diff --git a/mobile/app/login.tsx b/mobile/app/login.tsx
index d3e358a..ba6f0f2 100644
--- a/mobile/app/login.tsx
+++ b/mobile/app/login.tsx
@@ -1,6 +1,16 @@
 import { useRouter } from 'expo-router';
 import { useState } from 'react';
-import { Alert, Pressable, StyleSheet, Text, TextInput, View } from 'react-native';
+import {
+  Alert,
+  KeyboardAvoidingView,
+  Platform,
+  Pressable,
+  ScrollView,
+  StyleSheet,
+  Text,
+  TextInput,
+  View,
+} from 'react-native';
 import { useAuth } from '../context/AuthContext';
 import { ApiError } from '../api/client';
 import i18n from '../i18n';
@@ -46,49 +56,61 @@ export default function Login() {
   };
 
   return (
-    <View style={styles.container}>
-      <Text style={styles.title}>{i18n.t('login_subtitle')}</Text>
-      <TextInput
-        style={styles.input}
-        placeholder={i18n.t('login_username')}
-        autoCapitalize="none"
-        autoCorrect={false}
-        value={username}
-        onChangeText={setUsername}
-      />
-      <TextInput
-        style={styles.input}
-        placeholder={i18n.t('login_password')}
-        secureTextEntry
-        value={password}
-        onChangeText={setPassword}
-      />
-      {error ? <Text style={styles.error}>{error}</Text> : null}
-      <Pressable
-        style={[styles.button, submitting && styles.buttonDisabled]}
-        onPress={handleSubmit}
-        disabled={submitting}
+    <KeyboardAvoidingView
+      style={styles.flex}
+      behavior={Platform.OS === 'ios' ? 'padding' : undefined}
+    >
+      <ScrollView
+        contentContainerStyle={styles.container}
+        keyboardShouldPersistTaps="handled"
+        keyboardDismissMode="on-drag"
       >
-        <Text style={styles.buttonText}>
-          {submitting ? i18n.t('login_submitting') : i18n.t('login_submit')}
-        </Text>
-      </Pressable>
-      <Pressable
-        style={styles.skipButton}
-        onPress={() => {
-          continueWithoutAccount();
-          router.replace('/');
-        }}
-      >
-        <Text style={styles.skipButtonText}>{i18n.t('login_skip')}</Text>
-      </Pressable>
-    </View>
+        <Text style={styles.title}>{i18n.t('login_subtitle')}</Text>
+        <TextInput
+          style={styles.input}
+          placeholder={i18n.t('login_username')}
+          autoCapitalize="none"
+          autoCorrect={false}
+          value={username}
+          onChangeText={setUsername}
+        />
+        <TextInput
+          style={styles.input}
+          placeholder={i18n.t('login_password')}
+          secureTextEntry
+          value={password}
+          onChangeText={setPassword}
+        />
+        {error ? <Text style={styles.error}>{error}</Text> : null}
+        <Pressable
+          style={[styles.button, submitting && styles.buttonDisabled]}
+          onPress={handleSubmit}
+          disabled={submitting}
+        >
+          <Text style={styles.buttonText}>
+            {submitting ? i18n.t('login_submitting') : i18n.t('login_submit')}
+          </Text>
+        </Pressable>
+        <Pressable
+          style={styles.skipButton}
+          onPress={() => {
+            continueWithoutAccount();
+            router.replace('/');
+          }}
+        >
+          <Text style={styles.skipButtonText}>{i18n.t('login_skip')}</Text>
+        </Pressable>
+      </ScrollView>
+    </KeyboardAvoidingView>
   );
 }
 
 const styles = StyleSheet.create({
-  container: {
+  flex: {
     flex: 1,
+  },
+  container: {
+    flexGrow: 1,
     backgroundColor: '#fff',
     padding: 24,
     justifyContent: 'center',
diff --git a/mobile/context/AuthContext.tsx b/mobile/context/AuthContext.tsx
index b9544dd..2673c11 100644
--- a/mobile/context/AuthContext.tsx
+++ b/mobile/context/AuthContext.tsx
@@ -60,10 +60,12 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     };
 
     bootstrap();
-    useSyncDevice();
+    // Boucle de sync en arrière-plan (décalée, annulée au unmount).
+    const stopSync = useSyncDevice();
 
     return () => {
       active = false;
+      stopSync();
     };
   }, []);
 
diff --git a/mobile/features/syncDevice.ts b/mobile/features/syncDevice.ts
index bf9ca0c..662bddc 100644
--- a/mobile/features/syncDevice.ts
+++ b/mobile/features/syncDevice.ts
@@ -1,6 +1,7 @@
-import { listDirectory, listFolders } from '../services/safDirectory';
+import { listDirectory, listFoldersChunked, yieldToMainThread } from '../services/safDirectory';
 import type { FileEntry } from '../services/safDirectory.types';
 import {
+  checkpointDatabase,
   getFiles,
   getFolder,
   getFolders,
@@ -47,9 +48,9 @@ export async function syncRoot(rootResourceId: string): Promise<SyncResult> {
   return withTransaction(async () => {
     const seen = new Set<string>();
 
-    const folders = listFolders(root.uri as string, { recursive: true, includeRoot: true }).sort(
-      (a, b) => uriDepth(a.uri) - uriDepth(b.uri),
-    );
+    const folders = (
+      await listFoldersChunked(root.uri as string, { recursive: true, includeRoot: true })
+    ).sort((a, b) => uriDepth(a.uri) - uriDepth(b.uri));
 
     const resourceIdByUri = new Map<string, string>();
     const savedFolders: StoredFolder[] = [];
@@ -66,9 +67,14 @@ export async function syncRoot(rootResourceId: string): Promise<SyncResult> {
       savedFolders.push(saved);
     }
 
+    let lastYield = Date.now();
     let files = 0;
     for (const folder of savedFolders) {
       if (!folder.uri) continue;
+      if (Date.now() - lastYield >= 16) {
+        lastYield = Date.now();
+        await yieldToMainThread();
+      }
       for (const entry of listDirectory(folder.uri)) {
         if (entry.isDirectory) continue;
         seen.add(entry.uri);
@@ -109,15 +115,18 @@ export async function syncDevice(): Promise<SyncResult[]> {
   for (const root of roots) {
     results.push(await syncRoot(root.resource_id));
   }
+  await checkpointDatabase();
   return results;
 }
 
-export async function useSyncDevice(intervalMs = 30_000): Promise<void> {
-  const preferences = await getUserPreferences();
-  if (preferences.syncMode === 'none') return;
+export function useSyncDevice(intervalMs = 30_000): () => void {
+  let stopped = false;
 
-  while (true) {
+  const tick = async () => {
     try {
+      const preferences = await getUserPreferences();
+      if (preferences.syncMode === 'none') return;
+
       const results = await syncDevice();
       console.info('syncDevice', JSON.stringify(results));
       // Puis pousser l'outbox (si un token est disponible) et rafraîchir le
@@ -133,6 +142,24 @@ export async function useSyncDevice(intervalMs = 30_000): Promise<void> {
     } catch (error) {
       console.warn('syncDevice failed, retrying later', error);
     }
-    await new Promise((resolve) => setTimeout(resolve, intervalMs));
-  }
+  };
+
+  const loop = async () => {
+    while (!stopped) {
+      await new Promise((resolve) => setTimeout(resolve, intervalMs));
+      if (stopped) return;
+      await tick();
+    }
+  };
+
+  // Premier cycle différé : laisser le boot et l'écran actif répondre avant
+  // de lancer un walk SAF (potentiellement long) en arrière-plan.
+  const first = setTimeout(() => {
+    void loop();
+  }, 2000);
+
+  return () => {
+    stopped = true;
+    clearTimeout(first);
+  };
 }
\ No newline at end of file
diff --git a/mobile/package.json b/mobile/package.json
index 5710245..bb1a2e6 100644
--- a/mobile/package.json
+++ b/mobile/package.json
@@ -38,8 +38,9 @@
     "test:migrations": "tsx --test tests/migrations.test.ts",
     "test:api": "tsx --test tests/apiClient.test.ts",
     "test:sync": "tsx --test tests/syncOutbox.test.ts",
+    "test:saf": "tsx --test tests/safWalk.test.ts",
     "test:e2e": "tsx --test tests/e2e.live.test.ts",
-    "test": "npm run test:db && npm run test:api && npm run test:sync"
+    "test": "npm run test:db && npm run test:api && npm run test:sync && npm run test:saf"
   },
   "private": true
 }
diff --git a/mobile/services/db/client.ts b/mobile/services/db/client.ts
index 5bca1b4..da17b59 100644
--- a/mobile/services/db/client.ts
+++ b/mobile/services/db/client.ts
@@ -98,6 +98,15 @@ export async function closeDatabase(): Promise<void> {
   opening = null;
 }
 
+export async function checkpointDatabase(): Promise<void> {
+  try {
+    const db = await getDatabase();
+    await db.execAsync('PRAGMA wal_checkpoint(TRUNCATE)');
+  } catch {
+    // Best-effort : ne jamais faire échouer la sync sur un checkpoint.
+  }
+}
+
 export async function withTransaction<T>(
   work: (db: SQLiteDatabase) => Promise<T>,
 ): Promise<T> {
diff --git a/mobile/services/db/index.ts b/mobile/services/db/index.ts
index 4925371..f6ba47c 100644
--- a/mobile/services/db/index.ts
+++ b/mobile/services/db/index.ts
@@ -1,4 +1,9 @@
-export { getDatabase, closeDatabase, withTransaction } from './client';
+export {
+  getDatabase,
+  closeDatabase,
+  withTransaction,
+  checkpointDatabase,
+} from './client';
 export { migrateDatabase, type Migration, type MigrationDb } from './migrations';
 export * from './repositories';
 export type { AccessCheck, AccessSource } from './repositories/permissions';
diff --git a/mobile/services/safDirectory.ts b/mobile/services/safDirectory.ts
index 0536477..415c3ad 100644
--- a/mobile/services/safDirectory.ts
+++ b/mobile/services/safDirectory.ts
@@ -6,6 +6,14 @@ import type {
   FolderInfo,
   PickDirectoryOptions,
 } from './safDirectory.types';
+import { __setSafWalkImpl, yieldToMainThread } from './safWalk';
+export { listFoldersChunked, yieldToMainThread, DEFAULT_WALK_BUDGET_MS } from './safWalk';
+
+__setSafWalkImpl({
+  list: listDirectory,
+  info: getFolderInfo,
+  yield: yieldToMainThread,
+});
 
 export async function pickDirectory(initialUri?: string): Promise<Folder | null> {
   try {
diff --git a/mobile/services/safWalk.ts b/mobile/services/safWalk.ts
new file mode 100644
index 0000000..0adfe57
--- /dev/null
+++ b/mobile/services/safWalk.ts
@@ -0,0 +1,69 @@
+import type {
+  DirectoryEntry,
+  Folder,
+  FolderInfo,
+  PickDirectoryOptions,
+} from './safDirectory.types';
+
+export async function yieldToMainThread(): Promise<void> {
+  await new Promise<void>((resolve) => setTimeout(resolve, 0));
+}
+
+export const DEFAULT_WALK_BUDGET_MS = 16;
+
+export type SafWalkImpl = {
+  list: (uri: string) => DirectoryEntry[];
+  info: (uri: string) => FolderInfo;
+  yield: () => Promise<void>;
+};
+
+let walkImpl: SafWalkImpl | null = null;
+
+export function __setSafWalkImpl(impl: SafWalkImpl): void {
+  walkImpl = impl;
+}
+
+export function __setSafWalkForTests(impl: Partial<SafWalkImpl>): () => void {
+  const previous = walkImpl;
+  walkImpl = { ...previous, ...impl } as SafWalkImpl;
+  return () => {
+    walkImpl = previous;
+  };
+}
+
+export async function listFoldersChunked(
+  directoryUri: string,
+  options: PickDirectoryOptions = {},
+  budgetMs = DEFAULT_WALK_BUDGET_MS,
+): Promise<Folder[]> {
+  const impl = walkImpl;
+  if (!impl) throw new Error('SafWalkImpl not configured');
+
+  const { recursive = false, includeRoot = false } = options;
+  const result: Folder[] = [];
+  if (includeRoot) {
+    result.push({ ...impl.info(directoryUri), isDirectory: true });
+  }
+  if (!recursive) {
+    for (const entry of impl.list(directoryUri)) {
+      if (entry.isDirectory) result.push(entry);
+    }
+    return result;
+  }
+
+  let lastYield = Date.now();
+  const visit = async (uri: string) => {
+    if (Date.now() - lastYield >= budgetMs) {
+      lastYield = Date.now();
+      await impl.yield();
+    }
+    for (const entry of impl.list(uri)) {
+      if (entry.isDirectory) {
+        result.push(entry);
+        await visit(entry.uri);
+      }
+    }
+  };
+  await visit(directoryUri);
+  return result;
+}
\ No newline at end of file
diff --git a/mobile/tests/safWalk.test.ts b/mobile/tests/safWalk.test.ts
new file mode 100644
index 0000000..d39ebf6
--- /dev/null
+++ b/mobile/tests/safWalk.test.ts
@@ -0,0 +1,129 @@
+import { test, afterEach } from 'node:test';
+import assert from 'node:assert/strict';
+import { __setSafWalkForTests, listFoldersChunked } from '../services/safWalk';
+import type { DirectoryEntry, Folder } from '../services/safDirectory.types';
+
+function dir(uri: string): Folder {
+  return { uri, name: uri.split('/').pop() ?? uri, isDirectory: true, exists: true };
+}
+
+function file(uri: string): DirectoryEntry {
+  return {
+    uri,
+    name: uri.split('/').pop() ?? uri,
+    isDirectory: false,
+    extension: '',
+    exists: true,
+    size: 1,
+    type: 'text/plain',
+    lastModified: 0,
+  };
+}
+
+function info(uri: string): { uri: string; name: string; exists: boolean } {
+  return { uri, name: uri.split('/').pop() ?? uri, exists: true };
+}
+
+const tree: Record<string, DirectoryEntry[]> = {
+  '/root': [dir('/root/a'), dir('/root/b'), dir('/root/c'), file('/root/f1')],
+  '/root/a': [dir('/root/a/x'), file('/root/a/f2')],
+  '/root/a/x': [],
+  '/root/b': [file('/root/b/f3')],
+  '/root/c': [],
+};
+
+const restoreFns: Array<() => void> = [];
+
+afterEach(() => {
+  while (restoreFns.length) restoreFns.pop()?.();
+});
+
+function fakeSaf() {
+  return __setSafWalkForTests({
+    list: (uri) => tree[uri] ?? [],
+    info,
+  });
+}
+
+test('listFoldersChunked : parcours récursif identique à listFolders', async () => {
+  restoreFns.push(fakeSaf());
+  const folders = await listFoldersChunked('/root', { recursive: true, includeRoot: true });
+  assert.deepEqual(
+    folders.map((f) => f.uri),
+    ['/root', '/root/a', '/root/a/x', '/root/b', '/root/c'],
+  );
+});
+
+test('listFoldersChunked : non-récursif ne remonte que les sous-dossiers immédiats', async () => {
+  restoreFns.push(fakeSaf());
+  const folders = await listFoldersChunked('/root');
+  assert.deepEqual(
+    folders.map((f) => f.uri),
+    ['/root/a', '/root/b', '/root/c'],
+  );
+});
+
+test('listFoldersChunked : includeRoot=false ne retourne pas la racine', async () => {
+  restoreFns.push(fakeSaf());
+  const folders = await listFoldersChunked('/root', { recursive: true });
+  assert.deepEqual(
+    folders.map((f) => f.uri),
+    ['/root/a', '/root/a/x', '/root/b', '/root/c'],
+  );
+});
+
+test('listFoldersChunked : cède au event loop (budget 0 → yield par dossier)', async () => {
+  restoreFns.push(fakeSaf());
+  let yields = 0;
+  restoreFns.push(
+    __setSafWalkForTests({
+      yield: async () => {
+        yields++;
+      },
+    }),
+  );
+
+  const folders = await listFoldersChunked('/root', { recursive: true }, 0);
+  assert.deepEqual(
+    folders.map((f) => f.uri),
+    ['/root/a', '/root/a/x', '/root/b', '/root/c'],
+  );
+  assert.ok(yields >= 5, `expected at least one yield per folder, got ${yields}`);
+});
+
+test('listFoldersChunked : budget maximum → aucun yield, résultat inchangé', async () => {
+  restoreFns.push(fakeSaf());
+  let yields = 0;
+  restoreFns.push(
+    __setSafWalkForTests({
+      yield: async () => {
+        yields++;
+      },
+    }),
+  );
+
+  const folders = await listFoldersChunked('/root', { recursive: true }, Number.MAX_SAFE_INTEGER);
+  assert.deepEqual(
+    folders.map((f) => f.uri),
+    ['/root/a', '/root/a/x', '/root/b', '/root/c'],
+  );
+  assert.equal(yields, 0);
+});
+
+test('__setSafWalkForTests : la restauration rend l’implémentation d’origine', async () => {
+  restoreFns.push(fakeSaf());
+  const restore = __setSafWalkForTests({ list: () => [dir('/fake')] });
+  restore();
+
+  let listed = false;
+  restoreFns.push(
+    __setSafWalkForTests({
+      list: (uri) => {
+        listed = true;
+        return tree[uri] ?? [];
+      },
+    }),
+  );
+  await listFoldersChunked('/root', { recursive: true });
+  assert.equal(listed, true);
+});
\ No newline at end of file