diff --git a/packages/desktop-client/src/components/Titlebar.tsx b/packages/desktop-client/src/components/Titlebar.tsx
index 748c29de9fc..c4972cf3b07 100644
--- a/packages/desktop-client/src/components/Titlebar.tsx
+++ b/packages/desktop-client/src/components/Titlebar.tsx
@@ -117,8 +117,8 @@ function SyncButton({ style, isMobile = false }: SyncButtonProps) {
   >(null);
 
   useEffect(() => {
-    const unlisten = listen('sync-event', ({ type, subtype, syncDisabled }) => {
-      if (type === 'start') {
+    const unlisten = listen('sync-event', event => {
+      if (event.type === 'start') {
         setSyncing(true);
         setSyncState(null);
       } else {
@@ -130,19 +130,19 @@ function SyncButton({ style, isMobile = false }: SyncButtonProps) {
         }, 200);
       }
 
-      if (type === 'error') {
+      if (event.type === 'error') {
         // Use the offline state if either there is a network error or
         // if this file isn't a "cloud file". You can't sync a local
         // file.
-        if (subtype === 'network') {
+        if (event.subtype === 'network') {
           setSyncState('offline');
         } else if (!cloudFileId) {
           setSyncState('local');
         } else {
           setSyncState('error');
         }
-      } else if (type === 'success') {
-        setSyncState(syncDisabled ? 'disabled' : null);
+      } else if (event.type === 'success') {
+        setSyncState(event.syncDisabled ? 'disabled' : null);
       }
     });
 
diff --git a/packages/desktop-client/src/components/budget/index.tsx b/packages/desktop-client/src/components/budget/index.tsx
index 0012f46f0a7..43b0c4d62de 100644
--- a/packages/desktop-client/src/components/budget/index.tsx
+++ b/packages/desktop-client/src/components/budget/index.tsx
@@ -108,14 +108,16 @@ function BudgetInner(props: BudgetInnerProps) {
     run();
 
     const unlistens = [
-      listen('sync-event', ({ type, tables }) => {
-        if (
-          type === 'success' &&
-          (tables.includes('categories') ||
+      listen('sync-event', event => {
+        if (event.type === 'success') {
+          const tables = event.tables;
+          if (
+            tables.includes('categories') ||
             tables.includes('category_mapping') ||
-            tables.includes('category_groups'))
-        ) {
-          loadCategories();
+            tables.includes('category_groups')
+          ) {
+            loadCategories();
+          }
         }
       }),
 
diff --git a/packages/desktop-client/src/components/mobile/accounts/AccountTransactions.tsx b/packages/desktop-client/src/components/mobile/accounts/AccountTransactions.tsx
index 3b6c6780312..797035f941c 100644
--- a/packages/desktop-client/src/components/mobile/accounts/AccountTransactions.tsx
+++ b/packages/desktop-client/src/components/mobile/accounts/AccountTransactions.tsx
@@ -267,8 +267,9 @@ function TransactionListWithPreviews({
   }, [accountId, dispatch]);
 
   useEffect(() => {
-    return listen('sync-event', ({ type, tables }) => {
-      if (type === 'applied') {
+    return listen('sync-event', event => {
+      if (event.type === 'applied') {
+        const tables = event.tables;
         if (
           tables.includes('transactions') ||
           tables.includes('category_mapping') ||
diff --git a/packages/desktop-client/src/components/mobile/budget/CategoryTransactions.tsx b/packages/desktop-client/src/components/mobile/budget/CategoryTransactions.tsx
index 4eee5f6e2cb..8a3eabb5891 100644
--- a/packages/desktop-client/src/components/mobile/budget/CategoryTransactions.tsx
+++ b/packages/desktop-client/src/components/mobile/budget/CategoryTransactions.tsx
@@ -62,8 +62,9 @@ export function CategoryTransactions({
   const dateFormat = useDateFormat() || 'MM/dd/yyyy';
 
   useEffect(() => {
-    return listen('sync-event', ({ type, tables }) => {
-      if (type === 'applied') {
+    return listen('sync-event', event => {
+      if (event.type === 'applied') {
+        const tables = event.tables;
         if (
           tables.includes('transactions') ||
           tables.includes('category_mapping') ||
diff --git a/packages/desktop-client/src/components/mobile/budget/index.tsx b/packages/desktop-client/src/components/mobile/budget/index.tsx
index 20d233753e9..d2cc1645d65 100644
--- a/packages/desktop-client/src/components/mobile/budget/index.tsx
+++ b/packages/desktop-client/src/components/mobile/budget/index.tsx
@@ -69,15 +69,17 @@ export function Budget() {
 
     init();
 
-    const unlisten = listen('sync-event', ({ type, tables }) => {
-      if (
-        type === 'success' &&
-        (tables.includes('categories') ||
+    const unlisten = listen('sync-event', event => {
+      if (event.type === 'success') {
+        const tables = event.tables;
+        if (
+          tables.includes('categories') ||
           tables.includes('category_mapping') ||
-          tables.includes('category_groups'))
-      ) {
-        // TODO: is this loading every time?
-        dispatch(getCategories());
+          tables.includes('category_groups')
+        ) {
+          // TODO: is this loading every time?
+          dispatch(getCategories());
+        }
       }
     });
 
diff --git a/packages/desktop-client/src/components/payees/ManagePayeesWithData.tsx b/packages/desktop-client/src/components/payees/ManagePayeesWithData.tsx
index 064023fbad5..dedabaeb127 100644
--- a/packages/desktop-client/src/components/payees/ManagePayeesWithData.tsx
+++ b/packages/desktop-client/src/components/payees/ManagePayeesWithData.tsx
@@ -49,9 +49,9 @@ export function ManagePayeesWithData({
     }
     loadData();
 
-    const unlisten = listen('sync-event', async ({ type, tables }) => {
-      if (type === 'applied') {
-        if (tables.includes('rules')) {
+    const unlisten = listen('sync-event', async event => {
+      if (event.type === 'applied') {
+        if (event.tables.includes('rules')) {
           await refetchRuleCounts();
         }
       }
diff --git a/packages/desktop-client/src/global-events.ts b/packages/desktop-client/src/global-events.ts
index 619f673b259..129073274e5 100644
--- a/packages/desktop-client/src/global-events.ts
+++ b/packages/desktop-client/src/global-events.ts
@@ -21,19 +21,20 @@ export function handleGlobalEvents(actions: BoundActions, store: Store<State>) {
     });
   });
 
-  listen('schedules-offline', ({ payees }) => {
-    actions.pushModal('schedule-posts-offline-notification', { payees });
+  listen('schedules-offline', () => {
+    actions.pushModal('schedule-posts-offline-notification');
   });
 
   // This is experimental: we sync data locally automatically when
   // data changes from the backend
-  listen('sync-event', async ({ type, tables }) => {
+  listen('sync-event', async event => {
     // We don't need to query anything until the file is loaded, and
     // sync events might come in if the file is being synced before
     // being loaded (happens when downloading)
     const prefs = store.getState().prefs.local;
     if (prefs && prefs.id) {
-      if (type === 'applied') {
+      if (event.type === 'applied') {
+        const tables = event.tables;
         if (tables.includes('payees') || tables.includes('payee_mapping')) {
           actions.getPayees();
         }
diff --git a/packages/loot-core/src/client/query-helpers.ts b/packages/loot-core/src/client/query-helpers.ts
index c1e63e156c4..ee5f604ff8d 100644
--- a/packages/loot-core/src/client/query-helpers.ts
+++ b/packages/loot-core/src/client/query-helpers.ts
@@ -62,7 +62,7 @@ export class LiveQuery<TResponse = unknown> {
   private _data: Data<TResponse>;
   private _dependencies: Set<string>;
   private _listeners: Array<Listener<TResponse>>;
-  private _supportedSyncTypes: Set<string>;
+  private _supportedSyncTypes: Set<'applied' | 'success'>;
   private _query: Query;
   private _onError: (error: Error) => void;
 
@@ -107,8 +107,8 @@ export class LiveQuery<TResponse = unknown> {
 
     // TODO: error types?
     this._supportedSyncTypes = options.onlySync
-      ? new Set<string>(['success'])
-      : new Set<string>(['applied', 'success']);
+      ? new Set(['success'])
+      : new Set(['applied', 'success']);
 
     if (onData) {
       this.addListener(onData);
@@ -162,15 +162,18 @@ export class LiveQuery<TResponse = unknown> {
 
   protected subscribe = () => {
     if (this._unsubscribeSyncEvent == null) {
-      this._unsubscribeSyncEvent = listen('sync-event', ({ type, tables }) => {
+      this._unsubscribeSyncEvent = listen('sync-event', event => {
         // If the user is doing optimistic updates, they don't want to
         // always refetch whenever something changes because it would
         // refetch all data after they've already updated the UI. This
         // voids the perf benefits of optimistic updates. Allow querys
         // to only react to remote syncs. By default, queries will
         // always update to all changes.
-        if (this._supportedSyncTypes.has(type)) {
-          this.onUpdate(tables);
+        if (
+          (event.type === 'applied' || event.type === 'success') &&
+          this._supportedSyncTypes.has(event.type)
+        ) {
+          this.onUpdate(event.tables);
         }
       });
     }
diff --git a/packages/loot-core/src/client/shared-listeners.ts b/packages/loot-core/src/client/shared-listeners.ts
index eb970fe6026..581faca40f1 100644
--- a/packages/loot-core/src/client/shared-listeners.ts
+++ b/packages/loot-core/src/client/shared-listeners.ts
@@ -8,16 +8,14 @@ import type { Notification } from './state-types/notifications';
 export function listenForSyncEvent(actions, store) {
   let attemptedSyncRepair = false;
 
-  listen('sync-event', info => {
-    const { type, subtype, meta, tables } = info;
-
+  listen('sync-event', event => {
     const prefs = store.getState().prefs.local;
     if (!prefs || !prefs.id) {
       // Do nothing if no budget is loaded
       return;
     }
 
-    if (type === 'success') {
+    if (event.type === 'success') {
       if (attemptedSyncRepair) {
         attemptedSyncRepair = false;
 
@@ -28,6 +26,8 @@ export function listenForSyncEvent(actions, store) {
         });
       }
 
+      const tables = event.tables;
+
       if (tables.includes('prefs')) {
         actions.loadPrefs();
       }
@@ -47,7 +47,7 @@ export function listenForSyncEvent(actions, store) {
       if (tables.includes('accounts')) {
         actions.getAccounts();
       }
-    } else if (type === 'error') {
+    } else if (event.type === 'error') {
       let notif: Notification | null = null;
       const learnMore = t(
         '[Learn more](https://actualbudget.org/docs/getting-started/sync/#debugging-sync-issues)',
@@ -55,7 +55,7 @@ export function listenForSyncEvent(actions, store) {
       const githubIssueLink =
         'https://github.com/actualbudget/actual/issues/new?assignees=&labels=bug&template=bug-report.yml&title=%5BBug%5D%3A+';
 
-      switch (subtype) {
+      switch (event.subtype) {
         case 'out-of-sync':
           if (attemptedSyncRepair) {
             notif = {
@@ -217,7 +217,7 @@ export function listenForSyncEvent(actions, store) {
           break;
         case 'encrypt-failure':
         case 'decrypt-failure':
-          if (meta.isMissingKey) {
+          if (event.meta.isMissingKey) {
             notif = {
               title: t('Missing encryption key'),
               message: t(
@@ -254,7 +254,7 @@ export function listenForSyncEvent(actions, store) {
           }
           break;
         case 'invalid-schema':
-          console.trace('invalid-schema', meta);
+          console.trace('invalid-schema', event.meta);
           notif = {
             title: t('Update required'),
             message: t(
@@ -265,7 +265,7 @@ export function listenForSyncEvent(actions, store) {
           };
           break;
         case 'apply-failure':
-          console.trace('apply-failure', meta);
+          console.trace('apply-failure', event.meta);
           notif = {
             message: t(
               'We couldn’t apply that change to the database. Please report this as a bug by [opening a Github issue]({{githubIssueLink}}).',
@@ -289,7 +289,7 @@ export function listenForSyncEvent(actions, store) {
           };
           break;
         default:
-          console.trace('unknown error', info);
+          console.trace('unknown error', event);
           notif = {
             message: t(
               'We had problems syncing your changes. Please report this as a bug by [opening a Github issue]({{githubIssueLink}}).',
diff --git a/packages/loot-core/src/platform/server/connection/index.d.ts b/packages/loot-core/src/platform/server/connection/index.d.ts
index 419e9726264..c0bbfbe5f7c 100644
--- a/packages/loot-core/src/platform/server/connection/index.d.ts
+++ b/packages/loot-core/src/platform/server/connection/index.d.ts
@@ -9,7 +9,7 @@ export type Init = typeof init;
 
 export function send<K extends keyof ServerEvents>(
   type: K,
-  args?: ServerEvents[k],
+  args?: ServerEvents[K],
 ): void;
 export type Send = typeof send;
 
diff --git a/packages/loot-core/src/server/accounts/transactions.ts b/packages/loot-core/src/server/accounts/transactions.ts
index c91d0d95f0a..cacc9dbd4b3 100644
--- a/packages/loot-core/src/server/accounts/transactions.ts
+++ b/packages/loot-core/src/server/accounts/transactions.ts
@@ -1,7 +1,7 @@
 // @ts-strict-ignore
 import * as connection from '../../platform/server/connection';
 import { Diff } from '../../shared/util';
-import { TransactionEntity } from '../../types/models';
+import { PayeeEntity, TransactionEntity } from '../../types/models';
 import * as db from '../db';
 import { incrFetch, whereIn } from '../db/util';
 import { batchMessages } from '../sync';
@@ -55,7 +55,7 @@ export async function batchUpdateTransactions({
     ? await idsWithChildren(deleted.map(d => d.id))
     : [];
 
-  const oldPayees = new Set();
+  const oldPayees = new Set<PayeeEntity['id']>();
   const accounts = await db.all('SELECT * FROM accounts WHERE tombstone = 0');
 
   // We need to get all the payees of updated transactions _before_
diff --git a/packages/loot-core/src/server/app.ts b/packages/loot-core/src/server/app.ts
index fbb04a9110f..a8005a25fb5 100644
--- a/packages/loot-core/src/server/app.ts
+++ b/packages/loot-core/src/server/app.ts
@@ -1,15 +1,21 @@
 // @ts-strict-ignore
-import mitt from 'mitt';
+import mitt, { type Emitter } from 'mitt';
 
 import { captureException } from '../platform/exceptions';
+import { ServerEvents } from '../types/server-events';
 
 // This is a simple helper abstraction for defining methods exposed to
 // the client. It doesn't do much, but checks for naming conflicts and
 // makes it cleaner to combine methods. We call a group of related
 // methods an "app".
 
+type Events = {
+  sync: ServerEvents['sync-event'];
+  'load-budget': { id: string };
+};
+
 class App<Handlers> {
-  events;
+  events: Emitter<Events>;
   handlers: Handlers;
   services;
   unlistenServices;
diff --git a/packages/loot-core/src/server/main-app.ts b/packages/loot-core/src/server/main-app.ts
index 65c194a8220..2cde45a2334 100644
--- a/packages/loot-core/src/server/main-app.ts
+++ b/packages/loot-core/src/server/main-app.ts
@@ -6,6 +6,6 @@ import { createApp } from './app';
 // Main app
 export const app = createApp<Handlers>();
 
-app.events.on('sync', info => {
-  connection.send('sync-event', info);
+app.events.on('sync', event => {
+  connection.send('sync-event', event);
 });
diff --git a/packages/loot-core/src/server/schedules/app.ts b/packages/loot-core/src/server/schedules/app.ts
index 67f31d367cf..a1ee93fbdc9 100644
--- a/packages/loot-core/src/server/schedules/app.ts
+++ b/packages/loot-core/src/server/schedules/app.ts
@@ -533,7 +533,7 @@ async function advanceSchedulesService(syncSuccess) {
   }
 
   if (failedToPost.length > 0) {
-    connection.send('schedules-offline', { payees: failedToPost });
+    connection.send('schedules-offline');
   } else if (didPost) {
     // This forces a full refresh of transactions because it
     // simulates them coming in from a full sync. This not a
@@ -542,7 +542,7 @@ async function advanceSchedulesService(syncSuccess) {
     connection.send('sync-event', {
       type: 'success',
       tables: ['transactions'],
-      syncDisabled: 'false',
+      syncDisabled: false,
     });
   }
 }
diff --git a/packages/loot-core/src/types/server-events.d.ts b/packages/loot-core/src/types/server-events.d.ts
index cd0dabf8514..15a2bdbcdd5 100644
--- a/packages/loot-core/src/types/server-events.d.ts
+++ b/packages/loot-core/src/types/server-events.d.ts
@@ -1,23 +1,86 @@
 import { type Backup } from '../server/backups';
 import { type UndoState } from '../server/undo';
 
+type SyncSubtype =
+  | 'out-of-sync'
+  | 'apply-failure'
+  | 'decrypt-failure'
+  | 'encrypt-failure'
+  | 'invalid-schema'
+  | 'network'
+  | 'file-old-version'
+  | 'file-key-mismatch'
+  | 'file-not-found'
+  | 'file-needs-upload'
+  | 'file-has-reset'
+  | 'file-has-new-key'
+  | 'token-expired'
+  | string;
+
+type SyncEvent = {
+  meta?: Record<string, unknown>;
+} & (
+  | {
+      type: 'applied';
+      tables: string[];
+      data?: Map<string, unknown>;
+      prevData?: Map<string, unknown>;
+    }
+  | {
+      type: 'success';
+      tables: string[];
+      syncDisabled?: boolean;
+    }
+  | {
+      type: 'error';
+      subtype?: SyncSubtype;
+    }
+  | {
+      type: 'start';
+    }
+  | {
+      type: 'unauthorized';
+    }
+);
+
+type BackupUpdatedEvent = Backup[];
+
+type CellsChangedEvent = Array<{
+  name: string;
+  value: string | number | boolean;
+}>;
+
+type FallbackWriteErrorEvent = undefined;
+type FinishImportEvent = undefined;
+type FinishLoadEvent = undefined;
+
+type OrphanedPayeesEvent = {
+  orphanedIds: string[];
+  updatedPayeeIds: string[];
+};
+
+type PrefsUpdatedEvent = undefined;
+type SchedulesOfflineEvent = undefined;
+type ServerErrorEvent = undefined;
+type ShowBudgetsEvent = undefined;
+type StartImportEvent = { budgetName: string };
+type StartLoadEvent = undefined;
+type ApiFetchRedirectedEvent = undefined;
+
 export interface ServerEvents {
-  'backups-updated': Backup[];
-  'cells-changed': Array<{ name }>;
-  'fallback-write-error': unknown;
-  'finish-import': unknown;
-  'finish-load': unknown;
-  'orphaned-payees': {
-    orphanedIds: string[];
-    updatedPayeeIds: string[];
-  };
-  'prefs-updated': unknown;
-  'schedules-offline': { payees: unknown[] };
-  'server-error': unknown;
-  'show-budgets': unknown;
-  'start-import': unknown;
-  'start-load': unknown;
-  'sync-event': { type; subtype; meta; tables; syncDisabled };
+  'backups-updated': BackupUpdatedEvent;
+  'cells-changed': CellsChangedEvent;
+  'fallback-write-error': FallbackWriteErrorEvent;
+  'finish-import': FinishImportEvent;
+  'finish-load': FinishLoadEvent;
+  'orphaned-payees': OrphanedPayeesEvent;
+  'prefs-updated': PrefsUpdatedEvent;
+  'schedules-offline': SchedulesOfflineEvent;
+  'server-error': ServerErrorEvent;
+  'show-budgets': ShowBudgetsEvent;
+  'start-import': StartImportEvent;
+  'start-load': StartLoadEvent;
+  'sync-event': SyncEvent;
   'undo-event': UndoState;
-  'api-fetch-redirected': unknown;
+  'api-fetch-redirected': ApiFetchRedirectedEvent;
 }