diff --git a/android/app/src/main/AndroidManifest.xml b/android/app/src/main/AndroidManifest.xml
index 3800d0c..123c275 100644
--- a/android/app/src/main/AndroidManifest.xml
+++ b/android/app/src/main/AndroidManifest.xml
@@ -9,7 +9,7 @@
         <activity
             android:name=".MainActivity"
             android:exported="true"
-            android:launchMode="singleTop"
+            android:launchMode="singleTask"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:hardwareAccelerated="true"
diff --git a/android/app/src/main/kotlin/eu/mhsl/marianum/mobile/client/MainActivity.kt b/android/app/src/main/kotlin/eu/mhsl/marianum/mobile/client/MainActivity.kt
index cf439fc..3c68c8a 100644
--- a/android/app/src/main/kotlin/eu/mhsl/marianum/mobile/client/MainActivity.kt
+++ b/android/app/src/main/kotlin/eu/mhsl/marianum/mobile/client/MainActivity.kt
@@ -1,15 +1,38 @@
 package eu.mhsl.marianum.mobile.client
 
 import android.content.Intent
+import android.os.Bundle
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
 import io.flutter.plugin.common.MethodChannel
 
 class MainActivity : FlutterActivity() {
     private val widgetChannel = "eu.mhsl.marianum.widget"
+    private val shareChannel = "eu.mhsl.marianum.share"
     /// Last seen widget tap target. Cleared by Dart via `consumePendingNavigation`
     /// so the same intent isn't replayed on every resume.
     private var pendingTimetableTap: Boolean = false
+    private val shareActions = setOf(Intent.ACTION_SEND, Intent.ACTION_SEND_MULTIPLE)
+
+    /// receive_sharing_intent only emits warm shares to a live Dart listener and
+    /// does not buffer them. After a relaunch into an existing task the share
+    /// arrives via onNewIntent before Dart subscribed, so it is held here until
+    /// Dart reports `listenerReady`.
+    private var shareListenerReady = false
+    private var bufferedShare: Intent? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        // Android replays the original launch intent when the activity is
+        // recreated from recents or after process death. A share or widget tap
+        // that was already handled would otherwise run again — for shares with
+        // temp files that are long gone.
+        val replayed = savedInstanceState != null ||
+            (intent.flags and Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY) != 0
+        if (replayed && (intent.action in shareActions || isWidgetTap(intent))) {
+            intent = Intent(Intent.ACTION_MAIN).addCategory(Intent.CATEGORY_LAUNCHER)
+        }
+        super.onCreate(savedInstanceState)
+    }
 
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
@@ -26,17 +49,35 @@ class MainActivity : FlutterActivity() {
                 else -> result.notImplemented()
             }
         }
+        MethodChannel(
+            flutterEngine.dartExecutor.binaryMessenger,
+            shareChannel
+        ).setMethodCallHandler { call, result ->
+            when (call.method) {
+                "listenerReady" -> {
+                    shareListenerReady = true
+                    bufferedShare?.let { flutterEngine.activityControlSurface.onNewIntent(it) }
+                    bufferedShare = null
+                    result.success(null)
+                }
+                else -> result.notImplemented()
+            }
+        }
         consumeIntentData(intent)
     }
 
     override fun onNewIntent(intent: Intent) {
         super.onNewIntent(intent)
+        if (!shareListenerReady && intent.action in shareActions) {
+            bufferedShare = intent
+        }
         consumeIntentData(intent)
     }
 
+    private fun isWidgetTap(intent: Intent?): Boolean =
+        intent?.getBooleanExtra("widget_open_timetable", false) == true
+
     private fun consumeIntentData(intent: Intent?) {
-        if (intent?.getBooleanExtra("widget_open_timetable", false) == true) {
-            pendingTimetableTap = true
-        }
+        if (isWidgetTap(intent)) pendingTimetableTap = true
     }
 }
diff --git a/ios/Runner/SceneDelegate.swift b/ios/Runner/SceneDelegate.swift
index eb61b78..6c8a831 100644
--- a/ios/Runner/SceneDelegate.swift
+++ b/ios/Runner/SceneDelegate.swift
@@ -13,21 +13,44 @@ class SceneDelegate: FlutterSceneDelegate {
     options connectionOptions: UIScene.ConnectionOptions
   ) {
     super.scene(scene, willConnectTo: session, options: connectionOptions)
-    for context in connectionOptions.urlContexts {
+    var handledShare = false
+    for context in connectionOptions.urlContexts where isShareUrl(context.url) {
       _ = ReceiveSharingIntentPlugin.instance.application(
         UIApplication.shared,
         didFinishLaunchingWithOptions: [UIApplication.LaunchOptionsKey.url: context.url]
       )
+      handledShare = true
     }
+    if handledShare { clearSharedPayload() }
   }
 
   override func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
-    for context in URLContexts {
+    let shares = URLContexts.filter { isShareUrl($0.url) }
+    for context in shares {
       _ = ReceiveSharingIntentPlugin.instance.application(
         UIApplication.shared,
         open: context.url,
         options: [:]
       )
     }
+    if !shares.isEmpty { clearSharedPayload() }
+    let others = URLContexts.subtracting(shares)
+    if !others.isEmpty { super.scene(scene, openURLContexts: others) }
+  }
+
+  private func isShareUrl(_ url: URL) -> Bool {
+    ReceiveSharingIntentPlugin.instance.hasMatchingSchemePrefix(url: url)
+  }
+
+  // The plugin keeps the payload in memory once read but never removes it
+  // from the App Group defaults. The Share Extension opens the app twice per
+  // share and a scene reconnect replays the URL, so every later delivery
+  // would publish the finished share again.
+  private func clearSharedPayload() {
+    let groupId = Bundle.main.object(forInfoDictionaryKey: "AppGroupId") as? String
+    let defaults = UserDefaults(
+      suiteName: groupId ?? "group.\(Bundle.main.bundleIdentifier ?? "")")
+    defaults?.removeObject(forKey: "ShareKey")
+    defaults?.removeObject(forKey: "ShareMessageKey")
   }
 }
diff --git a/ios/Share Extension/ShareViewController.swift b/ios/Share Extension/ShareViewController.swift
index 881b42f..a54b551 100644
--- a/ios/Share Extension/ShareViewController.swift	
+++ b/ios/Share Extension/ShareViewController.swift	
@@ -152,17 +152,54 @@ final class ShareViewController: UIViewController {
     }
   }
 
-  private func copyIntoAppGroup(src: URL) -> URL? {
+  // loadItem-Callbacks laufen parallel; Ordneranlage und Namenswahl seriell.
+  private let fileQueue = DispatchQueue(label: "share.files")
+
+  // Ein Ordner pro Share: Gleichnamige Dateien (z. B. bearbeitete Fotos, alle
+  // "FullSizeRender.jpg") überschrieben sich sonst gegenseitig, auch über
+  // zwei Shares hinweg. Die App löscht den Ordner, sobald der Share erledigt ist.
+  private lazy var shareDir: URL? = {
     guard let container = FileManager.default
       .containerURL(forSecurityApplicationGroupIdentifier: appGroupId) else {
       return nil
     }
-    let name = src.lastPathComponent.isEmpty ? UUID().uuidString : src.lastPathComponent
-    let dst = container.appendingPathComponent(name)
+    let root = container.appendingPathComponent("share_intent", isDirectory: true)
+    sweepStaleShares(in: root)
+    let dir = root.appendingPathComponent(UUID().uuidString, isDirectory: true)
+    do {
+      try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
+      return dir
+    } catch {
+      return nil
+    }
+  }()
+
+  // Shares, deren App-Flow nie abgeschlossen wurde (Prozess beendet o. ä.),
+  // räumt sonst niemand weg — der App-Group-Container wird nie geleert.
+  private func sweepStaleShares(in root: URL) {
+    let fm = FileManager.default
+    guard let entries = try? fm.contentsOfDirectory(
+      at: root, includingPropertiesForKeys: [.creationDateKey]) else { return }
+    let cutoff = Date().addingTimeInterval(-24 * 60 * 60)
+    for entry in entries {
+      let created = (try? entry.resourceValues(forKeys: [.creationDateKey]))?.creationDate
+      if let created, created < cutoff { try? fm.removeItem(at: entry) }
+    }
+  }
+
+  private func copyIntoAppGroup(src: URL) -> URL? {
+    fileQueue.sync { copyIntoShareDir(src: src) }
+  }
+
+  private func copyIntoShareDir(src: URL) -> URL? {
+    guard let dir = shareDir else { return nil }
+    let name = src.lastPathComponent.isEmpty ? UUID().uuidString : src.lastPathComponent
+    var dst = dir.appendingPathComponent(name)
+    // Mehrfachauswahl mit gleichem Namen innerhalb eines Shares.
+    if FileManager.default.fileExists(atPath: dst.path) {
+      dst = dir.appendingPathComponent("\(UUID().uuidString.prefix(8))-\(name)")
+    }
     do {
-      if FileManager.default.fileExists(atPath: dst.path) {
-        try FileManager.default.removeItem(at: dst)
-      }
       try FileManager.default.copyItem(at: src, to: dst)
       return dst
     } catch {
@@ -171,10 +208,9 @@ final class ShareViewController: UIViewController {
   }
 
   private func writePng(image: UIImage) -> URL? {
-    guard let container = FileManager.default
-            .containerURL(forSecurityApplicationGroupIdentifier: appGroupId),
-          let data = image.pngData() else { return nil }
-    let dst = container.appendingPathComponent("\(UUID().uuidString).png")
+    guard let data = image.pngData(),
+          let dir = fileQueue.sync(execute: { shareDir }) else { return nil }
+    let dst = dir.appendingPathComponent("\(UUID().uuidString).png")
     return (try? data.write(to: dst)) != nil ? dst : nil
   }
 
diff --git a/lib/api/errors/stale_session_exception.dart b/lib/api/errors/stale_session_exception.dart
new file mode 100644
index 0000000..52936e1
--- /dev/null
+++ b/lib/api/errors/stale_session_exception.dart
@@ -0,0 +1,11 @@
+import 'app_exception.dart';
+
+/// A request finished after the account it was started for signed out. Its
+/// result must not reach the state or cache of whoever is signed in now.
+class StaleSessionException extends AppException {
+  const StaleSessionException()
+    : super(
+        userMessage: 'Die Anmeldung hat sich geändert. Bitte lade neu.',
+        technicalDetails: 'result of a previous session discarded',
+      );
+}
diff --git a/lib/api/marianumcloud/talk/share_files_to_chat.dart b/lib/api/marianumcloud/talk/share_files_to_chat.dart
index 9be0faa..5a7facb 100644
--- a/lib/api/marianumcloud/talk/share_files_to_chat.dart
+++ b/lib/api/marianumcloud/talk/share_files_to_chat.dart
@@ -17,6 +17,10 @@ Future<void>? _shareFolderReady;
 Future<void> ensureTalkShareFolder() =>
     _shareFolderReady ??= _createTalkShareFolder();
 
+/// The folder is per user; after a sign-out the next account has to check
+/// again.
+void resetTalkShareFolderCache() => _shareFolderReady = null;
+
 Future<void> _createTalkShareFolder() async {
   try {
     final webdav = await WebdavApi.webdav;
diff --git a/lib/api/marianumcloud/webdav/webdav_api.dart b/lib/api/marianumcloud/webdav/webdav_api.dart
index 942b560..5395706 100644
--- a/lib/api/marianumcloud/webdav/webdav_api.dart
+++ b/lib/api/marianumcloud/webdav/webdav_api.dart
@@ -18,7 +18,10 @@ abstract class WebdavApi<T> {
   /// changes (app password minted/renewed, account switch) so it never keeps
   /// authenticating with stale credentials.
   static Future<WebDavClient> get webdav {
-    final secret = AccountData().getNextcloudSecret();
+    // Keyed by user too: two accounts may share a password (no app password
+    // minted), and the client would keep the previous login name.
+    final secret =
+        '${AccountData().getUsername()}:${AccountData().getNextcloudSecret()}';
     if (_webdav == null || _webdavSecret != secret) {
       _webdavSecret = secret;
       _webdav = establishWebdavConnection();
diff --git a/lib/api/marianumconnect/auth/auth_interceptor.dart b/lib/api/marianumconnect/auth/auth_interceptor.dart
index b78ac97..7dc4e2a 100644
--- a/lib/api/marianumconnect/auth/auth_interceptor.dart
+++ b/lib/api/marianumconnect/auth/auth_interceptor.dart
@@ -88,17 +88,29 @@ class MarianumConnectAuthInterceptor extends Interceptor {
 
   Future<bool> _performReLogin() async {
     if (!AccountData().isPopulated()) return false;
+    final username = AccountData().getUsername();
+    // A background engine (widget task) keeps the account it loaded. When
+    // the app signed that account out, its revoked token answers 401 — a
+    // re-login would mint a fresh token for it into the shared keystore.
+    if (await AccountData().readStoredUsername() != username) return false;
     try {
       await _loginClient.run(
-        username: AccountData().getUsername(),
+        username: username,
         password: AccountData().getPassword(),
         tokenName: await DeviceTokenName.resolve(),
       );
-      return true;
     } catch (_) {
-      await _tokenStorage.clear();
+      if (await AccountData().readStoredUsername() == username) {
+        await _tokenStorage.clear();
+      }
       return false;
     }
+    final stored = await AccountData().readStoredUsername();
+    if (stored == username) return true;
+    // Signed out during the login: drop the orphaned token, unless another
+    // account already stored its own.
+    if (stored == null) await _tokenStorage.clear();
+    return false;
   }
 
   Future<Response<dynamic>> _retryWithFreshToken(
diff --git a/lib/api/marianumconnect/auth/session_validator.dart b/lib/api/marianumconnect/auth/session_validator.dart
index 4280b4b..355b0bb 100644
--- a/lib/api/marianumconnect/auth/session_validator.dart
+++ b/lib/api/marianumconnect/auth/session_validator.dart
@@ -19,10 +19,14 @@ class SessionValidator {
     if (AccountData().isDemo) return;
     final username = AccountData().getUsername();
     final password = AccountData().getPassword();
+    final epoch = AccountData().sessionEpoch;
     try {
       await AuthVerify().run(username: username, password: password);
     } on AuthException catch (e) {
       if (e.statusCode != 401) return;
+      // The probed account already signed out; the 401 must not sign out
+      // whoever logged in meanwhile.
+      if (!AccountData().isCurrentSession(epoch)) return;
       log('MC: stored credentials rejected — forcing re-login');
       await AuthLogout().run();
       await const MarianumConnectTokenStorage().clear();
diff --git a/lib/api/marianumconnect/queries/timetable_custom_events/custom_events_migration.dart b/lib/api/marianumconnect/queries/timetable_custom_events/custom_events_migration.dart
index ab63377..613e598 100644
--- a/lib/api/marianumconnect/queries/timetable_custom_events/custom_events_migration.dart
+++ b/lib/api/marianumconnect/queries/timetable_custom_events/custom_events_migration.dart
@@ -31,18 +31,23 @@ class CustomEventsMigration {
     if (DemoMode.active) return;
     if (await _isDone()) return;
 
+    final epoch = AccountData().sessionEpoch;
     try {
       final response = await GetCustomTimetableEvent(
         GetCustomTimetableEventParams(AccountData().getUserSecret()),
       ).run();
 
       for (final event in response.events) {
+        // The POST authenticates with whoever is signed in now; after a
+        // sign-out the previous account's events would land in the next one.
+        if (!AccountData().isCurrentSession(epoch)) return;
         await TimetableCustomEventsAdd().run(event);
         await RemoveCustomTimetableEvent(
           RemoveCustomTimetableEventParams(event.id),
         ).run();
       }
 
+      if (!AccountData().isCurrentSession(epoch)) return;
       await _markDone();
       log('Custom events migration: moved ${response.events.length} event(s) to Marianum-Connect.');
     } catch (e) {
diff --git a/lib/api/request_cache.dart b/lib/api/request_cache.dart
index 86d705b..bdf86ea 100644
--- a/lib/api/request_cache.dart
+++ b/lib/api/request_cache.dart
@@ -3,8 +3,10 @@ import 'dart:convert';
 
 import 'package:localstore/localstore.dart';
 
+import '../model/account_data.dart';
 import 'api_response.dart';
 import 'errors/parse_exception.dart';
+import 'errors/stale_session_exception.dart';
 
 abstract class RequestCache<T extends ApiResponse?> {
   static const int cacheNothing = 0;
@@ -48,6 +50,7 @@ abstract class RequestCache<T extends ApiResponse?> {
   static void ignore(Exception e) {}
 
   Future<void> start(String document) async {
+    final epoch = AccountData().sessionEpoch;
     try {
       final tableData = await Localstore.instance
           .collection(collection)
@@ -67,6 +70,12 @@ abstract class RequestCache<T extends ApiResponse?> {
 
       try {
         final newValue = await onLoad();
+        // The collection is shared, so a late response of a signed-out
+        // account would otherwise be cached for the next one.
+        if (!AccountData().isCurrentSession(epoch)) {
+          onError(const StaleSessionException());
+          return;
+        }
         onUpdate?.call(newValue);
         onNetworkData?.call(newValue);
         unawaited(
@@ -141,8 +150,10 @@ Future<T> resolveFromCache<T extends ApiResponse?>(
     onError?.call(e);
   });
   await cache.ready;
-  if (latest != null) return latest as T;
   final err = capturedError;
+  // `latest` may still hold the cache hit read before the sign-out.
+  if (err is StaleSessionException) throw err;
+  if (latest != null) return latest as T;
   if (err != null) throw err;
   throw ParseException(
     technicalDetails: operationName != null
diff --git a/lib/app.dart b/lib/app.dart
index c78f748..c346f69 100644
--- a/lib/app.dart
+++ b/lib/app.dart
@@ -145,13 +145,14 @@ class _AppState extends State<App> with WidgetsBindingObserver {
   void _handlePendingShare() {
     if (!mounted) return;
     final share = ShareIntentListener.pending.value;
-    if (share == null) return;
+    if (share == null || ShareIntentListener.instance.isShown(share)) return;
     // A second share would otherwise leave the previous share-flow page
     // on top with stale (already-cleared) file paths.
     final navigator = Navigator.of(context);
     if (navigator.canPop()) {
       navigator.popUntil((route) => route.isFirst || route is PopupRoute);
     }
+    ShareIntentListener.instance.markShown(share);
     AppRoutes.openShareTarget(context, share);
   }
 
@@ -200,7 +201,6 @@ class _AppState extends State<App> with WidgetsBindingObserver {
         );
       }
       unawaited(_handlePendingWidgetNavigation());
-      ShareIntentListener.instance.attach();
       ShareIntentListener.pending.addListener(_handlePendingShare);
       _handlePendingShare();
       _syncChatListPolling();
@@ -261,7 +261,6 @@ class _AppState extends State<App> with WidgetsBindingObserver {
     PushTapRouter.pendingChatToken.removeListener(_onPushTapPending);
     PushTapRouter.pendingNewsletterId.removeListener(_onNewsletterTapPending);
     ShareIntentListener.pending.removeListener(_handlePendingShare);
-    ShareIntentListener.instance.detach();
     Main.bottomNavigator.removeListener(_onTabControllerChanged);
     WidgetsBinding.instance.removeObserver(this);
     super.dispose();
diff --git a/lib/main.dart b/lib/main.dart
index e06a754..2eafc98 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -15,7 +15,6 @@ import 'package:jiffy/jiffy.dart';
 import 'package:loader_overlay/loader_overlay.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:persistent_bottom_nav_bar_v2/persistent_bottom_nav_bar_v2.dart';
-import 'package:shared_preferences/shared_preferences.dart';
 
 import 'api/marianumcloud/webdav/queries/list_files/list_files_cache.dart';
 import 'api/marianumconnect/auth/session_validator.dart';
@@ -27,6 +26,7 @@ import 'app.dart';
 import 'background/widget_background_task.dart';
 import 'firebase_options.dart';
 import 'model/account_data.dart';
+import 'model/session_wipe.dart';
 import 'notification/notification_service.dart';
 import 'push/push_message_handler.dart';
 import 'push/push_registration.dart';
@@ -54,7 +54,6 @@ import 'view/login/login.dart';
 import 'view/login/post_login_splash.dart';
 import 'widget/avatar_disk_cache.dart';
 import 'widget/breaker/breaker.dart';
-import 'widget/debug/cache_view.dart';
 import 'widget/downloads/download_tray.dart';
 import 'widget/emergency/emergency_notice_gate.dart';
 import 'widget_data/widget_sync.dart';
@@ -117,6 +116,7 @@ void _installErrorHandlers() {
 Future<void> main() async {
   log('MarianumMobile started');
   WidgetsFlutterBinding.ensureInitialized();
+  AccountData().markUiEngine();
   // Before any initialisation so startup failures reach the backend too.
   _installErrorHandlers();
 
@@ -272,11 +272,13 @@ class Main extends StatefulWidget {
 class _MainState extends State<Main> {
   bool _showPostLoginSplash = false;
   bool _appMounted = true;
+  late AccountStatus _lastStatus;
 
   @override
   void initState() {
     super.initState();
     Jiffy.setLocale('de');
+    _lastStatus = context.read<AccountBloc>().state.status;
 
     AccountData().waitForPopulation().then((value) {
       if (!mounted) return;
@@ -409,6 +411,8 @@ class _MainState extends State<Main> {
                   listenWhen: (previous, current) =>
                       previous.status != current.status,
                   listener: (context, accountState) {
+                    final wasLoggedIn = _lastStatus == AccountStatus.loggedIn;
+                    _lastStatus = accountState.status;
                     // Fresh login (loggedOut -> loggedIn): pull capability flags
                     // for the newly authenticated user, then register push right
                     // away instead of deferring it to the next app start.
@@ -434,9 +438,10 @@ class _MainState extends State<Main> {
                     }
                     if (accountState.status != AccountStatus.loggedOut) return;
                     // A pending share would otherwise survive logout and be
-                    // re-applied after re-login with file paths the OS may
-                    // already have evicted from the cache.
-                    ShareIntentListener.instance.clear();
+                    // re-applied to the next account. A cold-start share that
+                    // is merely waiting for the stored session to resolve as
+                    // signed out stays, to be sent after login.
+                    if (wasLoggedIn) SessionWipe.clearImmediate();
                     // Routes pushed via AppRoutes (e.g. Settings) live on the
                     // root navigator and survive the home swap below, so they
                     // would still cover the Login screen after logout. Pop
@@ -448,7 +453,6 @@ class _MainState extends State<Main> {
                     // Capture bloc references before the post-frame callback
                     // — by the time it runs the dialog/Settings context is
                     // gone but this listener context is still valid.
-                    final settingsCubit = context.read<SettingsCubit>();
                     final timetableBloc = context.read<TimetableBloc>();
                     final chatListBloc = context.read<ChatListBloc>();
                     final chatBloc = context.read<ChatBloc>();
@@ -462,8 +466,7 @@ class _MainState extends State<Main> {
                     // still in front caused a black-frame race.
                     WidgetsBinding.instance.addPostFrameCallback((_) {
                       unawaited(
-                        _wipeUserState(
-                          settingsCubit: settingsCubit,
+                        SessionWipe.run(
                           timetableBloc: timetableBloc,
                           chatListBloc: chatListBloc,
                           chatBloc: chatBloc,
@@ -507,45 +510,3 @@ class _MainState extends State<Main> {
     ),
   );
 }
-
-Future<void> _wipeUserState({
-  required SettingsCubit settingsCubit,
-  required TimetableBloc timetableBloc,
-  required ChatListBloc chatListBloc,
-  required ChatBloc chatBloc,
-  required BreakerBloc breakerBloc,
-  required CapabilitiesCubit capabilitiesCubit,
-  required NextcloudCapabilitiesCubit nextcloudCapabilitiesCubit,
-}) async {
-  try {
-    // Reset user-data blocs whose tree is no longer mounted after the
-    // home swap. We do NOT touch SettingsCubit here — its outer BlocBuilder
-    // wraps MaterialApp, so emit'ing a fresh state would tear down the
-    // freshly-mounted Login tree and leave the user with a blank screen
-    // (the MaterialApp.builder backdrop) until the next interaction.
-    await Future.wait([
-      timetableBloc.reset(),
-      chatListBloc.reset(),
-      chatBloc.reset(),
-      breakerBloc.reset(),
-      capabilitiesCubit.reset(),
-      nextcloudCapabilitiesCubit.reset(),
-    ]);
-    final prefs = await SharedPreferences.getInstance();
-    await prefs.clear();
-    await HydratedBloc.storage.clear();
-    await const CacheView().clear();
-    // The chat background image lives outside HydratedStorage, so clear it too
-    // (best-effort) to avoid orphaning the previous user's wallpaper.
-    final backgroundImage = File(AppPaths.chatBackgroundImage);
-    if (backgroundImage.existsSync()) backgroundImage.deleteSync();
-    // Stop the periodic widget refresh job so the background isolate doesn't
-    // wake up every 30 minutes only to write `loggedIn=false`. Re-registers
-    // on the next successful login.
-    await WidgetBackgroundTask.cancelAll();
-    await WidgetSync.clear();
-    await WidgetSync.triggerUpdate();
-  } catch (e, s) {
-    log('User state wipe failed: $e', stackTrace: s);
-  }
-}
diff --git a/lib/model/account_data.dart b/lib/model/account_data.dart
index 4f96459..518d5fb 100644
--- a/lib/model/account_data.dart
+++ b/lib/model/account_data.dart
@@ -55,6 +55,15 @@ class AccountData {
     unawaited(_loadWithRetry());
   }
 
+  int _sessionEpoch = 0;
+
+  /// Bumped on every sign-out. Async work captures it when it starts and
+  /// drops its result when it changed meanwhile, so a request of the previous
+  /// account cannot land in the next account's state or cache.
+  int get sessionEpoch => _sessionEpoch;
+
+  bool isCurrentSession(int epoch) => epoch == _sessionEpoch;
+
   String? _username;
   String? _password;
   String? _appPassword;
@@ -109,6 +118,7 @@ class AccountData {
   }
 
   Future<void> removeData() async {
+    _sessionEpoch++;
     _populated = Completer();
     _username = null;
     _password = null;
@@ -263,6 +273,52 @@ class AccountData {
     }
   }
 
+  bool _isUiEngine = false;
+
+  /// Called from `main()`; background entry points never run it.
+  void markUiEngine() => _isUiEngine = true;
+
+  /// Username currently in the keystore. Other engines (widget task, push
+  /// isolates) sign out or in without this instance noticing.
+  Future<String?> readStoredUsername() =>
+      _secureStorage.read(key: _usernameField);
+
+  /// Re-reads the session for long-lived background engines: they load once
+  /// and would otherwise keep acting with an account that signed out in the
+  /// app meanwhile. Keeps the known state when the keystore is unreadable.
+  Future<void> reloadFromStorage() async {
+    // The UI engine performs sign-in and sign-out itself, so its state is
+    // current; re-reading mid sign-out could resurrect the removed account.
+    if (_isUiEngine) return;
+    try {
+      final username = await _secureStorage.read(key: _usernameField);
+      final password = await _secureStorage.read(key: _passwordField);
+      final isDemo = (await _secureStorage.read(key: _demoField)) == 'true';
+      final usesLoginFlow =
+          (await _secureStorage.read(key: _loginFlowField)) == 'true';
+      String? appPassword;
+      String? appPasswordTalk;
+      try {
+        appPassword = await pushSecureStorage.read(key: _appPasswordField);
+        appPasswordTalk = await pushSecureStorage.read(
+          key: _appPasswordTalkField,
+        );
+      } on Object {
+        // Group keystore unavailable: fall back to the real password.
+      }
+      if (username != _username) _sessionEpoch++;
+      _username = username;
+      _password = password;
+      _isDemo = isDemo;
+      _usesLoginFlow = usesLoginFlow;
+      _appPassword = appPassword;
+      _appPasswordTalk = appPasswordTalk;
+      if (!_populated.isCompleted) _populated.complete();
+    } on Object catch (e) {
+      log('AccountData reload failed, keeping loaded state: $e');
+    }
+  }
+
   Future<bool> waitForPopulation() async {
     await _populated.future;
     return isPopulated();
diff --git a/lib/model/session_wipe.dart b/lib/model/session_wipe.dart
new file mode 100644
index 0000000..b54eff8
--- /dev/null
+++ b/lib/model/session_wipe.dart
@@ -0,0 +1,152 @@
+import 'dart:async';
+import 'dart:developer';
+import 'dart:io';
+
+import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:flutter_app_badge/flutter_app_badge.dart';
+import 'package:hydrated_bloc/hydrated_bloc.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import '../api/marianumcloud/talk/share_files_to_chat.dart';
+import '../background/widget_background_task.dart';
+import '../notification/notification_service.dart';
+import '../push/chat_thread_store.dart';
+import '../push/nid_store.dart';
+import '../push/push_keypair.dart';
+import '../push/push_tap_router.dart';
+import '../routing/app_routes.dart';
+import '../share_intent/share_intent_listener.dart';
+import '../state/app/modules/breaker/bloc/breaker_bloc.dart';
+import '../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
+import '../state/app/modules/chat/bloc/chat_bloc.dart';
+import '../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
+import '../state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart';
+import '../state/app/modules/timetable/bloc/timetable_bloc.dart';
+import '../utils/app_paths.dart';
+import '../utils/downloads/download_manager.dart';
+import '../utils/file_clipboard.dart';
+import '../widget/debug/cache_view.dart';
+import '../widget_data/widget_sync.dart';
+
+/// Removes everything the signed-out account left on the device. Every step
+/// is isolated: one failing step used to skip all later ones and leave the
+/// previous account's data behind.
+abstract final class SessionWipe {
+  static Future<void>? _running;
+
+  /// Completes once a running wipe finished. A login awaits it, otherwise the
+  /// wipe could clear what the next account just stored (widget job, caches).
+  static Future<void> get done => _running ?? Future.value();
+
+  /// State that must be gone before the next frame (a login screen can be
+  /// reached right away): pending navigation and in-memory singletons.
+  static void clearImmediate() {
+    _step('share intents', ShareIntentListener.instance.clearAll);
+    _step('share folder cache', resetTalkShareFolderCache);
+    _step('pending navigation', () {
+      AppRoutes.pendingChatToken.value = null;
+      PushTapRouter.pendingChatToken.value = null;
+      PushTapRouter.pendingNewsletterId.value = null;
+    });
+    _step('file clipboard', FileClipboard.instance.clear);
+    _step('downloads', DownloadManager.instance.clearAll);
+  }
+
+  static Future<void> run({
+    required TimetableBloc timetableBloc,
+    required ChatListBloc chatListBloc,
+    required ChatBloc chatBloc,
+    required BreakerBloc breakerBloc,
+    required CapabilitiesCubit capabilitiesCubit,
+    required NextcloudCapabilitiesCubit nextcloudCapabilitiesCubit,
+  }) {
+    final wipe = _run(
+      timetableBloc: timetableBloc,
+      chatListBloc: chatListBloc,
+      chatBloc: chatBloc,
+      breakerBloc: breakerBloc,
+      capabilitiesCubit: capabilitiesCubit,
+      nextcloudCapabilitiesCubit: nextcloudCapabilitiesCubit,
+    );
+    _running = wipe;
+    return wipe.whenComplete(() {
+      if (identical(_running, wipe)) _running = null;
+    });
+  }
+
+  static Future<void> _run({
+    required TimetableBloc timetableBloc,
+    required ChatListBloc chatListBloc,
+    required ChatBloc chatBloc,
+    required BreakerBloc breakerBloc,
+    required CapabilitiesCubit capabilitiesCubit,
+    required NextcloudCapabilitiesCubit nextcloudCapabilitiesCubit,
+  }) async {
+    // SettingsCubit is deliberately left alone: its BlocBuilder wraps
+    // MaterialApp, and emitting a fresh state here tore down the freshly
+    // mounted Login tree (blank screen until the next interaction).
+    await Future.wait([
+      _stepAsync('timetable', timetableBloc.reset),
+      _stepAsync('chat list', chatListBloc.reset),
+      _stepAsync('chat', chatBloc.reset),
+      _stepAsync('breakers', breakerBloc.reset),
+      _stepAsync('capabilities', capabilitiesCubit.reset),
+      _stepAsync('nc capabilities', nextcloudCapabilitiesCubit.reset),
+    ]);
+    await _stepAsync('shared preferences', () async {
+      await (await SharedPreferences.getInstance()).clear();
+    });
+    await _stepAsync('hydrated storage', HydratedBloc.storage.clear);
+    await _stepAsync('request cache', const CacheView().clear);
+    await _stepAsync('chat background', () async {
+      final image = File(AppPaths.chatBackgroundImage);
+      if (image.existsSync()) await image.delete();
+    });
+    await _stepAsync('download files', () async {
+      final dir = Directory('${(await getTemporaryDirectory()).path}/downloads');
+      if (dir.existsSync()) await dir.delete(recursive: true);
+    });
+
+    // Push: the tray and its bookkeeping belong to the previous account — a
+    // tap or inline reply there would otherwise act as the next one. A new
+    // keypair and FCM token make pushes still addressed to the previous
+    // registration undecryptable and undeliverable (an offline sign-out
+    // could not unregister it).
+    await _stepAsync(
+      'notification tray',
+      NotificationService().flutterLocalNotificationsPlugin.cancelAll,
+    );
+    await _stepAsync('app badge', () => FlutterAppBadge.count(0));
+    await _stepAsync('push nid store', NidStore().clear);
+    await _stepAsync('push thread store', ChatThreadStore().clearAll);
+    await _stepAsync('push keypair', const PushKeypair().clear);
+    await _stepAsync('fcm token', FirebaseMessaging.instance.deleteToken);
+
+    // Stop the periodic widget refresh job so the background isolate doesn't
+    // wake up every 30 minutes only to write `loggedIn=false`. Re-registers
+    // on the next successful login.
+    await _stepAsync('widget task', WidgetBackgroundTask.cancelAll);
+    await _stepAsync('widget data', WidgetSync.clear);
+    await _stepAsync('widget update', WidgetSync.triggerUpdate);
+  }
+
+  static void _step(String name, void Function() step) {
+    try {
+      step();
+    } catch (e, s) {
+      log('Session wipe step "$name" failed: $e', stackTrace: s);
+    }
+  }
+
+  static Future<void> _stepAsync(
+    String name,
+    Future<void> Function() step,
+  ) async {
+    try {
+      await step();
+    } catch (e, s) {
+      log('Session wipe step "$name" failed: $e', stackTrace: s);
+    }
+  }
+}
diff --git a/lib/push/push_actions.dart b/lib/push/push_actions.dart
index 3548143..a2d1f42 100644
--- a/lib/push/push_actions.dart
+++ b/lib/push/push_actions.dart
@@ -60,6 +60,10 @@ class PushActions {
     // auth header, the Talk POST never happens and the RemoteInput spinner
     // runs forever.
     DartPluginRegistrant.ensureInitialized();
+    // The action engine lives as long as the process: without a reload a
+    // reply would be sent with the account that was signed in when the
+    // engine first started.
+    await AccountData().reloadFromStorage();
 
     _plog(
       'action=${response.actionId} payload=${response.payload} '
diff --git a/lib/push/push_message_handler.dart b/lib/push/push_message_handler.dart
index 1d64116..277c2c0 100644
--- a/lib/push/push_message_handler.dart
+++ b/lib/push/push_message_handler.dart
@@ -4,6 +4,7 @@ import 'package:crypton/crypton.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 
 import '../background/widget_background_task.dart';
+import '../model/account_data.dart';
 import '../notification/notification_service.dart';
 import 'chat_thread_store.dart';
 import 'nid_store.dart';
@@ -54,6 +55,8 @@ PushKind classifyPush(Map<String, dynamic> data) {
 /// "must be annotated"), so a plain function is the reliable form.
 @pragma('vm:entry-point')
 Future<void> pushOnBackgroundMessage(RemoteMessage message) async {
+  // This engine outlives sign-outs and logins in the app.
+  await AccountData().reloadFromStorage();
   await NotificationService().initializeNotifications();
   await PushRenderer.ensureChannels();
   await PushMessageHandler().handle(message);
diff --git a/lib/push/push_registration.dart b/lib/push/push_registration.dart
index 1f0d1b7..52dc540 100644
--- a/lib/push/push_registration.dart
+++ b/lib/push/push_registration.dart
@@ -107,6 +107,7 @@ class PushRegistration {
   /// fire-and-forget (and simply ignore the result).
   Future<bool> register() async {
     if (DemoMode.active) return false;
+    final epoch = AccountData().sessionEpoch;
     final String? fcmToken;
     try {
       fcmToken = await FirebaseMessaging.instance.getToken();
@@ -159,6 +160,7 @@ class PushRegistration {
         fcmToken: fcmToken,
         pems: pems,
         appVersion: appVersion,
+        epoch: epoch,
       );
       allOk = allOk && ok;
     }
@@ -170,6 +172,7 @@ class PushRegistration {
     required String fcmToken,
     required PushKeypairPems pems,
     required String? appVersion,
+    required int epoch,
   }) async {
     try {
       final proxyServer = currentProxyServer;
@@ -185,6 +188,11 @@ class PushRegistration {
         userAgent: isTalk ? _talkUserAgent : null,
       );
 
+      // Signed out while registering: persisting or announcing this
+      // registration would keep delivering the previous account's pushes,
+      // and logoutCleanup already ran so nothing would unregister it.
+      if (!AccountData().isCurrentSession(epoch)) return false;
+
       await _store.save(
         type: type,
         deviceIdentifier: registration.deviceIdentifier,
diff --git a/lib/share_intent/pending_share.dart b/lib/share_intent/pending_share.dart
index 9f8590e..6c875e2 100644
--- a/lib/share_intent/pending_share.dart
+++ b/lib/share_intent/pending_share.dart
@@ -5,11 +5,17 @@ class PendingShare {
   final String? text;
   final DateTime receivedAt;
 
+  /// Paths as delivered by the platform, before the listener moved them into
+  /// a per-share folder. Duplicate detection compares these, since the
+  /// relocated [filePaths] differ for every delivery.
+  final List<String> sourcePaths;
+
   const PendingShare({
     required this.filePaths,
     required this.text,
     required this.receivedAt,
-  });
+    List<String>? sourcePaths,
+  }) : sourcePaths = sourcePaths ?? filePaths;
 
   bool get hasFiles => filePaths.isNotEmpty;
   bool get hasText => text != null && text!.isNotEmpty;
@@ -20,5 +26,5 @@ class PendingShare {
   /// the same share can arrive twice on the media stream — receivedAt is
   /// deliberately ignored here so such duplicates compare equal.
   bool contentEquals(PendingShare other) =>
-      text == other.text && listEquals(filePaths, other.filePaths);
+      text == other.text && listEquals(sourcePaths, other.sourcePaths);
 }
diff --git a/lib/share_intent/share_intent_listener.dart b/lib/share_intent/share_intent_listener.dart
index 27b429d..f1f355b 100644
--- a/lib/share_intent/share_intent_listener.dart
+++ b/lib/share_intent/share_intent_listener.dart
@@ -2,6 +2,8 @@ import 'dart:async';
 import 'dart:io';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+import 'package:path_provider/path_provider.dart';
 import 'package:receive_sharing_intent/receive_sharing_intent.dart';
 
 import 'pending_share.dart';
@@ -14,56 +16,63 @@ class ShareIntentListener {
 
   static final ValueNotifier<PendingShare?> pending = ValueNotifier(null);
 
-  StreamSubscription<List<SharedMediaFile>>? _streamSub;
-  bool _initialized = false;
+  static const _androidChannel = MethodChannel('eu.mhsl.marianum.share');
 
-  /// Reads the cold-start payload exactly once. Call from `main()` before
-  /// `runApp` so the share is queued before the UI mounts.
+  /// Per-share folders live below this directory name — on Android in the
+  /// cache dir (created here), on iOS in the App Group container (created by
+  /// the Share Extension).
+  static const _shareDirName = 'share_intent';
+
+  bool _initialized = false;
+  String? _cacheDir;
+
+  int _flowDepth = 0;
+  PendingShare? _queued;
+  PendingShare? _shown;
+
+  /// Subscribes to warm shares and reads the cold-start payload. Call from
+  /// `main()` before `runApp`. The subscription stays for the process
+  /// lifetime: the plugin drops shares that arrive while nobody listens
+  /// (login screen, app remount), and [pending] buffers until the UI is ready.
   Future<void> initialize() async {
     if (_initialized) return;
     _initialized = true;
     try {
-      final initial = await ReceiveSharingIntent.instance.getInitialMedia();
-      final share = _toPendingShare(initial);
-      if (share != null) _publish(share);
+      if (Platform.isAndroid) {
+        _cacheDir = (await getTemporaryDirectory()).path;
+        _sweepStaleAndroidShares();
+      }
+      ReceiveSharingIntent.instance.getMediaStream().listen(
+        _onItems,
+        onError: (Object e) => debugPrint('ShareIntentListener stream: $e'),
+      );
+      _onItems(await ReceiveSharingIntent.instance.getInitialMedia());
       await ReceiveSharingIntent.instance.reset();
+      if (Platform.isAndroid) {
+        await _androidChannel.invokeMethod<void>('listenerReady');
+      }
     } catch (e) {
       debugPrint('ShareIntentListener.initialize failed: $e');
     }
   }
 
-  /// Subscribes to warm-share stream events. Safe to call multiple times.
-  void attach() {
-    _streamSub ??= ReceiveSharingIntent.instance.getMediaStream().listen(
-      (items) {
-        final share = _toPendingShare(items);
-        if (share != null) _publish(share);
-      },
-      onError: (Object e) =>
-          debugPrint('ShareIntentListener stream error: $e'),
-    );
+  /// Whether the share flow for [share] is already on screen. Re-running the
+  /// navigation for it would pop its own page and thereby clear it.
+  bool isShown(PendingShare share) => identical(share, _shown);
+
+  void markShown(PendingShare share) => _shown = share;
+
+  /// Marks a share flow step that must not be interrupted (upload, share API
+  /// call). Shares arriving meanwhile are queued instead of replacing the
+  /// current one, whose files are still in use. Pair with [endFlow].
+  void beginFlow() => _flowDepth++;
+
+  void endFlow() {
+    if (_flowDepth > 0) _flowDepth--;
+    if (_flowDepth == 0) _drainQueue();
   }
 
-  /// The iOS Share Extension fires two `open(url)` requests per share, so the
-  /// same payload can arrive twice in quick succession. Publishing the
-  /// duplicate would re-trigger the share-flow navigation, pop the already
-  /// open ShareTargetPage and thereby delete the temp files of the share that
-  /// is still in flight — swallow it instead.
-  void _publish(PendingShare share) {
-    final current = pending.value;
-    if (current != null && current.contentEquals(share)) return;
-    pending.value = share;
-  }
-
-  /// Cancels the warm-share subscription. The singleton survives, so a
-  /// subsequent [attach] re-subscribes.
-  void detach() {
-    _streamSub?.cancel();
-    _streamSub = null;
-  }
-
-  /// Discards the current share and removes any temp files the plugin copied
-  /// into the app cache. Idempotent.
+  /// Discards the current share and deletes its temp files. Idempotent.
   ///
   /// Pass [ifCurrent] from UI that owns a specific share (e.g. the
   /// ShareTargetPage pop handler): the call then only acts while that share
@@ -73,18 +82,58 @@ class ShareIntentListener {
   void clear({PendingShare? ifCurrent}) {
     final current = pending.value;
     if (ifCurrent != null && !identical(current, ifCurrent)) return;
+    _shown = null;
     pending.value = null;
-    if (current != null) {
-      for (final path in current.filePaths) {
-        try {
-          final f = File(path);
-          if (f.existsSync()) f.deleteSync();
-        } catch (_) {
-          // best-effort cleanup; OS will reclaim cache eventually
-        }
+    if (current != null) _deleteFiles(current);
+    unawaited(ReceiveSharingIntent.instance.reset());
+    if (_flowDepth == 0) _drainQueue();
+  }
+
+  /// Drops every share, including a queued one — for sign-out.
+  void clearAll() {
+    final queued = _queued;
+    _queued = null;
+    _flowDepth = 0;
+    if (queued != null) _deleteFiles(queued);
+    clear();
+  }
+
+  void _onItems(List<SharedMediaFile> items) {
+    final share = _toPendingShare(items);
+    if (share == null) return;
+    // The iOS Share Extension opens the app twice per share, so the same
+    // payload can arrive again while it is still pending. Publishing it would
+    // re-run the navigation and pop the share that is in flight.
+    for (final live in [pending.value, _queued]) {
+      if (live != null && live.contentEquals(share)) {
+        _deleteFiles(share, keep: live.filePaths);
+        return;
       }
     }
-    unawaited(ReceiveSharingIntent.instance.reset());
+    final claimed = _claim(share);
+    if (_flowDepth > 0) {
+      final replaced = _queued;
+      _queued = claimed;
+      if (replaced != null) _deleteFiles(replaced);
+      return;
+    }
+    _replaceCurrent(claimed);
+  }
+
+  void _drainQueue() {
+    final queued = _queued;
+    if (queued == null) return;
+    _queued = null;
+    _replaceCurrent(queued);
+  }
+
+  // No flow is running, so nothing uses the previous share's files anymore;
+  // its pages are popped when the new share is routed.
+  void _replaceCurrent(PendingShare share) {
+    final previous = pending.value;
+    _shown = null;
+    pending.value = share;
+    if (previous != null) _deleteFiles(previous);
   }
 
   PendingShare? _toPendingShare(List<SharedMediaFile> items) {
@@ -96,7 +145,9 @@ class ShareIntentListener {
         case SharedMediaType.image:
         case SharedMediaType.video:
         case SharedMediaType.file:
-          files.add(item.path);
+          // A replayed share can point at temp copies deleted after the
+          // original share completed.
+          if (File(item.path).existsSync()) files.add(item.path);
         case SharedMediaType.text:
         case SharedMediaType.url:
           texts.add(item.path);
@@ -109,4 +160,77 @@ class ShareIntentListener {
       receivedAt: DateTime.now(),
     );
   }
+
+  /// The Android plugin copies shared content to `cacheDir/<display name>`,
+  /// so a second share with an equally named file would overwrite the first
+  /// one's copy. Move owned copies into a folder of their own. iOS shares
+  /// already arrive in a per-share folder.
+  PendingShare _claim(PendingShare share) {
+    final cacheDir = _cacheDir;
+    if (!Platform.isAndroid || cacheDir == null || !share.hasFiles) {
+      return share;
+    }
+    final dir = Directory(
+      '$cacheDir/$_shareDirName/${share.receivedAt.microsecondsSinceEpoch}',
+    );
+    final claimed = <String>[];
+    for (final (i, path) in share.filePaths.indexed) {
+      if (!_isOwned(path)) {
+        claimed.add(path);
+        continue;
+      }
+      try {
+        dir.createSync(recursive: true);
+        final name = path.split(Platform.pathSeparator).last;
+        var target = '${dir.path}/$name';
+        if (File(target).existsSync()) target = '${dir.path}/$i-$name';
+        claimed.add(File(path).renameSync(target).path);
+      } catch (_) {
+        claimed.add(path);
+      }
+    }
+    return PendingShare(
+      filePaths: claimed,
+      text: share.text,
+      receivedAt: share.receivedAt,
+      sourcePaths: share.sourcePaths,
+    );
+  }
+
+  /// Only temp copies are deleted: on Android the plugin hands out the real
+  /// path for some providers (e.g. a file in Downloads), which must survive.
+  bool _isOwned(String path) {
+    if (Platform.isIOS) return true;
+    final cacheDir = _cacheDir;
+    return cacheDir != null && path.startsWith('$cacheDir/');
+  }
+
+  void _deleteFiles(PendingShare share, {List<String> keep = const []}) {
+    for (final path in share.filePaths) {
+      if (keep.contains(path) || !_isOwned(path)) continue;
+      try {
+        final file = File(path);
+        if (file.existsSync()) file.deleteSync();
+        final dir = file.parent;
+        if (dir.parent.path.endsWith('/$_shareDirName') &&
+            dir.listSync().isEmpty) {
+          dir.deleteSync();
+        }
+      } catch (_) {
+        // best-effort cleanup; OS will reclaim cache eventually
+      }
+    }
+  }
+
+  // Shares whose flow never finished (process killed) leave their folder
+  // behind; the pending one of this process is not claimed yet.
+  void _sweepStaleAndroidShares() {
+    try {
+      final root = Directory('$_cacheDir/$_shareDirName');
+      if (!root.existsSync()) return;
+      root.deleteSync(recursive: true);
+    } catch (_) {
+      // best-effort
+    }
+  }
 }
diff --git a/lib/state/app/infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart b/lib/state/app/infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart
index 8fe3ffd..0234055 100644
--- a/lib/state/app/infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart
+++ b/lib/state/app/infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart
@@ -1,8 +1,11 @@
+import 'dart:async';
 import 'dart:developer';
 
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
 import '../../../../../api/errors/error_mapper.dart';
+import '../../../../../api/errors/stale_session_exception.dart';
+import '../../../../../model/account_data.dart';
 import '../../loadable_state/loadable_state.dart';
 import '../../loadable_state/loading_error.dart';
 import '../../repository/repository.dart';
@@ -114,6 +117,23 @@ abstract class LoadableHydratedBloc<
     add(Reset<TState>());
   }
 
+  static const _sessionKey = #loadableSessionEpoch;
+
+  /// Runs [body] tagged with the current session: events it adds, also from
+  /// its async continuations, are dropped once the account signed out, so a
+  /// late response of the previous account cannot refill the reset bloc.
+  R runInSession<R>(R Function() body) => runZoned(
+    body,
+    zoneValues: {_sessionKey: AccountData().sessionEpoch},
+  );
+
+  @override
+  void add(LoadableHydratedBlocEvent<TState> event) {
+    final epoch = Zone.current[_sessionKey];
+    if (epoch is int && !AccountData().isCurrentSession(epoch)) return;
+    super.add(event);
+  }
+
   TState? get innerState => state.data;
   TRepository get repo => _repository;
 
@@ -126,29 +146,35 @@ abstract class LoadableHydratedBloc<
   /// Maps [e] through the shared error mapper and emits it as an [Error] event.
   /// Does not guard [isClosed] — callers decide whether a late error still
   /// applies.
-  void addLoadingError(Object e) => add(
-    Error(
-      LoadingError(
-        message: errorToUserMessage(e),
-        technicalDetails: errorToTechnicalDetails(e),
-        allowRetry: errorAllowsRetry(e),
+  void addLoadingError(Object e) {
+    // Belongs to a signed-out account; the current one loads on its own.
+    if (e is StaleSessionException) return;
+    add(
+      Error(
+        LoadingError(
+          message: errorToUserMessage(e),
+          technicalDetails: errorToTechnicalDetails(e),
+          allowRetry: errorAllowsRetry(e),
+        ),
       ),
-    ),
-  );
+    );
+  }
 
   void fetch() {
     log('Fetching data for ${TState.toString()}');
-    gatherData()
-        .catchError((Object e) {
-          log('Error while fetching ${TState.toString()}: ${e.toString()}');
-          // The bloc may have been closed before this async error landed;
-          // adding to a closed bloc throws, so swallow that case.
-          if (isClosed) return;
-          addLoadingError(e);
-        })
-        .then((value) {
-          log('Fetch for ${TState.toString()} completed!');
-        });
+    runInSession(
+      () => gatherData()
+          .catchError((Object e) {
+            log('Error while fetching ${TState.toString()}: ${e.toString()}');
+            // The bloc may have been closed before this async error landed;
+            // adding to a closed bloc throws, so swallow that case.
+            if (isClosed) return;
+            addLoadingError(e);
+          })
+          .then((value) {
+            log('Fetch for ${TState.toString()} completed!');
+          }),
+    );
   }
 
   @override
diff --git a/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart b/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart
index 8290af6..1bc141b 100644
--- a/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart
+++ b/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart
@@ -5,6 +5,7 @@ import 'package:hydrated_bloc/hydrated_bloc.dart';
 import '../../../../../api/demo/data/demo_capabilities.dart';
 import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumconnect/queries/get_capabilities/get_capabilities.dart';
+import '../../../../../model/account_data.dart';
 import 'capabilities_state.dart';
 
 /// Holds the current user's mobile capability flags. Hydrated so the last
@@ -34,8 +35,12 @@ class CapabilitiesCubit extends HydratedCubit<CapabilitiesState> {
       emit(DemoCapabilities.state());
       return;
     }
+    final epoch = AccountData().sessionEpoch;
     try {
       final response = await GetCapabilities().run();
+      // A slow answer for the previous account must not decide the modules
+      // of the next one.
+      if (!AccountData().isCurrentSession(epoch)) return;
       emit(
         CapabilitiesState(
           viewForeignTimetables: response.viewForeignTimetables,
diff --git a/lib/state/app/modules/chat/bloc/chat_bloc.dart b/lib/state/app/modules/chat/bloc/chat_bloc.dart
index f8384b2..75dfd52 100644
--- a/lib/state/app/modules/chat/bloc/chat_bloc.dart
+++ b/lib/state/app/modules/chat/bloc/chat_bloc.dart
@@ -123,6 +123,15 @@ class ChatBloc
   /// No-op when the bloc has already moved on to a different token: when
   /// popping a stacked chat (B over A), A's didPopNext runs setToken(A)
   /// before B's dispose fires.
+  /// The chat view may still be popping when the sign-out resets this bloc,
+  /// so leaveChat would find no token and the long-poll would keep running.
+  @override
+  Future<void> reset() {
+    _chatViewActive = false;
+    _stopLongPoll();
+    return super.reset();
+  }
+
   void leaveChat(String fromToken) {
     if ((innerState?.currentToken ?? '') != fromToken) return;
     _chatViewActive = false;
diff --git a/lib/state/app/modules/chat_list/bloc/chat_list_bloc.dart b/lib/state/app/modules/chat_list/bloc/chat_list_bloc.dart
index a789254..caaa3e8 100644
--- a/lib/state/app/modules/chat_list/bloc/chat_list_bloc.dart
+++ b/lib/state/app/modules/chat_list/bloc/chat_list_bloc.dart
@@ -30,6 +30,13 @@ class ChatListBloc
     return super.close();
   }
 
+  // The timer outlives the app shell; the next shell re-arms it after login.
+  @override
+  Future<void> reset() {
+    setAutoRefreshInterval(null);
+    return super.reset();
+  }
+
   /// Silent refresh — explicit pull-to-refresh and tab-activation are non-silent.
   void setAutoRefreshInterval(Duration? interval) {
     if (interval == _autoRefreshInterval) return;
diff --git a/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart b/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart
index 6933eab..c2e34be 100644
--- a/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart
+++ b/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart
@@ -5,6 +5,7 @@ import 'package:hydrated_bloc/hydrated_bloc.dart';
 import '../../../../../api/demo/data/demo_capabilities.dart';
 import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumcloud/capabilities/get_nextcloud_capabilities.dart';
+import '../../../../../model/account_data.dart';
 import 'nextcloud_capabilities_state.dart';
 
 /// Holds the current user's Nextcloud `files_sharing` capabilities. Hydrated so
@@ -63,8 +64,12 @@ class NextcloudCapabilitiesCubit
       emit(DemoNextcloudCapabilities.state());
       return;
     }
+    final epoch = AccountData().sessionEpoch;
     try {
       final caps = await GetNextcloudCapabilities().run();
+      // A slow answer for the previous account must not decide the modules
+      // of the next one.
+      if (!AccountData().isCurrentSession(epoch)) return;
       emit(
         NextcloudCapabilitiesState(
           apiEnabled: caps.apiEnabled,
diff --git a/lib/state/app/modules/timetable/bloc/timetable_bloc.dart b/lib/state/app/modules/timetable/bloc/timetable_bloc.dart
index 8519361..e797e37 100644
--- a/lib/state/app/modules/timetable/bloc/timetable_bloc.dart
+++ b/lib/state/app/modules/timetable/bloc/timetable_bloc.dart
@@ -91,8 +91,10 @@ class TimetableBloc
     final current = innerState ?? fromNothing();
     if (current.startDate == startDate && current.endDate == endDate) return;
     add(Emit((s) => s.copyWith(startDate: startDate, endDate: endDate)));
-    _loadCurrentWeek(startDate, endDate);
-    _prefetchAdjacentWeeks(startDate, endDate);
+    runInSession(() {
+      _loadCurrentWeek(startDate, endDate);
+      _prefetchAdjacentWeeks(startDate, endDate);
+    });
   }
 
   void resetWeek() {
diff --git a/lib/view/login/login_controller.dart b/lib/view/login/login_controller.dart
index cb25b36..ee6c419 100644
--- a/lib/view/login/login_controller.dart
+++ b/lib/view/login/login_controller.dart
@@ -11,6 +11,7 @@ import '../../api/marianumconnect/auth/token_storage.dart';
 import '../../api/marianumconnect/queries/auth_login/auth_login.dart';
 import '../../api/marianumconnect/queries/auth_logout/auth_logout.dart';
 import '../../model/account_data.dart';
+import '../../model/session_wipe.dart';
 import '../../widget_data/widget_sync.dart';
 
 /// Outcome of a login attempt.
@@ -46,6 +47,10 @@ class LoginController extends ChangeNotifier {
     _errorDetails = null;
     notifyListeners();
 
+    // The previous account's wipe runs deferred; racing it would let it
+    // clear what this login stores (widget job, caches).
+    await SessionWipe.done;
+
     final user = username.trim().toLowerCase();
 
     // Demo login: the prefix enters local demo mode, password ignored, no
diff --git a/lib/view/pages/files/files_upload_dialog.dart b/lib/view/pages/files/files_upload_dialog.dart
index 95502b7..bec671f 100644
--- a/lib/view/pages/files/files_upload_dialog.dart
+++ b/lib/view/pages/files/files_upload_dialog.dart
@@ -53,15 +53,6 @@ class _FilesUploadDialogState extends State<FilesUploadDialog> {
     }).toList();
   }
 
-  void showHttpErrorCode(int httpErrorCode) {
-    InfoDialog.show(
-      context,
-      'Error code: $httpErrorCode',
-      title: 'Ein Fehler ist aufgetreten',
-      copyable: true,
-    );
-  }
-
   void _resetProgress() {
     _isUploading = false;
     _overallProgressValue = 0.0;
@@ -221,14 +212,17 @@ class _FilesUploadDialogState extends State<FilesUploadDialog> {
         return;
       }
 
+      if (!mounted) return;
+      // Stay on the dialog: popping here reported the partial result as a
+      // success to onUploadFinished and closed the error dialog right away.
       if (uploadTask.statusCode < 200 || uploadTask.statusCode > 299) {
-        setState(_resetProgress);
-        if (!mounted) return;
-        Navigator.of(context).pop();
-        showHttpErrorCode(uploadTask.statusCode);
-      } else {
-        uploadetFilePaths.add(fullRemotePath);
+        _showUploadError(
+          'Upload fehlgeschlagen für "$fileName" '
+          '(Fehlercode ${uploadTask.statusCode}).',
+        );
+        return;
       }
+      uploadetFilePaths.add(fullRemotePath);
     }
 
     setState(_resetProgress);
diff --git a/lib/view/pages/share_intent/share_chat_picker.dart b/lib/view/pages/share_intent/share_chat_picker.dart
index 905ebd9..10882a0 100644
--- a/lib/view/pages/share_intent/share_chat_picker.dart
+++ b/lib/view/pages/share_intent/share_chat_picker.dart
@@ -135,19 +135,24 @@ Future<void> _externalShareFlow(
   PendingShare share,
 ) async {
   if (share.hasFiles) {
-    await ensureTalkShareFolder();
-    if (!context.mounted) return;
-    await pushScreen(
-      context,
-      withNavBar: false,
-      screen: FilesUploadDialog(
-        filePaths: share.filePaths,
-        remotePath: talkShareFolder,
-        uniqueNames: true,
-        onUploadFinished: (uploaded) =>
-            _afterExternalFilesUploaded(context, room, uploaded, share),
-      ),
-    );
+    ShareIntentListener.instance.beginFlow();
+    try {
+      await ensureTalkShareFolder();
+      if (!context.mounted) return;
+      await pushScreen(
+        context,
+        withNavBar: false,
+        screen: FilesUploadDialog(
+          filePaths: share.filePaths,
+          remotePath: talkShareFolder,
+          uniqueNames: true,
+          onUploadFinished: (uploaded) =>
+              _afterExternalFilesUploaded(context, room, uploaded, share),
+        ),
+      );
+    } finally {
+      ShareIntentListener.instance.endFlow();
+    }
     return;
   }
   if (share.hasText) {
@@ -155,17 +160,28 @@ Future<void> _externalShareFlow(
   }
 }
 
+// Called synchronously when the upload dialog pops, so the flow is entered
+// before the upload step above releases it.
 Future<void> _afterExternalFilesUploaded(
   BuildContext context,
   GetRoomResponseObject room,
   List<String> uploadedRemotePaths,
   PendingShare share,
-) => _runShareFlow(
-  context,
-  action: () =>
-      shareFilesToChat(token: room.token, remoteFilePaths: uploadedRemotePaths),
-  onSuccess: () => _setExternalDraftAndOpenChat(context, room, share),
-);
+) async {
+  ShareIntentListener.instance.beginFlow();
+  try {
+    await _runShareFlow(
+      context,
+      action: () => shareFilesToChat(
+        token: room.token,
+        remoteFilePaths: uploadedRemotePaths,
+      ),
+      onSuccess: () => _setExternalDraftAndOpenChat(context, room, share),
+    );
+  } finally {
+    ShareIntentListener.instance.endFlow();
+  }
+}
 
 /// Shared share-flow scaffolding: shows the blocking spinner, runs [action],
 /// maps failures to an error dialog (popping the spinner first), and invokes
diff --git a/lib/view/pages/share_intent/share_folder_picker.dart b/lib/view/pages/share_intent/share_folder_picker.dart
index 1c94522..e6f5fc9 100644
--- a/lib/view/pages/share_intent/share_folder_picker.dart
+++ b/lib/view/pages/share_intent/share_folder_picker.dart
@@ -206,16 +206,21 @@ Future<void> _externalUploadFlow(
   List<String> targetPath,
   PendingShare share,
 ) async {
-  await pushScreen(
-    context,
-    withNavBar: false,
-    screen: FilesUploadDialog(
-      filePaths: share.filePaths,
-      remotePath: targetPath.join('/'),
-      onUploadFinished: (_) =>
-          _afterExternalUploaded(context, targetPath, share),
-    ),
-  );
+  ShareIntentListener.instance.beginFlow();
+  try {
+    await pushScreen(
+      context,
+      withNavBar: false,
+      screen: FilesUploadDialog(
+        filePaths: share.filePaths,
+        remotePath: targetPath.join('/'),
+        onUploadFinished: (_) =>
+            _afterExternalUploaded(context, targetPath, share),
+      ),
+    );
+  } finally {
+    ShareIntentListener.instance.endFlow();
+  }
 }
 
 void _afterExternalUploaded(
diff --git a/lib/widget_data/widget_publisher.dart b/lib/widget_data/widget_publisher.dart
index 9cac9a5..e5233f6 100644
--- a/lib/widget_data/widget_publisher.dart
+++ b/lib/widget_data/widget_publisher.dart
@@ -3,6 +3,7 @@ import 'dart:developer';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
+import '../model/account_data.dart';
 import '../state/app/modules/timetable/bloc/timetable_state.dart';
 import '../storage/settings.dart';
 import 'widget_data_mapper.dart';
@@ -24,6 +25,7 @@ class WidgetPublisher {
     Settings? settings,
     bool isTeacher = false,
   }) async {
+    final epoch = AccountData().sessionEpoch;
     try {
       final connectDouble =
           settings?.timetableSettings.connectDoubleLessons ?? true;
@@ -58,6 +60,9 @@ class WidgetPublisher {
         connectDoubleLessons: connectDouble,
         showClassInsteadOfTeacher: isTeacher,
       );
+      // A publish still running at sign-out would put the previous account's
+      // plan back onto the just cleared widget.
+      if (!AccountData().isCurrentSession(epoch)) return;
       await WidgetSync.writeDayData(dayData);
       await WidgetSync.writeWeekData(weekData);
       await WidgetSync.setLoggedIn(true);
diff --git a/test/share_intent/pending_share_test.dart b/test/share_intent/pending_share_test.dart
index 0e88987..a5e2987 100644
--- a/test/share_intent/pending_share_test.dart
+++ b/test/share_intent/pending_share_test.dart
@@ -62,5 +62,18 @@ void main() {
     test('empty shares compare equal', () {
       expect(_share().contentEquals(_share()), isTrue);
     });
+
+    test('relocated share still equals its raw delivery', () {
+      final raw = _share(filePaths: ['/cache/a.jpg']);
+      final claimed = PendingShare(
+        filePaths: ['/cache/share_intent/1/a.jpg'],
+        text: null,
+        receivedAt: DateTime(2026, 1, 1),
+        sourcePaths: raw.filePaths,
+      );
+
+      expect(claimed.contentEquals(raw), isTrue);
+      expect(raw.contentEquals(claimed), isTrue);
+    });
   });
 }