Resolving types from nested `node_modules`

[OliverJAsh]

👋 I am using Shiki Twoslash for my new blog (example, code) and I love it! Thank you.

I want each blog post to have its own package.json so I don't have to add all of the @types packages required by my code samples to the root package.json. For example, the code samples in posts/my-first-post/index.md should use @types defined in posts/my-first-post/node_modules. However, when I try to do this it seems that Twoslash is unable to resolve types from nested node_modules folders.

I've created a reduced test case here: https://github.com/OliverJAsh/twoslash-nested-projects-test

Steps to reproduce:

1. Clone the reduced test case and install all dependencies
2. Run Twoslash to compile posts/my-first-post/index.md
3. Inspect the output at posts/my-first-post/render/index.html

yarn

(cd posts/my-first-post && yarn)

twoslash posts/my-first-post posts/my-first-post/render

open posts/my-first-post/render/index.html

In the output we will see the following error:

Cannot find module 'express' or its corresponding type declarations.

This is despite the fact that @types/express is installed in posts/my-first-post/node_modules, which is in the same folder as the Markdown file we're compiling.

I can fix the error if I install @types/express in the root package.json, but I don't want to do that as described above.

I suspect the reason this happens is because the virtual TS file created by Twoslash has a path outside of the folder posts/my-first-post?

[orta]

Yeah, I think the 'find node_modules' resolver in the current shiki-twoslash to be quite naive (likely because I've only used it in a few repos and they've all largely had the root repo) - totally open to that expanding 👍🏻

[OliverJAsh]

Thanks for your response! I can try to do this myself but firstly I'd like to get your thoughts on how we should address this. Should it just find @types in any node_modules folders that exist in parent folders relative to the Markdown file that contains the code sample?

[orta]

Yeah, I'd try have have the backwards searching node resolution strategy start from the folder with the markdown inside it. It's a little hard to know how that affects everything, I'd imagine twoslash now needs knowledge about the current dir. and not just pwd, shiki-twoslash probably needs info of the current file also and maybe some of the larger tools might have to pass it in