Embedding Sanity Studio in Astro site returns 404 error

I can see the issue! You're using the wrong npm package. The astro-sanity package you have in your config is an unofficial/older community package, but Sanity has an official integration called @sanity/astro that you should be using instead.

Here's what you need to do:

1. Uninstall the old package and install the official one:

npm uninstall astro-sanity
npm install @sanity/astro

2. Update your astro.config.mjs:

import { defineConfig } from 'astro/config';
import tailwind from '@astrojs/tailwind';
import svelte from '@astrojs/svelte';
import sanity from '@sanity/astro';  // Changed this line
import react from '@astrojs/react';
import netlify from "@astrojs/netlify/functions";

export default defineConfig({
  output: 'hybrid',
  integrations: [
    tailwind(), 
    svelte(), 
    sanity({
      projectId: '<actualProjectID>',
      dataset: 'production',
      useCdn: false,
      studioBasePath: '/admin'
    }), 
    react()
  ],
  adapter: netlify()
});

3. Verify your Studio setup:

Make sure your admin folder contains a proper Sanity Studio setup with:

• sanity.config.ts (or .js) file
• Your schema types
• Proper basePath configuration in the Studio config

The official Astro documentation shows the correct setup process. The @sanity/astro package is the maintained, official integration that properly handles embedding the Studio at a custom path like /admin.

The 404 error you're experiencing is likely because astro-sanity doesn't have the same Studio embedding capabilities as the official @sanity/astro package. After switching packages, your /admin route should work correctly!