diff --git a/src/services/google-drive-session.js b/src/services/google-drive-session.js
index 0252349..8aa7ba6 100644
--- a/src/services/google-drive-session.js
+++ b/src/services/google-drive-session.js
@@ -43,12 +43,27 @@ const GoogleDriveSession = (() => {
       if (pickReject) { pickReject(Object.assign(new Error('cancelled'), { code: 'cancelled' })); pickReject = null; }
       if (pending) { pending.reject(Object.assign(new Error('cancelled'), { code: 'cancelled' })); pending = null; }
     }
+    // Picker is an optional UI, not a dependency of the drive.file API path.
+    // Preserve the synchronous user gesture when opening an already loaded Picker.
+    let pickerReady = false, pickerLoading = null;
+    function preparePicker() {
+      if (pickerReady) return Promise.resolve();
+      if (!pickerLoading) {
+        pickerLoading = (async () => {
+          if (!host.gapi?.load) await script('https://apis.google.com/js/api.js');
+          await new Promise((resolve, reject) => host.gapi.load('picker', { callback: resolve, onerror: () => reject(Object.assign(new Error('network'), { code: 'network' })), timeout: 20000, ontimeout: () => reject(Object.assign(new Error('network'), { code: 'network' })) }));
+          if (!host.google?.picker?.PickerBuilder) return fail('network');
+          pickerReady = true;
+        })().finally(() => { pickerLoading = null; });
+      }
+      return pickerLoading;
+    }
     async function prepare() {
       config(cfg, host.location.origin);
       if (!host.google?.accounts?.oauth2) await script('https://accounts.google.com/gsi/client');
-      if (!host.gapi?.load) await script('https://apis.google.com/js/api.js');
-      await new Promise((resolve, reject) => host.gapi.load('picker', { callback: resolve, onerror: () => reject(new Error('network')), timeout: 20000, ontimeout: () => reject(new Error('network')) }));
       prepared = true;
+      // Never make an optional Picker outage block OAuth or dedicated-folder API.
+      void preparePicker().catch(() => {});
     }
     // Chaque demande a son propre callback/epoch : une réponse tardive de la
     // fenêtre de l'ancien compte ne peut pas authentifier la nouvelle demande.
@@ -116,6 +131,12 @@ const GoogleDriveSession = (() => {
       if (pickReject) return Promise.reject(Object.assign(new Error('busy'), { code: 'busy' }));
       if (!token || Date.now() >= until) { disconnect(); return Promise.reject(Object.assign(new Error('auth'), { code: 'auth' })); }
       try { fileAccess(); } catch (e) { return Promise.reject(e); }
+      if (!pickerReady) {
+        // This button may be pressed before Picker is ready or after its load failed.
+        // No popup is attempted outside the next explicit user gesture.
+        void preparePicker().catch(() => {});
+        return Promise.reject(Object.assign(new Error('network'), { code: 'network' }));
+      }
       const lease = epoch;
       return new Promise((resolve, reject) => {
         pickReject = reject;
diff --git a/src/services/opaque-drive.ts b/src/services/opaque-drive.ts
index d17d82c..254f04f 100644
--- a/src/services/opaque-drive.ts
+++ b/src/services/opaque-drive.ts
@@ -159,7 +159,7 @@ export class OpaqueDrive {
       if (next) params.set('pageToken', next);
       const page = await this.json(await this.request(API + '/files?' + params, { signal }, epoch), signal);
       this.check(epoch, signal);
-      if (page.incompleteSearch !== false || !Array.isArray(page.files) || page.files.length > 100) return fail('incomplete');
+      if ((page.incompleteSearch !== undefined && page.incompleteSearch !== false) || !Array.isArray(page.files) || page.files.length > 100) return fail('incomplete');
       for (const f of page.files) {
         if (!object(f) || typeof f.id !== 'string' || typeof f.name !== 'string' || !f.name || f.name.length > 1024 ||
           typeof f.createdTime !== 'string' || f.createdTime.length > 40 || !Number.isFinite(Date.parse(f.createdTime)) ||
@@ -211,7 +211,7 @@ export class OpaqueDrive {
         pageSize: '1000', fields: 'nextPageToken,incompleteSearch,files(id,size,trashed,parents,appProperties)' });
       if (next) params.set('pageToken', next);
       const page = await this.json(await this.request(API + '/files?' + params, { signal }, epoch), signal);
-      if (page.incompleteSearch !== false || !Array.isArray(page.files)) return fail('incomplete');
+      if ((page.incompleteSearch !== undefined && page.incompleteSearch !== false) || !Array.isArray(page.files)) return fail('incomplete');
       for (const f of page.files) {
         if (!object(f) || typeof f.id !== 'string' || f.trashed === true || !Array.isArray(f.parents) || !f.parents.includes(folder) ||
           !object(f.appProperties) || f.appProperties.cv_contract !== 'rc-key-a1' || !hash(f.appProperties.cv_file) ||
@@ -267,7 +267,7 @@ export class OpaqueDrive {
         pageSize: '1000', fields: 'nextPageToken,incompleteSearch,files(id,size,trashed,parents,appProperties)' });
       if (next) p.set('pageToken', next);
       const page = await this.json(await this.request(API + '/files?' + p, { signal }, epoch), signal);
-      if (page.incompleteSearch !== false || !Array.isArray(page.files)) return fail('incomplete');
+      if ((page.incompleteSearch !== undefined && page.incompleteSearch !== false) || !Array.isArray(page.files)) return fail('incomplete');
       for (const raw of page.files) {
         if (!object(raw) || !Array.isArray(raw.parents) || !raw.parents.includes(folder)) return fail('conflict');
         const v = this.version(raw), old = versions.get(v.fileId);
diff --git a/tests/unit/dedicated-folders.test.ts b/tests/unit/dedicated-folders.test.ts
index d8bbc48..51678ca 100644
--- a/tests/unit/dedicated-folders.test.ts
+++ b/tests/unit/dedicated-folders.test.ts
@@ -44,11 +44,18 @@ describe('dossiers dédiés déjà autorisés, transport simulé', () => {
     await expect(p.folders()).rejects.toMatchObject({ code: 'conflict' });
   });
   it.each([
-    { incompleteSearch: true, files: [] }, { files: [] }, { incompleteSearch: false, files: null },
+    { incompleteSearch: true, files: [] }, { incompleteSearch: null, files: [] }, { incompleteSearch: false, files: null },
     { incompleteSearch: false, files: Array.from({ length: 101 }, (_, n) => entry('id-' + n)) },
   ])('n’annonce pas de liste partielle comme complète', async response => {
     await expect(client(vi.fn(async () => json(response))).folders()).rejects.toMatchObject({ code: 'incomplete' });
   });
+  it('accepte la valeur par défaut omise de incompleteSearch mais conserve les validations des dossiers', async () => {
+    const network = vi.fn<typeof fetch>(async () => json({ files: [entry()] }));
+    expect(await client(network).folders()).toEqual([
+      { id: 'dedicated-A', name: 'Dossier fictif', createdTime: '2026-10-28T00:00:00.000Z' },
+    ]);
+    expect(network).toHaveBeenCalledTimes(1);
+  });
   it('refuse doublon et boucle de pagination', async () => {
     for (const duplicate of [true, false]) {
       let n = 0;
diff --git a/tests/unit/drive-boundary.test.ts b/tests/unit/drive-boundary.test.ts
index 361c92c..396bade 100644
--- a/tests/unit/drive-boundary.test.ts
+++ b/tests/unit/drive-boundary.test.ts
@@ -125,3 +125,35 @@ describe('référence du téléchargement figée avant le contrôle du dossier',
     expect(fetcher.mock.calls.some(c=>String(c[0]).includes('/other-archive'))).toBe(false);
   });
 });
+
+
+describe('Picker facultatif : API Drive utilisable sans bibliothèque Picker', () => {
+  it('autorise OAuth et sélection dédiée quand le chargement Picker échoue', async () => {
+    const clients: any[] = [];
+    const host = {
+      location: { origin }, crypto: webcrypto,
+      gapi: { load: (_name: string, callbacks: any) => callbacks.onerror() },
+      google: { accounts: { oauth2: {
+        initTokenClient: (options: any) => { clients.push(options); return { requestAccessToken: () => {} }; },
+        hasGrantedAllScopes: () => true,
+      } } },
+    };
+    const folder = { id: 'folder-fixture', name: 'Dossier fictif', createdTime: '2026-10-28T00:00:00Z' };
+    const provider = {
+      connect: vi.fn(), disconnect: vi.fn(), identity: vi.fn(async () => ({ id: 'fixture-account', label: 'fixture@example.invalid' })),
+      account: vi.fn(async () => 'fixture-account'), folders: vi.fn(async () => [folder]),
+      folder: vi.fn(async () => {}),
+    };
+    const session = (GoogleDriveSession.create as any)(config, provider, host);
+    await expect(session.prepare()).resolves.toBeUndefined();
+    const pending = session.connect();
+    await clients.at(-1).callback({ access_token: 'fixture-token', scope, expires_in: 3600 });
+    await pending;
+    session.confirmAccount('fixture-account');
+    expect(await session.listDedicatedFolders()).toEqual([folder]);
+    expect((await session.chooseDedicatedFolder('folder-fixture')).folder).toBe('folder-fixture');
+    await expect(session.chooseFolder()).rejects.toMatchObject({ code: 'network' });
+    expect(provider.folder).toHaveBeenCalledWith('folder-fixture');
+    session.disconnect();
+  });
+});