I am debugging the failing tests and working on fixing them.

So, the reason for still keeping the index.js in the root is a workaround for a circular dependency issue during TypeScript migration.

The @wordpress/browserslist-config package is a foundational dependency that other packages need during their build process. As we migrate packages to TypeScript in a specific order, we've hit a circular dependency problem.

Here's what happens when the main entry points to build/index.js:

Cannot find module '/Users/hp/gutenberg/node_modules/@wordpress/browserslist-config/build/index.js' 

This error occurs because:

• Other packages try to import from @wordpress/browserslist-config
• The package.json main field points to build/index.js
• But build/index.js doesn't exist because TypeScript hasn't been compiled yet
• TypeScript can't be compiled because the build process itself needs browserslist-config
• This creates a dependency loop; the build system needs browserslist-config to build other packages, but browserslist-config itself needs to be built first

This same issue affects other config packages too - see #70533

So the question is: What's the proper solution? The current workaround prevents build failures but isn't a complete migration.

This also raises another question: Do config packages even need to be migrated? They don't have complex logic that would benefit from type safety. They're just low-level dependencies that other packages import during build.

cc: @manzoorwanijk @t-hamano

I think it's fine to leave this package as js only.

I think it's fine to leave this package as js only.

I agree with this; this package is just a configuration file and does not contain any logic.