diff --git a/src/app/marketplace/page.tsx b/src/app/marketplace/page.tsx
index f606f80..a08d7e8 100644
--- a/src/app/marketplace/page.tsx
+++ b/src/app/marketplace/page.tsx
@@ -3,7 +3,8 @@
 import { useEffect, useState } from 'react';
 import { useRouter } from 'next/navigation';
 import { useAuth } from '@/lib/auth-context';
-import { apiFetch, ApiError } from '@/lib/api';
+import { apiFetch } from '@/lib/api';
+import { actionErrorMessage } from '@/lib/action-error';
 import { signAndSubmit } from '@/lib/onchain';
 import type { ResaleListing } from '@/lib/types';
 import { FormError } from '@/components/form-error';
@@ -52,7 +53,7 @@ export default function MarketplacePage() {
       setNotice('Ticket purchased — find it under My tickets.');
       setListings((prev) => prev.filter((l) => l.ticketId !== ticketId));
     } catch (err) {
-      setError(err instanceof ApiError ? err.message : 'Could not complete the purchase.');
+      setError(actionErrorMessage(err, 'Could not complete the purchase.'));
     } finally {
       setBuyingTicketId(null);
     }
diff --git a/src/lib/action-error.test.ts b/src/lib/action-error.test.ts
new file mode 100644
index 0000000..3ab7b45
--- /dev/null
+++ b/src/lib/action-error.test.ts
@@ -0,0 +1,35 @@
+import { describe, expect, it, vi } from 'vitest';
+
+vi.mock('@stellar/freighter-api', () => ({
+  isConnected: vi.fn(),
+  requestAccess: vi.fn(),
+  getAddress: vi.fn(),
+  signTransaction: vi.fn(),
+}));
+
+import { actionErrorMessage } from './action-error';
+import { ApiError } from './api';
+import { WalletError } from './wallet';
+
+describe('actionErrorMessage', () => {
+  it('surfaces ApiError messages', () => {
+    expect(actionErrorMessage(new ApiError('Listing sold out', 409), 'fallback')).toBe(
+      'Listing sold out',
+    );
+  });
+
+  it('surfaces WalletError messages', () => {
+    expect(
+      actionErrorMessage(new WalletError('User declined access'), 'fallback'),
+    ).toBe('User declined access');
+  });
+
+  it('falls back for unknown errors', () => {
+    expect(actionErrorMessage(new Error('boom'), 'fallback')).toBe('fallback');
+    expect(actionErrorMessage('nope', 'fallback')).toBe('fallback');
+  });
+
+  it('falls back when a known error has an empty message', () => {
+    expect(actionErrorMessage(new WalletError(''), 'fallback')).toBe('fallback');
+  });
+});
diff --git a/src/lib/action-error.ts b/src/lib/action-error.ts
new file mode 100644
index 0000000..4faf476
--- /dev/null
+++ b/src/lib/action-error.ts
@@ -0,0 +1,14 @@
+import { ApiError } from './api';
+import { WalletError } from './wallet';
+
+/**
+ * User-facing message for a failed wallet-backed action. API and wallet errors
+ * (rejected Freighter popup, locked extension, wrong network) carry an
+ * actionable message; anything else falls back to `fallback`.
+ */
+export function actionErrorMessage(err: unknown, fallback: string): string {
+  if ((err instanceof ApiError || err instanceof WalletError) && err.message) {
+    return err.message;
+  }
+  return fallback;
+}