feature: 新增支持拆书自选保留章节数，或者整本拆书功能

backend/app/api/book_import.py

@@ -15,6 +15,7 @@ from app.schemas.book_import import (
     BookImportPreviewResponse,
     BookImportRetryRequest,
     BookImportTaskCreateResponse,
+    BookImportTaskCreateRequest,
     BookImportTaskStatusResponse,
 )
 from app.services.book_import_service import book_import_service
@@ -33,6 +34,8 @@ async def create_book_import_task(
     project_id: str | None = Form(default=None, description="兼容参数：当前版本固定新建项目，不支持传入"),
     create_new_project: bool = Form(default=True, description="兼容参数：当前版本仅支持 true"),
     import_mode: str = Form(default="append", description="导入模式：append/overwrite"),
+    extract_mode: str = Form(default="tail", description="解析范围：tail=截取末章，full=整本"),
+    tail_chapter_count: int = Form(default=10, description="当 extract_mode=tail 时，截取末尾章节数，需为5的倍数；超过50按整本拆处理"),
 ):
     user_id = getattr(request.state, "user_id", None)
     if not user_id:
@@ -44,11 +47,26 @@ async def create_book_import_task(
     if import_mode not in {"append", "overwrite"}:
         raise HTTPException(status_code=400, detail="import_mode 仅支持 append 或 overwrite")
 
+    if extract_mode not in {"tail", "full"}:
+        raise HTTPException(status_code=400, detail="extract_mode 仅支持 tail 或 full")
+    if tail_chapter_count < 5:
+        raise HTTPException(status_code=400, detail="tail_chapter_count 不能小于 5")
+    if tail_chapter_count % 5 != 0:
+        raise HTTPException(status_code=400, detail="tail_chapter_count 必须是 5 的倍数")
+
+    if tail_chapter_count > 50:
+        extract_mode = "full"
+
     if project_id:
         raise HTTPException(status_code=400, detail="当前仅支持新建项目导入，不支持指定 project_id")
     if not create_new_project:
         raise HTTPException(status_code=400, detail="当前仅支持新建项目导入")
 
+    create_payload = BookImportTaskCreateRequest(
+        extract_mode=extract_mode,
+        tail_chapter_count=tail_chapter_count,
+    )
+
     content = await file.read()
     if len(content) > MAX_TXT_SIZE:
         raise HTTPException(status_code=413, detail="文件大小超过 50MB 限制")
@@ -60,6 +78,8 @@ async def create_book_import_task(
         project_id=None,
         create_new_project=True,
         import_mode=import_mode,
+        extract_mode=create_payload.extract_mode,
+        tail_chapter_count=create_payload.tail_chapter_count,
     )
     return task
 

backend/app/schemas/book_import.py

@@ -9,6 +9,7 @@ TaskStatus = Literal["pending", "running", "completed", "failed", "cancelled"]
 ImportMode = Literal["append", "overwrite"]
 ExtractLevel = Literal["basic", "standard", "deep"]
 WarningLevel = Literal["info", "warning", "error"]
+BookImportExtractMode = Literal["tail", "full"]
 
 
 class BookImportWarning(BaseModel):
@@ -45,6 +46,12 @@ class BookImportOutline(BaseModel):
     structure: Optional[dict[str, Any]] = Field(None, description="结构化大纲（与系统大纲生成结构一致）")
 
 
+class BookImportTaskCreateRequest(BaseModel):
+    """创建拆书任务请求"""
+    extract_mode: BookImportExtractMode = Field(default="tail", description="提取范围：tail=截取末章，full=整本")
+    tail_chapter_count: int = Field(default=10, ge=5, le=9999, description="当 extract_mode=tail 时，截取末尾章节数；需为5的倍数，超过50将按整本处理")
+
+
 class BookImportTaskCreateResponse(BaseModel):
     """创建任务响应"""
     task_id: str
@@ -89,4 +96,4 @@ class BookImportApplyResponse(BaseModel):
 
 class BookImportRetryRequest(BaseModel):
     """重试失败步骤请求"""
-    steps: list[str] = Field(..., min_length=1, description="需要重试的步骤名列表，如 world_building / career_system / characters")
+    steps: list[str] = Field(..., min_length=1, description="需要重试的步骤名列表，如 world_building / career_system / characters")

backend/app/services/book_import_service.py

@@ -34,6 +34,7 @@ from app.schemas.book_import import (
     BookImportApplyRequest,
     BookImportApplyResponse,
     BookImportChapter,
+    BookImportExtractMode,
     BookImportOutline,
     BookImportPreviewResponse,
     BookImportTaskCreateResponse,
@@ -65,6 +66,8 @@ class _BookImportTask:
     project_id: Optional[str]
     create_new_project: bool
     import_mode: str
+    extract_mode: BookImportExtractMode = "tail"
+    tail_chapter_count: int = 10
     status: str = "pending"
     progress: int = 0
     message: Optional[str] = "任务已创建"
@@ -95,7 +98,16 @@ class BookImportService:
         project_id: Optional[str],
         create_new_project: bool,
         import_mode: str,
+        extract_mode: BookImportExtractMode = "tail",
+        tail_chapter_count: int = 10,
     ) -> BookImportTaskCreateResponse:
+        normalized_tail_count = max(5, int(tail_chapter_count))
+        normalized_extract_mode = extract_mode
+        if normalized_tail_count % 5 != 0:
+            normalized_tail_count = ((normalized_tail_count + 4) // 5) * 5
+        if normalized_tail_count > 50:
+            normalized_extract_mode = "full"
+
         task_id = str(uuid.uuid4())
         task = _BookImportTask(
             task_id=task_id,
@@ -104,6 +116,8 @@ class BookImportService:
             project_id=project_id,
             create_new_project=create_new_project,
             import_mode=import_mode,
+            extract_mode=normalized_extract_mode,
+            tail_chapter_count=normalized_tail_count,
         )
         async with self._tasks_lock:
             self._tasks[task_id] = task
@@ -150,15 +164,17 @@ class BookImportService:
         }
 
         warnings = list(task.preview.warnings) if task.preview else []
-        chapters_to_import, outlines_to_import, was_trimmed = self._trim_last_ten_for_apply(
+        chapters_to_import, outlines_to_import, was_trimmed = self._select_chapters_for_import(
             chapters=payload.chapters,
             outlines=payload.outlines,
+            extract_mode=task.extract_mode,
+            tail_chapter_count=task.tail_chapter_count,
         )
         if was_trimmed:
             warnings.append(
                 BookImportWarning(
-                    code="apply_trimmed_to_last_ten",
+                    code="apply_trimmed_for_extract_mode",
-                    message=f"导入阶段已强制仅保留最后 {len(chapters_to_import)} 章",
+                    message=f"导入阶段已按解析配置仅保留 {len(chapters_to_import)} 章",
                     level="info",
                 )
             )
@@ -248,15 +264,17 @@ class BookImportService:
         }
 
         warnings = list(task.preview.warnings) if task.preview else []
-        chapters_to_import, outlines_to_import, was_trimmed = self._trim_last_ten_for_apply(
+        chapters_to_import, outlines_to_import, was_trimmed = self._select_chapters_for_import(
             chapters=payload.chapters,
             outlines=payload.outlines,
+            extract_mode=task.extract_mode,
+            tail_chapter_count=task.tail_chapter_count,
         )
         if was_trimmed:
             warnings.append(
                 BookImportWarning(
-                    code="apply_trimmed_to_last_ten",
+                    code="apply_trimmed_for_extract_mode",
-                    message=f"导入阶段已强制仅保留最后 {len(chapters_to_import)} 章",
+                    message=f"导入阶段已按解析配置仅保留 {len(chapters_to_import)} 章",
                     level="info",
                 )
             )
@@ -580,7 +598,7 @@ class BookImportService:
             return
 
         try:
-            # 进度分配：编码识别 5%，文本清洗 10%，章节切分 15%，截取末10章 18%，AI反向生成 20%-95%，完成 100%
+            # 进度分配：编码识别 5%，文本清洗 10%，章节切分 15%，按配置筛选章节 18%，AI反向生成 20%-95%，完成 100%
             self._set_task_state(task, status="running", progress=5, message="正在识别编码并读取文本...")
             self._check_cancelled(task)
 
@@ -600,7 +618,7 @@ class BookImportService:
             )
             self._check_cancelled(task)
 
-            self._set_task_state(task, status="running", progress=18, message="仅保留末10章并重建预览结构...")
+            self._set_task_state(task, status="running", progress=18, message="正在按解析配置筛选章节并构建预览...")
             preview = await self._build_preview(
                 task=task,
                 filename=task.filename,
@@ -798,18 +816,26 @@ class BookImportService:
 
         return count, total_words
 
-    def _trim_last_ten_for_apply(
+    def _select_chapters_for_import(
         self,
         *,
         chapters: list[BookImportChapter],
         outlines: list[BookImportOutline],
+        extract_mode: BookImportExtractMode,
+        tail_chapter_count: int,
     ) -> tuple[list[BookImportChapter], list[BookImportOutline], bool]:
         if not chapters:
             return [], [], False
 
         sorted_chapters = sorted(chapters, key=lambda x: x.chapter_number)
-        selected = sorted_chapters[-10:]
+        normalized_tail_count = max(5, int(tail_chapter_count))
-        was_trimmed = len(sorted_chapters) > len(selected) or len(outlines) > 10
+        if normalized_tail_count > 50 or extract_mode == "full":
+            selected = sorted_chapters
+        else:
+            normalized_tail_count = min(normalized_tail_count, len(sorted_chapters))
+            selected = sorted_chapters[-normalized_tail_count:]
+
+        was_trimmed = len(sorted_chapters) > len(selected)
 
         normalized_chapters: list[BookImportChapter] = []
         for idx, item in enumerate(selected, start=1):
@@ -826,7 +852,10 @@ class BookImportService:
         normalized_outlines: list[BookImportOutline] = []
         sorted_outlines = sorted(outlines, key=lambda x: x.order_index) if outlines else []
         if sorted_outlines:
-            selected_outlines = sorted_outlines[-len(normalized_chapters):]
+            if extract_mode == "full":
+                selected_outlines = sorted_outlines[:len(normalized_chapters)]
+            else:
+                selected_outlines = sorted_outlines[-len(normalized_chapters):]
             for idx, item in enumerate(selected_outlines, start=1):
                 normalized_outlines.append(
                     BookImportOutline(
@@ -853,6 +882,30 @@ class BookImportService:
 
         return normalized_chapters, normalized_outlines, was_trimmed
 
+    def _select_raw_chapters_for_preview(
+        self,
+        *,
+        chapters_data: list[dict],
+        extract_mode: BookImportExtractMode,
+        tail_chapter_count: int,
+    ) -> tuple[list[dict], bool]:
+        if not chapters_data:
+            return [], False
+
+        normalized_tail_count = max(5, int(tail_chapter_count))
+        if normalized_tail_count > 50 or extract_mode == "full":
+            return chapters_data, False
+
+        normalized_tail_count = min(normalized_tail_count, len(chapters_data))
+
+        selected = chapters_data[-normalized_tail_count:]
+        return selected, len(selected) < len(chapters_data)
+
+    def _get_extract_mode_label(self, extract_mode: BookImportExtractMode, selected_total: int) -> str:
+        if extract_mode == "full" or selected_total > 50:
+            return "整本"
+        return f"末{selected_total}章"
+
     def _derive_world_settings(
         self,
         *,
@@ -974,9 +1027,13 @@ class BookImportService:
         chapters: list[BookImportChapter] = []
         warnings: list[BookImportWarning] = []
 
-        # 仅保留最后10章用于最终导入，重建章节序号为 1..N
+        selected_chapters_raw, was_trimmed = self._select_raw_chapters_for_preview(
-        selected_chapters_raw = chapters_data[-10:] if len(chapters_data) > 10 else chapters_data
+            chapters_data=chapters_data,
+            extract_mode=task.extract_mode,
+            tail_chapter_count=task.tail_chapter_count,
+        )
         selected_total = len(selected_chapters_raw)
+        selection_label = self._get_extract_mode_label(task.extract_mode, selected_total)
 
         title_counter: Counter[str] = Counter()
         for idx, chapter in enumerate(selected_chapters_raw, start=1):
@@ -1020,7 +1077,7 @@ class BookImportService:
                     task,
                     status="running",
                     progress=chapter_progress,
-                    message=f"已处理末章 {idx}/{selected_total} 个章节结构...",
+                    message=f"已处理{selection_label} {idx}/{selected_total} 个章节结构...",
                 )
 
         for title, count in title_counter.items():
@@ -1033,11 +1090,11 @@ class BookImportService:
                     )
                 )
 
-        if len(chapters_data) > selected_total:
+        if was_trimmed:
             warnings.append(
                 BookImportWarning(
-                    code="trimmed_to_last_ten_chapters",
+                    code="trimmed_for_extract_mode",
-                    message=f"已按规则仅保留最后 {selected_total} 章用于导入（原始识别 {len(chapters_data)} 章）",
+                    message=f"已按解析配置仅保留{selection_label} {selected_total} 章用于导入（原始识别 {len(chapters_data)} 章）",
                     level="info",
                 )
             )

frontend/src/pages/BookImport.tsx

@@ -28,6 +28,7 @@ import { InboxOutlined, PlayCircleOutlined, ReloadOutlined, StopOutlined, Warnin
 import { bookImportApi } from '../services/api';
 import type {
   BookImportApplyPayload,
+  BookImportExtractMode,
   BookImportPreview,
   BookImportStepFailure,
   BookImportTask,
@@ -111,6 +112,8 @@ export default function BookImport() {
   const { token } = theme.useToken();
   const isMobile = window.innerWidth <= 768;
   const [file, setFile] = useState<File | null>(null);
+  const [extractMode, setExtractMode] = useState<BookImportExtractMode>('tail');
+  const [tailChapterCount, setTailChapterCount] = useState(10);
 
   const [taskId, setTaskId] = useState<string | null>(null);
   const [taskStatus, setTaskStatus] = useState<BookImportTask | null>(null);
@@ -322,8 +325,13 @@ export default function BookImport() {
       setPreview(null);
       setTaskStatus(null);
 
+      const normalizedTailChapterCount = Math.max(5, Math.ceil(tailChapterCount / 5) * 5);
+      const normalizedExtractMode = normalizedTailChapterCount > 50 ? 'full' : extractMode;
+
       const response = await bookImportApi.createTask({
         file,
+        extract_mode: normalizedExtractMode,
+        tail_chapter_count: normalizedTailChapterCount,
       });
 
       setTaskId(response.task_id);
@@ -546,6 +554,8 @@ export default function BookImport() {
     setRetrying(false);
     setRetryProgress(0);
     setRetryMessage('');
+    setExtractMode('tail');
+    setTailChapterCount(10);
 
     message.success('已重新开始，请重新上传 TXT 并解析');
   }, []);
@@ -688,6 +698,38 @@ export default function BookImport() {
             <p className="ant-upload-hint">首版仅支持 .txt，建议不超过 50MB</p>
           </Dragger>
 
+          <Card size="small" title="解析范围设置">
+            <Space direction="vertical" style={{ width: '100%' }} size={12}>
+              <Select
+                value={extractMode}
+                onChange={(value) => setExtractMode(value)}
+                options={[
+                  { label: '截取末 x 章反向生成', value: 'tail' },
+                  { label: '整本反向生成', value: 'full' },
+                ]}
+                style={{ width: '100%' }}
+              />
+              <InputNumber
+                min={5}
+                max={55}
+                step={5}
+                precision={0}
+                value={tailChapterCount}
+                disabled={extractMode !== 'tail'}
+                onChange={(value) => setTailChapterCount(typeof value === 'number' ? value : 10)}
+                addonBefore="末尾章节数"
+                style={{ width: '100%' }}
+              />
+              <Text type="secondary">
+                {extractMode === 'tail'
+                  ? tailChapterCount > 50
+                    ? '当前输入已超过 50 章，将自动按整本拆处理。'
+                    : `当前将截取末 ${Math.max(5, Math.ceil(tailChapterCount / 5) * 5)} 章进行反向生成；章节数必须为 5 的倍数，最多 50 章。`
+                  : '当前将基于整本内容进行反向生成，适合完整拆书但耗时可能更长。'}
+              </Text>
+            </Space>
+          </Card>
+
           <Alert
             type="info"
             showIcon
@@ -713,7 +755,7 @@ export default function BookImport() {
             }
           />
           
-          <Space>
+          <Space wrap>
             <Button
               type="primary"
               icon={<PlayCircleOutlined />}

frontend/src/services/api.ts

@@ -53,6 +53,7 @@ import type {
   BookImportTask,
   BookImportPreview,
   BookImportApplyPayload,
+  BookImportCreateTaskPayload,
   BookImportResult,
   BookImportRetryResult,
   BatchAnalysisStatusResponse,
@@ -455,11 +456,12 @@ export const projectApi = {
 };
 
 export const bookImportApi = {
-  createTask: (params: {
+  createTask: (params: BookImportCreateTaskPayload) => {
-    file: File;
-  }) => {
     const formData = new FormData();
     formData.append('file', params.file);
+    const tailChapterCount = params.tail_chapter_count ?? 10;
+    formData.append('extract_mode', params.extract_mode ?? 'tail');
+    formData.append('tail_chapter_count', String(tailChapterCount));
 
     return api.post<unknown, { task_id: string; status: BookImportTask['status'] }>(
       '/book-import/tasks',

frontend/src/types/index.ts

@@ -985,6 +985,7 @@ export interface ForeshadowContextResponse {
 
 export type BookImportTaskStatus = 'pending' | 'running' | 'completed' | 'failed' | 'cancelled';
 export type BookImportWarningLevel = 'info' | 'warning' | 'error';
+export type BookImportExtractMode = 'tail' | 'full';
 
 export interface BookImportWarning {
   code: string;
@@ -1041,6 +1042,12 @@ export interface BookImportApplyPayload {
   import_mode?: 'append' | 'overwrite';
 }
 
+export interface BookImportCreateTaskPayload {
+  file: File;
+  extract_mode?: BookImportExtractMode;
+  tail_chapter_count?: number;
+}
+
 export interface BookImportResult {
   success: boolean;
   project_id: string;