Keep active task transcripts in memory for instant task switching

web/src/api.ts

@@ -123,6 +123,7 @@ export function subscribe(
   filter: { task_id?: string; lead?: boolean },
   onEvent: (ev: ByreEvent) => void,
   onState: (connected: boolean) => void,
+  onReady: () => void,
 ): () => void {
   let last = after;
   let heard = Date.now();
@@ -155,6 +156,10 @@ export function subscribe(
     s.addEventListener("ping", () => {
       heard = Date.now();
     });
+    s.addEventListener("ready", () => {
+      heard = Date.now();
+      onReady();
+    });
     s.onmessage = (msg: MessageEvent<string>) => {
       heard = Date.now();
       const ev = JSON.parse(msg.data) as ByreEvent;