fix: 删书彻底清理文件与DB + 阅读位置跨设备同步

删除不彻底的根因是库里 file_path 存了旧 Windows 相对路径（uploads\xxx.epub），Linux 容器里 os.path.exists 永远为假：

- 新增 _upload_file() 归一化路径（取文件名挂到当前 uploads 目录），读/删都走它，老库迁移的文件也能定位；文件删除挪到后台任务，失败不影响接口

- 删除后对 SQLite 执行 VACUUM，让 db 文件真正缩小

- 删除时一并清理 reading_progress

阅读位置原来只存 localStorage，换设备丢失：

- 新增 reading_progress 表 + GET/PUT /books/{id}/progress 接口

- 前端打开时优先取服务端位置（本地兜底并双端拉齐），翻页防抖同步到服务端，关闭时把防抖窗口内的最后一页立即刷上去

backend/app/api/books.py

@@ -5,19 +5,45 @@ import aiofiles
 from fastapi import APIRouter, UploadFile, File, Depends, HTTPException, BackgroundTasks
 from fastapi.responses import FileResponse
 from sqlalchemy.ext.asyncio import AsyncSession
-from sqlalchemy import select, func
+from sqlalchemy import select, func, delete
 
-from app.core.database import get_db, async_session
+from app.core.database import get_db, async_session, engine
 from app.core.config import settings
-from app.models.book import Book, Chapter, Segment, ReadingNote
+from app.models.book import Book, Chapter, Segment, ReadingNote, ReadingProgress
 from app.models.chat import Conversation
-from app.schemas.book import BookOut, BookDetailOut, ChapterOut, SegmentOut, ReadingNoteCreate, ReadingNoteOut, ReadingNoteUpdate
+from app.schemas.book import BookOut, BookDetailOut, ChapterOut, SegmentOut, ReadingNoteCreate, ReadingNoteOut, ReadingNoteUpdate, ReadingProgressOut, ReadingProgressUpdate
 from app.epub.parser import parse_epub
 from app.rag.vector import ensure_embeddings
 
 router = APIRouter(prefix="/books", tags=["books"])
 
 
+def _upload_file(file_path: str | None) -> Path | None:
+    """把库里存的 file_path 归一化到 uploads 目录下的真实文件。
+
+    旧库曾存进相对 Windows 路径（uploads\\xxx.epub），在云服务器 Linux 上会
+    变成带反斜杠的「假文件名」，读不到也删不掉。统一取最后一段文件名，
+    挂到当前 upload_path 下，再校验存在性 —— 这样从 Windows 迁移的库也能删除。
+    """
+    if not file_path:
+        return None
+    name = file_path.replace("\\", "/").split("/")[-1]
+    if not name or not name.lower().endswith(".epub"):
+        return None
+    candidate = settings.upload_path / name
+    return candidate if candidate.is_file() else None
+
+
+async def _vacuum_db():
+    """删书后压缩 SQLite 文件（DELETE 只打标，文件不缩水）。失败不影响主流程。"""
+    try:
+        async with engine.connect() as conn:
+            await conn.execution_options(isolation_level="AUTOCOMMIT")
+            await conn.exec_driver_sql("VACUUM")
+    except Exception:
+        pass
+
+
 async def _embed_book_in_background(book_id: str):
     """上传后后台批量生成向量；失败时状态记 failed，首次对话会懒补。"""
     async with async_session() as session:
@@ -108,11 +134,8 @@ async def read_book_file(book_id: str, db: AsyncSession = Depends(get_db)):
     book = await db.get(Book, book_id)
     if not book:
         raise HTTPException(404, "书不存在")
-    file_path = Path(book.file_path).resolve()
-    upload_root = Path(settings.upload_dir).resolve()
-    if not file_path.is_relative_to(upload_root) or file_path.suffix.lower() != ".epub":
-        raise HTTPException(404, "书籍文件不可用")
-    if not file_path.is_file():
+    file_path = _upload_file(book.file_path)
+    if not file_path or not file_path.is_file():
         raise HTTPException(404, "原始 EPUB 文件已丢失，请重新导入")
     return FileResponse(
         file_path,
@@ -195,12 +218,42 @@ async def delete_reading_note(book_id: str, note_id: str, db: AsyncSession = Dep
     return {"deleted": note_id}
 
 
+@router.get("/{book_id}/progress", response_model=ReadingProgressOut | None)
+async def get_reading_progress(book_id: str, db: AsyncSession = Depends(get_db)):
+    """读取每本书的最近阅读位置（跨设备同步用）。没记录返回 null。"""
+    if not await db.get(Book, book_id):
+        raise HTTPException(404, "书不存在")
+    progress = await db.get(ReadingProgress, book_id)
+    return progress
+
+
+@router.put("/{book_id}/progress", response_model=ReadingProgressOut)
+async def save_reading_progress(book_id: str, payload: ReadingProgressUpdate, db: AsyncSession = Depends(get_db)):
+    """保存每本书的最近阅读位置（跨设备同步用）。"""
+    if not await db.get(Book, book_id):
+        raise HTTPException(404, "书不存在")
+    if not payload.cfi.strip() or len(payload.cfi) > 2000:
+        raise HTTPException(422, "阅读位置无效")
+    progress = await db.get(ReadingProgress, book_id)
+    if progress is None:
+        progress = ReadingProgress(book_id=book_id, cfi=payload.cfi.strip())
+        db.add(progress)
+    else:
+        progress.cfi = payload.cfi.strip()
+    await db.commit()
+    await db.refresh(progress)
+    return progress
+
+
 @router.delete("/{book_id}")
-async def delete_book(book_id: str, db: AsyncSession = Depends(get_db)):
+async def delete_book(
+    book_id: str,
+    db: AsyncSession = Depends(get_db),
+    background_tasks: BackgroundTasks = BackgroundTasks(),
+):
     book = await db.get(Book, book_id)
     if not book:
         raise HTTPException(404, "书不存在")
-    file_path = book.file_path
     # 删书即删对话（与前端确认文案「书、目录和对话都会被删除」一致）。
     # Conversation 与 Book 没有 ORM 级联关系、SQLite 外键又未强制开启，
     # 必须显式删除该书的对话；其消息经 Conversation.messages 的 cascade 一并删除。
@@ -210,12 +263,28 @@ async def delete_book(book_id: str, db: AsyncSession = Depends(get_db)):
     notes = (await db.execute(
         select(ReadingNote).where(ReadingNote.book_id == book_id)
     )).scalars().all()
+    # 先取出原始文件路径再删 ORM 对象（delete 后再访问属性可能触发已过期对象的加载）
+    file_path = _upload_file(book.file_path)
     for c in convs:
         await db.delete(c)
     for note in notes:
         await db.delete(note)
+    # 阅读位置随书清理
+    await db.execute(delete(ReadingProgress).where(ReadingProgress.book_id == book_id))
     await db.delete(book)
     await db.commit()
-    if file_path and os.path.exists(file_path):
-        os.remove(file_path)
+    # 原始 EPUB 文件在后台任务里删除：路径可能因旧库（Windows 相对路径）不直接可用，
+    # _upload_file 已归一化到当前 uploads 目录；失败不拖垮删除接口。
+    if file_path:
+        background_tasks.add_task(_remove_file, file_path)
+    # DELETE 后 SQLite 文件不会自动缩小，后台 VACUUM 一次让「db 数据减少」可见
+    background_tasks.add_task(_vacuum_db)
     return {"deleted": book_id, "conversations": len(convs), "notes": len(notes)}
+
+
+def _remove_file(path: Path):
+    """后台任务：删除原始 EPUB。不抛出，避免拖垮删除流程。"""
+    try:
+        path.unlink(missing_ok=True)
+    except Exception:
+        pass

backend/app/main.py

@@ -16,7 +16,7 @@ from app.api.models import router as models_router
 from app.api.mcp import router as mcp_router
 from app.api.auth import router as auth_router
 
-from app.models.book import Book, Chapter, Segment
+from app.models.book import Book, Chapter, Segment, ReadingProgress
 from app.models.chat import Conversation, Message
 from app.models.ai_model import AiModel
 from app.models.mcp_server import McpServer

backend/app/models/book.py

@@ -74,3 +74,12 @@ class ReadingNote(Base):
     color: Mapped[str] = mapped_column(String(20), nullable=False, default="yellow")
     created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())
     updated_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now(), onupdate=func.now())
+
+
+class ReadingProgress(Base):
+    """每本书的最近阅读位置（跨设备同步；书删除时一并清理）。"""
+    __tablename__ = "reading_progress"
+
+    book_id: Mapped[str] = mapped_column(String(36), ForeignKey("books.id", ondelete="CASCADE"), primary_key=True)
+    cfi: Mapped[str] = mapped_column(String(2000), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now(), onupdate=func.now())

backend/app/schemas/book.py

@@ -84,3 +84,16 @@ class ReadingNoteCreate(BaseModel):
 class ReadingNoteUpdate(BaseModel):
     note: str | None = None
     color: str | None = None
+
+
+class ReadingProgressOut(BaseModel):
+    book_id: str
+    cfi: str
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class ReadingProgressUpdate(BaseModel):
+    cfi: str