diff --git a/web/vitest.setup.ts b/web/vitest.setup.ts
index d8082bca47..a7a48a1cc2 100644
--- a/web/vitest.setup.ts
+++ b/web/vitest.setup.ts
@@ -1,6 +1,8 @@
 import { ref } from 'vue';
 import { createPinia, setActivePinia } from 'pinia';
+import { provideApolloClient } from '@vue/apollo-composable';
 
+import { ApolloClient, ApolloLink, InMemoryCache, Observable } from '@apollo/client/core';
 import { beforeEach, vi } from 'vitest';
 
 vi.mock('@vue/apollo-composable', async () => {
@@ -20,6 +22,20 @@ vi.mock('@vue/apollo-composable', async () => {
   };
 });
 
+// Provide a no-op default Apollo client for the whole test run. Even with
+// useQuery mocked above, some components and generated composables resolve the
+// default client asynchronously (e.g. during teardown, after the test that
+// triggered them has finished). Without a provided client, @vue/apollo-composable
+// throws "Apollo client with id default not found" as an unhandled rejection,
+// polluting unrelated suites. A terminating link that emits an empty result keeps
+// any stray operation quiet without making network calls.
+provideApolloClient(
+  new ApolloClient({
+    cache: new InMemoryCache(),
+    link: new ApolloLink(() => Observable.of({ data: {} })),
+  })
+);
+
 // Mock WebSocket for test environment
 if (!global.WebSocket) {
   const mockWebSocket = vi.fn().mockImplementation(() => ({