These are features and PRs planned to land on main branch before we release v0.19:

• Make SharedRef types Send + Sync #438 : make BranchPtr and by extension all shared refs, impl Send and Sync.
• Observers API #449 : new observers API and Awareness (breaking changes).
  • Awareness support in ywasm.
  • Awareness update callback signature goes back to it's old shape prior v0.18: Fn(&Awareness, &AwarenessEvent) + Send + Sync + 'static.
  • Awareness now can be generic over type of client state: Awareness<S>. That state should be serializable in order to send it beyond process boundaries.
  • While the methods themselves are still compatible with v0.18, the generic function signature changes: now it requires support for Send and Sync traits for non-wasm targets in order to support calling methods across threads without undefined behaviours (including accidental memory leaks).
• Add TextRef::apply_delta method. #448 : introduce Text::apply_delta method and conversion between Delta/Diff types.
• rlib crate type for yffi #444 : compile yrs into rlib format.
• Error occurs in yffi when inserting nested Maps into document #447 : fix inserting nested types into yffi.
• Reinforce lib0 v2 encoding against mallicious updates #450 : fix vulnerabilities in lib0 v2 encoding.
• feature: sync #460 : new feature flag: sync to convert observable callbacks to implement Send+Sync requirements.
• MapRef::get_or_init and DefaultPrelim trait #461 : add ability to freely convert between Value and Prelim types and implement MapRef::get_or_init using these features.
• Delta prelim types #459 : rename Value → Out, introduce In which is univeral equivalent for values of any kind but with Prelim capabilities. Also Removed generic parameters from prelim types such as MapPrelim, ArrayPrelim, TextPrelim etc.
• UndoManager with no default scope #462 : removed mandatory shared ref scope when creating UndoManager.
• fixed: lib0 decoding panicing when bufer size was not decoded to valid usize.
• fixed: when encoding document state, pending update was not included as part of an update.