Step 12：后端轻量优化（API 稳定性 & 前端友好）

backend/app/core/deps.py

@@ -5,6 +5,7 @@ from fastapi import Depends, HTTPException, status
 from pydantic import ValidationError
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.core.exceptions import AppException
 from app.core.security import decode_token, oauth2_scheme
 from app.crud import user as user_crud
 from app.crud import member as member_crud
@@ -75,9 +76,10 @@ def require_study_member():
             return current_user
         membership = await member_crud.get_member(db, study_id, current_user.id)
         if not membership or not membership.is_active:
-            raise HTTPException(
+            raise AppException(
+                code="FORBIDDEN",
+                message="Not a member of this study",
                 status_code=status.HTTP_403_FORBIDDEN,
-                detail="Not a member of this study",
             )
         return current_user
 
@@ -96,9 +98,10 @@ def require_study_roles(roles: Iterable[str]):
             return current_user
         membership = await member_crud.get_member(db, study_id, current_user.id)
         if not membership or not membership.is_active or membership.role_in_study not in roles_set:
-            raise HTTPException(
+            raise AppException(
+                code="FORBIDDEN",
+                message="Insufficient study permissions",
                 status_code=status.HTTP_403_FORBIDDEN,
-                detail="Insufficient study permissions",
             )
         return current_user
 

backend/app/core/exceptions.py

@@ -0,0 +1,19 @@
+from fastapi import FastAPI, Request, status
+from fastapi.responses import JSONResponse
+
+
+class AppException(Exception):
+    def __init__(self, code: str, message: str, status_code: int = status.HTTP_400_BAD_REQUEST):
+        self.code = code
+        self.message = message
+        self.status_code = status_code
+        super().__init__(message)
+
+
+def register_exception_handlers(app: FastAPI) -> None:
+    @app.exception_handler(AppException)
+    async def app_exception_handler(_: Request, exc: AppException) -> JSONResponse:
+        return JSONResponse(
+            status_code=exc.status_code,
+            content={"code": exc.code, "message": exc.message},
+        )