diff --git a/web/database/worker/db-worker.js b/web/database/worker/db-worker.js
index 7fb3fecff..ecefc4c84 100644
--- a/web/database/worker/db-worker.js
+++ b/web/database/worker/db-worker.js
@@ -1,261 +1,258 @@
 // @flow
 
 import localforage from 'localforage';
 import _throttle from 'lodash/throttle.js';
 import initSqlJs, { type SqliteDatabase } from 'sql.js';
 
 import type {
   ClientDBDraftStoreOperation,
   DraftStoreOperation,
 } from 'lib/types/draft-types.js';
 import type { ClientDBStore } from 'lib/types/store-ops-types.js';
 
 import {
   type SharedWorkerMessageEvent,
   type WorkerRequestMessage,
   type WorkerResponseMessage,
   workerRequestMessageTypes,
   workerResponseMessageTypes,
   type WorkerRequestProxyMessage,
+  workerWriteRequests,
 } from '../../types/worker-types.js';
 import { getSQLiteDBVersion, setupSQLiteDB } from '../queries/db-queries.js';
 import {
   getAllDrafts,
   moveDraft,
   removeAllDrafts,
   updateDraft,
 } from '../queries/draft-queries.js';
 import { getMetadata, setMetadata } from '../queries/metadata-queries.js';
 import {
   getPersistStorageItem,
   removePersistStorageItem,
   setPersistStorageItem,
 } from '../queries/storage-engine-queries.js';
 import {
   CURRENT_USER_ID_KEY,
   DB_PERSIST_THROTTLE_WAIT_MS,
   SQLITE_CONTENT,
   SQLITE_ENCRYPTION_KEY,
 } from '../utils/constants.js';
 import {
   decryptDatabaseFile,
   encryptDatabaseFile,
   generateDatabaseCryptoKey,
 } from '../utils/worker-crypto-utils.js';
 
 const localforageConfig: PartialConfig = {
   driver: localforage.INDEXEDDB,
   name: 'comm',
   storeName: 'commStorage',
   description: 'Comm encrypted database storage',
   version: '1.0',
 };
 localforage.config(localforageConfig);
 
 let sqliteDb: ?SqliteDatabase = null;
 let encryptionKey: ?CryptoKey = null;
 
 async function initDatabase(sqljsFilePath: string, sqljsFilename: ?string) {
   encryptionKey = await localforage.getItem(SQLITE_ENCRYPTION_KEY);
   if (!encryptionKey) {
     const cryptoKey = await generateDatabaseCryptoKey();
     await localforage.setItem(SQLITE_ENCRYPTION_KEY, cryptoKey);
   }
 
   const encryptedContent = await localforage.getItem(SQLITE_CONTENT);
 
   let dbContent = null;
   try {
     if (encryptionKey && encryptedContent) {
       dbContent = await decryptDatabaseFile(encryptedContent, encryptionKey);
     }
   } catch (e) {
     console.error('Error while decrypting content, clearing database content');
     await localforage.removeItem(SQLITE_CONTENT);
   }
 
   const locateFile = defaultFilename => {
     if (sqljsFilename) {
       return `${sqljsFilePath}/${sqljsFilename}`;
     }
     return `${sqljsFilePath}/${defaultFilename}`;
   };
   const SQL = await initSqlJs({
     locateFile,
   });
 
   if (dbContent) {
     sqliteDb = new SQL.Database(dbContent);
     console.info(
       'Database exists and is properly encrypted, using persisted data',
     );
   } else {
     sqliteDb = new SQL.Database();
     setupSQLiteDB(sqliteDb);
     console.info('Creating fresh database');
   }
 
   const dbVersion = getSQLiteDBVersion(sqliteDb);
   console.info(`Db version: ${dbVersion}`);
 }
 
 function processDraftStoreOperations(
   operations: $ReadOnlyArray<ClientDBDraftStoreOperation>,
 ) {
   if (!sqliteDb) {
     throw new Error('Database not initialized');
   }
   for (const operation: DraftStoreOperation of operations) {
     if (operation.type === 'remove_all') {
       removeAllDrafts(sqliteDb);
     } else if (operation.type === 'update') {
       const { key, text } = operation.payload;
       updateDraft(sqliteDb, key, text);
     } else if (operation.type === 'move') {
       const { oldKey, newKey } = operation.payload;
       moveDraft(sqliteDb, oldKey, newKey);
     } else {
       throw new Error('Unsupported draft operation');
     }
   }
 }
 
 function getClientStore(): ClientDBStore {
   if (!sqliteDb) {
     throw new Error('Database not initialized');
   }
   return {
     drafts: getAllDrafts(sqliteDb),
     messages: [],
     threads: [],
   };
 }
 
 async function persist() {
   if (!sqliteDb) {
     throw new Error('Database not initialized');
   }
 
   if (!encryptionKey) {
     encryptionKey = await localforage.getItem(SQLITE_ENCRYPTION_KEY);
   }
 
   const dbData = sqliteDb.export();
   if (!encryptionKey) {
     throw new Error('Encryption key is missing');
   }
   const encryptedData = await encryptDatabaseFile(dbData, encryptionKey);
   await localforage.setItem(SQLITE_CONTENT, encryptedData);
 }
 
 const throttledPersist = _throttle(persist, DB_PERSIST_THROTTLE_WAIT_MS);
 
 async function processAppRequest(
   message: WorkerRequestMessage,
 ): Promise<?WorkerResponseMessage> {
   // non-database operations
   if (message.type === workerRequestMessageTypes.PING) {
     return {
       type: workerResponseMessageTypes.PONG,
       text: 'PONG',
     };
   } else if (
     message.type === workerRequestMessageTypes.GENERATE_DATABASE_ENCRYPTION_KEY
   ) {
     const cryptoKey = await generateDatabaseCryptoKey();
     await localforage.setItem(SQLITE_ENCRYPTION_KEY, cryptoKey);
     return;
   }
 
   // database operations
   if (message.type === workerRequestMessageTypes.INIT) {
     await initDatabase(message.sqljsFilePath, message.sqljsFilename);
     return;
   }
 
   if (!sqliteDb) {
     throw new Error('Database not initialized');
   }
 
   // read-only operations
   if (message.type === workerRequestMessageTypes.GET_CLIENT_STORE) {
     return {
       type: workerResponseMessageTypes.CLIENT_STORE,
       store: getClientStore(),
     };
   } else if (message.type === workerRequestMessageTypes.GET_CURRENT_USER_ID) {
     return {
       type: workerResponseMessageTypes.GET_CURRENT_USER_ID,
       userID: getMetadata(sqliteDb, CURRENT_USER_ID_KEY),
     };
   } else if (
     message.type === workerRequestMessageTypes.GET_PERSIST_STORAGE_ITEM
   ) {
     return {
       type: workerResponseMessageTypes.GET_PERSIST_STORAGE_ITEM,
       item: getPersistStorageItem(sqliteDb, message.key),
     };
   }
 
   // write operations
+  if (!workerWriteRequests.includes(message.type)) {
+    throw new Error('Request type not supported');
+  }
+
   if (message.type === workerRequestMessageTypes.PROCESS_STORE_OPERATIONS) {
     const { draftStoreOperations } = message.storeOperations;
     if (draftStoreOperations) {
       processDraftStoreOperations(draftStoreOperations);
     }
-    throttledPersist();
-    return;
   } else if (message.type === workerRequestMessageTypes.SET_CURRENT_USER_ID) {
     setMetadata(sqliteDb, CURRENT_USER_ID_KEY, message.userID);
-    throttledPersist();
-    return;
   } else if (
     message.type === workerRequestMessageTypes.SET_PERSIST_STORAGE_ITEM
   ) {
     setPersistStorageItem(sqliteDb, message.key, message.item);
-    throttledPersist();
-    return;
   } else if (
     message.type === workerRequestMessageTypes.REMOVE_PERSIST_STORAGE_ITEM
   ) {
     removePersistStorageItem(sqliteDb, message.key);
-    throttledPersist();
-    return;
   }
 
-  throw new Error('Request type not supported');
+  throttledPersist();
 }
 
 function connectHandler(event: SharedWorkerMessageEvent) {
   if (!event.ports.length) {
     return;
   }
   const port: MessagePort = event.ports[0];
   console.log('Web database worker alive!');
 
   port.onmessage = async function (messageEvent: MessageEvent) {
     const data: WorkerRequestProxyMessage = (messageEvent.data: any);
     const { id, message } = data;
 
     if (!id) {
       port.postMessage({
         error: new Error('Request without identifier'),
       });
     }
 
     try {
       const result = await processAppRequest(message);
       port.postMessage({
         id,
         message: result,
       });
     } catch (e) {
       port.postMessage({
         id,
         error: e,
       });
     }
   };
 }
 
 self.addEventListener('connect', connectHandler);
diff --git a/web/types/worker-types.js b/web/types/worker-types.js
index 759a2c050..c71dd1a3d 100644
--- a/web/types/worker-types.js
+++ b/web/types/worker-types.js
@@ -1,132 +1,139 @@
 // @flow
 
 import type {
   ClientDBStore,
   ClientDBStoreOperations,
 } from 'lib/types/store-ops-types.js';
 
 // The types of messages sent from app to worker
 export const workerRequestMessageTypes = Object.freeze({
   PING: 0,
   INIT: 1,
   GENERATE_DATABASE_ENCRYPTION_KEY: 2,
   PROCESS_STORE_OPERATIONS: 3,
   GET_CLIENT_STORE: 4,
   SET_CURRENT_USER_ID: 5,
   GET_CURRENT_USER_ID: 6,
   GET_PERSIST_STORAGE_ITEM: 7,
   SET_PERSIST_STORAGE_ITEM: 8,
   REMOVE_PERSIST_STORAGE_ITEM: 9,
 });
 
+export const workerWriteRequests: $ReadOnlyArray<number> = [
+  workerRequestMessageTypes.PROCESS_STORE_OPERATIONS,
+  workerRequestMessageTypes.SET_CURRENT_USER_ID,
+  workerRequestMessageTypes.SET_PERSIST_STORAGE_ITEM,
+  workerRequestMessageTypes.REMOVE_PERSIST_STORAGE_ITEM,
+];
+
 export type PingWorkerRequestMessage = {
   +type: 0,
   +text: string,
 };
 
 export type InitWorkerRequestMessage = {
   +type: 1,
   +sqljsFilePath: string,
   +sqljsFilename: ?string,
 };
 
 export type GenerateDatabaseEncryptionKeyRequestMessage = {
   +type: 2,
 };
 
 export type ProcessStoreOperationsRequestMessage = {
   +type: 3,
   +storeOperations: ClientDBStoreOperations,
 };
 
 export type GetClientStoreRequestMessage = {
   +type: 4,
 };
 
 export type SetCurrentUserIDRequestMessage = {
   +type: 5,
   +userID: string,
 };
 
 export type GetCurrentUserIDRequestMessage = {
   +type: 6,
 };
 
 export type GetPersistStorageItemRequestMessage = {
   +type: 7,
   +key: string,
 };
 
 export type SetPersistStorageItemRequestMessage = {
   +type: 8,
   +key: string,
   +item: string,
 };
 
 export type RemovePersistStorageItemRequestMessage = {
   +type: 9,
   +key: string,
 };
 
 export type WorkerRequestMessage =
   | PingWorkerRequestMessage
   | InitWorkerRequestMessage
   | GenerateDatabaseEncryptionKeyRequestMessage
   | ProcessStoreOperationsRequestMessage
   | GetClientStoreRequestMessage
   | SetCurrentUserIDRequestMessage
   | GetCurrentUserIDRequestMessage
   | GetPersistStorageItemRequestMessage
   | SetPersistStorageItemRequestMessage
   | RemovePersistStorageItemRequestMessage;
 
 export type WorkerRequestProxyMessage = {
   +id: number,
   +message: WorkerRequestMessage,
 };
 
 // The types of messages sent from worker to app
 export const workerResponseMessageTypes = Object.freeze({
   PONG: 0,
   CLIENT_STORE: 1,
   GET_CURRENT_USER_ID: 2,
   GET_PERSIST_STORAGE_ITEM: 3,
 });
 
 export type PongWorkerResponseMessage = {
   +type: 0,
   +text: string,
 };
 
 export type ClientStoreResponseMessage = {
   +type: 1,
   +store: ClientDBStore,
 };
 
 export type GetCurrentUserIDResponseMessage = {
   +type: 2,
   +userID: ?string,
 };
 
 export type GetPersistStorageItemResponseMessage = {
   +type: 3,
   +item: string,
 };
 
 export type WorkerResponseMessage =
   | PongWorkerResponseMessage
   | ClientStoreResponseMessage
   | GetCurrentUserIDResponseMessage
   | GetPersistStorageItemResponseMessage;
 
 export type WorkerResponseProxyMessage = {
   +id?: number,
   +message?: WorkerResponseMessage,
   +error?: Error,
 };
 
 // SharedWorker types
 export type SharedWorkerMessageEvent = MessageEvent & {
   +ports: $ReadOnlyArray<MessagePort>,
   ...
 };