feat: AI中间章节改写功能 + 滚动优化

server/app/routers/story.py

@@ -5,7 +5,7 @@ import random
 from fastapi import APIRouter, Depends, Query, HTTPException
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select, update, func, distinct
-from typing import Optional
+from typing import Optional, List
 from pydantic import BaseModel
 
 from app.database import get_db
@@ -25,6 +25,20 @@ class RewriteRequest(BaseModel):
     prompt: str
 
 
+class PathHistoryItem(BaseModel):
+    nodeKey: str
+    content: str = ""
+    choice: str = ""
+
+
+class RewriteBranchRequest(BaseModel):
+    userId: int
+    currentNodeKey: str
+    pathHistory: List[PathHistoryItem]
+    currentContent: str
+    prompt: str
+
+
 # ========== API接口 ==========
 
 @router.get("")
@@ -268,3 +282,59 @@ async def ai_rewrite_ending(story_id: int, request: RewriteRequest, db: AsyncSes
             "ending_type": "rewrite"
         }
     }
+
+
+@router.post("/{story_id}/rewrite-branch")
+async def ai_rewrite_branch(
+    story_id: int,
+    request: RewriteBranchRequest,
+    db: AsyncSession = Depends(get_db)
+):
+    """AI改写中间章节，生成新的剧情分支"""
+    if not request.prompt:
+        raise HTTPException(status_code=400, detail="请输入改写指令")
+    
+    # 获取故事信息
+    result = await db.execute(select(Story).where(Story.id == story_id))
+    story = result.scalar_one_or_none()
+    
+    if not story:
+        raise HTTPException(status_code=404, detail="故事不存在")
+    
+    # 将 Pydantic 模型转换为字典列表
+    path_history = [
+        {"nodeKey": item.nodeKey, "content": item.content, "choice": item.choice}
+        for item in request.pathHistory
+    ]
+    
+    # 调用 AI 服务
+    from app.services.ai import ai_service
+    
+    ai_result = await ai_service.rewrite_branch(
+        story_title=story.title,
+        story_category=story.category or "未知",
+        path_history=path_history,
+        current_content=request.currentContent,
+        user_prompt=request.prompt
+    )
+    
+    if ai_result and ai_result.get("nodes"):
+        return {
+            "code": 0,
+            "data": {
+                "nodes": ai_result["nodes"],
+                "entryNodeKey": ai_result.get("entryNodeKey", "branch_1"),
+                "tokensUsed": ai_result.get("tokens_used", 0)
+            }
+        }
+    
+    # AI 服务不可用时，返回空结果（不使用兜底模板）
+    return {
+        "code": 0,
+        "data": {
+            "nodes": None,
+            "entryNodeKey": None,
+            "tokensUsed": 0,
+            "error": "AI服务暂时不可用"
+        }
+    }