This looks very interesting, but I wonder how's the rewrite approach gonna impact the long-term maintenance and porting changes _back_ from Tree Sitter.

As you mention WASM-readiness, did you consider using the official Tree Sitter WASM builds nicely packaged with wazero (pure Go WASM runtime) ?

It may help staying sync with upstream for the long term and, while probably a bit slower, has nice security and GC advantages too.