diff --git a/lib/reducers/message-reducer.test.js b/lib/reducers/message-reducer.test.js
--- a/lib/reducers/message-reducer.test.js
+++ b/lib/reducers/message-reducer.test.js
@@ -296,6 +296,7 @@
         threadHashes: {},
         syncedMetadata: {},
         auxUserInfos: {},
+        threadActivityStore: {},
       },
     },
     {
diff --git a/lib/reducers/thread-activity-reducer.js b/lib/reducers/thread-activity-reducer.js
--- a/lib/reducers/thread-activity-reducer.js
+++ b/lib/reducers/thread-activity-reducer.js
@@ -2,6 +2,7 @@
 
 import invariant from 'invariant';
 
+import { setClientDBStoreActionType } from '../actions/client-db-store-actions.js';
 import { messageStorePruneActionType } from '../actions/message-actions.js';
 import {
   changeThreadMemberRolesActionTypes,
@@ -28,6 +29,33 @@
 import { updateTypes } from '../types/update-types-enum.js';
 import type { ClientUpdateInfo } from '../types/update-types.js';
 import { processUpdatesActionType } from '../types/update-types.js';
+import { getMessageForException } from '../utils/errors.js';
+import { assertObjectsAreEqual } from '../utils/objects.js';
+
+function assertThreadActivityStoresAreEqual(
+  processedThreadActivityStore: ThreadActivityStore,
+  expectedThreadActivityStore: ThreadActivityStore,
+  location: string,
+  onStateDifference?: (message: string) => mixed,
+) {
+  try {
+    assertObjectsAreEqual(
+      processedThreadActivityStore,
+      expectedThreadActivityStore,
+      `ThreadActivityStore - ${location}`,
+    );
+  } catch (e) {
+    console.log(
+      'Error processing ThreadActivityStore ops',
+      processedThreadActivityStore,
+      expectedThreadActivityStore,
+    );
+    const message = `Error processing ThreadActivityStore ops ${
+      getMessageForException(e) ?? '{no exception message}'
+    }`;
+    onStateDifference?.(message);
+  }
+}
 
 const { processStoreOperations: processStoreOps } =
   threadActivityStoreOpsHandlers;
@@ -35,6 +63,7 @@
 function reduceThreadActivity(
   state: ThreadActivityStore,
   action: BaseAction,
+  onStateDifference?: (message: string) => mixed,
 ): {
   +threadActivityStore: ThreadActivityStore,
   +threadActivityStoreOperations: $ReadOnlyArray<ThreadActivityStoreOperation>,
@@ -171,6 +200,17 @@
       threadActivityStore: processStoreOps(state, [removeOperation]),
       threadActivityStoreOperations: [removeOperation],
     };
+  } else if (action.type === setClientDBStoreActionType) {
+    assertThreadActivityStoresAreEqual(
+      action.payload.threadActivityStore ?? {},
+      state,
+      action.type,
+      onStateDifference,
+    );
+    return {
+      threadActivityStore: state,
+      threadActivityStoreOperations: [],
+    };
   }
   return {
     threadActivityStore: state,
diff --git a/lib/types/store-ops-types.js b/lib/types/store-ops-types.js
--- a/lib/types/store-ops-types.js
+++ b/lib/types/store-ops-types.js
@@ -15,6 +15,7 @@
 } from './message-types.js';
 import type { ClientReportCreationRequest } from './report-types.js';
 import type { SyncedMetadata } from './synced-metadata-types.js';
+import type { ThreadActivityStore } from './thread-activity-types.js';
 import type { ClientDBThreadInfo, ThreadStore } from './thread-types.js';
 import type { UserInfos } from './user-types.js';
 import type {
@@ -121,4 +122,5 @@
   +threadHashes: ?ThreadHashes,
   +syncedMetadata: ?SyncedMetadata,
   +auxUserInfos: ?AuxUserInfos,
+  +threadActivityStore: ?ThreadActivityStore,
 };
diff --git a/native/data/sqlite-data-handler.js b/native/data/sqlite-data-handler.js
--- a/native/data/sqlite-data-handler.js
+++ b/native/data/sqlite-data-handler.js
@@ -13,6 +13,7 @@
 import { keyserverStoreOpsHandlers } from 'lib/ops/keyserver-store-ops.js';
 import { reportStoreOpsHandlers } from 'lib/ops/report-store-ops.js';
 import { syncedMetadataStoreOpsHandlers } from 'lib/ops/synced-metadata-store-ops.js';
+import { threadActivityStoreOpsHandlers } from 'lib/ops/thread-activity-store-ops.js';
 import { threadStoreOpsHandlers } from 'lib/ops/thread-store-ops.js';
 import { userStoreOpsHandlers } from 'lib/ops/user-store-ops.js';
 import { isLoggedIn } from 'lib/selectors/user-selectors.js';
@@ -210,6 +211,7 @@
           integrityThreadHashes,
           syncedMetadata,
           auxUserInfos,
+          threadActivityEntries,
         } = await commCoreModule.getClientDBStore();
         const threadInfosFromDB =
           threadStoreOpsHandlers.translateClientDBData(threads);
@@ -228,6 +230,10 @@
           syncedMetadataStoreOpsHandlers.translateClientDBData(syncedMetadata);
         const auxUserInfosFromDB =
           auxUserStoreOpsHandlers.translateClientDBData(auxUserInfos);
+        const threadActivityEntriesFromDB =
+          threadActivityStoreOpsHandlers.translateClientDBData(
+            threadActivityEntries,
+          );
 
         dispatch({
           type: setClientDBStoreActionType,
@@ -244,6 +250,7 @@
             threadHashes: threadHashesFromDB,
             syncedMetadata: syncedMetadataFromDB,
             auxUserInfos: auxUserInfosFromDB,
+            threadActivityEntries: threadActivityEntriesFromDB,
           },
         });
       } catch (setStoreException) {
diff --git a/web/shared-worker/utils/store.js b/web/shared-worker/utils/store.js
--- a/web/shared-worker/utils/store.js
+++ b/web/shared-worker/utils/store.js
@@ -36,6 +36,7 @@
     threadHashes: null,
     syncedMetadata: null,
     auxUserInfos: null,
+    threadActivityStore: null,
   };
   const data = await sharedWorker.schedule({
     type: workerRequestMessageTypes.GET_CLIENT_STORE,
@@ -123,6 +124,17 @@
       messageStoreThreads: data.store.messageStoreThreads,
     };
   }
+  if (
+    data?.store?.threadActivityEntries &&
+    data.store.threadActivityEntries.length > 0
+  ) {
+    result = {
+      ...result,
+      threadActivityStore: threadActivityStoreOpsHandlers.translateClientDBData(
+        data.store.threadActivityEntries,
+      ),
+    };
+  }
   return result;
 }