Google Cloud Shell环境下SvelteKit对接Laravel的CORS错误求助

背景 #

• 开发环境：Google Cloud Shell（使用终端、云编辑器、Web预览功能），因公司政策限制无法在本地搭建开发环境，后续将部署至Google Cloud Run生产环境
• 技术栈：前端使用SvelteKit（首次接触），后端使用Laravel；本人具备丰富前端开发经验

问题重现 #

1. 前端启动命令：npm run dev -- --host 或 npm run preview -- --host，运行端口为5173
2. 后端启动命令：php artisan serve --host=0.0.0.0 --port=8000，通过该终端的Web预览功能获取Cloud Shell生成的域名（格式示例：https://8000-cs-<some ID number>-default.cs-europe-west1-onse.cloudshell.dev）
3. 前端发起AJAX请求代码：

const response = await fetch(`https://8000-cs-<some ID number>-default.cs-europe-west1-onse.cloudshell.dev/api/my_route_here`);

错误表现 #

• 请求返回302 Found状态码，触发CORS错误
• 开发者控制台报错：

Access to internal resource at 'https://accounts.google.com/o/oauth2/v2/auth?client_id=<some code>&redirect_uri=https%3A%2F%2Fssh.cloud.google.com%2Fdevshell%2Fgateway%2Foauth&response_type=code&scope=email&state=<some code>' (redirected from 'https://5173-cs-<some code>-default.cs-europe-west1-onse.cloudshell.dev/manifest.json') from origin 'https://5173-cs-<some code>-default.cs-europe-west1-onse.cloudshell.dev' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

已确认的配置与信息 #

• 后端URL验证：直接在浏览器粘贴后端Cloud Shell域名可正常显示Laravel默认页面
• Laravel的config/cors.php配置：

<?php

return [

    /*
    |--------------------------------------------------------------------------
    | Cross-Origin Resource Sharing (CORS) Configuration
    |--------------------------------------------------------------------------
    |
    | Here you may configure your settings for cross-origin resource sharing
    | or "CORS". This determines what cross-origin operations may execute
    | in web browsers. You are free to adjust these settings as needed.
    |
    */

    'paths' => ['api/*', 'sanctum/csrf-cookie'],

    'allowed_methods' => ['*'],

    'allowed_origins' => ['*'],

    'allowed_origins_patterns' => [],

    'allowed_headers' => ['*'],

    'exposed_headers' => [],

    'max_age' => 0,

    'supports_credentials' => true,

];

请求解决方案 #

目前无法定位问题根源，恳请提供可行的CORS问题解决方法。

内容的提问来源于stack exchange，提问作者Alex Kerr