.d.ts files are produced by Typescript compiler automatically from .ts files (and can be written manually for .js files). ML signature files are much like .h files and I think for the same reason - to make compiler work easier.

Edit: as this is LLM thread - ML is Meta Language as in OCaml and SML.

? What’s a ML module signature?

I’m not sure what you’re imagining, but in this case I would not imagine you would generate js or write .d.ts files?

An LLM pass with a high level goal would generate a file list, then a series of .d.ts files from it.

Then (after perhaps a review of the type definition files, possibly also LLM assisted) a second pass taking the .d.ts files as input would generate a typescript file for every .d.ts file.

You would then discard the .d.ts files and just have a scaffolded .ts code base?

My point was doing the same trick with say, Java, seems like a harder problem to solve, but you could do the above right now with existing LLMs.