I've been wondering how WASM GC works with multiple wasm modules, it sounds like you might know. Does WASM GC exist outside individual modules managing memory for many, or is it "contained" inside each module? Does it allow for efficient sharing and minimal copies of memory between modules when host calls both?

For example say you have some data like (eg. string "abc123") in host memory and then pass into module A which then reads/operates the data, and then returns some other data to the host. The host then calls into module B passing the original host data and data returned from call to module A. Can that original host data be shared efficiently and managed by WASM GC between modules?

Are you referring to the weak references or to interior pointers? What I've been surprised by over the years it that a simplified, perhaps slightly broken version of a language comes to Wasm first, then as features expand, more of the guest language features, libraries, platform, and ecosystem comes, piece by piece. CheerpJ claims to have a fully-featured JVM, and Google is fielding Java compiled to Wasm GC with pretty good results. Wasm is bringing these platforms over piece by piece; so far there haven't been few "boom, here's full Language X on Wasm" moments. Instead we're progressing quite incrementally.