feat: 全局「第二大脑」AI 助手（跨书跨对话 + bm_* 工具 + DSML 兜底）

- Conversation 加 kind(book/assistant)、book_id 可空；SQLite 老表迁移保留数据
- rag/engine.py: search_all_books 跨书混合检索；citations 带 book_title 出处
- app/assistant/service.py: 知识库概览 + 第二大脑 persona + 原生工具
  (bm_list_conversations / bm_read_conversation / bm_search_books)，并入 MCP agent 循环
- chat.py: create/list 支持 kind；send_message 委托助手管线
- llm/hub.py: 解析 DeepSeek DSML 文本工具调用（模型非确定性输出标准/DSML）
- mcp/agent.py: 工具轮中段追加强制文本收尾，防模型反复调工具不出答案
- 前端: 侧栏「AI 助手」入口 + 抽取共享 ChatPanel 复用书/助手两套对话 UI

Co-Authored-By: Claude Code <noreply@anthropic.com>

backend/app/api/chat.py

@@ -16,6 +16,7 @@ from app.rag.engine import (
     estimate_tokens, match_chapters, _trim_messages,
 )
 from app.mcp.agent import agent_stream, build_mcp_context, execute_mcp_tool
+from app.assistant.service import stream_assistant
 
 logger = logging.getLogger(__name__)
 
@@ -23,7 +24,9 @@ router = APIRouter(prefix="/chat", tags=["chat"])
 
 
 class CreateConversationRequest(BaseModel):
-    book_id: str
+    # kind="book" 绑定单本书（book_id 必填）；kind="assistant" 为全局「第二大脑」对话
+    kind: str = "book"
+    book_id: str | None = None
     title: str | None = None
     model: str = "claude"
 
@@ -38,7 +41,8 @@ class SendMessageRequest(BaseModel):
 
 class ConversationOut(BaseModel):
     id: str
-    book_id: str
+    kind: str
+    book_id: str | None
     title: str | None
     model: str
     created_at: str
@@ -62,29 +66,42 @@ class MessageOut(BaseModel):
 
 
 @router.get("/conversations", response_model=list[ConversationOut])
-async def list_conversations(book_id: str | None = None, db: AsyncSession = Depends(get_db)):
+async def list_conversations(
+    book_id: str | None = None,
+    kind: str | None = None,
+    db: AsyncSession = Depends(get_db),
+):
     q = select(Conversation).order_by(Conversation.updated_at.desc())
     if book_id:
         q = q.where(Conversation.book_id == book_id)
+    if kind:
+        q = q.where(Conversation.kind == kind)
     result = await db.execute(q)
     convs = result.scalars().all()
     return [ConversationOut(
-        id=c.id, book_id=c.book_id, title=c.title, model=c.model,
+        id=c.id, kind=c.kind, book_id=c.book_id, title=c.title, model=c.model,
         created_at=c.created_at.isoformat() if c.created_at else "",
     ) for c in convs]
 
 
 @router.post("/conversations", response_model=ConversationOut)
 async def create_conversation(req: CreateConversationRequest, db: AsyncSession = Depends(get_db)):
-    book = await db.get(Book, req.book_id)
+    if req.kind == "assistant":
-    if not book:
+        # 全局「第二大脑」对话：不绑定书
-        raise HTTPException(404, "书不存在")
+        book_id = None
-    conv = Conversation(book_id=req.book_id, title=req.title or f"与《{book.title}》的对话", model=req.model)
+        title = req.title or "与 AI 助手的对话"
+    else:
+        book = await db.get(Book, req.book_id)
+        if not book:
+            raise HTTPException(404, "书不存在")
+        book_id = req.book_id
+        title = req.title or f"与《{book.title}》的对话"
+    conv = Conversation(book_id=book_id, title=title, model=req.model, kind=req.kind)
     db.add(conv)
     await db.commit()
     await db.refresh(conv)
     return ConversationOut(
-        id=conv.id, book_id=conv.book_id, title=conv.title, model=conv.model,
+        id=conv.id, kind=conv.kind, book_id=conv.book_id, title=conv.title, model=conv.model,
         created_at=conv.created_at.isoformat() if conv.created_at else "",
     )
 
@@ -107,10 +124,6 @@ async def send_message(conv_id: str, req: SendMessageRequest, db: AsyncSession =
     if not conv:
         raise HTTPException(404, "会话不存在")
 
-    book = await db.get(Book, conv.book_id)
-    if not book:
-        raise HTTPException(404, "书不存在")
-
     model_name = req.model or conv.model
 
     # 重试：复用被重试的用户消息（不新建），新回答作为它的新版本
@@ -125,6 +138,17 @@ async def send_message(conv_id: str, req: SendMessageRequest, db: AsyncSession =
         db.add(user_msg)
         await db.commit()
 
+    # 全局「第二大脑」对话：book_id 为空，走独立管线（跨书检索 + 知识库概览 + 原生工具 + MCP）
+    if conv.kind == "assistant":
+        provider = await resolve_provider(db, model_name)
+        if provider is None:
+            raise HTTPException(400, f"模型 {model_name} 未配置，请先在页面「管理模型」中添加或选择可用模型")
+        return await stream_assistant(conv, user_msg, req.content, db, provider)
+
+    book = await db.get(Book, conv.book_id)
+    if not book:
+        raise HTTPException(404, "书不存在")
+
     chapters = (await db.execute(
         select(Chapter).where(Chapter.book_id == book.id).order_by(Chapter.order_idx)
     )).scalars().all()
@@ -325,7 +349,7 @@ async def branch_conversation(conv_id: str, from_message_id: str = Query(...), d
     conv = await db.get(Conversation, conv_id)
     if not conv:
         raise HTTPException(404, "会话不存在")
-    branch = Conversation(book_id=conv.book_id, title=f"{conv.title or '对话'} (分支)", model=conv.model)
+    branch = Conversation(book_id=conv.book_id, title=f"{conv.title or '对话'} (分支)", model=conv.model, kind=conv.kind)
     db.add(branch)
     await db.flush()
 
@@ -364,9 +388,10 @@ async def export_conversation(conv_id: str, fmt: str = "markdown", db: AsyncSess
         select(Message).where(Message.conversation_id == conv_id).order_by(Message.created_at)
     )
     msgs = result.scalars().all()
-    book = await db.get(Book, conv.book_id)
+    book = await db.get(Book, conv.book_id) if conv.book_id else None
 
-    lines = [f"# {conv.title or '对话'}", f"书籍: {book.title if book else '未知'}\n"]
+    book_label = "全局助手" if conv.kind == "assistant" else (book.title if book else "未知")
+    lines = [f"# {conv.title or '对话'}", f"书籍: {book_label}\n"]
     for m in msgs:
         role_label = "🧑 用户" if m.role == "user" else "🤖 AI"
         # 把 mermaid mindmap 转成 flowchart LR：老版阅读器渲染 mindmap 是放射状粗线，很难读

backend/app/assistant/service.py

@@ -0,0 +1,466 @@
+"""assistant — 全局 AI 助手（第二大脑）管线
+
+与单书对话相对：不绑定某本书。每次请求注入「知识库概览」+ 跨书检索段，
+并给模型提供三个原生内部工具（bm_*，走与 MCP 工具同一套 function-calling 循环）：
+  - bm_list_conversations：遍历全部对话（摸清时间/精力去向）
+  - bm_read_conversation：读取某次对话完整原文
+  - bm_search_books：跨全部书籍检索原文
+外部信息继续走 MCP 工具。不支持的 provider（Anthropic 未接工具循环）则纯流式回答，
+行为与单书对话一致。
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+from typing import AsyncGenerator, Awaitable
+
+from fastapi.responses import StreamingResponse
+from sqlalchemy import select, func, or_
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.llm.hub import LLMProvider
+from app.mcp.agent import build_mcp_context, execute_mcp_tool, agent_stream
+from app.models.book import Book, Chapter, Segment
+from app.models.chat import Conversation, Message
+from app.rag.engine import (
+    search_all_books, parse_citations, estimate_tokens, _trim_messages,
+)
+
+logger = logging.getLogger(__name__)
+
+NATIVE_PREFIX = "bm_"
+NATIVE_TOOL_RESULT_CHARS = 6000  # 单条原生工具结果上限，与 MCP 的 TOOL_RESULT_CHARS 一致
+DIGEST_BUDGET_TOKENS = 6000  # 「知识库概览」system 注入预算
+
+
+# ======================= 知识库概览 =======================
+
+async def _conversation_stats(db: AsyncSession, conv_ids: list[str]) -> dict[str, dict]:
+    """每会话的消息数与最后一条消息时间。"""
+    if not conv_ids:
+        return {}
+    rows = await db.execute(
+        select(Message.conversation_id, func.count(Message.id), func.max(Message.created_at))
+        .where(Message.conversation_id.in_(conv_ids))
+        .group_by(Message.conversation_id)
+    )
+    return {r[0]: {"count": r[1], "last": r[2]} for r in rows.all()}
+
+
+async def _recent_message_digest(db: AsyncSession, conv_id: str, limit: int = 2) -> str:
+    """会话末尾最近几条消息的紧凑摘要（预算内注入，帮模型感知聊了什么）。"""
+    rows = await db.execute(
+        select(Message)
+        .where(Message.conversation_id == conv_id)
+        .order_by(Message.created_at.desc())
+        .limit(limit)
+    )
+    msgs = list(rows.scalars().all())
+    msgs.reverse()
+    parts = []
+    for m in msgs:
+        who = "🧑 用户" if m.role == "user" else "🤖 AI"
+        text = (m.content or "").replace("\n", " ")[:120]
+        parts.append(f"  {who}：{text}")
+    return "\n".join(parts)
+
+
+def _fmt_time(dt) -> str:
+    return dt.strftime("%Y-%m-%d %H:%M") if dt else ""
+
+
+async def build_assistant_context(db: AsyncSession) -> tuple[str, list[Book]]:
+    """生成「知识库概览」文本 + 全书列表。
+
+    概览包含：书库规模、每本书的对话/消息/活跃情况、最近对话摘要、模型使用统计。
+    全程按 token 预算截断，避免每次请求塞大量原文。
+    """
+    books = (await db.execute(select(Book).order_by(Book.created_at.desc()))).scalars().all()
+    book_map = {b.id: b for b in books}
+
+    convs = (await db.execute(
+        select(Conversation).order_by(Conversation.updated_at.desc())
+    )).scalars().all()
+    conv_stats = await _conversation_stats(db, [c.id for c in convs])
+
+    # 每本书聚合：会话数 / 消息数 / 最后活跃
+    per_book: dict[str, dict] = {}
+    for b in books:
+        per_book[b.id] = {"convs": 0, "msgs": 0, "last": None}
+    for c in convs:
+        st = per_book.setdefault(c.book_id, {"convs": 0, "msgs": 0, "last": None})
+        st["convs"] += 1
+        cs = conv_stats.get(c.id)
+        if cs:
+            st["msgs"] += cs["count"]
+            if cs["last"] and (st["last"] is None or cs["last"] > st["last"]):
+                st["last"] = cs["last"]
+
+    model_rows = (await db.execute(
+        select(Message.model, func.count(Message.id))
+        .group_by(Message.model)
+        .order_by(func.count(Message.id).desc())
+    )).all()
+    model_usage = [(r[0], r[1]) for r in model_rows if r[0]]
+
+    total_msgs = sum(st["msgs"] for st in per_book.values())
+    lines: list[str] = []
+    lines.append("## 知识库概览（自动生成）")
+    lines.append(f"- 共 {len(books)} 本书、{len(convs)} 次对话、{total_msgs} 条消息。")
+
+    if books:
+        lines.append("\n### 书籍")
+        for b in books:
+            st = per_book.get(b.id, {})
+            last = _fmt_time(st.get("last"))
+            suffix = f"，最后活跃 {last}" if last else ""
+            lines.append(
+                f"- 《{b.title or b.filename}》（{b.author or '未知作者'}，约 {b.char_count:,} 字）："
+                f"{st.get('convs', 0)} 次对话 · {st.get('msgs', 0)} 条消息{suffix}"
+            )
+
+    used = estimate_tokens("\n".join(lines))
+
+    if convs:
+        conv_lines: list[str] = ["\n### 最近对话"]
+        for c in convs:
+            cs = conv_stats.get(c.id)
+            if not cs:
+                continue
+            book = book_map.get(c.book_id)
+            src = f"《{book.title or book.filename}》" if book else "全局助手"
+            head = f"- {src} / {c.title or '对话'}（{cs['count']} 条消息，最后活跃 {_fmt_time(cs['last'])}）"
+            recent = await _recent_message_digest(db, c.id)
+            if used + estimate_tokens(head) + estimate_tokens(recent) > DIGEST_BUDGET_TOKENS:
+                break  # 预算内从新到旧追加，超预算即停
+            conv_lines.append(head)
+            if recent:
+                conv_lines.append(recent)
+            used += estimate_tokens(head) + estimate_tokens(recent)
+        if len(conv_lines) > 1:
+            lines.extend(conv_lines)
+
+    if model_usage:
+        lines.append("\n### 模型使用")
+        for name, cnt in model_usage:
+            lines.append(f"- {name or '未知'} × {cnt}")
+
+    return "\n".join(lines), books
+
+
+# ======================= Prompt 组装 =======================
+
+def build_assistant_prompt(
+    digest: str,
+    segments: list[Segment],
+    history: list[dict],
+    query: str,
+) -> list[dict]:
+    system = (
+        "# 你是 BookMate 的第二大脑助手，用户跨书籍、跨对话的综合思考伙伴。\n\n"
+        "你的职责：\n"
+        "1. 梳理总结：帮用户看清时间和精力消耗在哪些书、哪些主题、哪些对话上，以及究竟获得了什么；\n"
+        "2. 连接知识：跨书籍、跨对话建立概念联系，把零散内容串成体系；\n"
+        "3. 回顾沉淀：复盘最近读了什么、讨论了什么、收获了什么，指出待办与存疑之处；\n"
+        "4. 需要书中具体内容时检索并引用原文；需要外部信息（时事/数据/网络）时调用外部工具。\n\n"
+    )
+    system += digest + "\n"
+
+    if segments:
+        system += "\n## 与问题直接相关的全书检索段落（含出处）\n"
+        for i, seg in enumerate(segments, 1):
+            bt = getattr(seg, "_book_title", None)
+            ct = getattr(seg, "_chapter_title", None)
+            src = f"{bt}{'·' + ct if ct else ''}" if bt else seg.book_id
+            system += f"\n[[ref:{i}]] [{src}] {seg.text[:800].replace(chr(10), ' ')}\n"
+    else:
+        system += (
+            "\n## 检索说明\n"
+            "本次没有检索到与问题直接匹配的原文。请基于上方知识库概览与你的判断回答，"
+            "并明确说明哪些是推断。\n"
+        )
+
+    system += (
+        "\n## 回答要求\n"
+        "1. 区分信息来源：「书中原文」带 [[ref:N]] 引用；「对话记录」说明是哪次对话；「外部工具」注明来源与时效\n"
+        "2. 引用原文时用 [[ref:N]]（N 对应上方段落编号），同一段只引用一次，整体引用控制在 5 条左右\n"
+        "3. 用中文回答；检索不到就诚实说明，不要编造统计数字或原文\n"
+        "4. 涉及精力/时间/收获的梳理时，尽量给出有依据的归纳，标注哪些来自对话记录、哪些是推断"
+    )
+
+    messages = [{"role": "system", "content": system}]
+    if history:
+        messages.extend(history[-10:])
+    messages.append({"role": "user", "content": query})
+    return messages
+
+
+# ======================= 原生内部工具 =======================
+
+NATIVE_TOOLS: list[dict] = [
+    {
+        "type": "function",
+        "function": {
+            "name": "bm_search_books",
+            "description": "在用户的全部书籍中做全文检索，返回相关段落（每条带书名与章节）。当用户问题需要书中具体原文/出处时调用。",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "query": {"type": "string", "description": "要检索的问题或关键词（中文亦可）"},
+                    "top_k": {"type": "integer", "description": "返回段落条数，默认 6，最大 15"},
+                },
+                "required": ["query"],
+            },
+        },
+    },
+    {
+        "type": "function",
+        "function": {
+            "name": "bm_read_conversation",
+            "description": "读取某一次完整对话的原文（该对话所有用户与 AI 消息）。conversation_id 从 bm_list_conversations 或知识库概览中获得。",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "conversation_id": {"type": "string", "description": "要读取的对话 id"},
+                },
+                "required": ["conversation_id"],
+            },
+        },
+    },
+    {
+        "type": "function",
+        "function": {
+            "name": "bm_list_conversations",
+            "description": "列出用户的全部对话（可按书名/标题/消息关键词过滤），含每段对话的书名、消息数与最后活跃时间。用于梳理时间和精力都花在哪些书、哪些话题上。",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "query": {"type": "string", "description": "可选过滤关键词（匹配书名、标题、消息内容）"},
+                    "limit": {"type": "integer", "description": "最多返回的对话数，默认 20，最大 50"},
+                },
+            },
+        },
+    },
+]
+
+
+async def _tool_search_books(db: AsyncSession, args: dict) -> str:
+    query = str(args.get("query") or "").strip()
+    if not query:
+        return "[bm_search_books] 缺少 query 参数"
+    top_k = max(1, min(int(args.get("top_k") or 6), 15))
+    books = (await db.execute(select(Book))).scalars().all()
+    segs = await search_all_books(db, query, top_k=top_k, books=books)
+    if not segs:
+        return "[bm_search_books] 没有检索到相关段落"
+    ch_ids = {s.chapter_id for s in segs}
+    chapters = (await db.execute(select(Chapter).where(Chapter.id.in_(ch_ids)))).scalars().all()
+    ch_map = {c.id: c for c in chapters}
+    book_map = {b.id: b for b in books}
+    lines = []
+    for i, s in enumerate(segs, 1):
+        book = book_map.get(s.book_id)
+        ch = ch_map.get(s.chapter_id)
+        if book:
+            src = f"《{book.title or book.filename}》{(' / ' + ch.title) if ch and ch.title else ''}"
+        else:
+            src = s.book_id
+        lines.append(f"[{i}] {src}：{s.text[:300].replace(chr(10), ' ')}")
+    return "\n".join(lines)
+
+
+async def _tool_read_conversation(db: AsyncSession, args: dict) -> str:
+    conv_id = str(args.get("conversation_id") or "").strip()
+    conv = await db.get(Conversation, conv_id)
+    if not conv:
+        return "[bm_read_conversation] 对话不存在"
+    book = await db.get(Book, conv.book_id) if conv.book_id else None
+    msgs = (await db.execute(
+        select(Message).where(Message.conversation_id == conv_id).order_by(Message.created_at)
+    )).scalars().all()
+    title = f"《{book.title or book.filename}》" if book else "全局助手"
+    lines = [f"# {title} / {conv.title or '对话'}（共 {len(msgs)} 条消息）"]
+    for m in msgs:
+        who = "🧑 用户" if m.role == "user" else "🤖 AI"
+        lines.append(f"{who}：{(m.content or '')[:600].replace(chr(10), ' ')}")
+    return "\n".join(lines)[:NATIVE_TOOL_RESULT_CHARS]
+
+
+async def _tool_list_conversations(db: AsyncSession, args: dict) -> str:
+    query = str(args.get("query") or "").strip()
+    limit = max(1, min(int(args.get("limit") or 20), 50))
+    q = select(Conversation).order_by(Conversation.updated_at.desc())
+    if query:
+        books_match = select(Book.id).where(
+            or_(Book.title.contains(query), Book.filename.contains(query))
+        )
+        msgs_match = select(Message.conversation_id).where(Message.content.contains(query))
+        q = q.where(or_(
+            Conversation.title.contains(query),
+            Conversation.book_id.in_(books_match),
+            Conversation.id.in_(msgs_match),
+        ))
+    convs = (await db.execute(q.limit(limit))).scalars().all()
+    if not convs:
+        return "[bm_list_conversations] 没有匹配的对话"
+    book_map = {b.id: b for b in (await db.execute(select(Book))).scalars().all()}
+    stats = await _conversation_stats(db, [c.id for c in convs])
+    lines = []
+    for c in convs:
+        book = book_map.get(c.book_id)
+        src = f"《{book.title or book.filename}》" if book else "全局助手"
+        st = stats.get(c.id, {})
+        last = _fmt_time(st.get("last"))
+        lines.append(
+            f"- [{c.id}] {src} / {c.title or '对话'}（{st.get('count', 0)} 条消息"
+            + (f"，最后活跃 {last}" if last else "")
+            + "）"
+        )
+    return "\n".join(lines)
+
+
+async def execute_native_tool(db: AsyncSession, name: str, args: dict) -> str:
+    if name == "bm_search_books":
+        return await _tool_search_books(db, args)
+    if name == "bm_read_conversation":
+        return await _tool_read_conversation(db, args)
+    if name == "bm_list_conversations":
+        return await _tool_list_conversations(db, args)
+    return f"[内部工具] 未知工具：{name}"
+
+
+def _dispatch_tool(db: AsyncSession, name: str, args: dict, mcp_ctx) -> Awaitable[str]:
+    """按前缀分发：bm_ 内部工具，其余交给 MCP。返回可等待的工具结果。"""
+    if name.startswith(NATIVE_PREFIX):
+        return execute_native_tool(db, name, args)
+    if mcp_ctx is not None:
+        return execute_mcp_tool(mcp_ctx, name, args)
+    return _noop_tool_result(f"[工具] 无法执行：{name}")
+
+
+async def _noop_tool_result(text: str) -> str:
+    return text
+
+
+def _describe_tool(name: str, mcp_ctx) -> str:
+    if name.startswith(NATIVE_PREFIX):
+        return name
+    return mcp_ctx.display_name(name) if mcp_ctx is not None else name
+
+
+# ======================= 流式回答 =======================
+
+async def _annotate_segments(db: AsyncSession, books: list[Book], segments: list[Segment]) -> list[Segment]:
+    """给跨书检索段临时标注书名/章节名，供 prompt 出处与 citations 使用。"""
+    if not segments:
+        return segments
+    book_map = {b.id: b for b in books}
+    ch_ids = {s.chapter_id for s in segments}
+    chapters = (await db.execute(select(Chapter).where(Chapter.id.in_(ch_ids)))).scalars().all()
+    ch_map = {c.id: c for c in chapters}
+    for s in segments:
+        b = book_map.get(s.book_id)
+        s._book_title = (b.title or b.filename) if b else None
+        c = ch_map.get(s.chapter_id)
+        s._chapter_title = c.title if c else None
+    return segments
+
+
+async def stream_assistant(
+    conv: Conversation,
+    user_msg: Message,
+    content: str,
+    db: AsyncSession,
+    provider: LLMProvider,
+) -> StreamingResponse:
+    """全局助手对话的 SSE 流式回答。SSE 事件格式与单书对话完全一致。"""
+    digest, books = await build_assistant_context(db)
+    segments = await _annotate_segments(
+        db, books, await search_all_books(db, content, top_k=10, books=books)
+    )
+
+    # 本会话历史：正常发送时当前 user 消息是最后一条，去掉它；
+    # 重试时它可能是中间某条，历史只取它之前（旧版本回答不进 prompt）
+    history_rows = (await db.execute(
+        select(Message).where(Message.conversation_id == conv.id).order_by(Message.created_at)
+    )).scalars().all()
+    ids = {m.id for m in history_rows}
+    if user_msg.id in ids:
+        idx = next(i for i, m in enumerate(history_rows) if m.id == user_msg.id)
+        history = [{"role": m.role, "content": m.content} for m in history_rows[:idx]]
+    else:
+        history = [{"role": m.role, "content": m.content} for m in history_rows[:-1]]
+
+    messages = build_assistant_prompt(digest, segments, history, content)
+
+    mcp_ctx = await build_mcp_context(db) if provider.supports_tools else None
+    tools: list[dict] = []
+    if provider.supports_tools:
+        tools = list(NATIVE_TOOLS)
+        if mcp_ctx is not None:
+            tools.extend(mcp_ctx.ai_tools)
+        system = messages[0]["content"]
+        system += (
+            "\n\n## 内部工具\n"
+            "你有三个内部工具可以调用：\n"
+            "- bm_list_conversations：列出全部对话（可按关键词过滤），摸清时间精力去向；\n"
+            "- bm_read_conversation：读取某次对话的完整原文；\n"
+            "- bm_search_books：跨全部书籍检索原文段落。\n"
+            "涉及「读了什么 / 收获 / 时间精力去向」的梳理时，先调用工具核实再回答。\n"
+        )
+        if mcp_ctx is not None:
+            system += (
+                "\n## 外部信息工具\n"
+                f"需要书中/对话之外的外部信息（最新动态、时事、网络资料、行业数据等）时，"
+                f"可调用：{', '.join(mcp_ctx.names)}\n"
+                "- 外部信息要说明来源与时效；回答主体仍以书中内容与对话记录为准。\n"
+            )
+        messages[0]["content"] = system
+
+    total_tokens = estimate_tokens("".join(m["content"] for m in messages))
+    if total_tokens > provider.max_context * 0.8:
+        messages = _trim_messages(messages, int(provider.max_context * 0.8))
+
+    async def stream_response() -> AsyncGenerator[str, None]:
+        full_content = ""
+        try:
+            if provider.supports_tools:
+                async for kind, payload in agent_stream(
+                    messages,
+                    provider,
+                    tools,
+                    execute=lambda name, args: _dispatch_tool(db, name, args, mcp_ctx),
+                    describe=lambda name: _describe_tool(name, mcp_ctx),
+                ):
+                    if kind == "token":
+                        full_content += payload
+                        yield f"data: {json.dumps({'type': 'token', 'content': payload}, ensure_ascii=False)}\n\n"
+                    elif kind == "tool":
+                        yield f"data: {json.dumps({'type': 'tool', 'name': payload, 'status': 'start'}, ensure_ascii=False)}\n\n"
+                    elif kind == "tool_done":
+                        yield f"data: {json.dumps({'type': 'tool', 'name': payload, 'status': 'done'}, ensure_ascii=False)}\n\n"
+            else:
+                async for token in provider.chat_stream(messages, temperature=0.7):
+                    full_content += token
+                    yield f"data: {json.dumps({'type': 'token', 'content': token}, ensure_ascii=False)}\n\n"
+        except Exception as e:
+            logger.exception("助手流式生成失败（conversation=%s）", conv.id)
+            yield f"data: {json.dumps({'type': 'error', 'content': str(e)}, ensure_ascii=False)}\n\n"
+            return
+
+        parsed = parse_citations(full_content, segments)
+        assistant_msg = Message(
+            conversation_id=conv.id,
+            parent_message_id=user_msg.id,
+            role="assistant",
+            content=parsed["text"],
+            citations=json.dumps(parsed["citations"], ensure_ascii=False),
+            model=user_msg.model or conv.model,
+        )
+        db.add(assistant_msg)
+        await db.commit()
+        await db.refresh(assistant_msg)
+        yield f"data: {json.dumps({'type': 'done', 'message_id': assistant_msg.id, 'citations': parsed['citations']}, ensure_ascii=False)}\n\n"
+
+    return StreamingResponse(stream_response(), media_type="text/event-stream")

backend/app/core/database.py

@@ -20,13 +20,39 @@ async def init_db():
 
 
 async def _migrate():
-    """轻量迁移：SQLite 下给已有 segments 表补 embedding 列（create_all 不会改老表）。"""
+    """轻量迁移：SQLite 下补列 / 重建表（create_all 不会改老表）。"""
     async with engine.begin() as conn:
         rows = (await conn.exec_driver_sql("PRAGMA table_info(segments)")).all()
         cols = {row[1] for row in rows}
         if rows and "embedding" not in cols:
             await conn.exec_driver_sql("ALTER TABLE segments ADD COLUMN embedding TEXT")
 
+        # conversations：全局「第二大脑」对话需要 book_id 可空 + kind 列（book/assistant）。
+        # SQLite 无法 ALTER 去掉 NOT NULL，这里整表重建（保留数据，旧会话统一 kind='book'）；
+        # 新建库由 create_all 直接按新 ORM schema 建表，走到这里时 kind 已存在 → 跳过。
+        rows = (await conn.exec_driver_sql("PRAGMA table_info(conversations)")).all()
+        cols = {row[1] for row in rows}
+        if rows and "kind" not in cols:
+            await conn.exec_driver_sql("ALTER TABLE conversations RENAME TO conversations_old")
+            await conn.exec_driver_sql(
+                "CREATE TABLE conversations ("
+                " id VARCHAR(36) NOT NULL PRIMARY KEY,"
+                " book_id VARCHAR(36),"
+                " title VARCHAR(500),"
+                " model VARCHAR(50) NOT NULL,"
+                " created_at DATETIME DEFAULT CURRENT_TIMESTAMP,"
+                " updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,"
+                " kind VARCHAR(20) DEFAULT 'book',"
+                " FOREIGN KEY (book_id) REFERENCES books (id) ON DELETE CASCADE"
+                ")"
+            )
+            await conn.exec_driver_sql(
+                "INSERT INTO conversations (id, book_id, title, model, created_at, updated_at, kind)"
+                " SELECT id, book_id, title, model, created_at, updated_at, 'book'"
+                " FROM conversations_old"
+            )
+            await conn.exec_driver_sql("DROP TABLE conversations_old")
+
 
 async def get_db():
     async with async_session() as session:

backend/app/llm/hub.py

@@ -1,11 +1,49 @@
 import json
 import os
+import re
 from abc import ABC, abstractmethod
 from dataclasses import dataclass, field
 from typing import AsyncGenerator
 
 from sqlalchemy.ext.asyncio import AsyncSession
 
+# DeepSeek 部分模型会以「纯文本 content」输出 DSML 工具调用而不是标准 tool_calls：
+#   <｜｜DSML｜｜ calls>
+#   <｜｜DSML｜｜ invoke name="tool">
+#     <｜｜DSML｜｜ parameter name="k" string="true">v</｜｜DSML｜｜ parameter>
+#   </｜｜DSML｜｜ invoke>
+#   </｜｜DSML｜｜ calls>
+# 这里把 DSML 块解析成 OpenAI 兼容的 tool_calls，保证工具循环不中断（模型选型不确定时也能兜底）。
+DSML_CALLS_START = "<｜｜DSML｜｜ calls>"
+DSML_CALLS_END = "</｜｜DSML｜｜ calls>"
+_DSML_CALLS_RE = re.compile(r"<｜｜DSML｜｜ calls>(.*?)</｜｜DSML｜｜ calls>", re.DOTALL)
+_DSML_INVOKE_RE = re.compile(r'<｜｜DSML｜｜ invoke name="([^"]+)">(.*?)</｜｜DSML｜｜ invoke>', re.DOTALL)
+_DSML_PARAM_RE = re.compile(r'<｜｜DSML｜｜ parameter name="([^"]+)"(?: string="true")?>(.*?)</｜｜DSML｜｜ parameter>', re.DOTALL)
+
+
+def _parse_dsml_calls(block: str) -> list[dict]:
+    """把一段 DSML calls 块解析成 OpenAI 兼容的 tool_calls 列表（参数统一按字符串）。
+
+    id 必须生成真实值：后续第二轮会带 role="tool" 的消息（tool_call_id 指向它），
+    空 id 会导致模型 API 拒绝、工具循环第二轮中断。
+    """
+    calls: list[dict] = []
+    m = _DSML_CALLS_RE.search(block)
+    if not m:
+        return calls
+    for n, inv in enumerate(_DSML_INVOKE_RE.finditer(m.group(1))):
+        name = inv.group(1).strip()
+        args: dict = {}
+        for pm in _DSML_PARAM_RE.finditer(inv.group(2)):
+            key = pm.group(1).strip()
+            args[key] = pm.group(2).strip()
+        calls.append({
+            "id": f"call_{name}_{n}",
+            "type": "function",
+            "function": {"name": name, "arguments": json.dumps(args, ensure_ascii=False)},
+        })
+    return calls
+
 
 @dataclass
 class ChatResponse:
@@ -83,6 +121,8 @@ class OpenAIProvider(LLMProvider):
                 json=payload,
             ) as resp:
                 tool_calls_acc: dict[int, dict] = {}
+                dsml_buf = ""
+                in_dsml = False
                 async for line in resp.aiter_lines():
                     if line.startswith("data: "):
                         data_str = line[6:]
@@ -97,8 +137,38 @@ class OpenAIProvider(LLMProvider):
                             delta = choices[0].get("delta", {})
                             content = delta.get("content", "")
                             if content:
-                                self.last_content += content
+                                dsml_buf += content
-                                yield content
+                                if in_dsml:
+                                    # 正在 DSML 块内：等结束标记后解析工具调用
+                                    end = dsml_buf.find(DSML_CALLS_END)
+                                    if end != -1:
+                                        block = dsml_buf[: end + len(DSML_CALLS_END)]
+                                        self.tool_calls.extend(_parse_dsml_calls(block))
+                                        tail = dsml_buf[end + len(DSML_CALLS_END):]
+                                        in_dsml = False
+                                        dsml_buf = tail
+                                        # 块后的残余文本（罕见）按正常内容继续
+                                        if dsml_buf:
+                                            self.last_content += dsml_buf
+                                            yield dsml_buf
+                                            dsml_buf = ""
+                                else:
+                                    idx = dsml_buf.find(DSML_CALLS_START)
+                                    if idx != -1:
+                                        before = dsml_buf[:idx]
+                                        if before:
+                                            self.last_content += before
+                                            yield before
+                                        dsml_buf = dsml_buf[idx:]
+                                        in_dsml = True
+                                    else:
+                                        # 未发现 DSML 标记：yield 除检测窗口外的文本（跨 chunk 检测需保留尾部）
+                                        keep = len(DSML_CALLS_START) - 1
+                                        if len(dsml_buf) > keep:
+                                            head = dsml_buf[:-keep]
+                                            self.last_content += head
+                                            yield head
+                                            dsml_buf = dsml_buf[-keep:]
                             # 流式 tool_calls：每个 index 首个 delta 带 id/name，后续增量拼 arguments
                             for tc in delta.get("tool_calls") or []:
                                 idx = tc.get("index", 0)
@@ -114,8 +184,12 @@ class OpenAIProvider(LLMProvider):
                                     entry["function"]["arguments"] += fn["arguments"]
                         except json.JSONDecodeError:
                             continue
+                # 流结束：把检测窗口残留的文本冲出来，避免丢失内容
+                if dsml_buf:
+                    self.last_content += dsml_buf
+                    yield dsml_buf
                 if tool_calls_acc:
-                    self.tool_calls = [tool_calls_acc[i] for i in sorted(tool_calls_acc)]
+                    self.tool_calls.extend(tool_calls_acc[i] for i in sorted(tool_calls_acc))
 
 
 class AnthropicProvider(LLMProvider):

backend/app/mcp/agent.py

@@ -154,7 +154,18 @@ async def agent_stream(
       - ("tool", "<服务器>/<工具>") —— 工具调用开始
       - ("tool_done", "<服务器>/<工具>") —— 工具执行完成
     """
-    for _round in range(MAX_TOOL_ROUNDS):
+    # 前 MAX_TOOL_ROUNDS 轮正常工具循环；若模型持续调工具仍不收尾（DeepSeek 用 DSML
+    # 反复输出工具调用尤甚），中段追加「强制收尾」指令再续同样轮数，之后兜底无工具流式。
+    total_rounds = MAX_TOOL_ROUNDS * 2
+    for _round in range(total_rounds):
+        if _round == MAX_TOOL_ROUNDS:
+            messages.append({
+                "role": "user",
+                "content": (
+                    "（工具调用已结束）请直接基于以上已有信息，用中文给出最终回答，"
+                    "不要再调用任何工具，也不要输出任何工具调用标记。"
+                ),
+            })
         provider.tool_calls = []
         provider.last_content = ""
         async for token in provider.chat_stream(messages, temperature=0.7, tools=tools):
@@ -192,6 +203,6 @@ async def agent_stream(
                 "tool_call_id": call["id"],
                 "content": (out or "[工具无返回内容]")[:TOOL_RESULT_CHARS],
             })
-    # 达到最大轮数仍未见收尾：用已收集上下文走无工具流式生成，保证必出最终答案
+    # 兜底：无工具流式生成，保证必出最终答案
     async for token in provider.chat_stream(messages, temperature=0.7):
         yield ("token", token)

backend/app/models/chat.py

@@ -13,7 +13,9 @@ class Conversation(Base):
     __tablename__ = "conversations"
 
     id: Mapped[str] = mapped_column(String(36), primary_key=True, default=gen_uuid)
-    book_id: Mapped[str] = mapped_column(String(36), ForeignKey("books.id", ondelete="CASCADE"))
+    # kind="book" 绑定具体书（book_id 必填）；kind="assistant" 为全局「第二大脑」对话（book_id 为 NULL）
+    kind: Mapped[str] = mapped_column(String(20), default="book")
+    book_id: Mapped[str | None] = mapped_column(String(36), ForeignKey("books.id", ondelete="CASCADE"), nullable=True)
     title: Mapped[str | None] = mapped_column(String(500))
     model: Mapped[str] = mapped_column(String(50), default="claude")
     created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())

backend/app/rag/engine.py

@@ -65,15 +65,18 @@ def match_chapters(chapters: list[Chapter], query: str, tokens: list[str] | None
     return hits
 
 
-async def _keyword_candidates(db: AsyncSession, book_id: str, tokens: list[str], limit: int) -> list[Segment]:
+async def _keyword_candidates(db: AsyncSession, book_ids: list[str], tokens: list[str], limit: int) -> list[Segment]:
-    """关键词候选：SQL LIKE 召回（含整句子串），按命中词数 + 长词加权打分。"""
+    """关键词候选：SQL LIKE 召回（含整句子串），按命中词数 + 长词加权打分。
-    if not tokens:
+
+    book_ids 传单个书名 id 的列表（单书检索）或多个 id（跨书检索）。
+    """
+    if not tokens or not book_ids:
         return []
     ordered = sorted(tokens, key=len, reverse=True)[:8]
     conds = [Segment.text.contains(w) for w in ordered]
     q = (
         select(Segment)
-        .where(Segment.book_id == book_id, or_(*conds))
+        .where(Segment.book_id.in_(book_ids), or_(*conds))
         .order_by(Segment.order_idx)
         .limit(limit * 4)
     )
@@ -124,7 +127,7 @@ async def search_segments(
             status = "failed"
 
     # 1. 关键词候选
-    kw_candidates = await _keyword_candidates(db, book_id, tokens, top_k * 3)
+    kw_candidates = await _keyword_candidates(db, [book_id], tokens, top_k * 3)
 
     # 2. 向量候选
     vec_candidates: list[Segment] = []
@@ -163,6 +166,93 @@ async def search_segments(
     return merged[:top_k]
 
 
+async def _empty_fallback_all(db: AsyncSession, books: list[Book], top_k: int) -> list[Segment]:
+    """跨书空检索兜底：每本书取最先的非空开头段，保证 AI 至少有所依据。"""
+    out: list[Segment] = []
+    for b in books:
+        result = await db.execute(
+            select(Segment)
+            .where(Segment.book_id == b.id)
+            .order_by(Segment.order_idx)
+            .limit(top_k)
+        )
+        for s in result.scalars().all():
+            if (s.text or "").strip():
+                out.append(s)
+                break
+    return out[:top_k]
+
+
+async def search_all_books(
+    db: AsyncSession,
+    query: str,
+    top_k: int = 12,
+    books: list[Book] | None = None,
+) -> list[Segment]:
+    """跨书混合检索（全局「第二大脑」用）：关键词跨书一次 SQL + 每书向量余弦 → RRF → rerank。
+
+    与 search_segments 的区别：
+      - 不调用 ensure_embeddings（全局检索不阻塞向量生成，缺向量的书靠关键词兜底）；
+      - 向量部分逐书扫描后合并（query embedding 只算一次）。
+    """
+    tokens = _tokenize(query)
+    if books is None:
+        result = await db.execute(select(Book).order_by(Book.created_at))
+        books = list(result.scalars().all())
+    book_ids = [b.id for b in books]
+    if not book_ids:
+        return []
+
+    # 1. 关键词候选（一次 SQL 跨全部书）
+    kw_candidates = await _keyword_candidates(db, book_ids, tokens, top_k * 4)
+
+    # 2. 向量候选（每书全量余弦，合并）
+    vec_candidates: list[Segment] = []
+    if tokens:
+        qvecs = await embed_texts([query])
+        qvec = qvecs[0] if qvecs else None
+        if qvec:
+            for bid in book_ids:
+                mat, vec_segments = await load_vectors(db, bid)
+                if mat is not None and len(mat) > 0:
+                    idxs = vector_search(qvec, mat, top_k * 2)
+                    vec_candidates.extend(vec_segments[i] for i in idxs)
+
+    # 3. RRF 融合
+    if kw_candidates and vec_candidates:
+        by_id = {s.id: s for s in kw_candidates + vec_candidates}
+        fused = rrf_fuse(
+            [s.id for s in kw_candidates],
+            [s.id for s in vec_candidates],
+        )
+        merged = [by_id[sid] for sid in fused if sid in by_id]
+    elif vec_candidates:
+        merged = vec_candidates
+    else:
+        merged = kw_candidates
+
+    # 4. rerank 精排（对融合后的 top50 段打分）
+    if merged and RERANK_ENABLED:
+        docs = [s.text[:800] for s in merged[:50]]
+        idxs = await rerank_documents(query, docs, top_n=top_k)
+        if idxs is not None:
+            merged = [merged[i] for i in idxs if i < len(merged)]
+
+    # 5. 兜底：完全没召回时给各书开头段
+    if not merged:
+        merged = await _empty_fallback_all(db, books, top_k)
+
+    # 去重（跨书向量合并可能撞段）
+    seen: set[str] = set()
+    out: list[Segment] = []
+    for s in merged:
+        if s.id in seen:
+            continue
+        seen.add(s.id)
+        out.append(s)
+    return out[:top_k]
+
+
 def _chapter_full_text(chapter_segments: list[Segment], budget_tokens: int = 6000) -> str:
     """整章注入：按 token 预算截取命中章节的原文。"""
     parts = []
@@ -274,6 +364,8 @@ def parse_citations(content: str, segments: list[Segment]) -> dict:
                 "segment_id": seg.id,
                 "cfi": seg.cfi,
                 "excerpt": seg.text[:200],
+                # 跨书检索时由调用方在段上临时标注 _book_title，供前端显示出处
+                "book_title": getattr(seg, "_book_title", None),
             })
     clean_text = CITATION_RE.sub("", content)
     return {"text": clean_text, "citations": citations}

frontend/src/app/page.tsx

@@ -2,35 +2,67 @@
 
 import { useState, useEffect, useMemo, useRef, useContext } from "react";
 import {
-  BookMarked, BookOpen, Bot, Check, ChevronDown, ChevronLeft, ChevronRight, Copy,
+  BookMarked, BookOpen, Bot, ChevronRight, Clock,
-  Download, GitBranch, Globe, Loader2, LogOut, Paperclip, Plus, RotateCcw, Send, Settings2,
+  Download, GitBranch, Globe, Loader2, LogOut, Plus, RotateCcw, Send, Settings2,
-  Sparkles, Trash2, Upload, User, Wrench, X, ArrowUpRight, Library, Search, Menu, MessageSquare, ArrowLeft,
+  Sparkles, Trash2, Upload, X, ArrowUpRight, Library, Search, Menu, MessageSquare, ArrowLeft,
 } from "lucide-react";
 import { api, Book, Conversation, Message, Citation, AiModelEntry, McpServer, formatCharCount } from "@/lib/api";
-import MarkdownRenderer from "@/components/MarkdownRenderer";
+import ChatPanel, { buildTurns, WelcomeConfig, ActionBtn } from "@/components/ChatPanel";
 import ModelManagerDialog from "@/components/ModelManagerDialog";
 import McpManagerDialog from "@/components/McpManagerDialog";
 import AuthGate, { AuthContext } from "@/components/AuthGate";
 import { auth } from "@/lib/auth";
-import CitationReaderDialog from "@/components/CitationReaderDialog";
 import EpubReader from "@/components/EpubReader";
 
 const SIDEBAR_MIN = 180;
 const SIDEBAR_MAX = 480;
 
+// 书模式欢迎屏基础配置（副标题按当前书动态生成）
+const BOOK_WELCOME_BASE: Omit<WelcomeConfig, "subtitle"> = {
+  Icon: BookOpen,
+  eyebrow: "READ · THINK · DISCOVER",
+  title: "从一个好问题开始。",
+  placeholder: "问这本书的任何问题...",
+  listLabel: "对话历史",
+  newButtonText: "新建对话",
+  prompts: [
+    { Icon: BookOpen, title: "读懂这本书", prompt: "请梳理这本书的核心观点与整体结构。" },
+    { Icon: MessageSquare, title: "深入一个观点", prompt: "这本书中有哪些值得深入思考的观点？请结合原文展开。" },
+    { Icon: GitBranch, title: "连接知识", prompt: "请整理这本书中重要概念之间的联系。" },
+  ],
+};
+
+// 全局「第二大脑」助手欢迎屏
+const ASSISTANT_WELCOME: WelcomeConfig = {
+  Icon: Sparkles,
+  eyebrow: "SECOND BRAIN · 第二大脑",
+  title: "问关于你读过的一切。",
+  subtitle: "跨书籍、跨对话的综合思考伙伴：帮你梳理时间和精力都花在了哪，究竟获得了什么。",
+  placeholder: "问我关于你读过的一切...",
+  listLabel: "助手对话",
+  newButtonText: "新建助手对话",
+  prompts: [
+    { Icon: BookOpen, title: "复盘最近的阅读", prompt: "梳理我最近读了什么、讨论了什么、收获了什么。" },
+    { Icon: Clock, title: "时间精力去向", prompt: "我的时间和精力主要消耗在哪些书和哪些话题上？" },
+    { Icon: GitBranch, title: "待办与存疑", prompt: "列出我在对话中提到的待办、疑问和未完成的想法。" },
+  ],
+};
+
 function BookmateApp() {
   const [books, setBooks] = useState<Book[]>([]);
   const [selectedBook, setSelectedBook] = useState<Book | null>(null);
+  // 全局「第二大脑」助手模式：与单书对话并列，不绑定书
+  const [assistantMode, setAssistantMode] = useState(false);
   const [conversations, setConversations] = useState<Conversation[]>([]);
   const [activeConv, setActiveConv] = useState<Conversation | null>(null);
   const [messages, setMessages] = useState<Message[]>([]);
-  const [input, setInput] = useState("");
+  // EpubReader「解读原文」→ 输入框的交接：ChatPanel 消费后清空
+  const [pendingInput, setPendingInput] = useState("");
   const [streaming, setStreaming] = useState(false);
   const [streamContent, setStreamContent] = useState("");
   const [uploading, setUploading] = useState(false);
   const [model, setModel] = useState("deepseek");
   const [aiModels, setAiModels] = useState<AiModelEntry[]>([]);
-  const [pickerOpen, setPickerOpen] = useState(false);
   const [managerOpen, setManagerOpen] = useState(false);
   const [mcpOpen, setMcpOpen] = useState(false);
   const [mcpServers, setMcpServers] = useState<McpServer[]>([]);
@@ -42,7 +74,6 @@ function BookmateApp() {
   const [sidebarOpen, setSidebarOpen] = useState(false);
   const [booksLoading, setBooksLoading] = useState(true);
   const [booksError, setBooksError] = useState(false);
-  const chatEndRef = useRef<HTMLDivElement>(null);
   const fileInputRef = useRef<HTMLInputElement>(null);
   const [sidebarWidth, setSidebarWidth] = useState(256);
   const sidebarDragRef = useRef<{ startX: number; startW: number } | null>(null);
@@ -96,8 +127,6 @@ function BookmateApp() {
     api.listMcpServers().then(setMcpServers).catch(() => setMcpServers([]));
   }, []);
 
-  const currentModel = aiModels.find((m) => m.name === model) ?? aiModels[0];
-
   // 恢复/保存侧栏宽度（localStorage）
   useEffect(() => {
     const saved = localStorage.getItem("bookmate.sidebarWidth");
@@ -116,8 +145,6 @@ function BookmateApp() {
     if (activeConv) api.getMessages(activeConv.id).then(setMessages);
   }, [activeConv]);
 
-  useEffect(() => { chatEndRef.current?.scrollIntoView({ behavior: "smooth" }); }, [messages, streamContent]);
-
   const handleUpload = async (e: React.ChangeEvent<HTMLInputElement>) => {
     const file = e.target.files?.[0];
     if (!file) return;
@@ -125,6 +152,7 @@ function BookmateApp() {
     try {
       const book = await api.uploadBook(file);
       setBooks((prev) => [book, ...prev]);
+      setAssistantMode(false);
       setSelectedBook(book);
     } catch (err: unknown) {
       alert(err instanceof Error ? err.message : "Upload failed");
@@ -133,8 +161,29 @@ function BookmateApp() {
     if (fileInputRef.current) fileInputRef.current.value = "";
   };
 
+  // 全局「第二大脑」助手模式
+  const enableAssistant = async () => {
+    setAssistantMode(true);
+    setSelectedBook(null);
+    setActiveConv(null);
+    setMessages([]);
+    setSidebarOpen(false);
+    const convs = await api.listConversations(undefined, "assistant");
+    setConversations(convs);
+    if (convs.length > 0) setActiveConv(convs[0]);
+  };
+
+  const enableLibrary = () => {
+    setAssistantMode(false);
+    setSelectedBook(null);
+    setActiveConv(null);
+    setMessages([]);
+    setSidebarOpen(false);
+  };
+
   const startChat = async (book: Book) => {
     setSidebarOpen(false);
+    setAssistantMode(false);
     setSelectedBook(book);
     setActiveConv(null);
     setMessages([]);
@@ -149,18 +198,19 @@ function BookmateApp() {
     }
   };
 
-  const handleSend = async () => {
+  const handleSend = async (content: string) => {
-    if (!input.trim() || streaming) return;
+    if (!content.trim() || streaming) return;
     let conv = activeConv;
-    if (!conv && selectedBook) {
+    if (!conv) {
-      conv = await api.createConversation(selectedBook.id, model);
+      if (assistantMode) conv = await api.createConversation(null, model, "assistant");
+      else if (selectedBook) conv = await api.createConversation(selectedBook.id, model, "book");
+      if (!conv) return;
       setConversations((prev) => [conv!, ...prev]);
       setActiveConv(conv);
     }
     if (!conv) return;
 
-    const userContent = input;
+    const userContent = content;
-    setInput("");
     const tempId = `temp-${Date.now()}`;
     setMessages((prev) => [...prev, { id: tempId, conversation_id: conv!.id, parent_message_id: null, role: "user", content: userContent, citations: null, model, created_at: new Date().toISOString() }]);
     setStreaming(true);
@@ -299,10 +349,6 @@ function BookmateApp() {
     clearTools();
   };
 
-  const handleCopy = async (text: string) => {
-    await navigator.clipboard.writeText(text);
-  };
-
   const handleDelete = async (msgId: string) => {
     if (!confirm("删除这条消息？其名下的回答版本也会一并删除。")) return;
     try {
@@ -326,9 +372,13 @@ function BookmateApp() {
   };
 
   const handleNewConversation = async () => {
-    if (!selectedBook) return;
     try {
-      const conv = await api.createConversation(selectedBook.id, model);
+      const conv = assistantMode
+        ? await api.createConversation(null, model, "assistant")
+        : selectedBook
+          ? await api.createConversation(selectedBook.id, model, "book")
+          : null;
+      if (!conv) return;
       setConversations((prev) => [conv, ...prev]);
       setActiveConv(conv);
       setMessages([]);
@@ -430,7 +480,8 @@ function BookmateApp() {
         </div>
 
         <div className="px-4 pt-2 pb-5">
-          <button className={`nav-library ${!selectedBook ? "active" : ""}`} onClick={() => { setSelectedBook(null); setSidebarOpen(false); }}><Library size={18} /> 我的书库 <span>{books.length}</span></button>
+          <button className={`nav-library ${assistantMode ? "active" : ""}`} onClick={enableAssistant}><Bot size={18} /> AI 助手</button>
+          <button className={`nav-library ${!assistantMode && !selectedBook ? "active" : ""}`} onClick={enableLibrary}><Library size={18} /> 我的书库 <span>{books.length}</span></button>
           <input ref={fileInputRef} type="file" accept=".epub" onChange={handleUpload} className="hidden" />
           <button
             onClick={() => fileInputRef.current?.click()}
@@ -494,224 +545,108 @@ function BookmateApp() {
 
       {/* Main */}
       <main className="main-panel flex-1 flex flex-col min-w-0">
-        {selectedBook ? (
+        {assistantMode ? (
-          <>
+          <ChatPanel
-            <header className="reader-header border-b border-[var(--border)] flex items-center gap-3 shrink-0">
+            header={
-              <button className="back-library" onClick={() => setSelectedBook(null)} aria-label="返回书库"><ArrowLeft size={18} /></button>
+              <header className="reader-header border-b border-[var(--border)] flex items-center gap-3 shrink-0">
-              <div className="flex-1 min-w-0">
+                <button className="back-library" onClick={enableLibrary} aria-label="返回书库"><ArrowLeft size={18} /></button>
-                <h2 className="text-[15px] font-semibold truncate text-[var(--fg)]">{selectedBook.title || selectedBook.filename}</h2>
+                <div className="flex-1 min-w-0">
-                <p className="text-[11px] text-[var(--fg-muted)]">{selectedBook.author}</p>
+                  <h2 className="text-[15px] font-semibold truncate text-[var(--fg)]">AI 助手</h2>
-              </div>
+                  <p className="text-[11px] text-[var(--fg-muted)]">第二大脑 · 跨书籍跨对话的思考伙伴</p>
-              <button
+                </div>
-                onClick={() => setReaderBook(selectedBook)}
-                className="open-full-book"
-                title="打开完整 EPUB"
-              >
-                <BookOpen size={16} />
-                <span>阅读全书</span>
-              </button>
-              <button
-                onClick={handleExport}
-                disabled={!activeConv}
-                className="text-xs px-3 py-1.5 rounded-lg hover:bg-[var(--bg-hover)] disabled:opacity-50 transition-colors flex items-center gap-1.5 text-[var(--fg-muted)] hover:text-[var(--fg)]"
-                title="导出对话"
-              >
-                <Download size={13} />
-                导出
-              </button>
-            </header>
-
-            <div className="flex-1 flex min-h-0">
-              <div className="conversation-sidebar overflow-y-auto overflow-x-hidden py-3 shrink-0">
-                <p className="text-[11px] text-[var(--fg-muted)] px-3 py-2 font-medium tracking-wider">对话历史</p>
                 <button
-                  onClick={handleNewConversation}
+                  onClick={handleExport}
-                  disabled={!selectedBook}
+                  disabled={!activeConv}
-                  className="w-full mb-1 px-3 py-2 rounded-xl text-xs text-[var(--fg-muted)] hover:text-[var(--fg)] hover:bg-[var(--bg-hover)] disabled:opacity-50 transition-colors flex items-center justify-center gap-1.5"
+                  className="text-xs px-3 py-1.5 rounded-lg hover:bg-[var(--bg-hover)] disabled:opacity-50 transition-colors flex items-center gap-1.5 text-[var(--fg-muted)] hover:text-[var(--fg)]"
+                  title="导出对话"
                 >
-                  <Plus size={12} />
+                  <Download size={13} />
-                  新建对话
+                  导出
                 </button>
-                {conversations.map((c) => (
+              </header>
-                  <div key={c.id} className="flex items-center group">
+            }
-                    <button
+            conversations={conversations}
-                      onClick={() => selectConv(c)}
+            activeConv={activeConv}
-                      className={`flex-1 min-w-0 text-left px-3 py-2 rounded-xl text-[13px] truncate text-[var(--fg)] transition-colors ${
+            messages={messages}
-                        activeConv?.id === c.id ? "bg-[var(--accent-soft)]" : "hover:bg-[var(--bg-hover)]"
+            turns={turns}
-                      }`}
+            streaming={streaming}
-                    >
+            streamContent={streamContent}
-                      {c.title || "对话"}
+            streamTurnId={streamTurnId}
-                    </button>
+            activeTools={activeTools}
-                    <ActionBtn danger title="删除对话" onClick={() => handleDeleteConversation(c.id)}>
+            activeVersions={activeVersions}
-                      <X size={14} />
+            setActiveVersions={setActiveVersions}
-                    </ActionBtn>
+            aiModels={aiModels}
-                  </div>
+            model={model}
-                ))}
+            setModel={setModel}
-              </div>
+            welcome={ASSISTANT_WELCOME}
-
+            onSelectConv={selectConv}
-              <div className="flex-1 flex flex-col min-w-0">
+            onNewConversation={handleNewConversation}
-                <div className="flex-1 overflow-y-auto px-6 pt-6 pb-10 space-y-6">
+            onDeleteConversation={handleDeleteConversation}
-                  <div className="max-w-3xl mx-auto w-full space-y-6">
+            onSend={handleSend}
-                  {turns.length === 0 && !streaming && (
+            onRetry={handleRetry}
-                    <div className="chat-welcome">
+            onDelete={handleDelete}
-                      <div className="chat-welcome-icon"><BookOpen size={30} strokeWidth={1.4} /></div>
+            onBranch={handleBranch}
-                      <span className="eyebrow">READ · THINK · DISCOVER</span>
+            onManage={() => setManagerOpen(true)}
-                      <h2>从一个好问题开始。</h2>
+            externalInput={pendingInput}
-                      <p>关于《{selectedBook.title || selectedBook.filename}》，你想了解什么？</p>
+            onConsumeExternalInput={() => setPendingInput("")}
-                      <div className="prompt-grid">
+          />
-                        {[{ icon: BookOpen, title: "读懂这本书", prompt: "请梳理这本书的核心观点与整体结构。" }, { icon: MessageSquare, title: "深入一个观点", prompt: "这本书中有哪些值得深入思考的观点？请结合原文展开。" }, { icon: GitBranch, title: "连接知识", prompt: "请整理这本书中重要概念之间的联系。" }].map(({ icon: Icon, title, prompt }) => (
+        ) : selectedBook ? (
-                          <button key={title} onClick={() => setInput(prompt)}><Icon size={19} /><strong>{title}</strong><span>{prompt}</span><ArrowUpRight size={15} /></button>
+          <ChatPanel
-                        ))}
+            header={
-                      </div>
+              <header className="reader-header border-b border-[var(--border)] flex items-center gap-3 shrink-0">
-                    </div>
+                <button className="back-library" onClick={enableLibrary} aria-label="返回书库"><ArrowLeft size={18} /></button>
-                  )}
+                <div className="flex-1 min-w-0">
-                  {turns.map((turn) => {
+                  <h2 className="text-[15px] font-semibold truncate text-[var(--fg)]">{selectedBook.title || selectedBook.filename}</h2>
-                    const isLastTurn = turn.user.id === turns[turns.length - 1]?.user.id;
+                  <p className="text-[11px] text-[var(--fg-muted)]">{selectedBook.author}</p>
-                    const versions = [...turn.versions];
-                    const activeIdx = activeVersions[turn.user.id] ?? versions.length - 1;
-                    const shown = versions[activeIdx] ?? null;
-                    const streamingHere = streaming && streamTurnId === turn.user.id && (!!streamContent || activeTools.length > 0);
-                    return (
-                      <div key={turn.user.id} className="space-y-1.5">
-                        <ChatBubble
-                          message={turn.user}
-                          onCopy={handleCopy}
-                          onRetry={isLastTurn ? handleRetry : undefined}
-                          onDelete={handleDelete}
-                        />
-                        {versions.length > 1 && (
-                          <div className="flex items-center gap-1 pl-10">
-                            <button
-                              type="button"
-                              onClick={() => setActiveVersions((prev) => ({ ...prev, [turn.user.id]: activeIdx - 1 }))}
-                              disabled={activeIdx <= 0}
-                              className="p-1 rounded-md text-[var(--fg-muted)] hover:bg-white/10 hover:text-[var(--fg)] disabled:opacity-30 transition-colors"
-                              title="上一个版本"
-                            >
-                              <ChevronLeft size={14} />
-                            </button>
-                            <span className="px-2 py-0.5 rounded-md bg-white/5 text-xs text-[var(--fg-muted)]">
-                              版本 {activeIdx + 1} / {versions.length}
-                            </span>
-                            <button
-                              type="button"
-                              onClick={() => setActiveVersions((prev) => ({ ...prev, [turn.user.id]: activeIdx + 1 }))}
-                              disabled={activeIdx >= versions.length - 1}
-                              className="p-1 rounded-md text-[var(--fg-muted)] hover:bg-white/10 hover:text-[var(--fg)] disabled:opacity-30 transition-colors"
-                              title="下一个版本"
-                            >
-                              <ChevronRight size={14} />
-                            </button>
-                          </div>
-                        )}
-                        {shown && (
-                          <ChatBubble
-                            key={shown.id}
-                            message={shown}
-                            onCopy={handleCopy}
-                            onDelete={handleDelete}
-                            onBranch={handleBranch}
-                          />
-                        )}
-                        {streamingHere && (
-                          <div className="pl-10 space-y-1">
-                            {activeTools.length > 0 && <ToolChips tools={activeTools} />}
-                            {streamContent && (
-                              <ChatBubble
-                                message={{ id: "stream", conversation_id: "", parent_message_id: turn.user.id, role: "assistant", content: streamContent, citations: null, model, created_at: "" }}
-                                isStreaming={true}
-                              />
-                            )}
-                          </div>
-                        )}
-                      </div>
-                    );
-                  })}
-                  {streaming && !streamTurnId && (streamContent || activeTools.length > 0) && (
-                    <div className="max-w-3xl mx-auto space-y-1">
-                      {activeTools.length > 0 && <ToolChips tools={activeTools} />}
-                      {streamContent && (
-                        <ChatBubble
-                          message={{ id: "stream", conversation_id: "", parent_message_id: null, role: "assistant", content: streamContent, citations: null, model, created_at: "" }}
-                          isStreaming={true}
-                        />
-                      )}
-                    </div>
-                  )}
-                  <div ref={chatEndRef} />
-                  </div>
                 </div>
-
+                <button
-                <div className="composer-area px-4 pt-3 pb-4">
+                  onClick={() => setReaderBook(selectedBook)}
-                  {/* 输入胶囊：模型选择 + 输入合并（Perplexity 风） */}
+                  className="open-full-book"
-                  <div className="max-w-3xl mx-auto">
+                  title="打开完整 EPUB"
-                    <div className="composer rounded-2xl px-4 py-3">
+                >
-                      <div className="flex items-center justify-between mb-1">
+                  <BookOpen size={16} />
-                        <div className="relative">
+                  <span>阅读全书</span>
-                          {pickerOpen && <div className="fixed inset-0 z-10" onClick={() => setPickerOpen(false)} />}
+                </button>
-                          <button
+                <button
-                            onClick={() => setPickerOpen((v) => !v)}
+                  onClick={handleExport}
-                            className="flex items-center gap-1.5 text-xs px-2 py-1 rounded-md bg-white/5 text-[var(--fg-muted)] hover:text-[var(--fg)] hover:bg-white/10 transition-colors"
+                  disabled={!activeConv}
-                            title={currentModel ? `${currentModel.model_id} · ${currentModel.base_url || currentModel.kind}` : (aiModels.length ? "" : "尚未配置模型")}
+                  className="text-xs px-3 py-1.5 rounded-lg hover:bg-[var(--bg-hover)] disabled:opacity-50 transition-colors flex items-center gap-1.5 text-[var(--fg-muted)] hover:text-[var(--fg)]"
-                          >
+                  title="导出对话"
-                            <Sparkles size={12} className="text-[var(--accent)]" />
+                >
-                            <span className="max-w-40 truncate">{currentModel?.label ?? (aiModels.length ? model : "未配置模型")}</span>
+                  <Download size={13} />
-                            <ChevronDown size={12} />
+                  导出
-                          </button>
+                </button>
-                          {pickerOpen && (
+              </header>
-                            <div className="absolute z-20 bottom-full mb-1.5 left-0 w-64 rounded-xl border border-[var(--border)] bg-[var(--bg-card)] shadow-2xl p-1.5 max-h-72 overflow-y-auto">
+            }
-                              <p className="text-[10px] text-[var(--fg-muted)] px-2 pt-1 pb-1.5 font-medium tracking-wider">选择回答模型</p>
+            conversations={conversations}
-                              {aiModels.map((m) => (
+            activeConv={activeConv}
-                                <button
+            messages={messages}
-                                  key={m.name}
+            turns={turns}
-                                  onClick={() => { setModel(m.name); setPickerOpen(false); }}
+            streaming={streaming}
-                                  className={`w-full flex items-center justify-between gap-2 px-2.5 py-2 rounded-lg text-left text-sm transition-colors ${
+            streamContent={streamContent}
-                                    model === m.name ? "bg-[var(--accent-soft)] text-[var(--accent)]" : "text-[var(--fg)] hover:bg-[var(--bg-hover)]"
+            streamTurnId={streamTurnId}
-                                  }`}
+            activeTools={activeTools}
-                                >
+            activeVersions={activeVersions}
-                                  <span className="truncate">{m.label}</span>
+            setActiveVersions={setActiveVersions}
-                                  <span className="text-[10px] text-[var(--fg-muted)] shrink-0">{m.builtin ? "内置" : "自定义"}</span>
+            aiModels={aiModels}
-                                </button>
+            model={model}
-                              ))}
+            setModel={setModel}
-                              {aiModels.length === 0 && (
+            welcome={{
-                                <p className="px-2 py-3 text-xs text-[var(--fg-muted)] text-center">尚未配置模型，点「管理」添加</p>
+              ...BOOK_WELCOME_BASE,
-                              )}
+              subtitle: `关于《${selectedBook.title || selectedBook.filename}》，你想了解什么？`,
-                            </div>
+            }}
-                          )}
+            onSelectConv={selectConv}
-                        </div>
+            onNewConversation={handleNewConversation}
-                        <button
+            onDeleteConversation={handleDeleteConversation}
-                          onClick={() => setManagerOpen(true)}
+            onSend={handleSend}
-                          className="text-xs px-2 py-1 rounded-md text-[var(--fg-muted)] hover:text-[var(--fg)] hover:bg-white/5 transition-colors flex items-center gap-1"
+            onRetry={handleRetry}
-                        >
+            onDelete={handleDelete}
-                          <Settings2 size={12} />
+            onBranch={handleBranch}
-                          管理模型
+            onManage={() => setManagerOpen(true)}
-                        </button>
+            composerDisabled={!selectedBook}
-                      </div>
+            externalInput={pendingInput}
-
+            onConsumeExternalInput={() => setPendingInput("")}
-                      <div className="flex items-center gap-2">
+          />
-                        <input
-                          value={input}
-                          onChange={(e) => setInput(e.target.value)}
-                          onKeyDown={(e) => e.key === "Enter" && !e.shiftKey && !e.nativeEvent.isComposing && handleSend()}
-                          placeholder={selectedBook ? "问这本书的任何问题..." : "先选择一本书"}
-                          disabled={!selectedBook || streaming}
-                          className="flex-1 bg-transparent px-1 py-1.5 text-sm text-[var(--fg)] placeholder-[var(--fg-muted)] focus:outline-none disabled:opacity-50"
-                        />
-                        <button
-                          onClick={handleSend}
-                          disabled={!input.trim() || streaming}
-                          className="p-2 rounded-xl bg-[var(--accent)] text-white hover:bg-[var(--accent-hover)] disabled:opacity-40 disabled:hover:bg-[var(--accent)] transition-colors shrink-0"
-                          title="发送"
-                        >
-                          {streaming ? <Loader2 size={16} className="animate-spin" /> : <Send size={16} />}
-                        </button>
-                      </div>
-                    </div>
-                  </div>
-                </div>
-              </div>
-            </div>
-          </>
         ) : (
           <div className="library-page">
             <header className="library-topbar"><span>我的阅读空间 <span className="breadcrumb-slash">/</span> <strong>书库</strong></span><span className="topbar-note"><span /> 与好书，慢慢相处</span></header>
@@ -757,7 +692,7 @@ function BookmateApp() {
             }
             try {
               if (selectedBook?.id !== readerBook.id || !activeConv) await startChat(readerBook);
-              setInput(text);
+              setPendingInput(text);
               setReaderBook(null);
             } catch {
               alert("暂时无法打开对话，请稍后重试。");
@@ -790,201 +725,3 @@ export default function Home() {
   );
 }
 
-function ChatBubble({
-  message,
-  isStreaming,
-  onCopy,
-  onDelete,
-  onBranch,
-  onRetry,
-}: {
-  message: Message;
-  isStreaming?: boolean;
-  onCopy?: (text: string) => void;
-  onDelete?: (id: string) => void;
-  onBranch?: (id: string) => void;
-  onRetry?: (msg: Message) => void;
-}) {
-  const [copied, setCopied] = useState(false);
-  const [citationsOpen, setCitationsOpen] = useState(false);
-  const [readerSegmentId, setReaderSegmentId] = useState<string | null>(null);
-  const isUser = message.role === "user";
-  const isStream = isStreaming || message.id === "stream";
-
-  // 同一段落被 AI 重复引用时只显示一条（引用渲染去重，不影响已注入的检索内容）
-  const uniqCitations = useMemo(() => {
-    const seen = new Set<string>();
-    return (message.citations ?? []).filter((c) => {
-      if (seen.has(c.segment_id)) return false;
-      seen.add(c.segment_id);
-      return true;
-    });
-  }, [message.citations]);
-
-  const handleCopy = () => {
-    onCopy?.(message.content);
-    setCopied(true);
-    setTimeout(() => setCopied(false), 1500);
-  };
-
-  return (
-    <>
-    <div className={`flex group ${isUser ? "justify-end" : "justify-start"}`}>
-      <div className={`flex items-end gap-1.5 max-w-[82%] ${isUser ? "flex-row-reverse" : "flex-row"}`}>
-        <div
-          className={`w-6 h-6 rounded-full flex items-center justify-center shrink-0 mb-1 ${
-            isUser
-              ? "bg-[var(--accent)] text-white"
-              : "bg-[var(--accent-soft)] text-[var(--accent)]"
-          }`}
-        >
-          {isUser ? <User size={12} /> : <Bot size={12} />}
-        </div>
-
-        <div className="min-w-0">
-          <div
-            className={`${
-              isUser
-                ? "rounded-2xl rounded-br-md px-4 py-2.5 text-[15px] leading-relaxed bg-[var(--accent)] text-white shadow-sm"
-                : "px-0.5 py-0.5 text-[15px] leading-[1.75] text-[var(--fg)]"
-            } ${isStream ? "streaming-answer" : ""}`}
-          >
-            <MarkdownRenderer content={message.content} variant={isUser ? "dark" : "light"} />
-            {uniqCitations.length > 0 && (
-              <div className={`mt-3 pt-2 border-t ${isUser ? "border-white/25" : "border-[var(--border)]"}`}>
-                <button
-                  type="button"
-                  onClick={() => setCitationsOpen((v) => !v)}
-                  className={`text-xs font-medium flex items-center gap-1 transition-colors ${
-                    isUser ? "text-white/80" : "text-[var(--fg-muted)] hover:text-[var(--fg)]"
-                  }`}
-                >
-                  <Paperclip size={11} />
-                  引用来源（{uniqCitations.length}）
-                  {uniqCitations.length < (message.citations?.length ?? 0) && (
-                    <span className="opacity-70">已合并重复</span>
-                  )}
-                  <ChevronDown size={11} className={`transition-transform ${citationsOpen ? "rotate-180" : ""}`} />
-                </button>
-
-                {citationsOpen && (
-                  <div className="mt-2 space-y-1.5">
-                    {uniqCitations.map((c, i) => (
-                      <div
-                        key={i}
-                        className={`text-xs py-1.5 px-2 rounded flex items-start gap-2 ${
-                          isUser ? "text-white/85 bg-white/10" : "text-[var(--fg-muted)] bg-[var(--bg)]"
-                        }`}
-                      >
-                        <span className={`font-medium shrink-0 ${isUser ? "text-white" : "text-[var(--accent)]"}`}>[{i + 1}]</span>
-                        <span className="flex-1 min-w-0 leading-relaxed">
-                          {(c.excerpt || "").replace(/《heading_path》\s*/g, "").slice(0, 80)}{(c.excerpt || "").length > 80 ? "…" : ""}
-                        </span>
-                        <button
-                          type="button"
-                          onClick={() => setReaderSegmentId(c.segment_id)}
-                          className="shrink-0 flex items-center gap-0.5 font-medium text-[var(--accent-hover)] hover:underline mt-0.5"
-                          title="阅读该段原文"
-                        >
-                          <BookOpen size={11} />
-                          原文
-                        </button>
-                      </div>
-                    ))}
-                  </div>
-                )}
-              </div>
-            )}
-          </div>
-
-          {!isStream && (
-            <div className={`flex gap-0.5 mt-1 px-1 opacity-0 group-hover:opacity-100 transition-opacity ${isUser ? "justify-end" : "justify-start"}`}>
-              <ActionBtn title="复制" onClick={handleCopy}>
-                {copied ? <Check size={15} className="text-[var(--success)]" /> : <Copy size={15} />}
-              </ActionBtn>
-              {onRetry && (
-                <ActionBtn title="重新回答" onClick={() => onRetry(message)}>
-                  <RotateCcw size={15} />
-                </ActionBtn>
-              )}
-              {onBranch && (
-                <ActionBtn title="从此分支" onClick={() => onBranch(message.id)}>
-                  <GitBranch size={15} />
-                </ActionBtn>
-              )}
-              {onDelete && (
-                <ActionBtn title="删除" onClick={() => onDelete(message.id)}>
-                  <Trash2 size={15} />
-                </ActionBtn>
-              )}
-            </div>
-          )}
-        </div>
-      </div>
-    </div>
-    <CitationReaderDialog
-      open={!!readerSegmentId}
-      segmentId={readerSegmentId}
-      onClose={() => setReaderSegmentId(null)}
-    />
-    </>
-  );
-}
-
-interface Turn {
-  user: Message;
-  versions: Message[];
-}
-
-/**
- * 把平铺的消息流聚合成「回合」列表：每个 user 消息 + 它名下的所有 AI 回答版本。
- * assistant 按 parent_message_id 归属；旧数据 parent 为 null 时，挂到它之前最近的 user。
- */
-function buildTurns(msgs: Message[]): Turn[] {
-  const turns: Turn[] = [];
-  const byUser = new Map<string, Turn>();
-  let lastTurn: Turn | null = null;
-  for (const m of msgs) {
-    if (m.role === "user") {
-      lastTurn = { user: m, versions: [] };
-      turns.push(lastTurn);
-      byUser.set(m.id, lastTurn);
-    } else if (m.role === "assistant") {
-      const target = (m.parent_message_id && byUser.get(m.parent_message_id)) || lastTurn;
-      if (target) target.versions.push(m);
-    }
-  }
-  return turns;
-}
-
-function ToolChips({ tools }: { tools: string[] }) {
-  return (
-    <div className="flex items-center gap-1.5 text-xs text-[var(--fg-muted)]">
-      {tools.map((t) => (
-        <span key={t} className="px-2 py-1 rounded-lg bg-[var(--accent-soft)] text-[var(--accent)] flex items-center gap-1.5">
-          <Wrench size={12} />
-          {t}
-        </span>
-      ))}
-      <span className="text-[11px]">调用外部工具中…</span>
-    </div>
-  );
-}
-
-function ActionBtn({ title, onClick, children, danger }: { title: string; onClick: () => void; children: React.ReactNode; danger?: boolean }) {
-  return (
-    <button
-      type="button"
-      onClick={(e) => { e.stopPropagation(); onClick(); }}
-      className={`w-7 h-7 flex items-center justify-center rounded-lg shrink-0 touch-manipulation opacity-0 group-hover:opacity-100 focus-visible:opacity-100 transition-opacity ${
-        danger
-          ? "text-[var(--fg-muted)] hover:text-[var(--danger)] hover:bg-red-500/10 active:bg-red-500/15"
-          : "text-[var(--fg-muted)] hover:bg-white/10 hover:text-[var(--fg)] active:bg-white/10"
-      }`}
-      title={title}
-      aria-label={title}
-    >
-      {children}
-    </button>
-  );
-}

frontend/src/components/ChatPanel.tsx

@@ -0,0 +1,502 @@
+"use client";
+
+import { useEffect, useMemo, useRef, useState } from "react";
+import {
+  BookOpen, Bot, Check, ChevronDown, ChevronLeft, ChevronRight, Copy,
+  GitBranch, Loader2, Paperclip, Plus, RotateCcw, Send, Settings2,
+  Sparkles, Trash2, User, Wrench, X, ArrowUpRight,
+} from "lucide-react";
+import { Conversation, Message, Citation, AiModelEntry } from "@/lib/api";
+import MarkdownRenderer from "@/components/MarkdownRenderer";
+import CitationReaderDialog from "@/components/CitationReaderDialog";
+
+/* ======================= 消息 → 回合 ======================= */
+
+export interface Turn {
+  user: Message;
+  versions: Message[];
+}
+
+/**
+ * 把平铺的消息流聚合成「回合」列表：每个 user 消息 + 它名下的所有 AI 回答版本。
+ * assistant 按 parent_message_id 归属；旧数据 parent 为 null 时，挂到它之前最近的 user。
+ */
+export function buildTurns(msgs: Message[]): Turn[] {
+  const turns: Turn[] = [];
+  const byUser = new Map<string, Turn>();
+  let lastTurn: Turn | null = null;
+  for (const m of msgs) {
+    if (m.role === "user") {
+      lastTurn = { user: m, versions: [] };
+      turns.push(lastTurn);
+      byUser.set(m.id, lastTurn);
+    } else if (m.role === "assistant") {
+      const target = (m.parent_message_id && byUser.get(m.parent_message_id)) || lastTurn;
+      if (target) target.versions.push(m);
+    }
+  }
+  return turns;
+}
+
+/* ======================= 共享 UI 小件 ======================= */
+
+function ToolChips({ tools }: { tools: string[] }) {
+  return (
+    <div className="flex items-center gap-1.5 text-xs text-[var(--fg-muted)]">
+      {tools.map((t) => (
+        <span key={t} className="px-2 py-1 rounded-lg bg-[var(--accent-soft)] text-[var(--accent)] flex items-center gap-1.5">
+          <Wrench size={12} />
+          {t}
+        </span>
+      ))}
+      <span className="text-[11px]">调用外部工具中…</span>
+    </div>
+  );
+}
+
+export function ActionBtn({ title, onClick, children, danger }: { title: string; onClick: () => void; children: React.ReactNode; danger?: boolean }) {
+  return (
+    <button
+      type="button"
+      onClick={(e) => { e.stopPropagation(); onClick(); }}
+      className={`w-7 h-7 flex items-center justify-center rounded-lg shrink-0 touch-manipulation opacity-0 group-hover:opacity-100 focus-visible:opacity-100 transition-opacity ${
+        danger
+          ? "text-[var(--fg-muted)] hover:text-[var(--danger)] hover:bg-red-500/10 active:bg-red-500/15"
+          : "text-[var(--fg-muted)] hover:bg-white/10 hover:text-[var(--fg)] active:bg-white/10"
+      }`}
+      title={title}
+      aria-label={title}
+    >
+      {children}
+    </button>
+  );
+}
+
+function ChatBubble({
+  message,
+  isStreaming,
+  onCopy,
+  onDelete,
+  onBranch,
+  onRetry,
+}: {
+  message: Message;
+  isStreaming?: boolean;
+  onCopy?: (text: string) => void;
+  onDelete?: (id: string) => void;
+  onBranch?: (id: string) => void;
+  onRetry?: (msg: Message) => void;
+}) {
+  const [copied, setCopied] = useState(false);
+  const [citationsOpen, setCitationsOpen] = useState(false);
+  const [readerSegmentId, setReaderSegmentId] = useState<string | null>(null);
+  const isUser = message.role === "user";
+  const isStream = isStreaming || message.id === "stream";
+
+  // 同一段落被 AI 重复引用时只显示一条（引用渲染去重，不影响已注入的检索内容）
+  const uniqCitations = useMemo(() => {
+    const seen = new Set<string>();
+    return (message.citations ?? []).filter((c) => {
+      if (seen.has(c.segment_id)) return false;
+      seen.add(c.segment_id);
+      return true;
+    });
+  }, [message.citations]);
+
+  const handleCopy = () => {
+    onCopy?.(message.content);
+    setCopied(true);
+    setTimeout(() => setCopied(false), 1500);
+  };
+
+  return (
+    <>
+    <div className={`flex group ${isUser ? "justify-end" : "justify-start"}`}>
+      <div className={`flex items-end gap-1.5 max-w-[82%] ${isUser ? "flex-row-reverse" : "flex-row"}`}>
+        <div
+          className={`w-6 h-6 rounded-full flex items-center justify-center shrink-0 mb-1 ${
+            isUser
+              ? "bg-[var(--accent)] text-white"
+              : "bg-[var(--accent-soft)] text-[var(--accent)]"
+          }`}
+        >
+          {isUser ? <User size={12} /> : <Bot size={12} />}
+        </div>
+
+        <div className="min-w-0">
+          <div
+            className={`${
+              isUser
+                ? "rounded-2xl rounded-br-md px-4 py-2.5 text-[15px] leading-relaxed bg-[var(--accent)] text-white shadow-sm"
+                : "px-0.5 py-0.5 text-[15px] leading-[1.75] text-[var(--fg)]"
+            } ${isStream ? "streaming-answer" : ""}`}
+          >
+            <MarkdownRenderer content={message.content} variant={isUser ? "dark" : "light"} />
+            {uniqCitations.length > 0 && (
+              <div className={`mt-3 pt-2 border-t ${isUser ? "border-white/25" : "border-[var(--border)]"}`}>
+                <button
+                  type="button"
+                  onClick={() => setCitationsOpen((v) => !v)}
+                  className={`text-xs font-medium flex items-center gap-1 transition-colors ${
+                    isUser ? "text-white/80" : "text-[var(--fg-muted)] hover:text-[var(--fg)]"
+                  }`}
+                >
+                  <Paperclip size={11} />
+                  引用来源（{uniqCitations.length}）
+                  {uniqCitations.length < (message.citations?.length ?? 0) && (
+                    <span className="opacity-70">已合并重复</span>
+                  )}
+                  <ChevronDown size={11} className={`transition-transform ${citationsOpen ? "rotate-180" : ""}`} />
+                </button>
+
+                {citationsOpen && (
+                  <div className="mt-2 space-y-1.5">
+                    {uniqCitations.map((c, i) => (
+                      <div
+                        key={i}
+                        className={`text-xs py-1.5 px-2 rounded flex items-start gap-2 ${
+                          isUser ? "text-white/85 bg-white/10" : "text-[var(--fg-muted)] bg-[var(--bg)]"
+                        }`}
+                      >
+                        <span className={`font-medium shrink-0 ${isUser ? "text-white" : "text-[var(--accent)]"}`}>[{i + 1}]</span>
+                        <span className="flex-1 min-w-0 leading-relaxed">
+                          {c.book_title && <em className="not-italic text-[var(--accent)] mr-1">《{c.book_title}》</em>}
+                          {(c.excerpt || "").replace(/《heading_path》\s*/g, "").slice(0, 80)}{(c.excerpt || "").length > 80 ? "…" : ""}
+                        </span>
+                        <button
+                          type="button"
+                          onClick={() => setReaderSegmentId(c.segment_id)}
+                          className="shrink-0 flex items-center gap-0.5 font-medium text-[var(--accent-hover)] hover:underline mt-0.5"
+                          title="阅读该段原文"
+                        >
+                          <BookOpen size={11} />
+                          原文
+                        </button>
+                      </div>
+                    ))}
+                  </div>
+                )}
+              </div>
+            )}
+          </div>
+
+          {!isStream && (
+            <div className={`flex gap-0.5 mt-1 px-1 opacity-0 group-hover:opacity-100 transition-opacity ${isUser ? "justify-end" : "justify-start"}`}>
+              <ActionBtn title="复制" onClick={handleCopy}>
+                {copied ? <Check size={15} className="text-[var(--success)]" /> : <Copy size={15} />}
+              </ActionBtn>
+              {onRetry && (
+                <ActionBtn title="重新回答" onClick={() => onRetry(message)}>
+                  <RotateCcw size={15} />
+                </ActionBtn>
+              )}
+              {onBranch && (
+                <ActionBtn title="从此分支" onClick={() => onBranch(message.id)}>
+                  <GitBranch size={15} />
+                </ActionBtn>
+              )}
+              {onDelete && (
+                <ActionBtn title="删除" onClick={() => onDelete(message.id)}>
+                  <Trash2 size={15} />
+                </ActionBtn>
+              )}
+            </div>
+          )}
+        </div>
+      </div>
+    </div>
+    <CitationReaderDialog
+      open={!!readerSegmentId}
+      segmentId={readerSegmentId}
+      onClose={() => setReaderSegmentId(null)}
+    />
+    </>
+  );
+}
+
+/* ======================= 欢迎屏配置 ======================= */
+
+export interface WelcomePrompt {
+  Icon: React.ComponentType<{ size?: number; strokeWidth?: number }>;
+  title: string;
+  prompt: string;
+}
+
+export interface WelcomeConfig {
+  Icon: React.ComponentType<{ size?: number; strokeWidth?: number }>;
+  eyebrow: string;
+  title: string;
+  subtitle: string;
+  placeholder: string;
+  listLabel: string;
+  newButtonText: string;
+  prompts: WelcomePrompt[];
+}
+
+/* ======================= 对话面板（书模式 / 助手模式共用） ======================= */
+
+interface ChatPanelProps {
+  header: React.ReactNode;
+  conversations: Conversation[];
+  activeConv: Conversation | null;
+  messages: Message[];
+  turns: Turn[];
+  streaming: boolean;
+  streamContent: string;
+  streamTurnId: string | null;
+  activeTools: string[];
+  activeVersions: Record<string, number>;
+  setActiveVersions: (updater: (prev: Record<string, number>) => Record<string, number>) => void;
+  aiModels: AiModelEntry[];
+  model: string;
+  setModel: (m: string) => void;
+  welcome: WelcomeConfig;
+  onSelectConv: (c: Conversation) => void;
+  onNewConversation: () => void;
+  onDeleteConversation: (id: string) => void;
+  onSend: (content: string) => void;
+  onRetry: (msg: Message) => void;
+  onDelete: (id: string) => void;
+  onBranch: (id: string) => void;
+  onManage: () => void;
+  composerDisabled?: boolean;
+  // 外部传入的初始输入（如 EpubReader「解读原文」）：非空时填入输入框并消费
+  externalInput?: string;
+  onConsumeExternalInput?: () => void;
+}
+
+export default function ChatPanel(props: ChatPanelProps) {
+  const {
+    conversations, activeConv, messages, turns, streaming, streamContent, streamTurnId,
+    activeTools, activeVersions, setActiveVersions, aiModels, model, setModel,
+    welcome, onSelectConv, onNewConversation, onDeleteConversation,
+    onSend, onRetry, onDelete, onBranch, onManage, composerDisabled,
+    externalInput, onConsumeExternalInput,
+  } = props;
+
+  const [input, setInput] = useState("");
+  const [pickerOpen, setPickerOpen] = useState(false);
+  const chatEndRef = useRef<HTMLDivElement>(null);
+
+  useEffect(() => { chatEndRef.current?.scrollIntoView({ behavior: "smooth" }); }, [messages, streamContent]);
+
+  // 外部初始输入（EpubReader「解读原文」）：填入输入框后消费掉，避免重复触发
+  useEffect(() => {
+    if (externalInput) {
+      setInput(externalInput);
+      onConsumeExternalInput?.();
+    }
+  }, [externalInput, onConsumeExternalInput]);
+
+  const currentModel = aiModels.find((m) => m.name === model) ?? aiModels[0];
+
+  const handleCopy = async (text: string) => {
+    await navigator.clipboard.writeText(text);
+  };
+
+  const handleSendClick = () => {
+    if (!input.trim() || streaming) return;
+    onSend(input);
+    setInput("");
+  };
+
+  const submit = () => {
+    if (input.trim() && !streaming && !composerDisabled) handleSendClick();
+  };
+
+  return (
+    <>
+      {props.header}
+      <div className="flex-1 flex min-h-0">
+        <div className="conversation-sidebar overflow-y-auto overflow-x-hidden py-3 shrink-0">
+          <p className="text-[11px] text-[var(--fg-muted)] px-3 py-2 font-medium tracking-wider">{welcome.listLabel}</p>
+          <button
+            onClick={onNewConversation}
+            disabled={composerDisabled}
+            className="w-full mb-1 px-3 py-2 rounded-xl text-xs text-[var(--fg-muted)] hover:text-[var(--fg)] hover:bg-[var(--bg-hover)] disabled:opacity-50 transition-colors flex items-center justify-center gap-1.5"
+          >
+            <Plus size={12} />
+            {welcome.newButtonText}
+          </button>
+          {conversations.map((c) => (
+            <div key={c.id} className="flex items-center group">
+              <button
+                onClick={() => onSelectConv(c)}
+                className={`flex-1 min-w-0 text-left px-3 py-2 rounded-xl text-[13px] truncate text-[var(--fg)] transition-colors ${
+                  activeConv?.id === c.id ? "bg-[var(--accent-soft)]" : "hover:bg-[var(--bg-hover)]"
+                }`}
+              >
+                {c.title || "对话"}
+              </button>
+              <ActionBtn danger title="删除对话" onClick={() => onDeleteConversation(c.id)}>
+                <X size={14} />
+              </ActionBtn>
+            </div>
+          ))}
+        </div>
+
+        <div className="flex-1 flex flex-col min-w-0">
+          <div className="flex-1 overflow-y-auto px-6 pt-6 pb-10 space-y-6">
+            <div className="max-w-3xl mx-auto w-full space-y-6">
+            {turns.length === 0 && !streaming && (
+              <div className="chat-welcome">
+                <div className="chat-welcome-icon"><welcome.Icon size={30} strokeWidth={1.4} /></div>
+                <span className="eyebrow">{welcome.eyebrow}</span>
+                <h2>{welcome.title}</h2>
+                <p>{welcome.subtitle}</p>
+                <div className="prompt-grid">
+                  {welcome.prompts.map(({ Icon, title, prompt }) => (
+                    <button key={title} onClick={() => setInput(prompt)}><Icon size={19} /><strong>{title}</strong><span>{prompt}</span><ArrowUpRight size={15} /></button>
+                  ))}
+                </div>
+              </div>
+            )}
+            {turns.map((turn) => {
+              const isLastTurn = turn.user.id === turns[turns.length - 1]?.user.id;
+              const versions = [...turn.versions];
+              const activeIdx = activeVersions[turn.user.id] ?? versions.length - 1;
+              const shown = versions[activeIdx] ?? null;
+              const streamingHere = streaming && streamTurnId === turn.user.id && (!!streamContent || activeTools.length > 0);
+              return (
+                <div key={turn.user.id} className="space-y-1.5">
+                  <ChatBubble
+                    message={turn.user}
+                    onCopy={handleCopy}
+                    onRetry={isLastTurn ? onRetry : undefined}
+                    onDelete={onDelete}
+                  />
+                  {versions.length > 1 && (
+                    <div className="flex items-center gap-1 pl-10">
+                      <button
+                        type="button"
+                        onClick={() => setActiveVersions((prev) => ({ ...prev, [turn.user.id]: activeIdx - 1 }))}
+                        disabled={activeIdx <= 0}
+                        className="p-1 rounded-md text-[var(--fg-muted)] hover:bg-white/10 hover:text-[var(--fg)] disabled:opacity-30 transition-colors"
+                        title="上一个版本"
+                      >
+                        <ChevronLeft size={14} />
+                      </button>
+                      <span className="px-2 py-0.5 rounded-md bg-white/5 text-xs text-[var(--fg-muted)]">
+                        版本 {activeIdx + 1} / {versions.length}
+                      </span>
+                      <button
+                        type="button"
+                        onClick={() => setActiveVersions((prev) => ({ ...prev, [turn.user.id]: activeIdx + 1 }))}
+                        disabled={activeIdx >= versions.length - 1}
+                        className="p-1 rounded-md text-[var(--fg-muted)] hover:bg-white/10 hover:text-[var(--fg)] disabled:opacity-30 transition-colors"
+                        title="下一个版本"
+                      >
+                        <ChevronRight size={14} />
+                      </button>
+                    </div>
+                  )}
+                  {shown && (
+                    <ChatBubble
+                      key={shown.id}
+                      message={shown}
+                      onCopy={handleCopy}
+                      onDelete={onDelete}
+                      onBranch={onBranch}
+                    />
+                  )}
+                  {streamingHere && (
+                    <div className="pl-10 space-y-1">
+                      {activeTools.length > 0 && <ToolChips tools={activeTools} />}
+                      {streamContent && (
+                        <ChatBubble
+                          message={{ id: "stream", conversation_id: "", parent_message_id: turn.user.id, role: "assistant", content: streamContent, citations: null, model, created_at: "" }}
+                          isStreaming={true}
+                        />
+                      )}
+                    </div>
+                  )}
+                </div>
+              );
+            })}
+            {streaming && !streamTurnId && (streamContent || activeTools.length > 0) && (
+              <div className="max-w-3xl mx-auto space-y-1">
+                {activeTools.length > 0 && <ToolChips tools={activeTools} />}
+                {streamContent && (
+                  <ChatBubble
+                    message={{ id: "stream", conversation_id: "", parent_message_id: null, role: "assistant", content: streamContent, citations: null, model, created_at: "" }}
+                    isStreaming={true}
+                  />
+                )}
+              </div>
+            )}
+            <div ref={chatEndRef} />
+            </div>
+          </div>
+
+          <div className="composer-area px-4 pt-3 pb-4">
+            {/* 输入胶囊：模型选择 + 输入合并（Perplexity 风） */}
+            <div className="max-w-3xl mx-auto">
+              <div className="composer rounded-2xl px-4 py-3">
+                <div className="flex items-center justify-between mb-1">
+                  <div className="relative">
+                    {pickerOpen && <div className="fixed inset-0 z-10" onClick={() => setPickerOpen(false)} />}
+                    <button
+                      onClick={() => setPickerOpen((v) => !v)}
+                      className="flex items-center gap-1.5 text-xs px-2 py-1 rounded-md bg-white/5 text-[var(--fg-muted)] hover:text-[var(--fg)] hover:bg-white/10 transition-colors"
+                      title={currentModel ? `${currentModel.model_id} · ${currentModel.base_url || currentModel.kind}` : (aiModels.length ? "" : "尚未配置模型")}
+                    >
+                      <Sparkles size={12} className="text-[var(--accent)]" />
+                      <span className="max-w-40 truncate">{currentModel?.label ?? (aiModels.length ? model : "未配置模型")}</span>
+                      <ChevronDown size={12} />
+                    </button>
+                    {pickerOpen && (
+                      <div className="absolute z-20 bottom-full mb-1.5 left-0 w-64 rounded-xl border border-[var(--border)] bg-[var(--bg-card)] shadow-2xl p-1.5 max-h-72 overflow-y-auto">
+                        <p className="text-[10px] text-[var(--fg-muted)] px-2 pt-1 pb-1.5 font-medium tracking-wider">选择回答模型</p>
+                        {aiModels.map((m) => (
+                          <button
+                            key={m.name}
+                            onClick={() => { setModel(m.name); setPickerOpen(false); }}
+                            className={`w-full flex items-center justify-between gap-2 px-2.5 py-2 rounded-lg text-left text-sm transition-colors ${
+                              model === m.name ? "bg-[var(--accent-soft)] text-[var(--accent)]" : "text-[var(--fg)] hover:bg-[var(--bg-hover)]"
+                            }`}
+                          >
+                            <span className="truncate">{m.label}</span>
+                            <span className="text-[10px] text-[var(--fg-muted)] shrink-0">{m.builtin ? "内置" : "自定义"}</span>
+                          </button>
+                        ))}
+                        {aiModels.length === 0 && (
+                          <p className="px-2 py-3 text-xs text-[var(--fg-muted)] text-center">尚未配置模型，点「管理」添加</p>
+                        )}
+                      </div>
+                    )}
+                  </div>
+                  <button
+                    onClick={onManage}
+                    className="text-xs px-2 py-1 rounded-md text-[var(--fg-muted)] hover:text-[var(--fg)] hover:bg-white/5 transition-colors flex items-center gap-1"
+                  >
+                    <Settings2 size={12} />
+                    管理模型
+                  </button>
+                </div>
+
+                <div className="flex items-center gap-2">
+                  <input
+                    value={input}
+                    onChange={(e) => setInput(e.target.value)}
+                    onKeyDown={(e) => e.key === "Enter" && !e.shiftKey && !e.nativeEvent.isComposing && submit()}
+                    placeholder={welcome.placeholder}
+                    disabled={composerDisabled || streaming}
+                    className="flex-1 bg-transparent px-1 py-1.5 text-sm text-[var(--fg)] placeholder-[var(--fg-muted)] focus:outline-none disabled:opacity-50"
+                  />
+                  <button
+                    onClick={handleSendClick}
+                    disabled={!input.trim() || streaming || composerDisabled}
+                    className="p-2 rounded-xl bg-[var(--accent)] text-white hover:bg-[var(--accent-hover)] disabled:opacity-40 disabled:hover:bg-[var(--accent)] transition-colors shrink-0"
+                    title="发送"
+                  >
+                    {streaming ? <Loader2 size={16} className="animate-spin" /> : <Send size={16} />}
+                  </button>
+                </div>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+    </>
+  );
+}

frontend/src/lib/api.ts

@@ -40,11 +40,13 @@ export interface Citation {
   segment_id: string;
   cfi: string | null;
   excerpt: string;
+  book_title?: string | null;
 }
 
 export interface Conversation {
   id: string;
-  book_id: string;
+  kind: "book" | "assistant";
+  book_id: string | null;
   title: string | null;
   model: string;
   created_at: string;
@@ -141,12 +143,18 @@ export const api = {
   deleteBook: (id: string) => request<{ deleted: string }>(`/books/${id}`, { method: "DELETE" }),
 
   // Conversations
-  listConversations: (bookId?: string) =>
+  listConversations: (bookId?: string, kind?: string) => {
-    request<Conversation[]>(`/chat/conversations${bookId ? `?book_id=${bookId}` : ""}`),
+    const params = new URLSearchParams();
-  createConversation: (bookId: string, model: string = "claude") =>
+    if (bookId) params.set("book_id", bookId);
+    if (kind) params.set("kind", kind);
+    const qs = params.toString();
+    return request<Conversation[]>(`/chat/conversations${qs ? `?${qs}` : ""}`);
+  },
+  // kind="book"（默认）绑定单本书；kind="assistant" 为全局「第二大脑」对话（bookId 传 null）
+  createConversation: (bookId: string | null, model: string = "claude", kind: string = "book") =>
     request<Conversation>("/chat/conversations", {
       method: "POST",
-      body: JSON.stringify({ book_id: bookId, model }),
+      body: JSON.stringify({ book_id: bookId, model, kind }),
     }),
   deleteConversation: (convId: string) =>
     request<{ deleted: string }>(`/chat/conversations/${convId}`, { method: "DELETE" }),