refactor: return readonly tuple from useActivityKeysOfSendStatus per hook convention

Author: isherstneva

packages/component/src/Transcript/LiveRegion/LongSend.tsx

@@ -31,7 +31,7 @@ const LiveRegionLongSend = () => {
   const [tick, setTick] = useState(0);
 
   /** Keys of outgoing non-presentational activities that are currently in the sending state. */
-  const sendingKeys = useActivityKeysOfSendStatus(SENDING);
+  const [sendingKeys] = useActivityKeysOfSendStatus(SENDING);
 
   /**
    * Arm a per-key timer when a key newly enters `sendingKeys`.

packages/component/src/Transcript/LiveRegion/SendFailed.tsx

@@ -27,7 +27,7 @@ const LiveRegionSendFailed = () => {
    * Activities which are presentational, such as `event` or `typing`, are ignored to reduce confusions.
    * "Failed to send message" should not be narrated for presentational activities.
    */
-  const activityKeysOfSendFailed = useActivityKeysOfSendStatus(SEND_FAILED);
+  const [activityKeysOfSendFailed] = useActivityKeysOfSendStatus(SEND_FAILED);
 
   /** Returns localized "Failed to send message." */
   const liveRegionSendFailedAlt = localize('TRANSCRIPT_LIVE_REGION_SEND_FAILED_ALT');

packages/component/src/Transcript/LiveRegion/useActivityKeysOfSendStatus.ts

@@ -12,19 +12,21 @@ const { useGetActivityByKey, useSendStatusByActivityKey } = hooks;
  *
  * Presentational activities (e.g. `event` or `typing`) are excluded to reduce noise.
  */
-export default function useActivityKeysOfSendStatus(status: SendStatus): Set<string> {
+export default function useActivityKeysOfSendStatus(status: SendStatus): readonly [Set<string>] {
   const [sendStatusByActivityKey] = useSendStatusByActivityKey();
   const getActivityByKey = useGetActivityByKey();
 
-  return useMemo<Set<string>>(() => {
-    const keys = new Set<string>();
+  return [
+    useMemo<Set<string>>(() => {
+      const keys = new Set<string>();
 
-    for (const [key, sendStatus] of sendStatusByActivityKey) {
-      if (sendStatus === status && !isPresentational(getActivityByKey(key))) {
-        keys.add(key);
+      for (const [key, sendStatus] of sendStatusByActivityKey) {
+        if (sendStatus === status && !isPresentational(getActivityByKey(key))) {
+          keys.add(key);
+        }
       }
-    }
 
-    return keys;
-  }, [getActivityByKey, sendStatusByActivityKey, status]);
+      return keys;
+    }, [getActivityByKey, sendStatusByActivityKey, status])
+  ] as const;
 }