diff --git a/resources/js/lib/sync-manager.test.ts b/resources/js/lib/sync-manager.test.ts
new file mode 100644
index 00000000..a4405124
--- /dev/null
+++ b/resources/js/lib/sync-manager.test.ts
@@ -0,0 +1,103 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { TransactionSyncManager } from './sync-manager';
+
+const dbMock = vi.hoisted(() => ({
+    transactions: {
+        toArray: vi.fn(),
+        get: vi.fn(),
+        clear: vi.fn(),
+        bulkPut: vi.fn(),
+        where: vi.fn(() => ({
+            equals: () => ({ toArray: vi.fn(async () => []) }),
+        })),
+    },
+    sync_metadata: {
+        get: vi.fn(),
+        put: vi.fn(),
+        delete: vi.fn(),
+    },
+}));
+
+// Keep the real isIndexedDbAvailable + withDb (they read globalThis live); only
+// swap the Dexie-backed `db` for spies so no real IndexedDB is needed.
+vi.mock('./dexie-db', async (importOriginal) => {
+    const actual = await importOriginal<typeof import('./dexie-db')>();
+    return { ...actual, db: dbMock };
+});
+
+vi.mock('axios', () => ({ default: { get: vi.fn() } }));
+
+function makeManager(): TransactionSyncManager {
+    return new TransactionSyncManager({ endpoint: '/api/sync/transactions' });
+}
+
+describe('TransactionSyncManager without IndexedDB', () => {
+    beforeEach(() => {
+        vi.clearAllMocks();
+        vi.stubGlobal('indexedDB', undefined);
+    });
+
+    afterEach(() => {
+        vi.unstubAllGlobals();
+    });
+
+    it('clearAll resolves without touching the database or throwing', async () => {
+        await expect(makeManager().clearAll()).resolves.toBeUndefined();
+        expect(dbMock.transactions.clear).not.toHaveBeenCalled();
+        expect(dbMock.sync_metadata.delete).not.toHaveBeenCalled();
+    });
+
+    it('sync returns a skipped result without a server round-trip', async () => {
+        const axios = (await import('axios')).default;
+
+        const result = await makeManager().sync();
+
+        expect(result).toEqual({
+            success: true,
+            inserted: 0,
+            updated: 0,
+            errors: [],
+        });
+        expect(axios.get).not.toHaveBeenCalled();
+    });
+
+    it('reads degrade to empty values instead of throwing', async () => {
+        const manager = makeManager();
+
+        await expect(manager.getAll()).resolves.toEqual([]);
+        await expect(manager.getById('id-1')).resolves.toBeNull();
+        await expect(manager.getByAccountId('acc-1')).resolves.toEqual([]);
+        await expect(manager.getLastSyncTime()).resolves.toBeNull();
+        await expect(manager.setLastSyncTime('now')).resolves.toBeUndefined();
+
+        expect(dbMock.transactions.toArray).not.toHaveBeenCalled();
+        expect(dbMock.sync_metadata.get).not.toHaveBeenCalled();
+    });
+});
+
+describe('TransactionSyncManager with IndexedDB', () => {
+    beforeEach(() => {
+        vi.clearAllMocks();
+        vi.stubGlobal('indexedDB', {} as IDBFactory);
+    });
+
+    afterEach(() => {
+        vi.unstubAllGlobals();
+    });
+
+    it('clearAll clears the transactions and sync metadata', async () => {
+        await makeManager().clearAll();
+
+        expect(dbMock.transactions.clear).toHaveBeenCalledTimes(1);
+        expect(dbMock.sync_metadata.delete).toHaveBeenCalledWith(
+            'last_sync_transactions',
+        );
+    });
+
+    it('getAll passes through the stored transactions', async () => {
+        const stored = [{ id: 't1' }];
+        dbMock.transactions.toArray.mockResolvedValueOnce(stored);
+
+        await expect(makeManager().getAll()).resolves.toBe(stored);
+    });
+});
diff --git a/resources/js/lib/sync-manager.ts b/resources/js/lib/sync-manager.ts
index 15eb7d97..b6a45cec 100644
--- a/resources/js/lib/sync-manager.ts
+++ b/resources/js/lib/sync-manager.ts
@@ -2,7 +2,7 @@ import type { Transaction } from '@/types/transaction';
 import type { UUID } from '@/types/uuid';
 import { __ } from '@/utils/i18n';
 import axios from 'axios';
-import { db } from './dexie-db';
+import { db, isIndexedDbAvailable, withDb } from './dexie-db';
 
 export interface SyncResult {
     success: boolean;
@@ -29,18 +29,29 @@ export class TransactionSyncManager {
     }
 
     async getLastSyncTime(): Promise<string | null> {
-        const metadata = await db.sync_metadata.get(LAST_SYNC_KEY);
-        return metadata?.value || null;
+        return withDb(async () => {
+            const metadata = await db.sync_metadata.get(LAST_SYNC_KEY);
+            return metadata?.value || null;
+        }, null);
     }
 
     async setLastSyncTime(timestamp: string): Promise<void> {
-        await db.sync_metadata.put({
-            key: LAST_SYNC_KEY,
-            value: timestamp,
-        });
+        await withDb<void>(async () => {
+            await db.sync_metadata.put({
+                key: LAST_SYNC_KEY,
+                value: timestamp,
+            });
+        }, undefined);
     }
 
     async sync(): Promise<SyncResult> {
+        // No offline store to sync into (see PHP-LARAVEL-43). Skip cleanly —
+        // empty errors so callers do not treat it as a failure — and avoid the
+        // pointless server round-trip that would only populate a missing cache.
+        if (!isIndexedDbAvailable()) {
+            return { success: true, inserted: 0, updated: 0, errors: [] };
+        }
+
         if (this.syncInProgress) {
             return {
                 success: false,
@@ -129,18 +140,22 @@ export class TransactionSyncManager {
     }
 
     async getAll(): Promise<Transaction[]> {
-        return await db.transactions.toArray();
+        return withDb<Transaction[]>(() => db.transactions.toArray(), []);
     }
 
     async getById(id: UUID): Promise<Transaction | null> {
-        return (await db.transactions.get(id)) || null;
+        return withDb<Transaction | null>(
+            async () => (await db.transactions.get(id)) || null,
+            null,
+        );
     }
 
     async getByAccountId(accountId: UUID): Promise<Transaction[]> {
-        return await db.transactions
-            .where('account_id')
-            .equals(accountId)
-            .toArray();
+        return withDb<Transaction[]>(
+            () =>
+                db.transactions.where('account_id').equals(accountId).toArray(),
+            [],
+        );
     }
 
     isSyncing(): boolean {
@@ -148,7 +163,9 @@ export class TransactionSyncManager {
     }
 
     async clearAll(): Promise<void> {
-        await db.transactions.clear();
-        await db.sync_metadata.delete(LAST_SYNC_KEY);
+        await withDb<void>(async () => {
+            await db.transactions.clear();
+            await db.sync_metadata.delete(LAST_SYNC_KEY);
+        }, undefined);
     }
 }