Reduce polling when app is backgrounded (#4192)

src/state/messages/events/agent.ts

@@ -4,7 +4,10 @@ import {nanoid} from 'nanoid/non-secure'
 
 import {networkRetry} from '#/lib/async/retry'
 import {logger} from '#/logger'
-import {DEFAULT_POLL_INTERVAL} from '#/state/messages/events/const'
+import {
+  BACKGROUND_POLL_INTERVAL,
+  DEFAULT_POLL_INTERVAL,
+} from '#/state/messages/events/const'
 import {
   MessagesEventBusDispatch,
   MessagesEventBusDispatchEvent,
@@ -287,6 +290,9 @@ export class MessagesEventBus {
         const lowest = Math.min(DEFAULT_POLL_INTERVAL, ...requested)
         return lowest
       }
+      case MessagesEventBusStatus.Backgrounded: {
+        return BACKGROUND_POLL_INTERVAL
+      }
       default:
         return DEFAULT_POLL_INTERVAL
     }

src/state/messages/events/const.ts

@@ -1 +1,2 @@
 export const DEFAULT_POLL_INTERVAL = 20e3
+export const BACKGROUND_POLL_INTERVAL = 60e3