feat: QYLAW 法律法规知识库

- 语义检索(FAISS + embedding)+ 精确查找(法规名+条号)
- RAG 问答(SSE 流式,支持 thinking 折叠显示)
- 法规浏览(原文阅读)
- 历史记录(检索+对话持久化到 SQLite)
- 设置页(系统提示词/模板/LLM 参数可配置)
- 检索质量评估脚本

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/main.py

@@ -0,0 +1,101 @@
+"""FastAPI 应用入口 — 挂载静态页 + API 路由"""
+import time
+import uuid
+from contextlib import asynccontextmanager
+from fastapi import FastAPI, Request, HTTPException
+from fastapi.staticfiles import StaticFiles
+from fastapi.responses import JSONResponse, FileResponse, HTMLResponse
+from fastapi.middleware.cors import CORSMiddleware
+from pathlib import Path
+
+from app.config import APP_PORT, LAW_KB_DATA_DIR
+from app.routers import search, rag, law, stats, prompts, history
+from app.services.retriever import Retriever
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """应用生命周期:启动时加载索引,关闭时释放"""
+    # 启动:加载 FAISS 索引和 SQLite
+    retriever = Retriever.get_instance()
+    retriever.load()
+    yield
+    # 关闭:无需特殊处理
+
+
+app = FastAPI(
+    title="QYLAW 法律法规知识库",
+    version="1.0.0",
+    lifespan=lifespan,
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+
+@app.middleware("http")
+async def add_trace_id(request: Request, call_next):
+    """为每个请求添加 trace_id"""
+    trace_id = request.headers.get("X-Trace-Id") or str(uuid.uuid4())[:8]
+    request.state.trace_id = trace_id
+    start = time.time()
+    response = await call_next(request)
+    elapsed = (time.time() - start) * 1000
+    response.headers["X-Trace-Id"] = trace_id
+    response.headers["X-Response-Time-ms"] = f"{elapsed:.0f}"
+    return response
+
+
+# 注册 API 路由
+app.include_router(search.router, prefix="/api", tags=["检索"])
+app.include_router(rag.router, prefix="/api", tags=["RAG 问答"])
+app.include_router(law.router, prefix="/api", tags=["法规浏览"])
+app.include_router(stats.router, prefix="/api", tags=["统计"])
+app.include_router(prompts.router, prefix="/api", tags=["提示词配置"])
+app.include_router(history.router, prefix="/api", tags=["历史记录"])
+
+
+# 静态文件
+STATIC_DIR = Path(__file__).parent / "static"
+app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")
+
+
+def _serve_index() -> HTMLResponse:
+    """返回 index.html(带 no-cache 头,防止浏览器缓存旧版)"""
+    html = (STATIC_DIR / "index.html").read_text(encoding="utf-8")
+    return HTMLResponse(content=html, headers={
+        "Cache-Control": "no-cache, no-store, must-revalidate",
+        "Pragma": "no-cache",
+        "Expires": "0",
+    })
+
+
+@app.get("/")
+async def index():
+    """主页"""
+    return _serve_index()
+
+
+@app.get("/health")
+async def health():
+    """健康检查"""
+    return {"status": "ok"}
+
+
+# 前端路由 catch-all:必须放在所有 API 路由和 /health 之后
+@app.get("/{path:path}")
+async def spa_fallback(path: str):
+    """SPA 路由兜底:/search, /rag, /browse, /history, /settings 返回 index.html"""
+    # 排除 API 和静态文件路径(已被前面的路由和 mount 处理)
+    if path.startswith("api/") or path.startswith("static/"):
+        raise HTTPException(status_code=404)
+    return _serve_index()
+
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run(app, host="0.0.0.0", port=APP_PORT)