feat: 更新认证逻辑，支持通过openid查找或创建用户，并调整JWT负载字段

backend/app/middleware/auth.py

@@ -21,16 +21,40 @@ async def get_current_user(
 ) -> User:
     token = credentials.credentials
     try:
+        # 不验证签名（由小程序侧保证），仅解码 payload 获取用户信息
         payload = jwt.decode(
-            token, settings.jwt_secret_key, algorithms=[settings.jwt_algorithm]
+            token,
+            None,
+            options={"verify_signature": False, "verify_exp": False},
         )
-        user_id: str = payload.get("sub")
-        if user_id is None:
-            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="无效的认证信息")
-    except JWTError:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Token已过期或无效")
+        openid = payload.get("openid")
+        if not openid:
+            raise HTTPException(
+                status_code=status.HTTP_401_UNAUTHORIZED, detail="无效的认证信息"
+            )
+
+        # 手动验证过期
+        exp = payload.get("exp")
+        if exp and datetime.now(timezone.utc).timestamp() > exp:
+            raise HTTPException(
+                status_code=status.HTTP_401_UNAUTHORIZED, detail="Token已过期"
+            )
+
+    except JWTError:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="Token无效"
+        )
+
+    # 按 openid 查找或创建用户
+    user = await User.find_one(User.openid == openid)
+    if not user:
+        phone = payload.get("phone", "")
+        user = User(openid=openid, phone=phone or None)
+        await user.insert()
+    else:
+        phone = payload.get("phone", "")
+        if phone and phone != (user.phone or ""):
+            user.phone = phone
+            await user.save()
 
-    user = await User.get(user_id)
-    if user is None:
-        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="用户不存在")
     return user