diff --git a/app/main.py b/app/main.py
index 5d0c926..307b0b7 100644
--- a/app/main.py
+++ b/app/main.py
@@ -58,6 +58,17 @@ app.include_router(chat_rest_router)
 app.mount("/static", StaticFiles(directory=str(STATIC_DIR)), name="static")
 
 
+@app.middleware("http")
+async def static_no_cache(request, call_next):
+    """静态资源协商缓存(2026-09-30 线上事件): 无 Cache-Control 时浏览器对
+    widget.js 走启发式缓存,修复部署后用户端仍跑旧脚本。no-cache=每次用
+    etag 轻量协商,有更新即时生效,未变则 304 几乎零开销。"""
+    resp = await call_next(request)
+    if request.url.path.startswith("/static/"):
+        resp.headers["Cache-Control"] = "no-cache"
+    return resp
+
+
 @app.get("/")
 async def index():
     from fastapi.responses import FileResponse