Coalesce session presentation invalidations through a disposable frame queue

src/lib/canvas-bindings/frame-queue.ts

@@ -0,0 +1,11 @@
+/** Presentation invalidations only. Commands, history and network work never wait here. */
+export type FrameClock={request(callback:()=>void):unknown;cancel(handle:unknown):void};
+export function createFrameQueue<K>(clock:FrameClock,publish:(dirty:ReadonlySet<K>)=>void){
+ let dirty=new Set<K>(),scheduled:{handle?:unknown}|undefined,disposed=false;
+ function flush(){if(disposed)return;const pending=scheduled;scheduled=undefined;if(pending)clock.cancel(pending.handle);if(!dirty.size)return;const batch=dirty;dirty=new Set();publish(batch);}
+ return Object.freeze({
+  invalidate(keys:Iterable<K>){if(disposed)return;for(const key of keys)dirty.add(key);if(!dirty.size||scheduled)return;const pending: {handle?:unknown}={};scheduled=pending;try{pending.handle=clock.request(()=>{if(scheduled!==pending)return;scheduled=undefined;flush();});}catch(error){scheduled=undefined;throw error;}},
+  flush,
+  dispose(){if(disposed)return;disposed=true;if(scheduled)clock.cancel(scheduled.handle);scheduled=undefined;dirty.clear();},
+ });
+}