b66a9536

By: Lucien Huber <im@lcnbr.ch>

avoid Rustdoc rebuilds for prose-only documentation edits

Keep a validated per-product Rustdoc sidecar in watch mode. Typst-only edits reuse that last-good tree, while crate inputs, the Rustdoc stylesheet, and the product registry mark it dirty and refresh it atomically. Keep ordinary and Pages builds cache-free, and document the distinction between Typst incremental recompilation and Rustdoc-visible Rust comments.

User prompt:

typst only changes should not require redoing rustdoc. In fact I think typst does it better there too, any prose even in the source does not recompile no?