Description

Noticed while working on #55547

Pinging @t-hamano @kevin940726 as I saw you recently contributed to this part of the codebase and certainly you are more familiat than me with it.

While working on #55547 I had the need to change something in the base styls and I was surprised to not see my changes reflected in my browseer. Turned out that when running npm run dev, any change to the base style is not 'watched'.

@aristath @SergeyBiryukov and myself spent ~2 hours in a joined troubleshooting session to understand why.

To our understanding, this is in some way by design. The base-styles package isn't included in the watched files. We are guessing that is because any change there would require to rebuild all the scss files where the bast styles are used? Anyways, the developer expeerience is less than ideal.

Te root causes are:

• hasModuleField returns true only if a package.json file has a module property. This is not the case for the base-styles package.
• isSourceFile returns true only if the checked file is within a src directory. The base-styles package doesn't have a src directory.

Although these files are built when running npm run build, the lack of a src directory is what makes us think not watching them when running npm run dev is by design. However, as mentioned earlier, the developer experience is less than ideal. As a contributor, I would expect that npm run dev watches all the files necessary to actually code anc copntribute to this repository.

WordPress.org is an open source project that historically focused on making contributing easy and open to everyone.

At the very least we'd think a couple things should be taken into consideration>

== Documentation
I couldn't find any reference in the documentation that mentions npm run dev will not watch for changes to the base-styles packages. As watching these files is supposed to work, such an exception should be documented in a very prominent way. The documentation just says:

There are two ways to build your code. While developing, you probably will want to use npm run dev to run continuous builds automatically as source files change.

The fact base-styles is not 'watched' is not mentioned anywhere, as far as I can tell:

• not mentioned in the Getting Started With Code Contribution documentation
• not mentioned in other documentation where npm run dev is mentioned, e.g. the Style Engine documentation Contributing documentation

To make contributing easy for everyone and not just something for initiated contributors, this should be docuemnted very clear to avoid contributors spend their time trying to understand why they don't see their changes reflected in teh browser.

== Consider to watch these files
We'd tend to think these files should be 'watched' anyways. By running npm run dev, contributors expect that everything 'just works'. However, there is at least one notable, undocumented, exception. This seems less than ideal for a smooth contributing experience.

Step-by-step reproduction instructions

• Run npm run dev in your terminal.
• Edit any file in the base-styles package and save your changes.
• Observe your terminal: nothing happens.

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes