diff --git a/README.rst b/README.rst
index d8e71ef..1565de7 100755
--- a/README.rst
+++ b/README.rst
@@ -66,10 +66,47 @@ You can also provide credentials with environment variables:
 
     WEBSSH_AUTH_USERNAME=admin WEBSSH_AUTH_PASSWORD='strong-password' wssh
 
-Saved connections are stored under the data directory too. WebSSH saves
-hostname, port, username, ssh password and terminal type for quick
-reconnects. It does not persist private keys, key passphrases or TOTP
-codes.
+Saved connections are stored under the data directory too. Connection
+details include hostname, port, username, terminal type, initial directory,
+name, group and notes. Search or filter saved connections by group, and use
+the Save notes button to update metadata without reconnecting.
+
+Saving connection details and saving credentials are separate options.
+Passwords and private keys are encrypted using the server cookie secret
+only when Save password / private key is selected. Saving the private-key
+passphrase requires its own checkbox. Credentials are never returned in
+connection listings, and TOTP codes are never saved. After a successful
+connection with Save connection enabled, deselecting Save credentials
+clears the previously saved credentials for that destination.
+
+Each terminal tab owns a separate SSH session. New connection opens another
+tab; switching or closing a tab does not interrupt other sessions. Reconnect
+starts a new SSH session using saved credentials when available. Encrypted
+keys without a saved passphrase and two-factor connections require fresh
+input. To retain remote processes across disconnects, use tmux on the SSH
+server. Reloading the browser closes its live sessions.
+
+The terminal toolbar provides output search (also Ctrl/Cmd+F), fullscreen,
+font size, themes and cursor settings. Terminal preferences and single-line
+command bookmarks are stored in the current browser. Inserting a bookmark
+does not send Enter; review it and press Enter yourself.
+
+File management uses the active tab's SSH connection and requires SFTP on
+the remote server. Browse directories and upload or download regular files
+up to 16 MiB. Uploads exclusively create a new file and never overwrite an
+existing filename. A failed upload may leave a partial file. One file
+operation at a time is allowed per SSH session; other terminals remain
+usable. HTTP requests are limited to 17 MiB to allow multipart overhead.
+
+Export configuration produces JSON without credentials. Encrypted backup
+includes stored credentials protected by an independent backup password
+(at least 10 characters). Keep this password to restore on another server;
+restored credentials are encrypted using that server's cookie secret.
+Import validates the whole batch before writing, accepts at most 500
+connections and merges by host, port and username under the current user.
+Configuration imports preserve existing credentials; encrypted backup
+imports replace them for matching destinations. Connection imports do not
+change active sessions, browser settings or command bookmarks.
 
 Use ``--auth=false`` only for a trusted private deployment where another
 layer already protects access to WebSSH.
diff --git a/tests/test_app.py b/tests/test_app.py
index cccebd9..906b036 100755
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -852,6 +852,44 @@ class TestAppWithUnknownEncoding(OtherTestBase):
 
 class TestAppWithSavedConnections(OtherTestBase):
 
+    def test_connection_form_exposes_separate_credential_controls(self):
+        response = self.fetch('/')
+        self.assertIn(b'name="save_credentials" value="1">', response.body)
+        self.assertIn(b'name="save_passphrase" value="1">', response.body)
+        self.assertIn(b'id="privatekey-hint"', response.body)
+
+    @tornado.testing.gen_test
+    def test_saved_key_can_connect_without_uploading_again(self):
+        privatekey = read_file(make_tests_data_path('user_rsa_key'))
+        body = dict(self.body, password='', privatekey=privatekey,
+                    save='1', save_credentials='1')
+        response = yield self.async_post('/', body)
+        data = json.loads(to_str(response.body))
+        self.assert_status_none(data)
+        self.assertTrue(data['profile']['has_privatekey'])
+        self.assertNotIn('privatekey_enc', data['profile'])
+        response = yield self.async_get('/connections')
+        self.assertNotIn(b'privatekey_enc', response.body)
+        self.assertNotIn(to_str(privatekey).encode('utf-8'), response.body)
+        response = yield self.async_post('/', dict(self.body, password=''))
+        self.assert_status_none(json.loads(to_str(response.body)))
+        response = yield self.async_post(
+            '/', dict(self.body, password='', username='bar')
+        )
+        self.assert_status_equal(
+            'Authentication failed.', json.loads(to_str(response.body))
+        )
+
+    @tornado.testing.gen_test
+    def test_save_without_credentials_clears_saved_password(self):
+        body = dict(self.body, save='1', save_credentials='1')
+        response = yield self.async_post('/', body)
+        self.assert_status_none(json.loads(to_str(response.body)))
+        response = yield self.async_post('/', dict(self.body, save='1'))
+        data = json.loads(to_str(response.body))
+        self.assert_status_none(data)
+        self.assertFalse(data['profile']['has_password'])
+
     def async_get(self, path):
         return self.get_http_client().fetch(
             self.get_url(path), headers=self.headers
@@ -859,7 +897,7 @@ class TestAppWithSavedConnections(OtherTestBase):
 
     @tornado.testing.gen_test
     def test_saved_password_never_reaches_the_browser(self):
-        body = dict(self.body, save='1')
+        body = dict(self.body, save='1', save_credentials='1')
         response = yield self.async_post('/', body)
         data = json.loads(to_str(response.body))
         self.assert_status_none(data)
@@ -880,7 +918,7 @@ class TestAppWithSavedConnections(OtherTestBase):
 
     @tornado.testing.gen_test
     def test_saved_password_is_reused_when_the_field_is_left_empty(self):
-        body = dict(self.body, save='1')
+        body = dict(self.body, save='1', save_credentials='1')
         response = yield self.async_post('/', body)
         self.assert_status_none(json.loads(to_str(response.body)))
 
@@ -891,7 +929,7 @@ class TestAppWithSavedConnections(OtherTestBase):
 
     @tornado.testing.gen_test
     def test_saved_password_is_not_sent_to_another_destination(self):
-        body = dict(self.body, save='1')
+        body = dict(self.body, save='1', save_credentials='1')
         response = yield self.async_post('/', body)
         self.assert_status_none(json.loads(to_str(response.body)))
 
diff --git a/tests/test_handler.py b/tests/test_handler.py
index 83deb4e..473ba3c 100755
--- a/tests/test_handler.py
+++ b/tests/test_handler.py
@@ -160,6 +160,7 @@ class TestPrivateKey(unittest.TestCase):
         with self.assertRaises(InvalidValueError) as ctx:
             pk.get_pkey_obj()
         self.assertIn('wrong passphrase', str(ctx.exception))
+        self.assertNotIn('wrongpass', str(ctx.exception))
 
         pk = self.get_pk_obj(fname, password=password)
         self.assertIsInstance(pk.get_pkey_obj(), klass)
@@ -318,12 +319,41 @@ class TestWsockHandler(unittest.TestCase):
         obj.close.assert_called_with(reason='Worker closed')
 
 class TestIndexHandler(unittest.TestCase):
+    def test_saved_encrypted_key_uses_supplied_or_saved_passphrase(self):
+        privatekey = read_file(
+            make_tests_data_path('test_rsa_password.key')
+        )
+        for supplied in ('', 'television'):
+            obj = Mock(spec=IndexHandler)
+            obj.get_hostname.return_value = '127.0.0.1'
+            obj.get_port.return_value = 22
+            obj.get_value.return_value = 'root'
+            obj.get_privatekey.return_value = ('', '')
+            obj.get_saved_privatekey.return_value = (
+                privatekey, 'television' if not supplied else 'wrong'
+            )
+            obj.get_saved_password.return_value = ''
+            obj.get_directory.return_value = ''
+            obj.policy = paramiko.WarningPolicy()
+            obj.ssh_client = Mock()
+            values = {'passphrase': supplied, 'save_credentials': '1',
+                      'save_passphrase': '1'}
+            obj.get_argument.side_effect = (
+                lambda name, default=u'': values.get(name, default)
+            )
+            args = IndexHandler.get_args(obj)
+            self.assertIsInstance(args[4], paramiko.RSAKey)
+            self.assertEqual('television', obj.connection_info['passphrase'])
+            self.assertEqual('privatekey', obj.connection_info['auth_type'])
+            self.assertTrue(obj.connection_info['save_credentials'])
+
     def test_get_args_keeps_password_for_saved_connection(self):
         obj = Mock(spec=IndexHandler)
         obj.get_hostname.return_value = '127.0.0.1'
         obj.get_port.return_value = 22
         obj.get_value.return_value = 'root'
         obj.get_privatekey.return_value = ('', '')
+        obj.get_saved_privatekey.return_value = ('', '')
         obj.get_directory.return_value = ''
         obj.policy = paramiko.WarningPolicy()
         obj.ssh_client = Mock()
@@ -352,6 +382,7 @@ class TestIndexHandler(unittest.TestCase):
         obj.get_port.return_value = 22
         obj.get_value.return_value = 'root'
         obj.get_privatekey.return_value = ('', '')
+        obj.get_saved_privatekey.return_value = ('', '')
         obj.get_directory.return_value = '/var/www'
         obj.policy = paramiko.WarningPolicy()
         obj.ssh_client = Mock()
@@ -362,6 +393,21 @@ class TestIndexHandler(unittest.TestCase):
         self.assertEqual('/var/www', args[6])
         self.assertEqual('/var/www', obj.connection_info['directory'])
 
+    def test_websocket_cannot_attach_twice_to_same_worker(self):
+        obj = Mock(spec=WsockHandler)
+        obj.current_user = 'admin'
+        obj.get_client_addr.return_value = ('127.0.0.1', 1234)
+        obj.get_client_key.return_value = 'user:test-double-attach'
+        obj.get_value.return_value = 'existing'
+        active_worker = Mock(handler=Mock())
+        worker.clients['user:test-double-attach'] = {'existing': active_worker}
+        try:
+            WsockHandler.open(obj)
+            obj.close.assert_called_once_with(reason='Websocket authentication failed.')
+            active_worker.set_handler.assert_not_called()
+        finally:
+            worker.clients.pop('user:test-double-attach', None)
+
     def test_get_directory(self):
         obj = Mock(spec=IndexHandler)
         values = {}
diff --git a/tests/test_storage.py b/tests/test_storage.py
index 07049f1..915b5b4 100755
--- a/tests/test_storage.py
+++ b/tests/test_storage.py
@@ -163,6 +163,119 @@ class TestConnectionStore(unittest.TestCase):
         })
         self.assertEqual('', profile['directory'])
 
+    def test_privatekey_is_encrypted_and_never_public(self):
+        profile = self.store.upsert('admin', {
+            'hostname': 'example.com', 'username': 'root',
+            'privatekey': 'private-key-material',
+            'passphrase': 'key-passphrase', 'save_passphrase': True,
+            'auth_type': 'privatekey'
+        })
+        raw = self.read_raw()
+        self.assertNotIn('private-key-material', raw)
+        self.assertNotIn('key-passphrase', raw)
+        self.assertTrue(profile['has_privatekey'])
+        self.assertTrue(profile['has_passphrase'])
+        for public in (profile, self.store.list('admin')[0]):
+            for field in ('privatekey', 'privatekey_enc', 'passphrase',
+                          'passphrase_enc'):
+                self.assertNotIn(field, public)
+        self.assertEqual(
+            ('private-key-material', 'key-passphrase'),
+            self.store.get_privatekey('admin', profile['id'])
+        )
+        self.assertEqual(
+            ('', ''), self.store.get_privatekey('other', profile['id'])
+        )
+        other_id = self.store.make_id('admin', 'evil.example', 22, 'root')
+        self.assertEqual(('', ''),
+                         self.store.get_privatekey('admin', other_id))
+        rotated = ConnectionStore(self.filename, 'other-secret')
+        self.assertEqual(('', ''),
+                         rotated.get_privatekey('admin', profile['id']))
+
+    def test_credentials_can_be_replaced_and_cleared(self):
+        connection = {
+            'hostname': 'example.com', 'username': 'root',
+            'password': 'password-secret', 'privatekey': 'old-key',
+            'passphrase': 'key-secret', 'save_passphrase': True
+        }
+        profile = self.store.upsert('admin', connection)
+        connection.update(privatekey='new-key', save_passphrase=False)
+        self.store.upsert('admin', connection)
+        self.assertEqual(('new-key', ''),
+                         self.store.get_privatekey('admin', profile['id']))
+        connection['save_credentials'] = False
+        public = self.store.upsert('admin', connection)
+        self.assertFalse(public['has_password'])
+        self.assertFalse(public['has_privatekey'])
+        self.assertFalse(public['has_passphrase'])
+        self.assertEqual('', self.store.get_password('admin', profile['id']))
+        self.assertEqual(('', ''),
+                         self.store.get_privatekey('admin', profile['id']))
+
+    def test_privatekey_requires_encryption_secret(self):
+        store = ConnectionStore(self.filename)
+        with self.assertRaises(ValueError):
+            store.upsert('admin', {
+                'hostname': 'example.com', 'username': 'root',
+                'privatekey': 'private-key-material'
+            })
+        self.assertFalse(os.path.exists(self.filename))
+
+    def test_metadata_update_keeps_credentials_and_owner_boundary(self):
+        profile = self.store.upsert('admin', {
+            'hostname': 'example.com', 'username': 'root',
+            'password': 'secret', 'name': 'Production', 'group': 'Servers'
+        })
+        self.assertIsNone(self.store.update_metadata(
+            'other', profile['id'], {'name': 'stolen'}
+        ))
+        updated = self.store.update_metadata('admin', profile['id'], {
+            'name': 'New name', 'group': 'Testing', 'notes': 'A note'
+        })
+        self.assertEqual('New name', updated['name'])
+        self.assertEqual('secret', self.store.get_password('admin', profile['id']))
+
+    def test_plain_export_omits_credentials_and_import_preserves_them(self):
+        profile = self.store.upsert('admin', {
+            'hostname': 'example.com', 'username': 'root', 'password': 'secret'
+        })
+        exported = self.store.export_connections('admin')
+        self.assertNotIn('password', exported[0])
+        self.assertNotIn('owner', exported[0])
+        exported[0].update(name='Imported', password='injected')
+        self.store.import_connections('admin', exported)
+        self.assertEqual('secret', self.store.get_password('admin', profile['id']))
+        self.assertEqual('Imported', self.store.list('admin')[0]['name'])
+
+    def test_invalid_import_is_atomic(self):
+        with self.assertRaises(ValueError):
+            self.store.import_connections('admin', [
+                {'hostname': 'example.com', 'username': 'root', 'port': 22},
+                {'hostname': 'example.com', 'username': 'root', 'port': -1}
+            ])
+        self.assertEqual([], self.store.list('admin'))
+        with self.assertRaises(ValueError):
+            self.store.import_connections('admin', [
+                {'hostname': 'example.com', 'username': 'root', 'port': 0}
+            ])
+
+    def test_encrypted_import_reencrypts_for_destination_server(self):
+        profile = self.store.upsert('admin', {
+            'hostname': 'example.com', 'username': 'root',
+            'privatekey': 'key-material', 'passphrase': 'key-secret',
+            'save_passphrase': True
+        })
+        exported = self.store.export_connections('admin', True)
+        destination = ConnectionStore(self.filename + '.new', 'new-server')
+        destination.import_connections('new-owner', exported, True)
+        new_id = destination.make_id('new-owner', 'example.com', 22, 'root')
+        self.assertEqual(('key-material', 'key-secret'),
+                         destination.get_privatekey('new-owner', new_id))
+        with open(destination.filename, encoding='utf-8') as saved:
+            self.assertNotIn('key-material', saved.read())
+        self.assertEqual([], destination.list('admin'))
+
 
 class TestSecretBox(unittest.TestCase):
 
diff --git a/tests/test_workspace.py b/tests/test_workspace.py
new file mode 100644
index 0000000..985a4f9
--- /dev/null
+++ b/tests/test_workspace.py
@@ -0,0 +1,177 @@
+import io
+import json
+import shutil
+import stat
+import tempfile
+import threading
+import unittest
+from unittest.mock import Mock
+
+from tornado.options import options
+from tornado.testing import AsyncHTTPTestCase
+
+from webssh.main import make_app, make_handlers
+from webssh.settings import get_app_settings
+from webssh.worker import clients
+from webssh.workspace import (
+    TRANSFER_LIMIT, decrypt_backup, encrypt_backup, transfer, validate_path
+)
+
+
+class TestBackup(unittest.TestCase):
+    def test_roundtrip_wrong_password_and_tampering(self):
+        connections = [{'hostname': 'example.com', 'password': 'secret'}]
+        document = encrypt_backup(connections, 'long-backup-password')
+        self.assertNotIn('secret', json.dumps(document))
+        self.assertEqual(connections, decrypt_backup(document, 'long-backup-password'))
+        with self.assertRaises(ValueError):
+            decrypt_backup(document, 'wrong-backup-password')
+        document['data'] = document['data'][:-4] + 'AAAA'
+        with self.assertRaises(ValueError):
+            decrypt_backup(document, 'long-backup-password')
+
+    def test_short_password_is_rejected(self):
+        with self.assertRaises(ValueError):
+            encrypt_backup([], 'short')
+
+
+class TestTransfer(unittest.TestCase):
+    def make_sftp(self):
+        ssh, sftp = Mock(), Mock()
+        ssh.open_sftp.return_value = sftp
+        sftp.normalize.side_effect = lambda path: path
+        return ssh, sftp
+
+    def test_list_sorts_directories_before_files(self):
+        ssh, sftp = self.make_sftp()
+        sftp.listdir_iter.return_value = [
+            Mock(filename='file', st_mode=stat.S_IFREG, st_size=10, st_mtime=0),
+            Mock(filename='dir', st_mode=stat.S_IFDIR, st_size=0, st_mtime=0)
+        ]
+        result = transfer(ssh, 'list', '/home')
+        self.assertEqual(['dir', 'file'], [item['name'] for item in result['entries']])
+        sftp.close.assert_called_once()
+        sftp.get_channel().settimeout.assert_called_once_with(30)
+
+    def test_upload_is_exclusive_and_rejects_path_in_filename(self):
+        ssh, sftp = self.make_sftp()
+        remote = Mock()
+        sftp.open.return_value.__enter__ = Mock(return_value=remote)
+        sftp.open.return_value.__exit__ = Mock(return_value=False)
+        transfer(ssh, 'upload', '/home', ('file.txt', b'content'))
+        sftp.open.assert_called_once_with('/home/file.txt', 'wx')
+        remote.write.assert_called_once_with(b'content')
+        for filename in ('../secret', 'a/b', 'a\\b', '..'):
+            with self.assertRaises(ValueError):
+                transfer(ssh, 'upload', '/home', (filename, b'content'))
+
+    def test_download_enforces_size_and_regular_file(self):
+        ssh, sftp = self.make_sftp()
+        sftp.stat.return_value = Mock(st_mode=stat.S_IFREG, st_size=3)
+        sftp.open.return_value = io.BytesIO(b'abc')
+        self.assertEqual(b'abc', transfer(ssh, 'download', '/home/file'))
+        sftp.stat.return_value.st_size = TRANSFER_LIMIT + 1
+        with self.assertRaises(ValueError):
+            transfer(ssh, 'download', '/home/file')
+        sftp.stat.return_value = Mock(st_mode=stat.S_IFDIR, st_size=0)
+        with self.assertRaises(ValueError):
+            transfer(ssh, 'download', '/home')
+
+    def test_sftp_is_closed_when_upload_fails(self):
+        ssh, sftp = self.make_sftp()
+        sftp.open.side_effect = OSError('Already exists')
+        with self.assertRaises(OSError):
+            transfer(ssh, 'upload', '/home', ('existing', b'new'))
+        sftp.close.assert_called_once()
+
+    def test_paths_reject_control_characters(self):
+        for path in ('a\x00b', 'a\nb', 'x' * 4097):
+            with self.assertRaises(ValueError):
+                validate_path(path)
+
+
+class TestWorkspaceAPI(AsyncHTTPTestCase):
+    def setUp(self):
+        self.tmpdir = tempfile.mkdtemp()
+        super(TestWorkspaceAPI, self).setUp()
+        self.store = self._app.settings['connection_store']
+
+    def tearDown(self):
+        clients.pop('user:admin', None)
+        super(TestWorkspaceAPI, self).tearDown()
+        shutil.rmtree(self.tmpdir)
+
+    def get_app(self):
+        options.auth = True
+        options.auth_username = 'admin'
+        options.auth_password = 'login-password'
+        options.auth_password_hash = ''
+        options.auth_session_days = 7
+        options.data_dir = self.tmpdir
+        options.debug = False
+        options.xsrf = True
+        options.policy = 'warning'
+        options.hostfile = options.syshostfile = options.tdstream = ''
+        options.origin = 'same'
+        return make_app(make_handlers(self.io_loop, options), get_app_settings(options))
+
+    def headers(self):
+        from tornado.web import create_signed_value
+        cookie = create_signed_value(self._app.settings['cookie_secret'], 'webssh_user', 'admin')
+        return {'Cookie': 'webssh_user=' + cookie.decode('utf-8') + '; _xsrf=token',
+                'X-XSRFToken': 'token', 'Content-Type': 'application/json'}
+
+    def post_json(self, path, data, headers=None):
+        return self.fetch(path, method='POST', body=json.dumps(data),
+                          headers=headers or self.headers(), follow_redirects=False)
+
+    def test_plain_export_and_metadata_keep_password_private(self):
+        profile = self.store.upsert('admin', {'hostname': 'example.com', 'username': 'root', 'password': 'secret'})
+        response = self.post_json('/connections/' + profile['id'] + '/metadata', {'name': 'Production'})
+        self.assertEqual(200, response.code)
+        self.assertNotIn(b'password_enc', response.body)
+        response = self.post_json('/connections/export', {})
+        self.assertEqual(200, response.code)
+        self.assertNotIn(b'secret', response.body)
+        self.assertEqual('Production', json.loads(response.body)['connections'][0]['name'])
+
+    def test_backup_is_encrypted_and_can_restore(self):
+        self.store.upsert('admin', {'hostname': 'example.com', 'username': 'root', 'privatekey': 'key-material'})
+        response = self.post_json('/connections/export', {'credentials': True, 'password': 'long-backup-password'})
+        self.assertEqual(200, response.code)
+        self.assertNotIn(b'key-material', response.body)
+        document = json.loads(response.body)
+        response = self.post_json('/connections/import', {'document': document, 'password': 'wrong-password'})
+        self.assertEqual(400, response.code)
+        response = self.post_json('/connections/import', {'document': document, 'password': 'long-backup-password'})
+        self.assertEqual(200, response.code)
+        self.assertNotIn(b'privatekey_enc', response.body)
+
+    def test_private_routes_require_login_and_xsrf_and_same_origin(self):
+        for path in ('/connections/export', '/connections/import'):
+            response = self.post_json(path, {}, {'Content-Type': 'application/json', 'Cookie': '_xsrf=token', 'X-XSRFToken': 'token'})
+            self.assertEqual(403, response.code)
+        headers = self.headers()
+        headers.pop('X-XSRFToken')
+        self.assertEqual(403, self.post_json('/connections/export', {}, headers).code)
+        headers = self.headers()
+        headers['Origin'] = 'https://other.example'
+        self.assertEqual(403, self.post_json('/connections/export', {}, headers).code)
+
+    def test_file_worker_is_scoped_to_user_and_rejects_busy_sessions(self):
+        response = self.fetch('/files/not-owned', headers=self.headers())
+        self.assertEqual(409, response.code)
+        worker = Mock(closed=False, handler=Mock(), file_lock=threading.Lock())
+        worker.file_lock.acquire()
+        clients['user:admin'] = {'busy': worker}
+        response = self.fetch('/files/busy', headers=self.headers())
+        self.assertEqual(409, response.code)
+        worker.file_lock.release()
+
+    def test_workspace_controls_are_present(self):
+        response = self.fetch('/', headers=self.headers())
+        for element in ('session-tabs', 'terminal-search', 'terminal-theme',
+                        'command-list', 'files-panel', 'import-config',
+                        'connection-search', 'connection-group'):
+            self.assertIn(('id="' + element + '"').encode('utf-8'), response.body)
+        self.assertIn(b'workspace.js', response.body)
diff --git a/webssh/handler.py b/webssh/handler.py
index 66d19ca..76e952f 100755
--- a/webssh/handler.py
+++ b/webssh/handler.py
@@ -255,8 +255,7 @@ class PrivateKey(object):
         logging.error(str(self.last_exception))
         msg = 'Invalid key'
         if self.password:
-            msg += ' or wrong passphrase "{}" for decrypting it.'.format(
-                    self.password)
+            msg += ' or wrong passphrase for decrypting it.'
         raise InvalidValueError(msg)
 
 
@@ -668,6 +667,11 @@ class IndexHandler(MixinHandler, tornado.web.RequestHandler):
         directory = self.get_directory()
 
         if not password and not privatekey:
+            privatekey, saved_passphrase = self.get_saved_privatekey(
+                hostname, port, username
+            )
+            if privatekey:
+                passphrase = passphrase or saved_passphrase
             password = self.get_saved_password(hostname, port, username)
 
         if isinstance(self.policy, paramiko.RejectPolicy):
@@ -685,14 +689,35 @@ class IndexHandler(MixinHandler, tornado.web.RequestHandler):
             'port': port,
             'username': username,
             'password': password,
+            'privatekey': privatekey,
+            'passphrase': passphrase,
+            'requires_totp': bool(totp),
+            'save_credentials': self.get_argument(
+                'save_credentials', u''
+            ) == '1',
+            'save_passphrase': self.get_argument(
+                'save_passphrase', u''
+            ) == '1',
             'term': term,
             'directory': directory,
+            'name': self.get_argument('name', u''),
+            'group': self.get_argument('group', u''),
+            'notes': self.get_argument('notes', u''),
             'auth_type': 'privatekey' if privatekey else 'password'
         }
-        logging.debug(args[:5])
+        logging.debug('SSH destination: %s:%s', hostname, port)
 
         return args
 
+    def get_saved_privatekey(self, hostname, port, username):
+        store = self.connection_store
+        if not store:
+            return u'', u''
+        profile_id = store.make_id(
+            self.current_user, hostname, port, username
+        )
+        return store.get_privatekey(self.current_user, profile_id)
+
     def parse_encoding(self, data):
         try:
             encoding = to_str(data.strip(), 'ascii')
@@ -894,8 +919,7 @@ class WsockHandler(MixinHandler, tornado.websocket.WebSocketHandler):
             self.close(reason=str(exc))
         else:
             worker = workers.get(worker_id)
-            if worker:
-                workers[worker_id] = None
+            if worker and not worker.handler:
                 self.set_nodelay(True)
                 worker.set_handler(self)
                 self.worker_ref = weakref.ref(worker)
@@ -904,7 +928,7 @@ class WsockHandler(MixinHandler, tornado.websocket.WebSocketHandler):
                 self.close(reason='Websocket authentication failed.')
 
     def on_message(self, message):
-        logging.debug('{!r} from {}:{}'.format(message, *self.src_addr))
+        logging.debug('Websocket message from %s:%s', *self.src_addr)
         worker = self.worker_ref()
         if not worker:
             # The worker has likely been closed. Do not process.
diff --git a/webssh/main.py b/webssh/main.py
index 261df4d..810ec26 100755
--- a/webssh/main.py
+++ b/webssh/main.py
@@ -12,6 +12,10 @@ from webssh.settings import (
     get_app_settings,  get_host_keys_settings, get_policy_setting,
     get_ssl_context, get_server_settings, check_encoding_setting
 )
+from webssh.workspace import (
+    ConnectionMetadataHandler, ConnectionExportHandler,
+    ConnectionImportHandler, FilesHandler
+)
 
 
 def make_handlers(loop, options):
@@ -22,7 +26,11 @@ def make_handlers(loop, options):
         (r'/login', LoginHandler),
         (r'/logout', LogoutHandler),
         (r'/connections', ConnectionsHandler),
+        (r'/connections/export', ConnectionExportHandler),
+        (r'/connections/import', ConnectionImportHandler),
+        (r'/connections/([a-f0-9]{24})/metadata', ConnectionMetadataHandler),
         (r'/connections/([a-f0-9]{24})', ConnectionHandler),
+        (r'/files/([A-Za-z0-9_-]+)', FilesHandler),
         (r'/', IndexHandler, dict(loop=loop, policy=policy,
                                   host_keys_settings=host_keys_settings)),
         (r'/ws', WsockHandler, dict(loop=loop))
diff --git a/webssh/settings.py b/webssh/settings.py
index 41c3883..c99af78 100755
--- a/webssh/settings.py
+++ b/webssh/settings.py
@@ -78,7 +78,7 @@ define('version', type=bool, help='Show version information',
 
 base_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 font_dirs = ['webssh', 'static', 'css', 'fonts']
-max_body_size = 1 * 1024 * 1024
+max_body_size = 17 * 1024 * 1024
 
 
 class Font(object):
diff --git a/webssh/static/css/app.css b/webssh/static/css/app.css
index f538a3a..af3057a 100755
--- a/webssh/static/css/app.css
+++ b/webssh/static/css/app.css
@@ -216,9 +216,85 @@ input[type="file"].form-control {
 
 .save-field {
   display: flex;
-  align-items: end;
+  flex-direction: column;
+  align-items: flex-start;
 }
 
+[hidden] { display: none !important; }
+.password-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 400;
+  display: grid;
+  place-items: center;
+  background: rgba(15, 23, 32, 0.55);
+}
+.password-card {
+  width: min(420px, calc(100% - 32px));
+  padding: 24px;
+  background: var(--surface);
+  border-radius: 8px;
+  box-shadow: var(--shadow);
+}
+
+#connection-search, #connection-group { margin-bottom: 10px; }
+
+.workspace-toolbar, #session-tabs, .tool-panel {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 8px;
+  padding: 10px;
+  background: var(--surface-soft);
+  border: 1px solid var(--line);
+}
+
+#session-tabs { flex-wrap: nowrap; overflow-x: auto; }
+.workspace-toolbar button, #session-tabs button, .tool-panel button {
+  padding: 8px 12px;
+  min-height: 38px;
+  color: var(--text);
+  background: var(--surface);
+  border: 1px solid var(--line);
+  border-radius: 6px;
+  cursor: pointer;
+}
+#session-tabs button { flex-shrink: 0; }
+#session-tabs button[aria-selected="true"] {
+  color: white;
+  background: var(--brand-dark);
+}
+.tool-panel input:not([type="checkbox"]), .tool-panel select, .tool-panel textarea {
+  max-width: 100%;
+  min-height: 38px;
+  padding: 7px;
+  border: 1px solid var(--line);
+  border-radius: 6px;
+}
+.tool-panel label { margin: 0; }
+.tool-panel small { flex-basis: 100%; color: var(--muted); }
+#command-text { flex: 1; min-width: 200px; }
+#file-list { flex-basis: 100%; max-height: 250px; overflow: auto; }
+#file-list .file-entry { display: block; width: 100%; text-align: left; overflow-wrap: anywhere; }
+.session-terminal { height: 65vh; min-height: 260px; padding: 8px; background: #0f1720; }
+.session-terminal .xterm { height: 100%; }
+#workspace { padding-bottom: 60px; }
+#workspace.workspace-fullscreen {
+  position: fixed;
+  inset: 0 0 46px;
+  inset: 0 0 calc(46px + env(safe-area-inset-bottom));
+  z-index: 255;
+  width: 100%;
+  margin: 0;
+  padding: 0;
+  display: flex;
+  flex-direction: column;
+  background: var(--surface);
+}
+.workspace-fullscreen #session-tools { flex: 0 0 auto; max-height: 55%; overflow: auto; }
+.workspace-fullscreen #terminal { flex: 1; min-height: 0; }
+.workspace-fullscreen .session-terminal { height: 100%; min-height: 0; }
+
 .save-toggle {
   display: inline-flex;
   gap: 10px;
diff --git a/webssh/static/js/main.js b/webssh/static/js/main.js
index 3fc53ef..6c51446 100755
--- a/webssh/static/js/main.js
+++ b/webssh/static/js/main.js
@@ -71,6 +71,7 @@ jQuery(function($){
       saved_connections = [],
       saved_connection_map = {},
       validated_form_data,
+      pending_connection,
       event_origin,
       hostname_tester = /((^\s*((([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]))\s*$)|(^\s*((([0-9A-Fa-f]{1,4}:){7}([0-9A-Fa-f]{1,4}|:))|(([0-9A-Fa-f]{1,4}:){6}(:[0-9A-Fa-f]{1,4}|((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){5}(((:[0-9A-Fa-f]{1,4}){1,2})|:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){4}(((:[0-9A-Fa-f]{1,4}){1,3})|((:[0-9A-Fa-f]{1,4})?:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){3}(((:[0-9A-Fa-f]{1,4}){1,4})|((:[0-9A-Fa-f]{1,4}){0,2}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){2}(((:[0-9A-Fa-f]{1,4}){1,5})|((:[0-9A-Fa-f]{1,4}){0,3}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){1}(((:[0-9A-Fa-f]{1,4}){1,6})|((:[0-9A-Fa-f]{1,4}){0,4}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(:(((:[0-9A-Fa-f]{1,4}){1,7})|((:[0-9A-Fa-f]{1,4}){0,5}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:)))(%.+)?\s*$))|(^\s*((?=.{1,255}$)(?=.*[A-Za-z].*)[0-9A-Za-z](?:(?:[0-9A-Za-z]|\b-){0,61}[0-9A-Za-z])?(?:\.[0-9A-Za-z](?:(?:[0-9A-Za-z]|\b-){0,61}[0-9A-Za-z])?)*)\s*$)/;
 
@@ -116,6 +117,13 @@ jQuery(function($){
       profile = saved_connections[i];
       saved_connection_map[profile.id] = profile;
     }
+    var group = $('#connection-group').val(), groups = [];
+    $('#connection-group').empty().append($('<option>').val('').text('全部分组'));
+    saved_connections.forEach(function(profile) {
+      if (profile.group && groups.indexOf(profile.group) < 0) { groups.push(profile.group); }
+    });
+    groups.sort().forEach(function(value) { $('#connection-group').append($('<option>').val(value).text(value)); });
+    $('#connection-group').val(groups.indexOf(group) >= 0 ? group : '');
     render_saved_connections();
   }
 
@@ -130,7 +138,10 @@ jQuery(function($){
 
     for (i = 0; i < saved_connections.length; i++) {
       profile = saved_connections[i];
-      option = $('<option>').val(profile.id).text(profile.title);
+      var query = ($('#connection-search').val() || '').toLowerCase(), group = $('#connection-group').val();
+      if ((group && profile.group !== group) ||
+          [profile.name, profile.group, profile.notes, profile.title].join(' ').toLowerCase().indexOf(query) < 0) { continue; }
+      option = $('<option>').val(profile.id).text((profile.group ? '[' + profile.group + '] ' : '') + (profile.name || profile.title));
       saved_connections_select.append(option);
     }
 
@@ -160,7 +171,9 @@ jQuery(function($){
     }
 
     saved_connection_map[profile.id] = profile;
+    set_saved_connections(saved_connections);
     render_saved_connections(profile.id);
+    update_saved_key_hint(profile);
   }
 
 
@@ -198,6 +211,7 @@ jQuery(function($){
     var profile = selected_connection();
     if (!profile) {
       apply_saved_password_hint(false);
+      update_saved_key_hint(null);
       return;
     }
 
@@ -208,12 +222,31 @@ jQuery(function($){
     $('#passphrase').val('');
     $('#totp').val('');
     $('#directory').val(profile.directory || '');
+    $('#connection-name').val(profile.name || '');
+    $('#connection-group-name').val(profile.group || '');
+    $('#connection-notes').val(profile.notes || '');
     term_type.val(profile.term || 'xterm-256color');
     apply_saved_password_hint(profile.has_password);
+    $('#save-credentials').prop(
+      'checked', !!(profile.has_password || profile.has_privatekey)
+    );
+    $('#save-passphrase').prop('checked', !!profile.has_passphrase);
+    update_saved_key_hint(profile);
     status.text('');
   }
 
 
+  function update_saved_key_hint(profile) {
+    $('#privatekey-hint').text(
+      profile && profile.has_privatekey ?
+      '已保存私钥，无需上传；上传新文件可替换' : ''
+    );
+    $('#passphrase').attr('placeholder',
+      profile && profile.has_passphrase ? '已保存口令，留空即可使用' : ''
+    );
+  }
+
+
   function apply_saved_password_hint(has_password) {
     // the server never sends saved passwords to the browser; an empty
     // field just tells it to use the one it already has on disk
@@ -243,6 +276,8 @@ jQuery(function($){
             return item.id !== profile.id;
           })
         );
+        apply_saved_password_hint(false);
+        update_saved_key_hint(null);
       },
       error: function(resp) {
         log_status(resp.status + ': ' + resp.statusText);
@@ -579,6 +614,7 @@ jQuery(function($){
 
   function log_status(text, to_populate) {
     text = translate_status(text);
+    if (to_populate) { $('#workspace').removeClass('workspace-fullscreen'); }
     if (text) {
       console.log(text);
     }
@@ -657,362 +693,58 @@ jQuery(function($){
 
   function ajax_complete_callback(resp) {
     button.prop('disabled', false);
-
-    if (resp.status !== 200) {
-      log_status(resp.status + ': ' + resp.statusText, true);
-      state = DISCONNECTED;
-      return;
-    }
-
+    state = DISCONNECTED;
+    waiter.hide();
     var msg = resp.responseJSON;
-    if (!msg.id) {
-      log_status(msg.status, true);
-      state = DISCONNECTED;
+    if (resp.status !== 200 || !msg || !msg.id) {
+      log_status(msg && msg.status || resp.status + ': ' + resp.statusText, true);
       return;
     }
-
-    if (msg.profile) {
-      upsert_saved_connection(msg.profile);
-    }
-
-    var ws_url = window.location.href.split(/\?|#/, 1)[0].replace('http', 'ws'),
-        join = (ws_url[ws_url.length-1] === '/' ? '' : '/'),
-        url = ws_url + join + 'ws?id=' + msg.id,
-        sock = new window.WebSocket(url),
-        encoding = 'utf-8',
-        decoder = window.TextDecoder ? new window.TextDecoder(encoding) : encoding,
-        terminal = document.getElementById('terminal'),
-        termOptions = {
-          cursorBlink: true,
-          theme: {
-            background: url_opts_data.bgcolor || '#0f1720',
-            foreground: url_opts_data.fontcolor || '#d9f1ee',
-            cursor: url_opts_data.cursor || url_opts_data.fontcolor || '#55c7ba'
+    if (msg.profile) { upsert_saved_connection(msg.profile); }
+    status.text('');
+    wssh.workspace.create(msg, pending_connection || {}, $.extend({}, url_opts_data), {
+      toast: show_terminal_toast, translate: translate_status,
+      copy: copy_text_to_clipboard, clipboard: read_clipboard_text,
+      font: update_font_family,
+      reconnect: function(connection) {
+        $('#workspace').removeClass('workspace-fullscreen');
+        $('#hostname').val(connection.hostname);
+        $('#port').val(connection.port);
+        $('#username').val(connection.username);
+        $('#directory').val(connection.directory || '');
+        $('#connection-name').val(connection.name || '');
+        $('#connection-group-name').val(connection.group || '');
+        $('#connection-notes').val(connection.notes || '');
+        $('#password, #privatekey, #passphrase, #totp').val('');
+        var id, profile;
+        for (id in saved_connection_map) {
+          profile = saved_connection_map[id];
+          if (profile.hostname === connection.hostname &&
+              Number(profile.port) === Number(connection.port || 22) &&
+              profile.username === connection.username) {
+            saved_connections_select.val(profile.id);
+            $('#connection-search').val('');
+            $('#connection-group').val('');
+            render_saved_connections(profile.id);
+            apply_saved_connection();
+            if (!profile.requires_totp && (profile.has_password ||
+                (profile.has_privatekey && (!profile.key_requires_passphrase || profile.has_passphrase)))) {
+              connect();
+            } else {
+              form_container.show();
+              log_status('连接已载入，可直接连接；加密私钥需补充口令，双因素认证需填写验证码。');
+            }
+            return;
           }
-        };
-
-    if (url_opts_data.fontsize) {
-      var fontsize = window.parseInt(url_opts_data.fontsize);
-      if (fontsize && fontsize > 0) {
-        termOptions.fontSize = fontsize;
-      }
-    }
-
-    clear_terminal();
-    var term = new window.Terminal(termOptions);
-    current_terminal = term;
-
-    term.fitAddon = new window.FitAddon.FitAddon();
-    term.loadAddon(term.fitAddon);
-
-    console.log(url);
-    if (!msg.encoding) {
-      console.log('无法检测服务器默认编码');
-      msg.encoding = encoding;
-    } else {
-      console.log('服务器默认编码是 ' + msg.encoding);
-    }
-
-    function term_write(text) {
-      if (term) {
-        term.write(text);
-        if (!term.resized) {
-          resize_terminal(term);
-          term.resized = true;
         }
-      }
-    }
-
-    function set_encoding(new_encoding) {
-      // for console use
-      if (!new_encoding) {
-        console.log('请提供编码名称');
-        return;
-      }
-
-      if (!window.TextDecoder) {
-        decoder = new_encoding;
-        encoding = decoder;
-        console.log('已将编码设置为 ' + encoding);
-      } else {
-        try {
-          decoder = new window.TextDecoder(new_encoding);
-          encoding = decoder.encoding;
-          console.log('已将编码设置为 ' + encoding);
-        } catch (RangeError) {
-          console.log('未知编码 ' + new_encoding);
-          return false;
-        }
-      }
-    }
-
-    wssh.set_encoding = set_encoding;
-
-    if (url_opts_data.encoding) {
-      if (set_encoding(url_opts_data.encoding) === false) {
-        set_encoding(msg.encoding);
-      }
-    } else {
-      set_encoding(msg.encoding);
-    }
-
-
-    wssh.geometry = function() {
-      // for console use
-      var geometry = current_geometry(term);
-      console.log('当前终端尺寸：' + JSON.stringify(geometry));
-    };
-
-    wssh.send = function(data) {
-      // for console use
-      if (!sock) {
-        console.log('WebSocket 已关闭');
-        return;
-      }
-
-      if (typeof data !== 'string') {
-        console.log('只允许发送字符串');
-        return;
-      }
-
-      try {
-        JSON.parse(data);
-        sock.send(data);
-      } catch (SyntaxError) {
-        data = data.trim() + '\r';
-        sock.send(JSON.stringify({'data': data}));
-      }
-    };
-
-    wssh.reset_encoding = function() {
-      // for console use
-      if (encoding === msg.encoding) {
-        console.log('已经恢复为 ' + msg.encoding);
-      } else {
-        set_encoding(msg.encoding);
-      }
-    };
-
-    wssh.resize = function(cols, rows) {
-      // for console use
-      if (term === undefined) {
-        console.log('终端已经关闭');
-        return;
-      }
-
-      var valid_args = false;
-
-      if (cols > 0 && rows > 0)  {
-        var geometry = current_geometry(term);
-        if (cols <= geometry.cols && rows <= geometry.rows) {
-          valid_args = true;
-        }
-      }
-
-      if (!valid_args) {
-        console.log('无法调整终端尺寸为：' + format_geometry(cols, rows));
-      } else {
-        term.on_resize(cols, rows);
-      }
-    };
-
-    wssh.set_bgcolor = function(color) {
-      set_backgound_color(term, color);
-    };
-
-    wssh.set_fontcolor = function(color) {
-      set_font_color(term, color);
-    };
-
-    wssh.custom_font = function() {
-      update_font_family(term);
-    };
-
-    wssh.default_font = function() {
-      reset_font_family(term);
-    };
-
-    term.on_resize = function(cols, rows) {
-      if (cols !== this.cols || rows !== this.rows) {
-        console.log('正在调整终端尺寸为：' + format_geometry(cols, rows));
-        this.resize(cols, rows);
-        sock.send(JSON.stringify({'resize': [cols, rows]}));
-      }
-    };
-
-    term.onData(function(data) {
-      // console.log(data);
-      sock.send(JSON.stringify({'data': data}));
-    });
-
-    function send_data(data) {
-      if (sock && sock.readyState === window.WebSocket.OPEN) {
-        sock.send(JSON.stringify({'data': data}));
-      }
-    }
-
-    function copy_terminal_selection() {
-      if (!term || !term.hasSelection()) {
-        return false;
-      }
-
-      var selection = term.getSelection();
-      copy_text_to_clipboard(selection, function(copied) {
-        if (copied && term) {
-          term.clearSelection();
-        }
-        if (term) {
-          term.focus();
-        }
-        show_terminal_toast(copied ? '已复制' : '复制失败');
-      });
-      return true;
-    }
-
-    function paste_into_terminal(show_unavailable) {
-      var started = read_clipboard_text(
-        function(text) {
-          if (text && term) {
-            // Let xterm normalize newlines and honor bracketed-paste mode.
-            term.paste(text);
-            term.focus();
-          }
-        },
-        function() {
-          show_terminal_toast('剪贴板权限被拒绝，请使用 Ctrl+V 粘贴');
-        }
-      );
-      if (!started && show_unavailable !== false) {
-        show_terminal_toast('浏览器不支持直接读取剪贴板，请使用 Ctrl+V');
-      }
-      return started;
-    }
-
-    term.attachCustomKeyEventHandler(function(e) {
-      if (e.type !== 'keydown') {
-        return true;
-      }
-
-      var key = e.key ? e.key.toLowerCase() : '';
-
-      // Ctrl+Shift+C / Cmd+C: copy the active terminal selection.
-      if (((e.ctrlKey && e.shiftKey) || e.metaKey) && key === 'c' &&
-          term.hasSelection()) {
-        e.preventDefault();
-        copy_terminal_selection();
-        return false;
-      }
-
-      // Do not let xterm translate Ctrl/Cmd+V into a control character. By
-      // returning false without preventDefault, the browser can dispatch its
-      // trusted paste event to xterm's hidden textarea. This works without the
-      // async Clipboard API and therefore also works on plain HTTP deployments.
-      if ((e.ctrlKey || e.metaKey) && !e.altKey && key === 'v') {
-        return false;
-      }
-      // Ctrl+C with an active selection copies instead of sending SIGINT
-      if (e.ctrlKey && !e.shiftKey && !e.altKey && key === 'c' &&
-          term.hasSelection()) {
-        e.preventDefault();
-        copy_terminal_selection();
-        return false;
-      }
-      return true;
-    });
-
-    // Right click: copy the selection if there is one, otherwise paste. When
-    // programmatic clipboard reads are unavailable, keep the native context
-    // menu so the browser's Paste command remains usable.
-    $('#terminal').off('contextmenu.wssh').on('contextmenu.wssh', function(e) {
-      if (!term) {
-        return;
-      }
-      if (term.hasSelection()) {
-        e.preventDefault();
-        copy_terminal_selection();
-      } else if (paste_into_terminal(false)) {
-        e.preventDefault();
-      } else {
-        show_terminal_toast('请从右键菜单选择粘贴，或使用 Ctrl+V');
-      }
-    });
-
-    // Keep terminal focus (and selection) when pressing quickbar buttons
-    quickbar.off('mousedown.wssh').on('mousedown.wssh', '.quickbar-btn',
-      function(e) {
-        e.preventDefault();
-      }
-    );
-
-    quickbar.off('click.wssh').on('click.wssh', '.quickbar-btn', function(e) {
-      var btn = $(this),
-          action = btn.attr('data-action'),
-          key = btn.attr('data-key'),
-          named_keys = {'ctrl-c': '\x03', 'tab': '\t', 'esc': '\x1b'};
-
-      e.preventDefault();
-
-      if (action === 'copy') {
-        if (!copy_terminal_selection()) {
-          show_terminal_toast('请先选中要复制的内容');
-        }
-      } else if (action === 'paste') {
-        paste_into_terminal();
-      } else if (key) {
-        send_data(named_keys[key] || key);
-      }
-
-      if (term) {
-        term.focus();
-      }
-    });
-
-    sock.onopen = function() {
-      term.open(terminal);
-      quickbar.show();
-      $('body').addClass('quickbar-open');
-      toggle_fullscreen(term);
-      update_font_family(term);
-      term.focus();
-      state = CONNECTED;
-      title_element.text = url_opts_data.title || default_title;
-      if (url_opts_data.command) {
-        setTimeout(function () {
-          sock.send(JSON.stringify({'data': url_opts_data.command+'\r'}));
-        }, 500);
-      }
-    };
-
-    sock.onmessage = function(msg) {
-      read_file_as_text(msg.data, term_write, decoder);
-    };
-
-    sock.onerror = function(e) {
-      console.error(e);
-    };
-
-    sock.onclose = function(e) {
-      var reason = write_disconnect_message(term, e.reason);
-
-      $('#terminal').removeClass('terminal-fullscreen');
-      quickbar.hide();
-      $('body').removeClass('quickbar-open');
-      sock = undefined;
-      reset_wssh();
-      log_status(reason, true);
-      term = undefined;
-      state = DISCONNECTED;
-      default_title = 'WebSSH';
-      title_element.text = default_title;
-    };
-
-    // namespaced so reconnecting replaces the handler instead of stacking
-    // another one on top of it
-    $(window).off('resize.wssh').on('resize.wssh', function(){
-      if (term) {
-        resize_terminal(term);
+        form_container.show();
+        log_status('请补充密码、私钥或动态验证码后连接。');
       }
     });
+    delete url_opts_data.command;
+    $('#password, #privatekey, #passphrase, #totp').val('');
+    validated_form_data = undefined;
+    pending_connection = undefined;
   }
 
 
@@ -1161,6 +893,7 @@ jQuery(function($){
     if (pk && pk.size && !debug) {
       read_file_as_text(pk, function(text) {
         if (text === undefined) {
+            state = DISCONNECTED;
             log_status('私钥文件无效：' + pk.name);
         } else {
           ajax_post();
@@ -1210,7 +943,7 @@ jQuery(function($){
     // for console use
     var result, opts;
 
-    if (state !== DISCONNECTED) {
+    if (state === CONNECTING) {
       console.log(messages[state]);
       return;
     }
@@ -1236,7 +969,12 @@ jQuery(function($){
       result = connect_with_options(opts);
     }
 
-    if (result) {
+    if (result && result.valid) {
+      pending_connection = {};
+      ['hostname', 'port', 'username', 'directory', 'term', 'name', 'group', 'notes'].forEach(function(key) {
+        pending_connection[key] = result.data.get(key) || '';
+      });
+      pending_connection.requires_totp = !!result.data.get('totp');
       state = CONNECTING;
       default_title = result.title;
       if (hostname) {
@@ -1258,9 +996,24 @@ jQuery(function($){
       update_password_visibility();
       saved_connections_select.val('');
       apply_saved_password_hint(false);
+      update_saved_key_hint(null);
     }, 0);
   });
 
+  $('#connection-search').on('input', function() { render_saved_connections(saved_connections_select.val()); });
+  $('#connection-group').on('change', function() { render_saved_connections(); });
+  wssh.refresh_connections = function(connections) { set_saved_connections(connections); };
+  $('#edit-connection').on('click', function() {
+    var profile = selected_connection();
+    if (!profile) { log_status('请先选择连接。'); return; }
+    $.ajax({url: 'connections/' + profile.id + '/metadata', type: 'POST',
+      contentType: 'application/json', headers: {'X-XSRFToken': get_xsrf_token()},
+      data: JSON.stringify({name: $('#connection-name').val(), group: $('#connection-group-name').val(), notes: $('#connection-notes').val()}),
+      success: function(data) { upsert_saved_connection(data.profile); set_saved_connections(saved_connections); saved_connections_select.val(data.profile.id); show_terminal_toast('备注已保存'); },
+      error: function() { log_status('保存备注失败。'); }
+    });
+  });
+
   load_connection_button.click(function() {
     apply_saved_connection();
   });
@@ -1269,6 +1022,18 @@ jQuery(function($){
     apply_saved_connection();
   });
 
+  $('#hostname, #port, #username').on('input', function() {
+    $('#password').attr('placeholder', '');
+    update_saved_key_hint(null);
+  });
+
+  $('#privatekey').on('change', function() {
+    $('#passphrase').val('').attr('placeholder', '');
+    $('#privatekey-hint').text(
+      this.files.length ? '成功连接并勾选保存凭据后替换已保存私钥' : ''
+    );
+  });
+
   delete_connection_button.click(function() {
     delete_saved_connection();
   });
diff --git a/webssh/static/js/workspace.js b/webssh/static/js/workspace.js
new file mode 100644
index 0000000..59e7ec8
--- /dev/null
+++ b/webssh/static/js/workspace.js
@@ -0,0 +1,435 @@
+/* Independent terminals and browser-local preferences. */
+(function($) {
+  'use strict';
+  var sessions = [], active, helpers, searchTimer,
+      settings = readLocal('webssh.terminal', {}),
+      commands = readLocal('webssh.commands', []), fileGeneration = 0;
+  var themes = {
+    dark: {background: '#0f1720', foreground: '#d9f1ee', cursor: '#55c7ba'},
+    light: {background: '#fafaf7', foreground: '#17252a', cursor: '#21776d'},
+    green: {background: '#122b24', foreground: '#d3ebd3', cursor: '#91c99d'}
+  };
+
+  function readLocal(key, fallback) {
+    try { return JSON.parse(window.localStorage.getItem(key)) || fallback; }
+    catch (e) { return fallback; }
+  }
+  function saveLocal(key, value) {
+    try { window.localStorage.setItem(key, JSON.stringify(value)); return true; }
+    catch (e) { notify('浏览器未允许保存设置。'); return false; }
+  }
+  function notify(text) {
+    if (helpers) { helpers.toast(text); }
+    else { $('#status').text(text); }
+  }
+  function xsrf() { return $('input[name="_xsrf"]').val() || ''; }
+  function api(url, data) {
+    return $.ajax({url: url, type: 'POST', contentType: 'application/json',
+      headers: {'X-XSRFToken': xsrf()}, data: JSON.stringify(data)});
+  }
+  function askPassword(title) {
+    return new Promise(function(resolve) {
+      var previous = document.activeElement;
+      $('#backup-password-title').text(title);
+      $('#backup-password-dialog').prop('hidden', false);
+      $('#backup-password').val('').focus();
+      function finish(value) {
+        $('#backup-password').val('');
+        $('#backup-password-dialog').prop('hidden', true);
+        $('#backup-password-form, #cancel-backup-password').off('.password');
+        $(document).off('keydown.password');
+        if (previous) { previous.focus(); }
+        resolve(value);
+      }
+      $('#backup-password-form').off('.password').on('submit.password', function(event) {
+        event.preventDefault(); finish($('#backup-password').val());
+      });
+      $('#cancel-backup-password').off('.password').on('click.password', function() { finish(null); });
+      $(document).on('keydown.password', function(event) {
+        if (event.key === 'Escape') { finish(null); }
+        if (event.key === 'Tab') {
+          var elements = $('#backup-password-form').find('input, button').toArray();
+          var index = elements.indexOf(document.activeElement);
+          event.preventDefault(); elements[(index + (event.shiftKey ? -1 : 1) + elements.length) % elements.length].focus();
+        }
+      });
+    });
+  }
+  function downloadBlob(blob, name) {
+    var url = URL.createObjectURL(blob), link = document.createElement('a');
+    link.href = url; link.download = name;
+    document.body.appendChild(link); link.click(); link.remove();
+    window.setTimeout(function() { URL.revokeObjectURL(url); }, 10000);
+  }
+  function send(session, text) {
+    if (session && session.socket.readyState === window.WebSocket.OPEN) {
+      session.socket.send(JSON.stringify({data: text}));
+    } else { notify('会话已断开，请重新连接。'); }
+  }
+  function fit(session) {
+    if (!session || !session.opened || session !== active) { return; }
+    try { session.fit.fit(); } catch (e) { /* Hidden containers cannot fit. */ }
+  }
+  function renderTabs() {
+    $('#session-tabs').empty();
+    sessions.forEach(function(session) {
+      var label = session.connection.name || session.connection.username + '@' + session.connection.hostname;
+      var tab = $('<button type="button" role="tab">').text(label + ' · ' + session.status)
+        .attr('aria-selected', session === active ? 'true' : 'false')
+        .on('click', function() { activate(session); });
+      $('#session-tabs').append(tab);
+    });
+    $('#session-tools').prop('hidden', sessions.length === 0);
+  }
+  function activate(session) {
+    active = session;
+    sessions.forEach(function(item) { item.container.hidden = item !== session; });
+    renderTabs();
+    $('#files-panel').prop('hidden', true); fileGeneration++;
+    $('#file-list').empty(); $('#file-status').text('');
+    $('#file-path').val(session && session.path || '.');
+    $('#search-result').text('');
+    $('#status').text(session && session.reason || '');
+    $('#quickbar').toggle(!!session);
+    $('body').toggleClass('quickbar-open', !!session);
+    document.title = session ? (session.connection.name || session.connection.hostname) + ' · WebSSH' : 'WebSSH';
+    if (session) { window.requestAnimationFrame(function() { fit(session); session.term.focus(); }); }
+  }
+  function closeSession(session) {
+    if (!session) { return; }
+    session.removed = true;
+    session.socket.close(); session.term.dispose(); session.container.remove();
+    sessions = sessions.filter(function(item) { return item !== session; });
+    if (session === active) { activate(sessions[sessions.length - 1]); }
+    else { renderTabs(); }
+    if (!sessions.length) {
+      $('#workspace').removeClass('workspace-fullscreen');
+      $('.form-container').show();
+    }
+  }
+  function terminalOptions(opts) {
+    return {fontSize: Math.max(10, Math.min(32, Number(settings.fontSize || opts.fontsize) || 14)),
+      cursorBlink: settings.cursorBlink !== false,
+      cursorStyle: ['block', 'bar', 'underline'].indexOf(settings.cursorStyle) >= 0 ? settings.cursorStyle : 'block',
+      scrollback: 5000,
+      theme: themes[settings.theme] || {background: opts.bgcolor || '#0f1720', foreground: opts.fontcolor || '#d9f1ee', cursor: opts.cursor || '#55c7ba'}};
+  }
+  function copySelection(session) {
+    if (!session || !session.term.hasSelection()) { return false; }
+    helpers.copy(session.term.getSelection(), function(ok) {
+      notify(ok ? '已复制' : '复制失败');
+      if (!session.removed) { session.term.focus(); }
+    });
+    return true;
+  }
+  function pasteClipboard(session) {
+    return helpers.clipboard(function(text) {
+      if (!session.removed && session.socket.readyState === window.WebSocket.OPEN) {
+        session.term.paste(text); session.term.focus();
+      }
+    }, function() { notify('请使用 Ctrl+V 粘贴。'); });
+  }
+  function create(msg, connection, opts, callbacks) {
+    helpers = callbacks;
+    var container = document.createElement('div');
+    container.className = 'session-terminal';
+    document.getElementById('terminal').appendChild(container);
+    var base = window.location.href.split(/[?#]/)[0].replace(/^http/, 'ws');
+    var socket = new window.WebSocket(base.replace(/\/$/, '') + '/ws?id=' + encodeURIComponent(msg.id));
+    socket.binaryType = 'arraybuffer';
+    var term = new window.Terminal(terminalOptions(opts)), fitAddon = new window.FitAddon.FitAddon();
+    term.loadAddon(fitAddon);
+    var session = {id: msg.id, connection: connection, socket: socket, term: term,
+      fit: fitAddon, container: container, status: '连接中', opened: false,
+      path: connection.directory || '.', removed: false, matches: [], matchIndex: -1};
+    session.defaultEncoding = msg.encoding || 'utf-8';
+    session.defaultFont = term.getOption('fontFamily');
+    sessions.push(session); activate(session);
+    var decoder;
+    function encoding(name) {
+      if (!window.TextDecoder) { decoder = null; return false; }
+      try { decoder = new window.TextDecoder(name || 'utf-8'); return true; }
+      catch (e) { decoder = new window.TextDecoder('utf-8'); return false; }
+    }
+    encoding(opts.encoding || msg.encoding);
+    session.encoding = encoding;
+    term.onData(function(data) { send(session, data); });
+    term.onResize(function(size) {
+      if (socket.readyState === window.WebSocket.OPEN) {
+        socket.send(JSON.stringify({resize: [size.cols, size.rows]}));
+      }
+    });
+    term.attachCustomKeyEventHandler(function(event) {
+      if (event.type !== 'keydown') { return true; }
+      var key = (event.key || '').toLowerCase();
+      if ((event.ctrlKey || event.metaKey) && key === 'f') {
+        event.preventDefault(); activate(session);
+        $('#search-panel').prop('hidden', false); $('#terminal-search').focus(); return false;
+      }
+      if ((event.ctrlKey || event.metaKey) && key === 'c' && term.hasSelection()) {
+        event.preventDefault(); copySelection(session); return false;
+      }
+      if ((event.ctrlKey || event.metaKey) && key === 'v') { return false; }
+      return true;
+    });
+    $(container).on('contextmenu', function(event) {
+      if (copySelection(session) || pasteClipboard(session)) { event.preventDefault(); }
+    });
+    socket.onopen = function() {
+      if (session.removed) { socket.close(); return; }
+      term.open(container); session.opened = true; session.status = '已连接';
+      helpers.font(term); renderTabs(); fit(session);
+      if (session === active) { $('.form-container').hide(); term.focus(); }
+      if (opts.command) { send(session, opts.command + '\r'); }
+    };
+    socket.onmessage = function(event) {
+      if (!session.removed) {
+        term.write(typeof event.data === 'string' ? event.data :
+          (decoder ? decoder.decode(new Uint8Array(event.data), {stream: true}) : new Uint8Array(event.data)));
+      }
+    };
+    socket.onerror = function() { session.status = '连接异常'; renderTabs(); };
+    socket.onclose = function(event) {
+      if (session.removed) { return; }
+      session.status = '已断开'; renderTabs();
+      var reason = helpers.translate(event.reason) || '连接已断开，点击“重新连接”可建立新会话。';
+      session.reason = reason;
+      session.term.write('\r\n\r\n' + reason.replace(/[\x00-\x1f\x7f]/g, ' ') + '\r\n');
+      session.term.setOption('disableStdin', true);
+      if (session === active) { $('#status').text(reason); }
+    };
+    return session;
+  }
+
+  // Map UTF-16 positions to terminal cells, including wide characters and wraps.
+  function findMatches(session, query) {
+    var buffer = session.term.buffer.active, text = '', positions = [];
+    for (var y = 0; y < buffer.length; y++) {
+      var line = buffer.getLine(y), next = buffer.getLine(y + 1);
+      if (!line) { continue; }
+      var limit = next && next.isWrapped ? session.term.cols : line.translateToString(true).length;
+      var lineText = '';
+      for (var x = 0; x < session.term.cols; x++) {
+        var cell = line.getCell(x);
+        if (!cell || cell.getWidth() === 0) { continue; }
+        var chars = cell.getChars() || ' ';
+        if (!(next && next.isWrapped) && lineText.length >= limit) { break; }
+        for (var unit = 0; unit < chars.length; unit++) {
+          positions.push({x: x, y: y, width: cell.getWidth()});
+        }
+        text += chars; lineText += chars;
+      }
+      if (!next || !next.isWrapped) { text += '\n'; positions.push(null); }
+    }
+    var matches = [], at = 0;
+    while (query && (at = text.indexOf(query, at)) >= 0) {
+      var start = positions[at], end = positions[at + query.length - 1];
+      if (start && end) { matches.push({start: start, end: end}); }
+      at += Math.max(1, query.length);
+    }
+    return matches;
+  }
+  function search(direction) {
+    if (!active || !active.opened) { return; }
+    var query = $('#terminal-search').val();
+    active.matches = findMatches(active, query);
+    if (active.searchQuery !== query) { active.matchIndex = -1; active.searchQuery = query; }
+    var count = active.matches.length;
+    if (!count) { active.term.clearSelection(); $('#search-result').text(query ? '未找到' : ''); return; }
+    active.matchIndex = (active.matchIndex + direction + count) % count;
+    var match = active.matches[active.matchIndex];
+    active.term.select(match.start.x, match.start.y,
+      (match.end.y - match.start.y) * active.term.cols + match.end.x + match.end.width - match.start.x);
+    active.term.scrollToLine(match.start.y);
+    $('#search-result').text((active.matchIndex + 1) + ' / ' + count);
+  }
+  function renderCommands() {
+    $('#command-list').empty().append($('<option>').val('').text('选择常用命令'));
+    commands.forEach(function(command, index) {
+      $('#command-list').append($('<option>').val(index).text(command.name));
+    });
+  }
+  function selectedCommand() {
+    var index = $('#command-list').val();
+    return index === '' ? null : commands[Number(index)];
+  }
+  function listFiles(path) {
+    var session = active;
+    if (!session || session.socket.readyState !== window.WebSocket.OPEN) { notify('请先连接服务器。'); return; }
+    var generation = ++fileGeneration;
+    $('#file-status').text('正在读取目录…'); $('#file-list').empty();
+    $.ajax({url: 'files/' + encodeURIComponent(session.id), data: {path: path}})
+      .done(function(result) {
+        if (active !== session || generation !== fileGeneration) { return; }
+        session.path = result.path; $('#file-path').val(result.path); $('#file-status').text('');
+        result.entries.forEach(function(entry) {
+          var button = $('<button type="button" class="file-entry">').text(
+            (entry.directory ? '📁 ' : '📄 ') + entry.name + (entry.directory ? '' : ' · ' + entry.size + ' B'));
+          button.on('click', function() {
+            var path = result.path.replace(/\/$/, '') + '/' + entry.name;
+            if (entry.directory) { listFiles(path); }
+            else { downloadFile(session, path, entry.name); }
+          });
+          $('#file-list').append(button);
+        });
+      }).fail(function() {
+        if (active === session && generation === fileGeneration) {
+          $('#file-status').text('目录读取失败，请检查 SFTP 支持、权限或连接状态。');
+        }
+      });
+  }
+  function downloadFile(session, path, name) {
+    $('#file-status').text('正在下载…');
+    var url = 'files/' + encodeURIComponent(session.id) + '?download=1&path=' + encodeURIComponent(path);
+    fetch(url, {credentials: 'same-origin'}).then(function(response) {
+      if (!response.ok) { throw new Error(); }
+      return response.blob();
+    }).then(function(blob) {
+      downloadBlob(blob, name);
+      if (active === session) { $('#file-status').text('下载完成'); }
+    }).catch(function() { if (active === session) { $('#file-status').text('下载失败，文件上限为 16 MiB。'); } });
+  }
+
+  window.wssh.workspace = {create: create};
+  window.wssh.send = function(text) {
+    if (typeof text !== 'string' || !active || active.socket.readyState !== window.WebSocket.OPEN) { return; }
+    try { JSON.parse(text); active.socket.send(text); }
+    catch (e) { send(active, text.trim() + '\r'); }
+  };
+  window.wssh.set_encoding = function(name) { if (active) { return active.encoding(name); } };
+  window.wssh.reset_encoding = function() { if (active) { active.encoding(active.defaultEncoding); } };
+  window.wssh.custom_font = function() { if (active) { helpers.font(active.term); } };
+  window.wssh.default_font = function() {
+    if (active) { active.term.setOption('fontFamily', active.defaultFont); active.term.font_family_updated = false; fit(active); }
+  };
+  window.wssh.geometry = function() { return active && {cols: active.term.cols, rows: active.term.rows}; };
+  window.wssh.resize = function(cols, rows) { if (active) { active.term.resize(cols, rows); } };
+  window.wssh.set_bgcolor = function(color) { if (active) { active.term.setOption('theme', {background: color}); } };
+  window.wssh.set_fontcolor = function(color) { if (active) { active.term.setOption('theme', {foreground: color}); } };
+
+  $(function() {
+    if (!Array.isArray(commands)) { commands = []; }
+    commands = commands.filter(function(item) { return item && typeof item.name === 'string' && typeof item.text === 'string'; });
+    renderCommands();
+    $('#terminal-fontsize').val(settings.fontSize || 14);
+    $('#terminal-theme').val(settings.theme || 'dark');
+    $('#terminal-cursor').val(settings.cursorStyle || 'block');
+    $('#terminal-blink').prop('checked', settings.cursorBlink !== false);
+    $('#new-session').on('click', function() {
+      $('#workspace').removeClass('workspace-fullscreen');
+      $('.form-container').show(); fit(active);
+      document.getElementById('connect').scrollIntoView({behavior: 'smooth'});
+    });
+    $('#close-session').on('click', function() { closeSession(active); });
+    $('#reconnect-session').on('click', function() {
+      if (!active) { return; }
+      if (active.socket.readyState === window.WebSocket.OPEN || active.socket.readyState === window.WebSocket.CONNECTING) {
+        notify('当前会话仍在连接，请先关闭或新建连接。'); return;
+      }
+      helpers.reconnect(active.connection);
+    });
+    ['search', 'settings', 'commands', 'files'].forEach(function(name) {
+      $('#toggle-' + name).on('click', function() {
+        var panel = $('#' + name + '-panel'); panel.prop('hidden', !panel.prop('hidden'));
+        if (name === 'files' && !panel.prop('hidden')) { listFiles(active && active.path || '.'); }
+        if (name === 'search' && !panel.prop('hidden')) { $('#terminal-search').focus(); }
+        fit(active);
+      });
+    });
+    $('#toggle-fullscreen').on('click', function() { $('#workspace').toggleClass('workspace-fullscreen'); fit(active); });
+    $(document).on('keydown.workspace', function(event) {
+      if (event.key === 'Escape' && $('#workspace').hasClass('workspace-fullscreen')) {
+        $('#workspace').removeClass('workspace-fullscreen'); fit(active);
+      }
+    });
+    $(window).on('resize.workspace', function() { fit(active); });
+    window.addEventListener('beforeunload', function(event) {
+      if (sessions.some(function(session) { return session.socket.readyState === window.WebSocket.OPEN; })) {
+        event.preventDefault(); event.returnValue = '';
+      }
+    });
+    $('#terminal-search').on('input', function() { window.clearTimeout(searchTimer); searchTimer = window.setTimeout(function() { search(1); }, 150); });
+    $('#terminal-search').on('keydown', function(event) { if (event.key === 'Enter') { event.preventDefault(); search(event.shiftKey ? -1 : 1); } });
+    $('#search-prev').on('click', function() { search(-1); });
+    $('#search-next').on('click', function() { search(1); });
+    $('#save-terminal-settings').on('click', function() {
+      settings = {fontSize: Math.max(10, Math.min(32, Number($('#terminal-fontsize').val()) || 14)),
+        theme: $('#terminal-theme').val(), cursorStyle: $('#terminal-cursor').val(), cursorBlink: $('#terminal-blink').prop('checked')};
+      sessions.forEach(function(session) {
+        var opts = terminalOptions({});
+        Object.keys(opts).forEach(function(key) { session.term.setOption(key, opts[key]); });
+      });
+      if (saveLocal('webssh.terminal', settings)) { notify('设置已保存'); }
+      fit(active);
+    });
+    $('#command-list').on('change', function() { var command = selectedCommand(); $('#command-name').val(command ? command.name : ''); $('#command-text').val(command ? command.text : ''); });
+    $('#save-command').on('click', function() {
+      var name = $('#command-name').val().trim(), text = $('#command-text').val().trim(), index = $('#command-list').val();
+      if (!name || !text || name.length > 100 || text.length > 4096 || /[\x00-\x1f\x7f]/.test(text)) {
+        notify('请输入名称和单行命令，不包含换行或控制字符。'); return;
+      }
+      if (index === '') { commands.push({name: name, text: text}); } else { commands[Number(index)] = {name: name, text: text}; }
+      saveLocal('webssh.commands', commands); renderCommands();
+    });
+    $('#delete-command').on('click', function() { var index = $('#command-list').val(); if (index !== '') { commands.splice(Number(index), 1); saveLocal('webssh.commands', commands); renderCommands(); $('#command-name, #command-text').val(''); } });
+    $('#insert-command').on('click', function() {
+      var command = selectedCommand();
+      if (!active || !command || active.socket.readyState !== window.WebSocket.OPEN) { notify('请连接服务器并选择命令。'); return; }
+      if (/[\x00-\x1f\x7f]/.test(command.text)) { notify('仅支持单行命令。'); return; }
+      active.term.paste(command.text); active.term.focus();
+    });
+    $('#quickbar').on('mousedown.workspace', 'button', function(event) { event.preventDefault(); });
+    $('#quickbar').on('click.workspace', 'button', function() {
+      if (!active) { return; }
+      var action = $(this).attr('data-action'), key = $(this).attr('data-key');
+      if (action === 'copy') { if (!copySelection(active)) { notify('请先选中内容。'); } }
+      else if (action === 'paste') { if (!pasteClipboard(active)) { notify('请使用 Ctrl+V。'); } }
+      else { send(active, {'ctrl-c': '\x03', tab: '\t', esc: '\x1b'}[key] || key); }
+      active.term.focus();
+    });
+    $('#file-refresh').on('click', function() { listFiles($('#file-path').val()); });
+    $('#file-path').on('keydown', function(event) { if (event.key === 'Enter') { event.preventDefault(); listFiles(this.value); } });
+    $('#file-parent').on('click', function() { listFiles((active && active.path || '.') + '/..'); });
+    $('#file-upload').on('change', function() {
+      var file = this.files[0], session = active;
+      this.value = '';
+      if (!file || !session || session.socket.readyState !== window.WebSocket.OPEN) { notify('请先连接服务器。'); return; }
+      if (file.size > 16 * 1024 * 1024) { notify('单个文件最大为 16 MiB。'); return; }
+      var data = new FormData(); data.append('file', file); data.append('path', session.path || '.');
+      $('#file-status').text('正在上传…');
+      $.ajax({url: 'files/' + encodeURIComponent(session.id), type: 'POST', data: data,
+        processData: false, contentType: false, headers: {'X-XSRFToken': xsrf()}})
+        .done(function() { if (session === active) { listFiles(session.path); notify('上传完成'); } })
+        .fail(function() { if (session === active) { $('#file-status').text('上传失败：同名文件已存在、权限不足或连接中断。'); } });
+    });
+    function exportConfig(credentials) {
+      var request = credentials ? askPassword('独立备份口令（至少 10 个字符，迁移时需要）：') : Promise.resolve('');
+      request.then(function(password) {
+        if (password === null) { return; }
+        api('connections/export', {credentials: credentials, password: password})
+        .done(function(document) { downloadBlob(new Blob([JSON.stringify(document, null, 2)], {type: 'application/json'}), credentials ? 'webssh-backup.json' : 'webssh-connections.json'); })
+        .fail(function() { notify('导出失败，请确认备份口令至少 10 个字符，且已保存凭据可解密。'); });
+      });
+    }
+    $('#export-config').on('click', function() { exportConfig(false); });
+    $('#backup-credentials').on('click', function() { exportConfig(true); });
+    $('#import-config').on('change', function() {
+      var file = this.files[0]; this.value = '';
+      if (!file) { return; }
+      if (file.size > 16 * 1024 * 1024) { notify('配置文件最大为 16 MiB。'); return; }
+      var reader = new FileReader();
+      reader.onload = function() {
+        var document;
+        try { document = JSON.parse(reader.result); } catch (e) { notify('配置文件不是有效 JSON。'); return; }
+        var request = document && document.format === 'webssh-encrypted' ? askPassword('请输入备份口令：') : Promise.resolve('');
+        request.then(function(password) {
+          if (password === null) { return; }
+          api('connections/import', {document: document, password: password})
+          .done(function(result) { window.wssh.refresh_connections(result.connections); notify('已导入 ' + result.imported + ' 个连接'); })
+          .fail(function() { notify('导入失败，请检查文件格式、地址或备份口令。'); });
+        });
+      };
+      reader.onerror = function() { notify('无法读取配置文件。'); }; reader.readAsText(file);
+    });
+  });
+}(jQuery));
diff --git a/webssh/storage.py b/webssh/storage.py
index 0ce597a..b8593d7 100755
--- a/webssh/storage.py
+++ b/webssh/storage.py
@@ -5,12 +5,18 @@ import threading
 import time
 
 from webssh.crypto import SecretBox, is_encrypted
+from webssh.utils import (
+    is_valid_directory, is_valid_hostname, is_valid_ip_address
+)
 
 
 DEFAULT_PORT = 22
 
 # keys that must never be handed out to a browser
-PRIVATE_FIELDS = ('password', 'password_enc')
+PRIVATE_FIELDS = (
+    'password', 'password_enc', 'privatekey', 'privatekey_enc',
+    'passphrase', 'passphrase_enc'
+)
 
 
 class ConnectionStore(object):
@@ -51,6 +57,141 @@ class ConnectionStore(object):
     def make_id(self, owner, hostname, port, username):
         return self._make_id(owner, hostname, port, username)
 
+    def get_privatekey(self, owner, profile_id):
+        """Return key material only to the server, scoped to its owner."""
+        with self.lock:
+            for profile in self._read().get('connections', []):
+                if (profile.get('owner') == owner and
+                        profile.get('id') == profile_id):
+                    if not self.box:
+                        return '', ''
+                    return (
+                        self.box.decrypt(profile.get('privatekey_enc')),
+                        self.box.decrypt(profile.get('passphrase_enc'))
+                    )
+        return '', ''
+
+    def update_metadata(self, owner, profile_id, metadata):
+        values = self._metadata(metadata)
+        with self.lock:
+            data = self._read()
+            for profile in data['connections']:
+                if (profile.get('owner') == owner and
+                        profile.get('id') == profile_id):
+                    profile.update(values)
+                    profile['updated_at'] = int(time.time())
+                    self._write(data)
+                    return self._public(profile)
+        return None
+
+    def export_connections(self, owner, credentials=False):
+        with self.lock:
+            profiles = []
+            for profile in self._read()['connections']:
+                if profile.get('owner') != owner:
+                    continue
+                item = {key: profile.get(key, '') for key in (
+                    'hostname', 'port', 'username', 'term', 'directory',
+                    'auth_type', 'name', 'group', 'notes'
+                )}
+                item['requires_totp'] = bool(profile.get('requires_totp'))
+                item['key_requires_passphrase'] = bool(
+                    profile.get('key_requires_passphrase')
+                )
+                if credentials:
+                    if not self.box:
+                        raise ValueError('Encryption is unavailable.')
+                    for field in ('password', 'privatekey', 'passphrase'):
+                        token = profile.get(field + '_enc')
+                        value = self.box.decrypt(token) if token else ''
+                        if token and not value:
+                            raise ValueError('Stored credentials cannot be decrypted.')
+                        if field == 'password' and not token:
+                            value = profile.get('password') or ''
+                        item[field] = value
+                profiles.append(item)
+            return profiles
+
+    def import_connections(self, owner, connections, credentials=False):
+        if not isinstance(connections, list) or len(connections) > 500:
+            raise ValueError('最多导入 500 个连接。')
+        normalized = []
+        for item in connections:
+            if not isinstance(item, dict):
+                raise ValueError('连接配置格式无效。')
+            connection = {key: item.get(key) for key in (
+                'hostname', 'port', 'username', 'term', 'directory',
+                'auth_type', 'name', 'group', 'notes'
+            )}
+            connection['requires_totp'] = item.get('requires_totp') is True
+            if credentials:
+                for field in ('password', 'privatekey', 'passphrase'):
+                    value = item.get(field, '')
+                    if not isinstance(value, str) or len(value) > 16384:
+                        raise ValueError('凭据格式无效。')
+                    connection[field] = value
+                connection['save_passphrase'] = True
+            hostname = connection.get('hostname')
+            username = connection.get('username')
+            directory = connection.get('directory') or ''
+            port = connection.get('port')
+            if port is None or port == '':
+                port = 22
+            connection['port'] = port
+            if (not isinstance(hostname, str) or
+                    not (is_valid_hostname(hostname) or
+                         is_valid_ip_address(hostname)) or
+                    not isinstance(username, str) or
+                    not username.strip() or len(username) > 256 or
+                    not isinstance(port, int) or isinstance(port, bool) or
+                    not 1 <= port <= 65535 or
+                    not isinstance(directory, str) or
+                    (directory and not is_valid_directory(directory)) or
+                    not isinstance(connection.get('term') or '', str) or
+                    len(connection.get('term') or '') > 100 or
+                    connection.get('auth_type') not in
+                    (None, '', 'password', 'privatekey')):
+                raise ValueError('连接地址、端口或目录无效。')
+            normalized.append(self._normalize(owner, connection))
+            normalized[-1]['key_requires_passphrase'] = (
+                item.get('key_requires_passphrase') is True
+            )
+        with self.lock:
+            data = self._read()
+            profiles = data['connections']
+            now = int(time.time())
+            for profile in normalized:
+                existing = next((p for p in profiles
+                                 if p['id'] == profile['id']), None)
+                profile['updated_at'] = now
+                if existing:
+                    if not credentials:
+                        for field in PRIVATE_FIELDS:
+                            if field in existing:
+                                profile[field] = existing[field]
+                        profile['key_requires_passphrase'] = bool(
+                            existing.get('key_requires_passphrase')
+                        )
+                    existing.update(profile)
+                    if credentials:
+                        for field in PRIVATE_FIELDS:
+                            if field not in profile:
+                                existing.pop(field, None)
+                else:
+                    profile['created_at'] = now
+                    profiles.append(profile)
+            self._write(data)
+        return len(normalized)
+
+    def _metadata(self, connection):
+        result = {}
+        for field, limit in (('name', 100), ('group', 100), ('notes', 1000)):
+            value = connection.get(field) or ''
+            if not isinstance(value, str) or len(value) > limit:
+                raise ValueError('连接备注或分组过长。')
+            result[field] = value.strip()
+        return result
+
     def upsert(self, owner, connection):
         profile = self._normalize(owner, connection)
 
@@ -121,6 +262,8 @@ class ConnectionStore(object):
         public['has_password'] = bool(
             profile.get('password_enc') or profile.get('password')
         )
+        public['has_privatekey'] = bool(profile.get('privatekey_enc'))
+        public['has_passphrase'] = bool(profile.get('passphrase_enc'))
         return public
 
     def _normalize(self, owner, connection):
@@ -148,13 +291,28 @@ class ConnectionStore(object):
             'directory': directory,
             'auth_type': auth_type
         }
-        if password:
+        profile['requires_totp'] = bool(connection.get('requires_totp'))
+        profile.update(self._metadata(connection))
+        save_credentials = connection.get('save_credentials', True)
+        if password and save_credentials:
             if self.box:
                 profile['password_enc'] = self.box.encrypt(password)
             else:
                 # no server secret to encrypt with; keep the legacy layout so
                 # encrypt_plaintext_passwords() can upgrade it later
                 profile['password'] = password
+        privatekey = connection.get('privatekey') or ''
+        if privatekey and save_credentials:
+            if not self.box:
+                raise ValueError('A server secret is required to save keys.')
+            profile['privatekey_enc'] = self.box.encrypt(privatekey)
+            profile['key_requires_passphrase'] = bool(
+                connection.get('passphrase')
+            )
+            if connection.get('save_passphrase'):
+                profile['passphrase_enc'] = self.box.encrypt(
+                    connection.get('passphrase') or ''
+                )
         return profile
 
     def _make_id(self, owner, hostname, port, username):
diff --git a/webssh/templates/index.html b/webssh/templates/index.html
index 7a22ee0..82beecd 100755
--- a/webssh/templates/index.html
+++ b/webssh/templates/index.html
@@ -47,6 +47,11 @@
 
         <div class="saved-bar">
           <div class="field">
+            <input class="form-control" id="connection-search" type="search"
+                   aria-label="搜索连接" placeholder="搜索名称、主机、备注">
+            <select class="form-control" id="connection-group" aria-label="按分组筛选">
+              <option value="">全部分组</option>
+            </select>
             <label for="saved-connections">已保存连接</label>
             <select class="form-control" id="saved-connections">
               <option value="">未选择保存的连接</option>
@@ -60,11 +65,28 @@
                     id="delete-connection">
               删除
             </button>
+            <button type="button" class="btn btn-secondary" id="edit-connection">保存备注</button>
+            <button type="button" class="btn btn-secondary" id="export-config">导出配置</button>
+            <button type="button" class="btn btn-secondary" id="backup-credentials">加密备份</button>
+            <label class="btn btn-secondary" for="import-config">导入配置 / 备份</label>
+            <input type="file" id="import-config" accept="application/json,.json" hidden>
           </div>
         </div>
 
         <form id="connect" class="connection-form" action="" method="post" enctype="multipart/form-data"{% if debug %} novalidate{% end %}>
           <div class="form-grid">
+            <div class="field">
+              <label for="connection-name">连接名称</label>
+              <input class="form-control" id="connection-name" name="name" maxlength="100" placeholder="例如：生产服务器">
+            </div>
+            <div class="field">
+              <label for="connection-group-name">分组</label>
+              <input class="form-control" id="connection-group-name" name="group" maxlength="100" placeholder="例如：生产环境">
+            </div>
+            <div class="field">
+              <label for="connection-notes">备注</label>
+              <textarea class="form-control" id="connection-notes" name="notes" maxlength="1000" rows="2"></textarea>
+            </div>
             <div class="field">
               <label for="hostname">主机地址</label>
               <input class="form-control" type="text" id="hostname"
@@ -95,6 +117,7 @@
               <label for="privatekey">私钥文件</label>
               <input class="form-control" type="file" id="privatekey"
                      name="privatekey" value="">
+              <small class="field-hint" id="privatekey-hint"></small>
             </div>
             <div class="field">
               <label for="passphrase">私钥口令</label>
@@ -120,6 +143,22 @@
                 <span>保存连接信息</span>
               </label>
             </div>
+            <div class="field save-field">
+              <label class="save-toggle" for="save-credentials">
+                <input type="checkbox" id="save-credentials"
+                       name="save_credentials" value="1">
+                <span>保存密码 / 私钥（加密）</span>
+              </label>
+              <small class="field-hint">取消后，成功连接并保存时清除原有凭据</small>
+            </div>
+            <div class="field save-field">
+              <label class="save-toggle" for="save-passphrase">
+                <input type="checkbox" id="save-passphrase"
+                       name="save_passphrase" value="1">
+                <span>同时保存私钥口令（加密）</span>
+              </label>
+              <small class="field-hint">不保存时，每次连接需输入口令；动态验证码不保存</small>
+            </div>
           </div>
 
           <input type="hidden" id="term" name="term" value="xterm-256color">
@@ -132,12 +171,68 @@
       </section>
     </main>
 
-    <section class="terminal-stage">
+    <section class="terminal-stage" id="workspace">
       <div id="status" class="status-message"></div>
+      <div id="session-tools" hidden>
+        <div id="session-tabs" role="tablist" aria-label="终端会话"></div>
+        <div class="workspace-toolbar">
+          <button type="button" id="new-session">新建连接</button>
+          <button type="button" id="reconnect-session">重新连接</button>
+          <button type="button" id="close-session">关闭标签</button>
+          <button type="button" id="toggle-search">搜索输出</button>
+          <button type="button" id="toggle-settings">终端设置</button>
+          <button type="button" id="toggle-commands">常用命令</button>
+          <button type="button" id="toggle-files">文件管理</button>
+          <button type="button" id="toggle-fullscreen">全屏</button>
+        </div>
+        <div id="search-panel" class="tool-panel" hidden>
+          <input id="terminal-search" type="search" placeholder="搜索终端输出" aria-label="搜索终端输出">
+          <button type="button" id="search-prev">上一处</button>
+          <button type="button" id="search-next">下一处</button>
+          <span id="search-result" role="status"></span>
+        </div>
+        <div id="settings-panel" class="tool-panel" hidden>
+          <label>字号 <input id="terminal-fontsize" type="number" min="10" max="32" value="14"></label>
+          <label>主题 <select id="terminal-theme"><option value="dark">深色</option><option value="light">浅色</option><option value="green">护眼绿</option></select></label>
+          <label>光标 <select id="terminal-cursor"><option value="block">方块</option><option value="bar">竖线</option><option value="underline">下划线</option></select></label>
+          <label><input id="terminal-blink" type="checkbox" checked>光标闪烁</label>
+          <button type="button" id="save-terminal-settings">应用并记住</button>
+        </div>
+        <div id="commands-panel" class="tool-panel" hidden>
+          <select id="command-list" aria-label="常用命令"></select>
+          <input id="command-name" maxlength="100" placeholder="命令名称" aria-label="命令名称">
+          <textarea id="command-text" rows="2" maxlength="4096" placeholder="命令内容" aria-label="命令内容"></textarea>
+          <button type="button" id="save-command">保存</button>
+          <button type="button" id="delete-command">删除</button>
+          <button type="button" id="insert-command">填入终端</button>
+          <small>填入后由你按回车执行；收藏保存在当前浏览器中，请勿包含密码。</small>
+        </div>
+        <div id="files-panel" class="tool-panel" hidden>
+          <input id="file-path" value="." aria-label="远端目录">
+          <button type="button" id="file-refresh">打开 / 刷新</button>
+          <button type="button" id="file-parent">上一级</button>
+          <label>上传文件（最大 16 MiB，不覆盖同名文件）<input id="file-upload" type="file"></label>
+          <span id="file-status" role="status"></span>
+          <div id="file-list"></div>
+          <small>连接中断时上传可能留下未完成文件，请在远端确认。</small>
+        </div>
+      </div>
       <div id="terminal"></div>
     </section>
 
     <div id="terminal-toast" class="terminal-toast" role="status"></div>
+    <div id="backup-password-dialog" class="password-overlay" hidden>
+      <form id="backup-password-form" class="password-card" role="dialog"
+            aria-modal="true" aria-labelledby="backup-password-title">
+        <label id="backup-password-title" for="backup-password">备份口令</label>
+        <input id="backup-password" class="form-control" type="password"
+               autocomplete="off" maxlength="1024" required>
+        <div class="action-row">
+          <button class="btn btn-primary" type="submit">继续</button>
+          <button class="btn btn-secondary" id="cancel-backup-password" type="button">取消</button>
+        </div>
+      </form>
+    </div>
 
     <div id="quickbar" class="quickbar" style="display: none">
       <button type="button" class="quickbar-btn" data-action="copy">复制</button>
@@ -162,5 +257,6 @@
     <script src="{{ static_url('js/xterm.min.js') }}"></script>
     <script src="{{ static_url('js/xterm-addon-fit.min.js') }}"></script>
     <script src="{{ static_url('js/main.js') }}"></script>
+    <script src="{{ static_url('js/workspace.js') }}"></script>
   </body>
 </html>
diff --git a/webssh/worker.py b/webssh/worker.py
index 4623e96..b2633fd 100755
--- a/webssh/worker.py
+++ b/webssh/worker.py
@@ -1,4 +1,5 @@
 import logging
+import threading
 try:
     import secrets
 except ImportError:
@@ -47,6 +48,7 @@ class Worker(object):
         self.closed = False
         self.src_addr = None
         self.client_key = None
+        self.file_lock = threading.Lock()
 
     def __call__(self, fd, events):
         if events & IOLoop.READ:
@@ -80,12 +82,10 @@ class Worker(object):
             if self.chan.closed or errno_from_exception(e) in _ERRNO_CONNRESET:
                 self.close(reason='chan error on reading')
         else:
-            logging.debug('{!r} from {}:{}'.format(data, *self.dst_addr))
             if not data:
                 self.close(reason='chan closed')
                 return
 
-            logging.debug('{!r} to {}:{}'.format(data, *self.handler.src_addr))
             try:
                 self.handler.write_message(data, binary=True)
             except tornado.websocket.WebSocketClosedError:
@@ -97,7 +97,6 @@ class Worker(object):
             return
 
         data = ''.join(self.data_to_dst)
-        logging.debug('{!r} to {}:{}'.format(data, *self.dst_addr))
 
         try:
             sent = self.chan.send(data)
diff --git a/webssh/workspace.py b/webssh/workspace.py
new file mode 100644
index 0000000..86cd82d
--- /dev/null
+++ b/webssh/workspace.py
@@ -0,0 +1,261 @@
+"""Saved connection backups and bounded SFTP operations."""
+import base64
+import hashlib
+import json
+import os
+import posixpath
+import stat
+
+import paramiko
+import tornado.gen
+import tornado.web
+from cryptography.hazmat.primitives.ciphers.aead import AESGCM
+
+from webssh.handler import IndexHandler, MixinHandler
+from webssh.worker import clients
+
+
+TRANSFER_LIMIT = 16 * 1024 * 1024
+BACKUP_AAD = b'webssh-backup-v1'
+
+
+def backup_key(password, salt):
+    if not isinstance(password, str) or not 10 <= len(password) <= 1024:
+        raise ValueError('备份口令长度需为 10 至 1024 个字符。')
+    return hashlib.pbkdf2_hmac('sha256', password.encode('utf-8'), salt,
+                               600000, dklen=32)
+
+
+def encrypt_backup(connections, password):
+    salt, nonce = os.urandom(16), os.urandom(12)
+    plaintext = json.dumps(connections).encode('utf-8')
+    encrypted = AESGCM(backup_key(password, salt)).encrypt(
+        nonce, plaintext, BACKUP_AAD
+    )
+    return dict(format='webssh-encrypted', version=1,
+                salt=base64.b64encode(salt).decode('ascii'),
+                nonce=base64.b64encode(nonce).decode('ascii'),
+                data=base64.b64encode(encrypted).decode('ascii'))
+
+
+def decrypt_backup(document, password):
+    try:
+        if document.get('version') != 1:
+            raise ValueError()
+        salt = base64.b64decode(document['salt'], validate=True)
+        nonce = base64.b64decode(document['nonce'], validate=True)
+        data = base64.b64decode(document['data'], validate=True)
+        if len(salt) != 16 or len(nonce) != 12:
+            raise ValueError()
+        plaintext = AESGCM(backup_key(password, salt)).decrypt(
+            nonce, data, BACKUP_AAD
+        )
+        return json.loads(plaintext)
+    except Exception:
+        raise ValueError('备份口令错误或文件已损坏。') from None
+
+
+class WorkspaceHandler(MixinHandler, tornado.web.RequestHandler):
+    executor = IndexHandler.executor
+
+    def initialize(self):
+        super(WorkspaceHandler, self).initialize()
+
+    def check_workspace_origin(self):
+        origin = self.request.headers.get('Origin')
+        if origin and not self.check_origin(origin):
+            raise tornado.web.HTTPError(403)
+
+    def read_json(self):
+        try:
+            data = json.loads(self.request.body)
+            if not isinstance(data, dict):
+                raise ValueError()
+            return data
+        except (ValueError, UnicodeDecodeError):
+            raise tornado.web.HTTPError(400, 'JSON 格式无效。')
+
+    def set_default_headers(self):
+        super(WorkspaceHandler, self).set_default_headers()
+        self.set_header('Cache-Control', 'no-store')
+        self.set_header('X-Content-Type-Options', 'nosniff')
+
+
+class ConnectionMetadataHandler(WorkspaceHandler):
+    @tornado.web.authenticated
+    @tornado.gen.coroutine
+    def post(self, profile_id):
+        self.check_workspace_origin()
+        metadata = self.read_json()
+        try:
+            profile = yield self.executor.submit(
+                self.connection_store.update_metadata,
+                self.current_user, profile_id, metadata
+            )
+        except ValueError as exc:
+            raise tornado.web.HTTPError(400, str(exc))
+        if profile is None:
+            raise tornado.web.HTTPError(404)
+        self.write({'profile': profile})
+
+
+class ConnectionExportHandler(WorkspaceHandler):
+    @tornado.web.authenticated
+    @tornado.gen.coroutine
+    def post(self):
+        self.check_workspace_origin()
+        data = self.read_json()
+        credentials = data.get('credentials') is True
+
+        def export():
+            profiles = self.connection_store.export_connections(
+                self.current_user, credentials
+            )
+            if credentials:
+                return encrypt_backup(profiles, data.get('password'))
+            return dict(format='webssh-config', version=1,
+                        connections=profiles)
+
+        try:
+            document = yield self.executor.submit(export)
+        except ValueError as exc:
+            raise tornado.web.HTTPError(400, str(exc))
+        self.write(document)
+
+
+class ConnectionImportHandler(WorkspaceHandler):
+    @tornado.web.authenticated
+    @tornado.gen.coroutine
+    def post(self):
+        self.check_workspace_origin()
+        data = self.read_json()
+        document = data.get('document')
+        if not isinstance(document, dict):
+            raise tornado.web.HTTPError(400, '配置格式无效。')
+
+        def restore():
+            credentials = document.get('format') == 'webssh-encrypted'
+            if credentials:
+                connections = decrypt_backup(document, data.get('password'))
+            elif (document.get('format') == 'webssh-config' and
+                  document.get('version') == 1):
+                connections = document.get('connections')
+            else:
+                raise ValueError('不支持的配置格式。')
+            return self.connection_store.import_connections(
+                self.current_user, connections, credentials
+            )
+
+        try:
+            count = yield self.executor.submit(restore)
+        except (ValueError, TypeError) as exc:
+            raise tornado.web.HTTPError(400, str(exc))
+        self.write(dict(imported=count,
+                        connections=self.connection_store.list(
+                            self.current_user)))
+
+
+def validate_path(path):
+    if (not isinstance(path, str) or len(path) > 4096 or
+            any(ord(char) < 32 or ord(char) == 127 for char in path)):
+        raise ValueError('文件路径无效。')
+    return path or '.'
+
+
+def transfer(ssh, action, path, upload=None):
+    """Runs exclusively in the thread pool; each operation owns its channel."""
+    sftp = ssh.open_sftp()
+    try:
+        sftp.get_channel().settimeout(30)
+        path = sftp.normalize(validate_path(path))
+        if action == 'list':
+            entries = []
+            for attr in sftp.listdir_iter(path):
+                if len(entries) >= 5000:
+                    raise ValueError('目录超过 5000 项，请使用终端查看。')
+                entries.append(dict(name=attr.filename,
+                                    directory=stat.S_ISDIR(attr.st_mode or 0),
+                                    size=attr.st_size or 0,
+                                    modified=attr.st_mtime or 0))
+            entries.sort(key=lambda item: (not item['directory'], item['name']))
+            return dict(path=path, entries=entries)
+        if action == 'download':
+            attr = sftp.stat(path)
+            if not stat.S_ISREG(attr.st_mode or 0):
+                raise ValueError('只能下载普通文件。')
+            if attr.st_size > TRANSFER_LIMIT:
+                raise ValueError('单个文件最大为 16 MiB。')
+            with sftp.open(path, 'rb') as remote:
+                content = remote.read(TRANSFER_LIMIT + 1)
+            if len(content) > TRANSFER_LIMIT:
+                raise ValueError('单个文件最大为 16 MiB。')
+            return content
+        filename, content = upload
+        if (not filename or filename in ('.', '..') or
+                '/' in filename or '\\' in filename):
+            raise ValueError('上传文件名无效。')
+        validate_path(filename)
+        if len(content) > TRANSFER_LIMIT:
+            raise ValueError('单个文件最大为 16 MiB。')
+        target = posixpath.join(path, filename)
+        # Exclusive creation prevents unintended replacement of remote files.
+        with sftp.open(target, 'wx') as remote:
+            for offset in range(0, len(content), 32768):
+                remote.write(content[offset:offset + 32768])
+        return dict(status='ok')
+    finally:
+        sftp.close()
+
+
+class FilesHandler(WorkspaceHandler):
+    def get_worker(self, worker_id):
+        worker = clients.get(self.get_client_key(), {}).get(worker_id)
+        if (not worker or worker.closed or not worker.handler or
+                not worker.file_lock.acquire(False)):
+            raise tornado.web.HTTPError(409, '会话已断开或正在传输文件。')
+        return worker
+
+    @tornado.web.authenticated
+    @tornado.gen.coroutine
+    def get(self, worker_id):
+        self.check_workspace_origin()
+        worker = self.get_worker(worker_id)
+        download = self.get_argument('download', '') == '1'
+        path = self.get_argument('path', '.')
+        try:
+            result = yield self.executor.submit(
+                transfer, worker.ssh, 'download' if download else 'list', path
+            )
+        except (OSError, paramiko.SSHException, ValueError):
+            raise tornado.web.HTTPError(
+                400, '文件操作失败，请检查路径、权限及 SFTP 支持。'
+            )
+        finally:
+            worker.file_lock.release()
+        if download:
+            self.set_header('Content-Type', 'application/octet-stream')
+            self.set_header('Content-Disposition', 'attachment')
+            self.write(result)
+        else:
+            self.write(result)
+
+    @tornado.web.authenticated
+    @tornado.gen.coroutine
+    def post(self, worker_id):
+        self.check_workspace_origin()
+        files = self.request.files.get('file', [])
+        if len(files) != 1:
+            raise tornado.web.HTTPError(400, '请选择一个文件。')
+        worker = self.get_worker(worker_id)
+        try:
+            result = yield self.executor.submit(
+                transfer, worker.ssh, 'upload', self.get_argument('path', '.'),
+                (files[0]['filename'], files[0]['body'])
+            )
+        except (OSError, paramiko.SSHException, ValueError):
+            raise tornado.web.HTTPError(
+                400, '上传失败：同名文件已存在、权限不足或连接中断。'
+            )
+        finally:
+            worker.file_lock.release()
+        self.write(result)