fix(cache): move Cache-Control middleware before mounts using @app.middleware decorator

app/main.py

@@ -1,8 +1,7 @@
 from pathlib import Path
 
-from fastapi import FastAPI, Request, Response
+from fastapi import FastAPI
 from fastapi.staticfiles import StaticFiles
-from starlette.middleware.base import BaseHTTPMiddleware
 
 from app.config import UPLOAD_DIR
 from app.database import init_db
@@ -11,20 +10,19 @@ from app.routers import web, api
 app = FastAPI(title="Mailova 星笺")
 
 UPLOAD_DIR.mkdir(exist_ok=True)
-app.mount("/static", StaticFiles(directory=str(Path(__file__).resolve().parent / "static")), name="static")
-app.mount("/uploads", StaticFiles(directory=str(UPLOAD_DIR)), name="uploads")
 
 
-# Browser cache: 30 days for uploaded images (they never change)
-class CacheControlMiddleware(BaseHTTPMiddleware):
-    async def dispatch(self, request: Request, call_next):
-        response: Response = await call_next(request)
+# Cache-Control for uploaded images (30 days, immutable — filenames contain UUID)
+@app.middleware("http")
+async def cache_control_middleware(request, call_next):
+    response = await call_next(request)
     if request.url.path.startswith("/uploads/"):
         response.headers["Cache-Control"] = "public, max-age=2592000, immutable"
     return response
 
 
-app.add_middleware(CacheControlMiddleware)
+app.mount("/static", StaticFiles(directory=str(Path(__file__).resolve().parent / "static")), name="static")
+app.mount("/uploads", StaticFiles(directory=str(UPLOAD_DIR)), name="uploads")
 
 app.include_router(web.router)
 app.include_router(api.router)