Always use static/cached selectors in useSelector

ts/state/selectors/inbox.ts

@@ -0,0 +1,17 @@
+// Copyright 2024 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { createSelector } from 'reselect';
+import type { StateType } from '../reducer';
+
+const getInboxState = (state: StateType) => state.inbox;
+
+export const getInboxEnvelopeTimestamp = createSelector(
+  getInboxState,
+  ({ envelopeTimestamp }) => envelopeTimestamp
+);
+
+export const getInboxFirstEnvelopeTimestamp = createSelector(
+  getInboxState,
+  ({ firstEnvelopeTimestamp }) => firstEnvelopeTimestamp
+);