Review

Informative

• I plan to bring this proposal up at the Wasm CG meeting next week to get Wasm's take. I think this is orthogonal and does not step on Wasm's toes. There is an interesting future design question for reflecting WasmGC Arrays of scalars as JS TypedArrays. I imagine those reflections will not have detachable buffers, but still warrants some discussion with the CG.

Normative

• DetachArrayBuffer needs to throw for immutable buffers.
  #38
• Please have a reviewed PR against HTML for structured clone. I don't think there's much design space here, so I'm personally happy for this to be a stage 3 blocker instead of a stage 2.7 blocker. But should WHATWG give feedback that requires this proposal to change, we'd need to make normative changes during 2.7.
  https://github.com/whatwg/html/pull/11033
• I'd love to implement this with mprotect. However, that requires page alignment. We can't reveal the page size to user code, as that's a fingerprinting vector. Fixing a page size seems too unergonomic. Ideas? (Using mprotect is a nice-to-have for V8, not a requirement.)

Editorial

• Prefer ValidateTypedArray's use argument be renamed accessMode. Ditto for the other Validate AOs.
  #33
• Rename [AllocateArrayBuffer]'s maxByteLength parameter to something more descriptive since it can be IMMUTABLE. (I suppose you're minimizing the diff for now?)
  #33

Start by reviewing the checklist in issue #30, then read the referenced #38, #33, and WHATWG structured-clone pull request. The issue is done when the remaining normative, editorial, and design questions have explicit decisions or documented follow-up.