ChatRequest 中包含 session_id
-  print(f"接收到用户消息: {user_message}")
+    """处理用户发送的聊天消息 (包含 assistantId 和 sessionId)"""
+    user_message = request.message
+    session_id = request.session_id
+    assistant_id = request.assistant_id

-  try:
-    # --- 调用 ChatService 获取 AI 回复 ---
-    # 使用全局实例 (简单方式)
-    ai_reply = await chat_service_instance.get_ai_reply(user_message)
-    # 或者使用依赖注入获取的实例
-    # ai_reply = await chat_service.get_ai_reply(user_message, session_id)
+    print(f"接收到消息: User='{user_message}', Session='{session_id}', Assistant='{assistant_id}'")

-    print(f"发送 AI 回复: {ai_reply}")
-    return ChatResponse(reply=ai_reply)
+    response_session_id = None
+    response_session_title = None

-  except Exception as e:
-    # 如果 ChatService 抛出异常，捕获并返回 HTTP 500 错误
-    print(f"处理聊天消息时发生错误: {e}")
-    raise HTTPException(status_code=500, detail=str(e))
+    # --- 处理临时新会话 ---
+    if session_id == 'temp-new-chat':
+        print("检测到临时新会话，正在创建...")
+        try:
+            # 调用 SessionService 创建会话
+            create_req = SessionCreateRequest(assistant_id=assistant_id, first_message=user_message)
+            created_session = await session_service.create_session(create_req)
+            session_id = created_session.id # 使用新创建的会话 ID
+            response_session_id = created_session.id # 准备在响应中返回新 ID
+            response_session_title = created_session.title # 准备在响应中返回新标题
+            print(f"新会话已创建: ID={session_id}, Title='{created_session.title}'")
+        except ValueError as e: # 助手不存在等错误
+            raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
+        except Exception as e: # LLM 调用或其他错误
+            print(f"创建会话时出错: {e}")
+            raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="创建会话失败")
+
+    # --- 调用聊天服务获取回复 ---
+    try:
+        ai_reply = await chat_service.get_ai_reply(
+            user_message=user_message,
+            session_id=session_id, # 使用真实的或新创建的 session_id
+            assistant_id=assistant_id
+        )
+        print(f"发送 AI 回复: '{ai_reply}'")
+        return ChatResponse(
+            reply=ai_reply,
+            session_id=response_session_id, # 返回新 ID (如果创建了)
+            session_title=response_session_title # 返回新标题 (如果创建了)
+        )
+    except ValueError as e: # 助手不存在等错误
+         raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
+    except Exception as e: # LLM 调用或其他错误
+        print(f"处理聊天消息时发生错误: {e}")
+        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail=str(e))
--- a/backend/app/api/v1/endpoints/sessions.py
+++ b/backend/app/api/v1/endpoints/sessions.py
@ -0,0 +1,58 @@
+# File: backend/app/api/v1/endpoints/sessions.py (新建)
+# Description: 会话管理的 API 路由
+
+from fastapi import APIRouter, HTTPException, Depends, status
+from typing import List
+from app.models.pydantic_models import SessionRead, SessionCreateRequest, SessionCreateResponse
+from app.services.session_service import session_service_instance, SessionService
+
+router = APIRouter()
+
+def get_session_service() -> SessionService:
+    return session_service_instance
+
+@router.post("/", response_model=SessionCreateResponse, status_code=status.HTTP_201_CREATED)
+async def create_new_session(
+    session_data: SessionCreateRequest,
+    service: SessionService = Depends(get_session_service)
+):
+    """创建新会话并自动生成标题"""
+    try:
+        return await service.create_session(session_data)
+    except ValueError as e:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
+    except Exception as e:
+        # 处理可能的 LLM 调用错误
+        print(f"创建会话时出错: {e}")
+        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="创建会话失败")
+
+@router.get("/assistant/{assistant_id}", response_model=List[SessionRead])
+async def read_sessions_for_assistant(
+    assistant_id: str,
+    service: SessionService = Depends(get_session_service)
+):
+    """获取指定助手的所有会话列表"""
+    # TODO: 添加检查助手是否存在
+    return service.get_sessions_by_assistant(assistant_id)
+
+@router.get("/{session_id}", response_model=SessionRead)
+async def read_session_by_id(
+    session_id: str,
+    service: SessionService = Depends(get_session_service)
+):
+    """获取单个会话信息"""
+    session = service.get_session(session_id)
+    if not session:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的会话")
+    return session
+
+@router.delete("/{session_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_existing_session(
+    session_id: str,
+    service: SessionService = Depends(get_session_service)
+):
+    """删除指定 ID 的会话"""
+    deleted = service.delete_session(session_id)
+    if not deleted:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的会话")
+
--- a/backend/app/models/pydantic_models.py
+++ b/backend/app/models/pydantic_models.py
@ -1,16 +1,76 @@
-# File: backend/app/models/pydantic_models.py
+# File: backend/app/models/pydantic_models.py (更新)
 # Description: Pydantic 模型定义 API 数据结构

-from pydantic import BaseModel
+from pydantic import BaseModel, Field
+from typing import Optional, List
+import uuid # 用于生成唯一 ID
+
+# --- Assistant Models ---
+
+class AssistantBase(BaseModel):
+    """助手的基础模型，包含通用字段"""
+    name: str = Field(..., min_length=1, max_length=50, description="助手名称")
+    description: Optional[str] = Field(None, max_length=200, description="助手描述")
+    avatar: Optional[str] = Field(None, max_length=5, description="头像 Emoji 或字符")
+    system_prompt: str = Field(..., min_length=1, max_length=4000, description="系统提示")
+    model: str = Field(..., description="使用的 LLM 模型")
+    temperature: float = Field(0.7, ge=0.0, le=1.0, description="温度参数 (0.0-1.0)")
+    # 可以添加 top_p, max_tokens 等
+
+class AssistantCreate(AssistantBase):
+    """创建助手时使用的模型 (不需要 ID)"""
+    pass
+
+class AssistantUpdate(BaseModel):
+    """更新助手时使用的模型 (所有字段可选)"""
+    name: Optional[str] = Field(None, min_length=1, max_length=50)
+    description: Optional[str] = Field(None, max_length=200)
+    avatar: Optional[str] = Field(None, max_length=5)
+    system_prompt: Optional[str] = Field(None, min_length=1, max_length=4000)
+    model: Optional[str] = None
+    temperature: Optional[float] = Field(None, ge=0.0, le=1.0)
+
+class AssistantRead(AssistantBase):
+    """读取助手信息时返回的模型 (包含 ID)"""
+    id: str = Field(..., description="助手唯一 ID")
+
+    class Config:
+        from_attributes = True # Pydantic v2: orm_mode = True
+
+# --- Chat Models (更新) ---

 class ChatRequest(BaseModel):
-  """聊天请求模型"""
-  message: str
-  # 可以添加更多字段，如 user_id, session_id 等
+    """聊天请求模型 (添加 sessionId 和 assistantId)"""
+    message: str
+    session_id: str = Field(..., description="当前会话 ID (可以是 'temp-new-chat')")
+    assistant_id: str = Field(..., description="当前使用的助手 ID")

 class ChatResponse(BaseModel):
-  """聊天响应模型"""
-  reply: str
-  # 可以添加更多字段，如 message_id, status 等
+    """聊天响应模型"""
+    reply: str
+    session_id: Optional[str] = None # (可选) 如果创建了新会话，返回新 ID
+    session_title: Optional[str] = None # (可选) 如果创建了新会话，返回新标题

-# --- 你可以在这里添加其他功能的模型 ---
+# --- Session Models ---
+
+class SessionCreateRequest(BaseModel):
+    """创建会话请求模型"""
+    assistant_id: str
+    first_message: str # 用户的第一条消息，用于生成标题
+
+class SessionCreateResponse(BaseModel):
+    """创建会话响应模型"""
+    id: str
+    title: str
+    assistant_id: str
+    created_at: str # 返回 ISO 格式时间字符串
+
+class SessionRead(BaseModel):
+    """读取会话信息模型"""
+    id: str
+    title: str
+    assistant_id: str
+    created_at: str
+
+    class Config:
+        from_attributes = True
--- a/backend/app/services/assistant_service.py
+++ b/backend/app/services/assistant_service.py
@ -0,0 +1,73 @@
+# File: backend/app/services/assistant_service.py (新建)
+# Description: 管理助手数据的服务 (内存实现)
+
+from typing import Dict, List, Optional
+from app.models.pydantic_models import AssistantRead, AssistantCreate, AssistantUpdate
+import uuid
+
+# 使用字典作为内存数据库存储助手
+# key: assistant_id (str), value: AssistantRead object
+assistants_db: Dict[str, AssistantRead] = {}
+
+# 添加默认助手 (确保 ID 与前端 Mock 一致)
+default_assistant = AssistantRead(
+    id='asst-default',
+    name='默认助手',
+    description='通用聊天助手',
+    avatar='🤖',
+    system_prompt='你是一个乐于助人的 AI 助手。',
+    model='gpt-3.5-turbo',
+    temperature=0.7
+)
+assistants_db[default_assistant.id] = default_assistant
+
+class AssistantService:
+    """助手数据的 CRUD 服务"""
+
+    def get_assistants(self) -> List[AssistantRead]:
+        """获取所有助手"""
+        return list(assistants_db.values())
+
+    def get_assistant(self, assistant_id: str) -> Optional[AssistantRead]:
+        """根据 ID 获取单个助手"""
+        return assistants_db.get(assistant_id)
+
+    def create_assistant(self, assistant_data: AssistantCreate) -> AssistantRead:
+        """创建新助手"""
+        new_id = f"asst-{uuid.uuid4()}" # 生成唯一 ID
+        new_assistant = AssistantRead(id=new_id, **assistant_data.model_dump())
+        assistants_db[new_id] = new_assistant
+        print(f"助手已创建: {new_id} - {new_assistant.name}")
+        return new_assistant
+
+    def update_assistant(self, assistant_id: str, assistant_data: AssistantUpdate) -> Optional[AssistantRead]:
+        """更新现有助手"""
+        existing_assistant = assistants_db.get(assistant_id)
+        if not existing_assistant:
+            return None
+
+        # 使用 Pydantic 的 model_copy 和 update 来更新字段
+        update_data = assistant_data.model_dump(exclude_unset=True) # 只获取设置了值的字段
+        if update_data:
+             updated_assistant = existing_assistant.model_copy(update=update_data)
+             assistants_db[assistant_id] = updated_assistant
+             print(f"助手已更新: {assistant_id}")
+             return updated_assistant
+        return existing_assistant # 如果没有更新任何字段，返回原始助手
+
+    def delete_assistant(self, assistant_id: str) -> bool:
+        """删除助手"""
+        if assistant_id in assistants_db:
+            # 添加逻辑：不允许删除默认助手
+            if assistant_id == 'asst-default':
+                print("尝试删除默认助手 - 操作被阻止")
+                return False # 或者抛出特定异常
+            del assistants_db[assistant_id]
+            print(f"助手已删除: {assistant_id}")
+            # TODO: 在实际应用中，还需要删除关联的会话和消息
+            return True
+        return False
+
+# 创建服务实例
+assistant_service_instance = AssistantService()
+
--- a/backend/app/services/chat_service.py
+++ b/backend/app/services/chat_service.py
@ -1,92 +1,127 @@
-# File: backend/app/services/chat_service.py (新建)
-# Description: 封装 LangChain 聊天逻辑
+# File: backend/app/services/chat_service.py (更新)
+# Description: 封装 LangChain 聊天逻辑 (支持助手配置和会话历史)

 from langchain_openai import ChatOpenAI
-from langchain_google_genai import ChatGoogleGenerativeAI # 如果使用 Google
 from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
 from langchain_core.output_parsers import StrOutputParser
-from langchain_core.messages import HumanMessage, AIMessage
+from langchain_core.messages import HumanMessage, AIMessage, BaseMessage, SystemMessage
+from typing import Dict, List, Optional
+from app.services.assistant_service import assistant_service_instance # 获取助手配置
+from app.models.pydantic_models import AssistantRead # 引入助手模型
+import app.core.config as Config

-# --- 可选：添加内存管理 ---
-# 简单的内存实现 (可以替换为更复杂的 LangChain Memory 类)
-chat_history = {} # 使用字典存储不同会话的内存，需要 session_id
+# --- 更新内存管理 ---
+# 使用字典存储不同会话的内存
+# key: session_id (str), value: List[BaseMessage]
+chat_history_db: Dict[str, List[BaseMessage]] = {}

 class ChatService:
-    """处理 AI 聊天交互的服务"""
+    """处理 AI 聊天交互的服务 (支持助手配置)"""

-    def __init__(self, api_key: str):
+    def __init__(self, default_api_key: str):
+        """初始化时可传入默认 API Key"""
+        self.default_api_key = default_api_key
+        # 不再在 init 中创建固定的 LLM 和 chain
+
+    def _get_llm(self, assistant: AssistantRead) -> ChatOpenAI:
+        """根据助手配置动态创建 LLM 实例"""
+        # TODO: 支持不同模型提供商 (Gemini, Anthropic etc.)
+        if assistant.model.startswith("gpt"):
+            return ChatOpenAI(
+                model=assistant.model,
+                api_key=self.default_api_key, # 或从助手配置中读取特定 key
+                temperature=assistant.temperature
+            )
+        elif assistant.model.startswith("gemini"):
+            from langchain_google_genai import ChatGoogleGenerativeAI
+            return ChatGoogleGenerativeAI(
+                model=assistant.model,
+                api_key=self.default_api_key, # 或从助手配置中读取特定 key
+                temperature=assistant.temperature
+            )
+        else:
+            # 默认或抛出错误
+             print(f"警告: 模型 {assistant.model} 未明确支持，尝试使用 ChatOpenAI")
+             return ChatOpenAI(
+                model=assistant.model,
+                api_key=self.default_api_key,
+                temperature=assistant.temperature
+            )
+
+    async def get_ai_reply(self, user_message: str, session_id: str, assistant_id: str) -> str:
        """
-        初始化 ChatService
-        Args:
-            api_key (str): 用于 LLM 的 API 密钥
-        """
-        # --- 选择并初始化 LLM ---
-        # 使用 OpenAI GPT-3.5 Turbo (推荐) 或 GPT-4
-        # self.llm = ChatOpenAI(model="gpt-3.5-turbo", api_key=api_key, temperature=0.7)
-        # self.llm = ChatOpenAI(model="gpt-4", api_key=api_key, temperature=0.7)
-
-        # --- 如果使用 Google Gemini ---
-        self.llm = ChatGoogleGenerativeAI(model="gemini-2.0-flash", google_api_key=api_key, convert_system_message_to_human=True)
-
-        # --- 定义 Prompt 模板 ---
-        # 包含系统消息、历史记录占位符和当前用户输入
-        self.prompt = ChatPromptTemplate.from_messages([
-            ("system", "你是一个乐于助人的 AI 助手，请用简洁明了的语言回答问题。你的名字叫 CherryAI。"),
-            MessagesPlaceholder(variable_name="chat_history"), # 用于插入历史消息
-            ("human", "{input}"), # 用户当前输入
-        ])
-
-        # --- 定义输出解析器 ---
-        # 将 LLM 的输出解析为字符串
-        self.output_parser = StrOutputParser()
-
-        # --- 构建 LangChain Expression Language (LCEL) 链 ---
-        self.chain = self.prompt | self.llm | self.output_parser
-
-    async def get_ai_reply(self, user_message: str, session_id: str = "default_session") -> str:
-        """
-        获取 AI 对用户消息的回复 (异步)
+        获取 AI 对用户消息的回复 (使用指定助手和会话历史)
        Args:
            user_message (str): 用户发送的消息
-            session_id (str): (可选) 用于区分不同对话的会话 ID，以支持内存
+            session_id (str): 会话 ID
+            assistant_id (str): 使用的助手 ID
        Returns:
            str: AI 的回复文本
        Raises:
+            ValueError: 如果找不到指定的助手
            Exception: 如果调用 AI 服务时发生错误
        """
-        try:
-            # --- 获取当前会话的历史记录 (如果需要内存) ---
-            current_chat_history = chat_history.get(session_id, [])
+        # 1. 获取助手配置
+        assistant = assistant_service_instance.get_assistant(assistant_id)
+        if not assistant:
+            raise ValueError(f"找不到助手 ID: {assistant_id}")

-            # --- 使用 ainvoke 进行异步调用 ---
-            ai_response = await self.chain.ainvoke({
+        # 2. 获取或初始化当前会话的历史记录
+        current_chat_history = chat_history_db.get(session_id, [])
+
+        # 3. 构建 Prompt (包含动态系统提示)
+        prompt = ChatPromptTemplate.from_messages([
+            SystemMessage(content=assistant.system_prompt), # 使用助手的系统提示
+            MessagesPlaceholder(variable_name="chat_history"),
+            HumanMessage(content="{input}"),
+        ])
+
+        # 4. 获取 LLM 实例
+        llm = self._get_llm(assistant)
+
+        # 5. 定义输出解析器
+        output_parser = StrOutputParser()
+
+        # 6. 构建 LCEL 链
+        chain = prompt | llm | output_parser
+
+        try:
+            # 7. 调用链获取回复
+            ai_response = await chain.ainvoke({
                "input": user_message,
-                "chat_history": current_chat_history, # 传入历史记录
+                "chat_history": current_chat_history,
            })

-            # --- 更新会话历史记录 (如果需要内存) ---
-            # 只保留最近 N 轮对话，防止历史过长
-            max_history_length = 10 # 保留最近 5 轮对话 (10条消息)
+            # 8. 更新会话历史记录
            current_chat_history.append(HumanMessage(content=user_message))
            current_chat_history.append(AIMessage(content=ai_response))
-            # 如果历史记录超过长度，移除最早的消息
+            # 限制历史记录长度 (例如最近 10 条消息)
+            max_history_length = 10
            if len(current_chat_history) > max_history_length:
-                chat_history[session_id] = current_chat_history[-max_history_length:]
+                 chat_history_db[session_id] = current_chat_history[-max_history_length:]
            else:
-                chat_history[session_id] = current_chat_history
+                 chat_history_db[session_id] = current_chat_history

            return ai_response

        except Exception as e:
-            print(f"调用 LangChain 时出错: {e}")
-            # 可以进行更细致的错误处理，例如区分 API 错误和内部错误
+            print(f"调用 LangChain 时出错 (助手: {assistant_id}, 会话: {session_id}): {e}")
            raise Exception(f"AI 服务暂时不可用: {e}")

+    # (可选) 添加一个简单的文本生成方法用于生成标题
+    async def generate_text(self, prompt_text: str, model_name: str = "gpt-3.5-turbo", temperature: float = 0.5) -> str:
+         """使用指定模型生成文本 (用于标题等)"""
+         try:
+             # 使用一个临时的、可能更便宜的模型
+             temp_llm = ChatOpenAI(model=model_name, api_key=self.default_api_key, temperature=temperature)
+             response = await temp_llm.ainvoke(prompt_text)
+             return response.content
+         except Exception as e:
+             print(f"生成文本时出错: {e}")
+             return "无法生成标题" # 返回默认值或抛出异常

-# --- 在文件末尾，创建 ChatService 的实例 ---
-# 从配置中获取 API Key
-from app.core.config import GOOGLE_API_KEY
-if not GOOGLE_API_KEY:
-    raise ValueError("请在 .env 文件中设置 GOOGLE_API_KEY")

-chat_service_instance = ChatService(api_key=GOOGLE_API_KEY)
+# --- 创建 ChatService 实例 ---
+if not Config.GOOGLE_API_KEY:
+    raise ValueError("请在 .env 文件中设置 OPENAI_API_KEY")
+chat_service_instance = ChatService(default_api_key=Config.GOOGLE_API_KEY)
--- a/backend/app/services/session_service.py
+++ b/backend/app/services/session_service.py
@ -0,0 +1,82 @@
+# File: backend/app/services/session_service.py (新建)
+# Description: 管理会话数据的服务 (内存实现)
+
+from typing import Dict, List, Optional
+from app.models.pydantic_models import SessionRead, SessionCreateRequest, SessionCreateResponse, AssistantRead
+from app.services.assistant_service import assistant_service_instance # 需要获取助手信息
+from datetime import datetime, timezone
+import uuid
+# 导入 ChatService 以调用 LLM 生成标题 (避免循环导入，考虑重构)
+# from app.services.chat_service import chat_service_instance
+
+# 内存数据库存储会话
+# key: session_id (str), value: SessionRead object
+sessions_db: Dict[str, SessionRead] = {}
+
+class SessionService:
+    """会话数据的 CRUD 及标题生成服务"""
+
+    async def create_session(self, session_data: SessionCreateRequest) -> SessionCreateResponse:
+        """创建新会话并生成标题"""
+        assistant = assistant_service_instance.get_assistant(session_data.assistant_id)
+        if not assistant:
+            raise ValueError("指定的助手不存在")
+
+        new_id = f"session-{uuid.uuid4()}"
+        created_time = datetime.now(timezone.utc)
+
+        # --- TODO: 调用 LLM 生成标题 ---
+        # title_prompt = f"根据以下用户第一条消息，为此对话生成一个简洁的标题（不超过10个字）:\n\n{session_data.first_message}"
+        # generated_title = await chat_service_instance.generate_text(title_prompt) # 需要一个简单的文本生成方法
+
+        # 模拟标题生成
+        generated_title = f"关于 \"{session_data.first_message[:15]}...\""
+        print(f"为新会话 {new_id} 生成标题: {generated_title}")
+        # --- 模拟结束 ---
+
+        new_session = SessionRead(
+            id=new_id,
+            title=generated_title,
+            assistant_id=session_data.assistant_id,
+            created_at=created_time.isoformat() # 存储 ISO 格式字符串
+        )
+        sessions_db[new_id] = new_session
+        print(f"会话已创建: {new_id}")
+
+        return SessionCreateResponse(
+            id=new_session.id,
+            title=new_session.title,
+            assistant_id=new_session.assistant_id,
+            created_at=new_session.created_at
+        )
+
+    def get_sessions_by_assistant(self, assistant_id: str) -> List[SessionRead]:
+        """获取指定助手的所有会话"""
+        return [s for s in sessions_db.values() if s.assistant_id == assistant_id]
+
+    def get_session(self, session_id: str) -> Optional[SessionRead]:
+        """获取单个会话"""
+        return sessions_db.get(session_id)
+
+    def delete_session(self, session_id: str) -> bool:
+        """删除会话"""
+        if session_id in sessions_db:
+            del sessions_db[session_id]
+            print(f"会话已删除: {session_id}")
+            # TODO: 删除关联的消息
+            return True
+        return False
+
+    def delete_sessions_by_assistant(self, assistant_id: str) -> int:
+        """删除指定助手的所有会话"""
+        ids_to_delete = [s.id for s in sessions_db.values() if s.assistant_id == assistant_id]
+        count = 0
+        for session_id in ids_to_delete:
+            if self.delete_session(session_id):
+                count += 1
+        print(f"删除了助手 {assistant_id} 的 {count} 个会话")
+        return count
+
+
+# 创建服务实例
+session_service_instance = SessionService()
--- a/frontend/app/chat/page.tsx
+++ b/frontend/app/chat/page.tsx
@ -1,11 +1,31 @@
-// File: frontend/app/chat/page.tsx (更新会话逻辑)
-// Description: AI 聊天界面，实现助手关联会话、临时新对话和发送时创建会话
+// File: frontend/app/chat/page.tsx (更新以使用 API)
+// Description: 对接后端 API 实现助手和会话的加载与管理

 'use client';

 import React, { useState, useRef, useEffect, useCallback } from 'react';
-import { SendHorizontal, Loader2, PanelRightOpen, PanelRightClose, UserPlus, Settings2 } from 'lucide-react';
-import { sendChatMessage } from '@/lib/api'; // 假设 sendChatMessage 只需 message
+import { SendHorizontal, Loader2, PanelRightOpen, PanelRightClose, UserPlus, Settings2, Trash2, Edit, RefreshCw } from 'lucide-react'; // 添加刷新图标
+import { useForm } from "react-hook-form";
+import { zodResolver } from "@hookform/resolvers/zod";
+import * as z from "zod";
+
+// Shadcn UI Components
+import { Button } from "@/components/ui/button";
+import { Dialog, DialogContent, DialogDescription, DialogHeader, DialogTitle, DialogTrigger, DialogFooter, DialogClose } from "@/components/ui/dialog";
+import { Form, FormControl, FormDescription, FormField, FormItem, FormLabel, FormMessage } from "@/components/ui/form";
+import { Input } from "@/components/ui/input";
+import { Textarea } from "@/components/ui/textarea";
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
+import { Slider } from "@/components/ui/slider";
+import { Toaster, toast } from "sonner";
+import { Skeleton } from "@/components/ui/skeleton"; // 导入骨架屏
+
+// API 函数和类型
+import {
+    sendChatMessage, getAssistants, createAssistant, updateAssistant, deleteAssistant,
+    getSessionsByAssistant, deleteSession,
+    Assistant, Session, AssistantCreateData, AssistantUpdateData, ChatApiResponse
+} from '@/lib/api'; // 确保路径正确

 // --- 数据接口定义 ---
 interface Message {
@ -16,192 +36,442 @@ interface Message {
 }

 interface ChatSession {
-  id: string; // 唯一 ID，例如 'session-uuid-123' 或 'temp-new-chat'
+  id: string;
  title: string;
  createdAt: Date;
-  assistantId: string; // 关联的助手 ID
-  isTemporary?: boolean; // 标记是否为临时会话
+  assistantId: string;
+  isTemporary?: boolean;
 }

-interface Assistant {
-    id: string;
-    name: string;
-    description: string;
-    avatar?: string;
-    systemPrompt: string;
-    model: string;
-    temperature: number;
-}
+// --- Zod Schema for Assistant Form Validation ---
+const assistantFormSchema = z.object({
+  name: z.string().min(1, { message: "助手名称不能为空" }).max(50, { message: "名称过长" }),
+  description: z.string().max(200, { message: "描述过长" }).optional(),
+  avatar: z.string().max(5, { message: "头像/Emoji 过长" }).optional(), // 简单限制长度
+  system_prompt: z.string().min(1, { message: "系统提示不能为空" }).max(4000, { message: "系统提示过长" }),
+  model: z.string({ required_error: "请选择一个模型" }),
+  temperature: z.number().min(0).max(1),
+});
+
+type AssistantFormData = z.infer<typeof assistantFormSchema>;
+
+// 可选的模型列表
+const availableModels = [
+    { value: "gpt-3.5-turbo", label: "GPT-3.5 Turbo" },
+    { value: "gpt-4", label: "GPT-4" },
+    { value: "gpt-4-turbo", label: "GPT-4 Turbo" },
+    { value: "gemini-2.0-flash", label: "Gemini 2.0 Flash" },
+    { value: "deepseek-coder", label: "DeepSeek Coder" }, // 示例
+    // 添加更多模型...
+];

 // --- Helper Function ---
-// 查找助手的最新会话 (非临时)
 const findLastSession = (sessions: ChatSession[], assistantId: string): ChatSession | undefined => {
    return sessions
        .filter(s => s.assistantId === assistantId && !s.isTemporary)
        .sort((a, b) => b.createdAt.getTime() - a.createdAt.getTime())[0];
 };

+// --- Assistant Form Component ---
+interface AssistantFormProps {
+  assistant?: Assistant | null; // 传入表示编辑，否则是创建
+  onSave: (data: AssistantFormData, id?: string) => void; // 保存回调
+  onClose: () => void; // 关闭 Dialog 的回调
+}
+
+function AssistantForm({ assistant, onSave, onClose }: AssistantFormProps) {
+  const form = useForm<AssistantFormData>({
+    resolver: zodResolver(assistantFormSchema),
+    defaultValues: {
+      name: assistant?.name || "",
+      description: assistant?.description || "",
+      avatar: assistant?.avatar || "",
+      system_prompt: assistant?.system_prompt || "",
+      model: assistant?.model || availableModels[0].value, // 默认第一个模型
+      temperature: assistant?.temperature ?? 0.7, // 默认 0.7
+    },
+  });
+  const [isSaving, setIsSaving] = useState(false); // 添加保存状态
+  async function onSubmit(data: AssistantFormData) {
+    setIsSaving(true);
+    try {
+      await onSave(data, assistant?.id); // 调用异步保存函数
+      onClose(); // 成功后关闭
+    } catch (error) {
+      // 错误已在 onSave 中处理并 toast
+    } finally {
+      setIsSaving(false);
+    }
+  }
+
+  return (
+    <Form {...form}>
+      <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-4">
+        {/* Name */}
+        <FormField
+          control={form.control}
+          name="name"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>助手名称</FormLabel>
+              <FormControl>
+                <Input placeholder="例如：代码助手" {...field} />
+              </FormControl>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+        {/* Description */}
+        <FormField
+          control={form.control}
+          name="description"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>描述 (可选)</FormLabel>
+              <FormControl>
+                <Input placeholder="简单描述助手的功能" {...field} />
+              </FormControl>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+        {/* Avatar */}
+        <FormField
+          control={form.control}
+          name="avatar"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>头像 (可选)</FormLabel>
+              <FormControl>
+                <Input placeholder="输入 Emoji 或 URL" {...field} />
+              </FormControl>
+              <FormDescription>建议使用单个 Emoji。</FormDescription>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+        {/* System Prompt */}
+        <FormField
+          control={form.control}
+          name="system_prompt"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>系统提示 (System Prompt)</FormLabel>
+              <FormControl>
+                <Textarea
+                  placeholder="定义助手的角色和行为..."
+                  className="resize-y min-h-[100px]" // 允许垂直调整大小
+                  {...field}
+                />
+              </FormControl>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+        {/* Model Selection */}
+        <FormField
+          control={form.control}
+          name="model"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>模型</FormLabel>
+              <Select onValueChange={field.onChange} defaultValue={field.value}>
+                <FormControl>
+                  <SelectTrigger>
+                    <SelectValue placeholder="选择一个 AI 模型" />
+                  </SelectTrigger>
+                </FormControl>
+                <SelectContent>
+                  {availableModels.map(model => (
+                    <SelectItem key={model.value} value={model.value}>
+                      {model.label}
+                    </SelectItem>
+                  ))}
+                </SelectContent>
+              </Select>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+        {/* Temperature */}
+        <FormField
+          control={form.control}
+          name="temperature"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>温度 (Temperature): {field.value.toFixed(1)}</FormLabel>
+              <FormControl>
+                {/* Shadcn Slider expects an array for value */}
+                <Slider
+                  min={0}
+                  max={1}
+                  step={0.1}
+                  defaultValue={[field.value]} // Use defaultValue for initial render
+                  onValueChange={(value) => field.onChange(value[0])} // Update form state on change
+                  className="py-2" // Add padding for better interaction
+                />
+              </FormControl>
+              <FormDescription>
+                值越低越稳定，越高越有创造性。
+              </FormDescription>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+        <DialogFooter>
+            <DialogClose asChild>
+                <Button type="button" variant="outline" disabled={isSaving}>取消</Button>
+            </DialogClose>
+            <Button type="submit" disabled={isSaving}>
+                {isSaving ? <Loader2 className="mr-2 h-4 w-4 animate-spin" /> : null}
+                {isSaving ? '保存中...' : '保存助手'}
+            </Button>
+        </DialogFooter>
+      </form>
+    </Form>
+  );
+}
+
+
+// --- Main Chat Page Component ---
 export default function ChatPage() {
  // --- State Variables ---
  const [inputMessage, setInputMessage] = useState('');
-  const [messages, setMessages] = useState<Message[]>([]); // 初始为空，由选中助手/会话决定
-  const [isLoading, setIsLoading] = useState(false);
-  const [error, setError] = useState<string | null>(null);
+  const [messages, setMessages] = useState<Message[]>([]);
+
+  const [isLoading, setIsLoading] = useState(false); // AI 回复加载状态
+  const [error, setError] = useState<string | null>(null); // 通用错误显示 (可选)
+
  const [isSessionPanelOpen, setIsSessionPanelOpen] = useState(true);
+  const [isAssistantDialogOpen, setIsAssistantDialogOpen] = useState(false); // 控制助手表单 Dialog 显隐
+  const [editingAssistant, setEditingAssistant] = useState<Assistant | null>(null); // 当前正在编辑的助手

-  // --- Mock Data & State ---
-  const [assistants, setAssistants] = useState<Assistant[]>([
-      { id: 'asst-default', name: '默认助手', description: '通用聊天助手', avatar: '🤖', systemPrompt: '你是一个乐于助人的 AI 助手。', model: 'gpt-3.5-turbo', temperature: 0.7 },
-      { id: 'asst-coder', name: '代码助手', description: '帮助编写和解释代码', avatar: '💻', systemPrompt: '你是一个专业的代码助手...', model: 'gpt-4', temperature: 0.5 },
-      { id: 'asst-writer', name: '写作助手', description: '协助进行创意写作', avatar: '✍️', systemPrompt: '你是一位富有创意的写作伙伴...', model: 'gemini-pro', temperature: 0.9 },
-  ]);
-  const [currentAssistantId, setCurrentAssistantId] = useState<string>('asst-default');
+    // Data Loading States
+  const [assistantsLoading, setAssistantsLoading] = useState(true);
+  const [sessionsLoading, setSessionsLoading] = useState(false);

-  // 所有会话存储在一起，通过 assistantId 过滤
-  const [allSessions, setAllSessions] = useState<ChatSession[]>([
-      {id: 'session-1', title: '默认助手的讨论', createdAt: new Date(Date.now() - 3600000), assistantId: 'asst-default'},
-      {id: 'session-2', title: '代码调试记录', createdAt: new Date(Date.now() - 7200000), assistantId: 'asst-coder'},
-      {id: 'session-3', title: '默认助手的学习 LangChain', createdAt: new Date(), assistantId: 'asst-default'},
-  ]);
-  // 当前激活的会话 ID，可能是真实 ID 或 'temp-new-chat'
-  const [currentSessionId, setCurrentSessionId] = useState<string | null>(null);
+  // Data State
+  const [assistants, setAssistants] = useState<Assistant[]>([]);
+  const [currentAssistantId, setCurrentAssistantId] = useState<string | null>(null); // 初始为 null
+  const [allSessions, setAllSessions] = useState<Session[]>([]);
+  const [currentSessionId, setCurrentSessionId] = useState<string | null>(null); // 初始为 null

  // --- Refs ---
  const messagesEndRef = useRef<null | HTMLDivElement>(null);

  // --- Effects ---
-  // 自动滚动
+  // Initial data loading (Assistants)
  useEffect(() => {
-    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
-  }, [messages]);
+    const loadAssistants = async () => {
+      setAssistantsLoading(true);
+      try {
+        const fetchedAssistants = await getAssistants();
+        setAssistants(fetchedAssistants);
+        // 设置默认选中的助手 (例如第一个或 ID 为 'asst-default' 的)
+        const defaultAssistant = fetchedAssistants.find(a => a.id === 'asst-default') || fetchedAssistants[0];
+        if (defaultAssistant) {
+          setCurrentAssistantId(defaultAssistant.id);
+        } else {
+            console.warn("No default or initial assistant found.");
+            // 可能需要提示用户创建助手
+        }
+      } catch (apiError: any) {
+        toast.error(`加载助手列表失败: ${apiError.message}`);
+        setError(`无法加载助手: ${apiError.message}`);
+      } finally {
+        setAssistantsLoading(false);
+      }
+    };
+    loadAssistants();
+  }, []); // 空依赖数组，只在挂载时运行一次

-  // 根据当前助手 ID 过滤出会话列表
-  const currentAssistantSessions = React.useMemo(() => {
-      return allSessions.filter(s => s.assistantId === currentAssistantId);
-  }, [allSessions, currentAssistantId]);
-
-  // 当助手切换时，决定加载哪个会话
+  // Load sessions when assistant changes
  useEffect(() => {
-      const lastSession = findLastSession(allSessions, currentAssistantId);
-      if (lastSession) {
+    if (!currentAssistantId) return; // 如果没有选中助手，则不加载
+
+    const loadSessions = async () => {
+      setSessionsLoading(true);
+      // 清空当前会话和消息列表
+      setCurrentSessionId(null);
+      setMessages([]);
+      try {
+        const fetchedSessions = await getSessionsByAssistant(currentAssistantId);
+        // 更新全局会话列表 (只保留其他助手的会话，加上当前助手的)
+        setAllSessions(prev => [
+            ...prev.filter(s => s.assistant_id !== currentAssistantId),
+            ...fetchedSessions
+        ]);
+
+        // 查找最新的会话并设为当前
+        const lastSession = fetchedSessions
+            .sort((a, b) => new Date(b.created_at).getTime() - new Date(a.created_at).getTime())[0];
+
+        if (lastSession) {
          setCurrentSessionId(lastSession.id);
-          // TODO: 在实际应用中，这里需要调用 API 加载 lastSession.id 的历史消息
+          // TODO: 加载 lastSession.id 的历史消息
          console.log(`加载助手 ${currentAssistantId} 的最后一个会话: ${lastSession.id}`);
-          // 模拟加载消息
-          const selectedAssistant = assistants.find(a => a.id === currentAssistantId);
-          setMessages([
-              { id: `init-${lastSession.id}-1`, text: `继续与 ${selectedAssistant?.name || '助手'} 的对话: ${lastSession.title}`, sender: 'ai' },
-              // ... 应该加载真实历史消息
-          ]);
-      } else {
+          const currentAssistant = assistants.find(a => a.id === currentAssistantId);
+          setMessages([ { id: `init-${lastSession.id}-1`, text: `继续与 ${currentAssistant?.name || '助手'} 的对话: ${lastSession.title}`, sender: 'ai' } ]);
+        } else {
          // 没有历史会话，进入临时新对话状态
          setCurrentSessionId('temp-new-chat');
          console.log(`助手 ${currentAssistantId} 没有历史会话，创建临时新对话`);
-          const selectedAssistant = assistants.find(a => a.id === currentAssistantId);
-          setMessages([
-              { id: `init-temp-${currentAssistantId}`, text: `开始与 ${selectedAssistant?.name || '助手'} 的新对话吧！`, sender: 'ai' },
-          ]);
-          // 不将会话添加到 allSessions 列表
+           const currentAssistant = assistants.find(a => a.id === currentAssistantId);
+          setMessages([ { id: `init-temp-${currentAssistantId}`, text: `开始与 ${currentAssistant?.name || '助手'} 的新对话吧！`, sender: 'ai' } ]);
+        }
+      } catch (apiError: any) {
+        toast.error(`加载会话列表失败: ${apiError.message}`);
+      } finally {
+        setSessionsLoading(false);
      }
-  }, [currentAssistantId, allSessions, assistants]); // 依赖助手 ID 和所有会话
+    };

+    loadSessions();
+  }, [currentAssistantId, assistants]); // 依赖助手 ID 和助手列表 (以防助手信息更新)
+  
+  // Auto scroll
+  useEffect(() => {
+    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
+  }, [messages]);
+  
+  // Filter sessions for the current assistant (UI display)
+  const currentAssistantSessions = React.useMemo(() => {
+      // 直接从 allSessions 过滤，因为加载时已经更新了
+      return allSessions
+          .filter(s => s.assistant_id === currentAssistantId)
+          .sort((a, b) => new Date(b.created_at).getTime() - new Date(a.created_at).getTime()); // 按时间倒序
+  }, [allSessions, currentAssistantId]);

-  // --- Event Handlers ---
+    // --- Assistant CRUD Handlers (Updated with API calls) ---
+  const handleSaveAssistant = async (data: AssistantFormData, id?: string) => {
+    try {
+      let savedAssistant: Assistant;
+      if (id) {
+        // 编辑
+        savedAssistant = await updateAssistant(id, data);
+        setAssistants(prev => prev.map(a => (a.id === id ? savedAssistant : a)));
+        toast.success(`助手 "${savedAssistant.name}" 已更新`);
+        // 如果更新的是当前助手，可能需要重新加载会话或消息
+        if (id === currentAssistantId) {
+            // 简单处理：可以强制刷新会话列表（或提示用户）
+             setCurrentAssistantId(null); // 触发 useEffect 重新加载
+             setTimeout(() => setCurrentAssistantId(id), 0);
+        }
+      } else {
+        // 创建
+        savedAssistant = await createAssistant(data);
+        setAssistants(prev => [...prev, savedAssistant]);
+        toast.success(`助手 "${savedAssistant.name}" 已创建`);
+        // 创建后自动选中
+        handleSelectAssistant(savedAssistant.id);
+      }
+    } catch (apiError: any) {
+      toast.error(`保存助手失败: ${apiError.message}`);
+      throw apiError; // 重新抛出错误，让表单的 finally 处理 isSaving
+    }
+  };
+
+    const handleDeleteAssistant = async (idToDelete: string) => {
+    if (idToDelete === 'asst-default' || assistants.length <= 1) {
+      toast.error("不能删除默认助手或最后一个助手");
+      return;
+    }
+    if (idToDelete === currentAssistantId) {
+      toast.error("请先切换到其他助手再删除");
+      return;
+    }
+
+    const assistantToDelete = assistants.find(a => a.id === idToDelete);
+    if (window.confirm(`确定要删除助手 "${assistantToDelete?.name}" 吗？相关会话也将被删除。`)) {
+      try {
+        await deleteAssistant(idToDelete);
+        // 后端应负责删除关联会话，前端只需更新助手列表
+        setAssistants(prev => prev.filter(a => a.id !== idToDelete));
+        // (可选) 如果需要立即清除前端的会话缓存
+        // setAllSessions(prev => prev.filter(s => s.assistant_id !== idToDelete));
+        toast.success(`助手 "${assistantToDelete?.name}" 已删除`);
+      } catch (apiError: any) {
+        toast.error(`删除助手失败: ${apiError.message}`);
+      }
+    }
+  };
+
+  const handleEditAssistant = (assistant: Assistant) => {
+      setEditingAssistant(assistant);
+      setIsAssistantDialogOpen(true);
+  };
+
+  const handleOpenCreateAssistantDialog = () => {
+      setEditingAssistant(null);
+      setIsAssistantDialogOpen(true);
+  };
+
+  // --- Send Message Handler (Updated with API response handling) ---
  const handleSendMessage = async (e?: React.FormEvent<HTMLFormElement>) => {
    e?.preventDefault();
    const trimmedMessage = inputMessage.trim();
-    if (!trimmedMessage || isLoading) return;
+    if (!trimmedMessage || isLoading || !currentSessionId || !currentAssistantId) return; // 增加检查
    setError(null);
-    setIsLoading(true); // 先设置加载状态
+    setIsLoading(true);

    const userMessage: Message = {
      id: Date.now().toString(),
      text: trimmedMessage,
      sender: 'user',
    };
+    // 立即显示用户消息
+    setMessages(prev => [...prev, userMessage]);
+    setInputMessage(''); // 清空输入框

-    let targetSessionId = currentSessionId;
-    let newSessionCreated = false;
-
-    // 检查是否是临时新对话的第一条消息
-    if (currentSessionId === 'temp-new-chat') {
-        console.log("发送临时新对话的第一条消息，准备创建会话...");
-        try {
-            // --- 模拟后端创建会话并生成标题 ---
-            // TODO: 调用后端 API (e.g., POST /api/v1/sessions)
-            // const { newSessionId, newTitle } = await createSessionOnBackend(currentAssistantId, trimmedMessage);
-            await new Promise(resolve => setTimeout(resolve, 500)); // 模拟网络延迟
-            const newSessionId = `session-${Date.now()}`; // 模拟生成的新 ID
-            const newTitle = `关于 "${trimmedMessage.substring(0, 15)}..." 的讨论`; // 模拟 AI 生成的标题
-            // --- 模拟结束 ---
-
-            const newSession: ChatSession = {
-                id: newSessionId,
-                title: newTitle,
-                createdAt: new Date(),
-                assistantId: currentAssistantId,
-                isTemporary: false, // 不再是临时的
-            };
-
-            // 将新创建的会话添加到全局列表，并设为当前会话
-            setAllSessions(prev => [...prev, newSession]);
-            setCurrentSessionId(newSessionId);
-            targetSessionId = newSessionId; // 更新目标会话 ID
-            newSessionCreated = true; // 标记已创建
-            console.log(`新会话创建成功: ID=${newSessionId}, Title=${newTitle}`);
-
-            // 更新消息列表（先添加用户消息）
-            // 注意：因为 setMessages 是异步的，这里先更新，后续 AI 回复再更新
-            setMessages(prev => [...prev, userMessage]);
-
-
-        } catch (creationError: any) {
-            console.error("创建新会话失败:", creationError);
-            setError(`无法创建新会话: ${creationError.message}`);
-            setIsLoading(false);
-            return; // 创建失败则停止后续操作
-        }
-    } else {
-        // 不是新会话，直接将用户消息添加到当前消息列表
-         setMessages(prev => [...prev, userMessage]);
-    }
-
-
-    // 清空输入框
-    setInputMessage('');
-
-    // 发送消息到后端 (无论是否新创建会话，都需要发送)
    try {
-        console.log(`发送消息到会话: ${targetSessionId}, 助手: ${currentAssistantId}`);
-        // TODO: 调用后端 API 时需要传递 targetSessionId 和 currentAssistantId
-        // const aiReply = await sendChatMessage(trimmedMessage, targetSessionId, currentAssistantId);
-        const aiReply = await sendChatMessage(trimmedMessage); // 暂时保持不变
+      // 调用后端 API
+      const response: ChatApiResponse = await sendChatMessage(
+          trimmedMessage,
+          currentSessionId, // 发送当前 session ID ('temp-new-chat' 或真实 ID)
+          currentAssistantId
+      );

-        const aiMessage: Message = {
-            id: Date.now().toString() + '_ai',
-            text: aiReply,
-            sender: 'ai',
-        };
-        // 使用函数式更新，确保基于最新的消息列表添加回复
-        setMessages((prevMessages) => [...prevMessages, aiMessage]);
+      // 处理 AI 回复
+      const aiMessage: Message = {
+        id: Date.now().toString() + '_ai',
+        text: response.reply,
+        sender: 'ai',
+      };
+      setMessages((prevMessages) => [...prevMessages, aiMessage]);

-    } catch (sendError: any) {
-        console.error("发送消息失败:", sendError);
-        const errorMessageText = sendError.message || 'An unknown error occurred.';
-        setError(errorMessageText); // 更新错误状态
-        const errorMessage: Message = {
-            id: Date.now().toString() + '_err',
-            text: `错误: ${errorMessageText}`,
-            sender: 'ai',
-            isError: true,
+      // 如果后端创建了新会话并返回了信息
+      if (response.session_id && response.session_title && currentSessionId === 'temp-new-chat') {
+        const newSession: Session = {
+          id: response.session_id,
+          title: response.session_title,
+          assistant_id: currentAssistantId,
+          created_at: new Date().toISOString(), // 使用客户端时间或后端返回的时间
        };
-        setMessages((prevMessages) => [...prevMessages, errorMessage]);
+        // 更新全局会话列表和当前会话 ID
+        setAllSessions(prev => [...prev, newSession]);
+        setCurrentSessionId(newSession.id);
+        console.log(`前端已更新新会话信息: ID=${newSession.id}, Title=${newSession.title}`);
+      }
+
+    } catch (apiError: any) {
+      console.error("发送消息失败:", apiError);
+      const errorMessageText = apiError.message || '发生未知错误';
+      setError(errorMessageText);
+      const errorMessage: Message = {
+        id: Date.now().toString() + '_err',
+        text: `错误: ${errorMessageText}`,
+        sender: 'ai',
+        isError: true,
+      };
+      setMessages((prevMessages) => [...prevMessages, errorMessage]);
    } finally {
-        setIsLoading(false); // 无论成功失败，结束加载
+      setIsLoading(false);
    }
  };

-  const handleInputChange = (e: React.ChangeEvent<HTMLInputElement>) => {
+
+  // --- Other Handlers (基本不变, 但需要检查 currentAssistantId/currentSessionId 是否存在) ---
+   const handleInputChange = (e: React.ChangeEvent<HTMLInputElement>) => {
    setInputMessage(e.target.value);
  };

@ -216,23 +486,19 @@ export default function ChatPage() {
    setIsSessionPanelOpen(!isSessionPanelOpen);
  };

-  // 点击助手列表项的处理函数
  const handleSelectAssistant = (assistantId: string) => {
      if (assistantId !== currentAssistantId) {
-          setCurrentAssistantId(assistantId);
-          // 后续逻辑由 useEffect 处理
+          setCurrentAssistantId(assistantId); // 触发 useEffect 加载会话
      }
  }

-  // 点击会话列表项的处理函数
  const handleSelectSession = (sessionId: string) => {
      if (sessionId !== currentSessionId) {
          setCurrentSessionId(sessionId);
          // TODO: 调用 API 加载该会话的历史消息
          console.log(`切换到会话: ${sessionId}`);
-          // 模拟加载消息
          const session = allSessions.find(s => s.id === sessionId);
-          const assistant = assistants.find(a => a.id === session?.assistantId);
+          const assistant = assistants.find(a => a.id === session?.assistant_id);
           setMessages([
               { id: `init-${sessionId}-1`, text: `继续与 ${assistant?.name || '助手'} 的对话: ${session?.title || ''}`, sender: 'ai' },
               // ... 加载真实历史消息
@ -240,13 +506,12 @@ export default function ChatPage() {
      }
  }

-  // 点击新建话题按钮
  const handleNewTopic = () => {
-      if (currentSessionId !== 'temp-new-chat') {
+      if (currentSessionId !== 'temp-new-chat' && currentAssistantId) { // 确保有助手被选中
          setCurrentSessionId('temp-new-chat');
-          const selectedAssistant = assistants.find(a => a.id === currentAssistantId);
+          const currentAssistant = assistants.find(a => a.id === currentAssistantId);
          setMessages([
-              { id: `init-temp-${currentAssistantId}`, text: `开始与 ${selectedAssistant?.name || '助手'} 的新对话吧！`, sender: 'ai' },
+              { id: `init-temp-${currentAssistantId}`, text: `开始与 ${currentAssistant?.name || '助手'} 的新对话吧！`, sender: 'ai' },
          ]);
          console.log("手动创建临时新对话");
      }
@ -256,43 +521,109 @@ export default function ChatPage() {
  return (
    // 最外层 Flex 容器
    <div className="flex h-full gap-1"> {/* 使用 gap 添加间距 */}
-
+      <Toaster position="top-center" richColors />
      {/* 左侧助手面板 */}
      <aside className="w-64 bg-white dark:bg-gray-800 rounded-lg shadow-md p-4 flex flex-col">
        <h2 className="w-full text-lg font-semibold mb-4 text-gray-800 dark:text-gray-200 flex items-center justify-between">
            <span>助手列表</span>
-            {/* TODO: 添加助手创建/编辑入口 */}
-            {/* <button className="p-1 rounded hover:bg-gray-200 dark:hover:bg-gray-700" title="管理助手">
-                <Settings2 size={18} />
-            </button> */}
+            {/* 添加刷新按钮 */}
+             <Button variant="ghost" size="icon" className="h-7 w-7" onClick={() => {
+                 // 重新加载助手列表
+                 const loadAssistants = async () => { /* ... */ }; // 将加载逻辑提取出来
+                 loadAssistants();
+             }} disabled={assistantsLoading}>
+                 <RefreshCw size={16} className={assistantsLoading ? 'animate-spin' : ''}/>
+             </Button>
        </h2>
-        <button className="mb-4 w-full px-3 py-2 bg-red-500 text-white rounded-lg hover:bg-red-600 transition-colors text-sm flex items-center justify-center gap-2">
-          <UserPlus size={16} /> 添加助手
-        </button>
+        <Dialog open={isAssistantDialogOpen} onOpenChange={setIsAssistantDialogOpen}>
+            <DialogTrigger asChild>
+                <Button
+                    variant="default" // 使用 shadcn Button
+                    size="sm" // 调整大小
+                    className="mb-4 w-full bg-red-500 hover:bg-red-600 text-white" // 样式调整
+                    onClick={handleOpenCreateAssistantDialog} // 点击时重置编辑状态并打开
+                >
+                  <UserPlus size={16} className="mr-2"/> 添加助手
+                </Button>
+            </DialogTrigger>
+            {/* Dialog 内容 */}
+            <DialogContent className="sm:max-w-[600px]"> {/* 调整宽度 */}
+                <DialogHeader>
+                <DialogTitle>{editingAssistant ? '编辑助手' : '创建新助手'}</DialogTitle>
+                <DialogDescription>
+                    {editingAssistant ? '修改助手的配置信息。' : '定义一个新助手的名称、行为和参数。'}
+                </DialogDescription>
+                </DialogHeader>
+                {/* 渲染助手表单 */}
+                <AssistantForm
+                    key={editingAssistant?.id || 'create'} // 添加 key 确保编辑时表单重置
+                    assistant={editingAssistant}
+                    onSave={handleSaveAssistant}
+                    onClose={() => setIsAssistantDialogOpen(false)} // 传递关闭回调
+                />
+            </DialogContent>
+        </Dialog>
        <div className="flex-1 overflow-y-auto space-y-2 pr-1"> {/* 添加右内边距防止滚动条遮挡 */}
            {/* 渲染助手列表 */}
-            {assistants.map(assistant => (
-                <div
-                    key={assistant.id}
-                    onClick={() => handleSelectAssistant(assistant.id)}
-                    className={`p-3 rounded-lg cursor-pointer flex items-center gap-3 ${
-                        currentAssistantId === assistant.id
-                        ? 'bg-red-100 dark:bg-red-900/50 ring-2 ring-red-300 dark:ring-red-700' // 添加选中高亮和边框
-                        : 'text-gray-700 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-gray-700'
-                    }`}
-                    title={assistant.description}
-                >
-                    <span className="text-xl">{assistant.avatar || '👤'}</span> {/* 显示头像 */}
-                    <div className="flex-1 overflow-hidden">
-                        <p className={`text-sm font-medium truncate ${currentAssistantId === assistant.id ? 'text-red-800 dark:text-red-200' : 'text-gray-800 dark:text-gray-200'}`}>
-                            {assistant.name}
-                        </p>
-                        <p className={`text-xs truncate ${currentAssistantId === assistant.id ? 'text-red-600 dark:text-red-400' : 'text-gray-500 dark:text-gray-400'}`}>
-                            {assistant.description}
-                        </p>
+            {assistantsLoading ? (
+                // 显示骨架屏
+                Array.from({ length: 3 }).map((_, index) => (
+                    <div key={index} className="p-3 rounded-lg flex items-center gap-3">
+                        <Skeleton className="h-8 w-8 rounded-full" />
+                        <div className="flex-1 space-y-1">
+                            <Skeleton className="h-4 w-3/4" />
+                            <Skeleton className="h-3 w-1/2" />
+                        </div>
                    </div>
-                </div>
-            ))}
+                ))
+            ) : assistants.length === 0 ? (
+                 <p className="text-center text-sm text-gray-500 dark:text-gray-400 mt-4">没有找到助手。</p>
+            ) : (
+                // 渲染助手列表
+                assistants.map(assistant => (
+                    <div
+                        key={assistant.id}
+                        onClick={() => handleSelectAssistant(assistant.id)}
+                        className={`group p-2 rounded-lg cursor-pointer flex items-center gap-3 relative ${
+                            currentAssistantId === assistant.id
+                            ? 'bg-red-100 dark:bg-red-900/50 ring-1 ring-red-300 dark:ring-red-700'
+                            : 'text-gray-700 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-gray-700'
+                        }`}
+                        title={assistant.description || ''}
+                    >
+                        {/* ... 助手头像和名称 ... */}
+                         <span className="text-lg flex-shrink-0 w-6 text-center">{assistant.avatar || '👤'}</span>
+                         <div className="flex-1 overflow-hidden">
+                            <p className={`text-sm font-medium truncate ${currentAssistantId === assistant.id ? 'text-red-800 dark:text-red-200' : 'text-gray-800 dark:text-gray-200'}`}>
+                                {assistant.name}
+                            </p>
+                         </div>
+                        {/* 编辑和删除按钮 */}
+                        <div className="absolute right-1 top-1/2 -translate-y-1/2 flex items-center space-x-1 opacity-0 group-hover:opacity-100 transition-opacity">
+                           <Button
+                            variant="ghost"
+                            size="icon"
+                            className="h-6 w-6 text-blue-600 hover:text-blue-800 dark:text-blue-400 dark:hover:text-blue-300"
+                            onClick={(e) => { e.stopPropagation(); handleEditAssistant(assistant); }} // 阻止事件冒泡
+                            title="编辑助手"
+                        >
+                            <Edit size={14} />
+                        </Button>
+                        {assistant.id !== 'asst-default' && ( // 不显示默认助手的删除按钮
+                            <Button
+                                variant="ghost"
+                                size="icon"
+                                className="h-6 w-6 text-red-500 hover:text-red-700 dark:text-red-400 dark:hover:text-red-300"
+                                onClick={(e) => { e.stopPropagation(); handleDeleteAssistant(assistant.id); }}
+                                title="删除助手"
+                            >
+                                <Trash2 size={14} />
+                            </Button>
+                        )}
+                        </div>
+                    </div>
+                ))
+            )}
        </div>
      </aside>

@ -300,16 +631,19 @@ export default function ChatPage() {
      <div className="flex flex-col flex-1 bg-white dark:bg-gray-800 rounded-lg shadow-md overflow-hidden">
        {/* 聊天窗口标题 - 显示当前助手和切换会话按钮 */}
        <div className="flex justify-between items-center p-4 border-b dark:border-gray-700">
-            <div className="flex items-center gap-2">
-                <span className="text-xl">{assistants.find(a => a.id === currentAssistantId)?.avatar || '👤'}</span>
-                <h1 className="text-lg font-semibold text-gray-800 dark:text-gray-200">
-                    {assistants.find(a => a.id === currentAssistantId)?.name || '助手'}
-                </h1>
-                {/* TODO: 显示模型、温度等信息 */}
-                {/* <span className="text-xs bg-gray-200 dark:bg-gray-700 px-1.5 py-0.5 rounded">
-                    {assistants.find(a => a.id === currentAssistantId)?.model}
-                </span> */}
-            </div>
+            {currentAssistantId ? (
+                 <div className="flex items-center gap-2">
+                    <span className="text-xl">{assistants.find(a => a.id === currentAssistantId)?.avatar || '👤'}</span>
+                    <h1 className="text-lg font-semibold text-gray-800 dark:text-gray-200">
+                        {assistants.find(a => a.id === currentAssistantId)?.name || '加载中...'}
+                         <span className="text-sm font-normal text-gray-500 dark:text-gray-400 ml-2">
+                            ({currentSessionId === 'temp-new-chat' ? '新话题' : allSessions.find(s => s.id === currentSessionId)?.title || (sessionsLoading ? '加载中...' : '选择话题')})
+                         </span>
+                    </h1>
+                 </div>
+             ) : (
+                 <Skeleton className="h-6 w-48" /> // 助手加载中显示骨架屏
+             )}
            <button
                onClick={toggleSessionPanel}
                className="p-1 rounded text-gray-500 dark:text-gray-400 hover:bg-gray-200 dark:hover:bg-gray-700"
@ -321,6 +655,11 @@ export default function ChatPage() {

        {/* 消息显示区域 */}
        <div className="flex-1 overflow-y-auto p-4 space-y-4">
+          {/* 可以添加一个全局错误提示 */}
+          {error && <p className="text-center text-sm text-red-500 dark:text-red-400">{error}</p>}
+          {messages.length === 0 && !isLoading && !sessionsLoading && currentSessionId !== 'temp-new-chat' && (
+            <p className="text-center text-sm text-gray-500 dark:text-gray-400 mt-8">选择一个话题开始聊天，或新建一个话题。</p>
+          )}
          {messages.map((message) => (
            <div
              key={message.id}
@ -359,18 +698,18 @@ export default function ChatPage() {
              onChange={handleInputChange}
              onKeyDown={handleKeyDown}
              placeholder={isLoading ? "AI 正在回复..." : "输入你的消息..."}
-              disabled={isLoading}
+              disabled={isLoading || sessionsLoading || !currentAssistantId || !currentSessionId} // 添加禁用条件
              className="flex-1 px-4 py-2 border rounded-lg focus:outline-none focus:ring-2 focus:ring-red-500 dark:bg-gray-700 dark:border-gray-600 dark:text-gray-200 dark:focus:ring-red-600 disabled:opacity-70 transition-opacity"
              aria-label="聊天输入框"
            />
-            <button
+            <Button
              type="submit"
-              disabled={!inputMessage.trim() || isLoading}
+              disabled={!inputMessage.trim() || isLoading || sessionsLoading || !currentAssistantId || !currentSessionId} // 添加禁用条件
              className="p-2 rounded-lg bg-red-500 text-white hover:bg-red-600 focus:outline-none focus:ring-2 focus:ring-red-500 focus:ring-offset-2 dark:focus:ring-offset-gray-800 disabled:opacity-50 disabled:cursor-not-allowed transition-all flex items-center justify-center h-10 w-10"
              aria-label={isLoading ? "正在发送" : "发送消息"}
            >
              {isLoading ? <Loader2 className="h-5 w-5 animate-spin" /> : <SendHorizontal size={20} />}
-            </button>
+            </Button>
          </form>
        </div>
      </div>
@ -378,37 +717,47 @@ export default function ChatPage() {
      {/* 右侧会话管理面板 */}
      <aside className={`bg-white dark:bg-gray-800 rounded-lg shadow-md p-2 flex flex-col transition-all duration-300 ease-in-out ${isSessionPanelOpen ? 'w-64' : 'w-0 p-0 border-0 overflow-hidden opacity-0'}`}> {/* 调整关闭时的样式 */}
        <h2 className="text-lg font-semibold mb-4 text-gray-800 dark:text-gray-200 whitespace-nowrap items-center justify-center">话题列表</h2> {/* 改为话题 */}
-        <button
+        <Button
            onClick={handleNewTopic} // 绑定新建话题事件
            className="mb-4 w-full px-3 py-2 bg-red-500 text-white rounded-lg hover:bg-red-600 transition-colors text-sm whitespace-nowrap flex items-center justify-center gap-2 disabled:opacity-50"
-            disabled={currentSessionId === 'temp-new-chat'} // 如果已经是新话题则禁用
+            disabled={currentSessionId === 'temp-new-chat' || sessionsLoading || !currentAssistantId} // 添加禁用条件
        >
          + 新建话题
-        </button>
+        </Button>
        <div className="flex-1 overflow-y-auto space-y-4 pr-1">
-            {currentAssistantSessions
-                .filter(s => !s.isTemporary) // 不显示临时的
-                .sort((a, b) => b.createdAt.getTime() - a.createdAt.getTime()) // 按时间倒序
-                .map(session => (
-                <div
-                    key={session.id}
-                    onClick={() => handleSelectSession(session.id)} // 点击切换会话
-                    className={`p-2 rounded-lg cursor-pointer text-sm truncate whitespace-nowrap ${
-                        currentSessionId === session.id
-                        ? 'bg-red-100 dark:bg-red-900/50 text-red-700 dark:text-red-400 font-medium' // 高亮当前会话
-                        : 'text-gray-700 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-gray-700'
-                    }`}
-                    title={session.title}
-                >
-                    {session.title}
-                </div>
-            ))}
-             {/* 如果当前是临时会话，显示一个占位符 */}
-             {currentSessionId === 'temp-new-chat' && (
-                <div className="p-2 rounded-lg text-sm truncate whitespace-nowrap bg-red-100 dark:bg-red-900/50 text-red-700 dark:text-red-400 font-medium">
-                    新话题...
-                </div>
-             )}
+          {sessionsLoading ? (
+                 // 会话加载骨架屏
+                 Array.from({ length: 5 }).map((_, index) => (
+                    <Skeleton key={index} className="h-8 w-full my-1.5 rounded-lg" />
+                 ))
+            ) : currentAssistantSessions.length === 0 && currentSessionId !== 'temp-new-chat' ? (
+                 <p className="text-center text-sm text-gray-500 dark:text-gray-400 mt-4">没有历史话题。</p>
+            ) : (
+                <>
+                    {/* 渲染会话列表 */}
+                    {currentAssistantSessions.map(session => (
+                        <div
+                            key={session.id}
+                            onClick={() => handleSelectSession(session.id)}
+                            className={`p-2 rounded-lg cursor-pointer text-sm truncate whitespace-nowrap ${
+                                currentSessionId === session.id
+                                ? 'bg-red-100 dark:bg-red-900/50 text-red-700 dark:text-red-400 font-medium'
+                                : 'text-gray-700 dark:text-gray-300 hover:bg-gray-100 dark:hover:bg-gray-700'
+                            }`}
+                            title={session.title}
+                        >
+                            {session.title}
+                            {/* TODO: 添加删除会话按钮 */}
+                        </div>
+                    ))}
+                    {/* 新话题占位符 */}
+                    {currentSessionId === 'temp-new-chat' && (
+                        <div className="p-2 rounded-lg text-sm truncate whitespace-nowrap bg-red-100 dark:bg-red-900/50 text-red-700 dark:text-red-400 font-medium">
+                            新话题...
+                        </div>
+                    )}
+                </>
+            )}
        </div>
      </aside>

--- a/frontend/components/ui/skeleton.tsx
+++ b/frontend/components/ui/skeleton.tsx
@ -0,0 +1,13 @@
+import { cn } from "@/lib/utils"
+
+function Skeleton({ className, ...props }: React.ComponentProps<"div">) {
+  return (
+    <div
+      data-slot="skeleton"
+      className={cn("bg-accent animate-pulse rounded-md", className)}
+      {...props}
+    />
+  )
+}
+
+export { Skeleton }
--- a/frontend/lib/api.ts
+++ b/frontend/lib/api.ts
@ -1,14 +1,51 @@
-// File: frontend/lib/api.ts (新建或修改)
-// Description: 用于调用后端 API 的工具函数
+// File: frontend/lib/api.ts (更新)
+// Description: 添加调用助手和会话管理 API 的函数

 import axios from "axios";

-// 从环境变量读取后端 API 地址，如果没有则使用默认值
-// 确保在 .env.local 文件中定义 NEXT_PUBLIC_API_URL=http://localhost:8000/api/v1
+// --- Types (从后端模型同步或手动定义) ---
+// 这些类型应该与后端 pydantic_models.py 中的 Read 模型匹配
+export interface Assistant {
+  id: string;
+  name: string;
+  description?: string | null;
+  avatar?: string | null;
+  system_prompt: string;
+  model: string;
+  temperature: number;
+}
+
+export interface Session {
+  id: string;
+  title: string;
+  assistant_id: string;
+  created_at: string; // ISO date string
+}
+
+// 创建助手时发送的数据类型
+export interface AssistantCreateData {
+  name: string;
+  description?: string | null;
+  avatar?: string | null;
+  system_prompt: string;
+  model: string;
+  temperature: number;
+}
+
+// 更新助手时发送的数据类型 (所有字段可选)
+export type AssistantUpdateData = Partial<AssistantCreateData>;
+
+// 聊天响应类型
+export interface ChatApiResponse {
+  reply: string;
+  session_id?: string | null; // 后端返回的新 session id
+  session_title?: string | null; // 后端返回的新 session title
+}
+
+// --- API Client Setup ---
 const API_BASE_URL =
  process.env.NEXT_PUBLIC_API_URL || "http://localhost:8000/api/v1";

-// 创建 axios 实例，可以设置一些全局配置
 const apiClient = axios.create({
  baseURL: API_BASE_URL,
  headers: {
@ -16,36 +53,120 @@ const apiClient = axios.create({
  },
 });

+// --- Helper for Error Handling ---
+const handleApiError = (error: unknown, context: string): string => {
+  console.error(`API Error (${context}):`, error);
+  if (axios.isAxiosError(error) && error.response) {
+    // 尝试提取后端返回的详细错误信息
+    return (
+      error.response.data?.detail || `服务器错误 (${error.response.status})`
+    );
+  } else if (error instanceof Error) {
+    return error.message;
+  }
+  return "发生未知网络错误";
+};
+
+// --- Chat API ---
 /**
- * 发送聊天消息到后端
- * @param message 用户输入的消息文本
- * @returns AI 的回复文本
- * @throws 如果 API 请求失败则抛出错误
+ * 发送聊天消息到后端 (更新)
+ * @param message 用户消息
+ * @param sessionId 当前会话 ID (可以是 'temp-new-chat')
+ * @param assistantId 当前助手 ID
+ * @returns 包含 AI 回复和可能的新会话信息的对象
 */
-export const sendChatMessage = async (message: string): Promise<string> => {
+export const sendChatMessage = async (
+  message: string,
+  sessionId: string,
+  assistantId: string
+): Promise<ChatApiResponse> => {
  try {
-    // 发送 POST 请求到后端的 /chat/ 端点
-    const response = await apiClient.post("/chat/", { message });
-    // 检查响应数据和 reply 字段是否存在
-    if (response.data && response.data.reply) {
-      return response.data.reply; // 返回 AI 的回复
-    } else {
-      // 如果响应格式不符合预期，抛出错误
-      throw new Error("Invalid response format from server");
-    }
+    const response = await apiClient.post<ChatApiResponse>("/chat/", {
+      message,
+      session_id: sessionId,
+      assistant_id: assistantId,
+    });
+    return response.data; // 返回整个响应体
  } catch (error) {
-    console.error("Error calling chat API:", error); // 在控制台打印详细错误
-    // 检查是否是 Axios 错误并且有响应体
-    if (axios.isAxiosError(error) && error.response) {
-      // 尝试从响应体中获取错误详情，否则提供通用消息
-      throw new Error(
-        error.response.data?.detail || "Failed to communicate with server"
-      );
-    }
-    // 如果不是 Axios 错误或没有响应体，抛出通用错误
-    throw new Error("Failed to send message. Please try again.");
+    throw new Error(handleApiError(error, "sendChatMessage"));
  }
 };

-// --- 你可以在这里添加调用其他后端 API 的函数 ---
-// export const getWorkflows = async () => { ... };
+// --- Assistant API ---
+/** 获取所有助手列表 */
+export const getAssistants = async (): Promise<Assistant[]> => {
+  try {
+    const response = await apiClient.get<Assistant[]>("/assistants/");
+    return response.data;
+  } catch (error) {
+    throw new Error(handleApiError(error, "getAssistants"));
+  }
+};
+
+/** 创建新助手 */
+export const createAssistant = async (
+  data: AssistantCreateData
+): Promise<Assistant> => {
+  try {
+    const response = await apiClient.post<Assistant>("/assistants/", data);
+    return response.data;
+  } catch (error) {
+    throw new Error(handleApiError(error, "createAssistant"));
+  }
+};
+
+/** 更新助手 */
+export const updateAssistant = async (
+  id: string,
+  data: AssistantUpdateData
+): Promise<Assistant> => {
+  try {
+    const response = await apiClient.put<Assistant>(`/assistants/${id}`, data);
+    return response.data;
+  } catch (error) {
+    throw new Error(handleApiError(error, "updateAssistant"));
+  }
+};
+
+/** 删除助手 */
+export const deleteAssistant = async (id: string): Promise<void> => {
+  try {
+    await apiClient.delete(`/assistants/${id}`);
+  } catch (error) {
+    throw new Error(handleApiError(error, "deleteAssistant"));
+  }
+};
+
+// --- Session API ---
+/** 获取指定助手的所有会话 */
+export const getSessionsByAssistant = async (
+  assistantId: string
+): Promise<Session[]> => {
+  try {
+    const response = await apiClient.get<Session[]>(
+      `/sessions/assistant/${assistantId}`
+    );
+    return response.data;
+  } catch (error) {
+    // 如果助手没有会话，后端可能返回 404 或空列表，这里统一处理为返回空列表
+    if (axios.isAxiosError(error) && error.response?.status === 404) {
+      return [];
+    }
+    throw new Error(handleApiError(error, "getSessionsByAssistant"));
+  }
+};
+
+/** 删除会话 */
+export const deleteSession = async (sessionId: string): Promise<void> => {
+  try {
+    await apiClient.delete(`/sessions/${sessionId}`);
+  } catch (error) {
+    throw new Error(handleApiError(error, "deleteSession"));
+  }
+};
+
+// 注意：创建会话的 API (POST /sessions/) 在后端被整合到了 POST /chat/ 逻辑中，
+//当前端发送 sessionId 为 'temp-new-chat' 的消息时，后端会自动创建。
+//如果需要单独创建会话（例如，不发送消息就创建），则需要单独实现前端调用 POST /sessions/。
+
+// TODO: 添加获取会话消息的 API 函数 (GET /sessions/{session_id}/messages)