Slate v2 IME / Mobile / Browser RC Review

Goal

Review the RC risk for the weirdest editor surface:

• IME
• mobile/composition-adjacent behavior
• browser-specific selection/focus/input edge cases

Review Question

Do we already have enough parity/proof against legacy Slate React to keep RC honest, or is a deeper dedicated analysis still required?

Review Method

1. pull the existing proof and learning docs
2. inspect current slate-react browser/input code
3. inspect the equivalent legacy Slate React paths
4. compare coverage and deliberate cuts
5. report findings first, then residual risks and recommendation