fix: Google Drive picks fail with 404 — call setAppId on Picker

web/src/pages/UploadPage/components/UploadForm/hooks/useGooglePicker.test.ts

@@ -25,6 +25,7 @@ function buildBuilder(
 ) {
   const built = { setVisible: vi.fn() };
   const builder: Record<string, unknown> = {};
+  builder.setAppId = vi.fn().mockReturnValue(builder);
   builder.setOAuthToken = vi.fn().mockReturnValue(builder);
   builder.setDeveloperKey = vi.fn().mockReturnValue(builder);
   builder.addView = vi.fn().mockReturnValue(builder);
@@ -153,5 +154,16 @@ describe('useGooglePicker', () => {
         /access_denied/
       );
     });
+
+    it('calls setAppId with the project number derived from the client id', async () => {
+      process.env.REACT_APP_GOOGLE_CLIENT_ID =
+        '806855830059-abc123def.apps.googleusercontent.com';
+      const { builder } = stubGoogle((cb) => {
+        queueMicrotask(() => cb({ action: 'cancel' }));
+      });
+      const { result } = renderHook(() => useGooglePicker());
+      await result.current.openPicker();
+      expect(builder.setAppId).toHaveBeenCalledWith('806855830059');
+    });
   });
 });

web/src/pages/UploadPage/components/UploadForm/hooks/useGooglePicker.ts

@@ -47,7 +47,7 @@ interface PickerBuilder {
   setDeveloperKey: (key: string) => PickerBuilder;
   setCallback: (cb: (data: PickerCallbackData) => void) => PickerBuilder;
   addView: (view: unknown) => PickerBuilder;
-  setAppId?: (id: string) => PickerBuilder;
+  setAppId: (id: string) => PickerBuilder;
   build: () => { setVisible: (visible: boolean) => void };
 }
 
@@ -204,6 +204,8 @@ export function useGooglePicker() {
     }
     inFlightRef.current = true;
 
+    const projectNumber = id.split('-')[0];
+
     return Promise.all([loadPicker(), loadIdentityServices()])
       .then(
         ([picker, oauth2]) =>
@@ -223,6 +225,7 @@ export function useGooglePicker() {
                 const view = new picker.DocsView();
                 view.setIncludeFolders(false);
                 const built = new picker.PickerBuilder()
+                  .setAppId(projectNumber)
                   .setOAuthToken(resp.access_token)
                   .setDeveloperKey(key)
                   .addView(view)

web/src/pages/WhatsNewPage/changelog.ts

@@ -5,6 +5,7 @@ export interface ChangelogEntry {
 }
 
 export const changelog: ChangelogEntry[] = [
+  { type: 'fix', title: 'Upload form: Google Drive picks convert into decks instead of erroring', date: '2026-05-16' },
   { type: 'feature', title: 'Upload form: pick a file from Google Drive in one click', date: '2026-05-16' },
   { type: 'feature', title: 'From Google Drive section on Downloads — see the files you picked from Drive and open any of them with one click', date: '2026-05-16' },
   { type: 'style', title: 'Upload form has tabs — Your computer and Dropbox sit side by side at the top of the page', date: '2026-05-15' },