devices widget: open file manager on dispvm block attach

qui/devices/actionable_widgets.py

@@ -31,6 +31,7 @@
 import qubesadmin
 import qubesadmin.devices
 import qubesadmin.vm
+from qubesadmin import exc
 
 import gi
 
@@ -324,6 +325,21 @@ async def widget_action(self, *_args):
 
         self.device.attach_to_vm(backend.VM(new_dispvm))
 
+        if self.device.device_class == "block" and self.vm.vm_object.features.get(
+            backend.FEATURE_OPEN_FILE_MANAGER, "1"
+        ):
+            try:
+                new_dispvm.run_service(
+                    "qubes.StartApp+qubes-open-file-manager",
+                    wait=False,
+                )
+            except exc.QubesException as ex:
+                new_dispvm.log.exception(
+                    "Failed to open file manager in %s: %s",
+                    new_dispvm.name,
+                    ex,
+                )
+
 
 class DetachAndAttachDisposableWidget(ActionableWidget, VMWithIcon):
     """Detach from all current attachments and attach to new disposable"""
@@ -340,6 +356,21 @@ async def widget_action(self, *_args):
 
         self.device.attach_to_vm(backend.VM(new_dispvm))
 
+        if self.device.device_class == "block" and self.vm.vm_object.features.get(
+            backend.FEATURE_OPEN_FILE_MANAGER, "1"
+        ):
+            try:
+                new_dispvm.run_service(
+                    "qubes.StartApp+qubes-open-file-manager",
+                    wait=False,
+                )
+            except exc.QubesException as ex:
+                new_dispvm.log.exception(
+                    "Failed to open file manager in %s: %s",
+                    new_dispvm.name,
+                    ex,
+                )
+
 
 class ToggleFeatureItem(ActionableWidget, SimpleActionWidget):
     def __init__(

qui/devices/backend.py

@@ -39,6 +39,7 @@
 FEATURE_HIDE_CHILDREN = "device-hide-children"
 FEATURE_ATTACH_WITH_MIC = "device-attach-with-mic"
 FEATURE_RESOLUTION = "device-qvc-resolution"  # dev_id=resolution, space delimited
+FEATURE_OPEN_FILE_MANAGER = "device-open-file-manager-on-attach"
 
 
 class VM:

qui/devices/tests/test_actionable_widgets.py

@@ -0,0 +1,158 @@
+# -*- encoding: utf8 -*-
+#
+# The Qubes OS Project, http://www.qubes-os.org
+#
+# Copyright (C) 2026 Sahil Kumar
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation; either version 2.1 of the License, or
+# (at your option) any later version.
+# pylint: disable=redefined-outer-name
+import asyncio
+import pytest
+from unittest.mock import patch, Mock
+from qubesadmin import exc
+from qubesadmin.tests.mock_app import MockQubesComplete
+from qui.devices.actionable_widgets import (
+    AttachDisposableWidget,
+    DetachAndAttachDisposableWidget,
+)
+
+
+@pytest.fixture
+def mock_qapp():
+    app = MockQubesComplete()
+    return app
+
+
+def make_mock_device(device_class="block"):
+    device = Mock()
+    device.device_class = device_class
+    device.interfaces = ""
+    device.is_valid_for_vm = Mock(return_value=True)
+    device.attach_to_vm = Mock()
+    device.detach_from_vm = Mock()
+    return device
+
+
+def make_mock_vm(qubes_app):
+    vm = Mock()
+    vm.icon_name = "appvm-green"
+    vm.name = "test-vm"
+    vm.vm_object = qubes_app._qubes["test-vm"]  # pylint: disable=protected-access
+    return vm
+
+
+class TestAttachDisposableWidget:
+
+    def test_block_device_opens_file_manager(self, mock_qapp):
+        """run_service is called for block device attach to dispvm"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_device = make_mock_device("block")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp123"
+        mock_dispvm.log = Mock()
+        mock_dispvm.devices_denied = ""
+
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = AttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+
+        mock_dispvm.run_service.assert_called_once_with(
+            "qubes.StartApp+qubes-open-file-manager",
+            wait=False,
+        )
+
+    def test_non_block_device_no_file_manager(self, mock_qapp):
+        """run_service is NOT called for non-block device"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_device = make_mock_device("usb")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp123"
+        mock_dispvm.devices_denied = ""
+
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = AttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+
+        mock_dispvm.run_service.assert_not_called()
+
+    def test_file_manager_exception_logged(self, mock_qapp):
+        """QubesException from run_service is logged via dispvm.log"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_device = make_mock_device("block")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp123"
+        mock_dispvm.log = Mock()
+        mock_dispvm.devices_denied = ""
+        mock_dispvm.run_service.side_effect = exc.QubesException("failed")
+
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = AttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+
+        mock_dispvm.log.exception.assert_called_once()
+
+    def test_feature_flag_disables_file_manager(self, mock_qapp):
+        """run_service is NOT called when feature flag is disabled"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_vm.vm_object.features["device-open-file-manager-on-attach"] = ""
+        mock_device = make_mock_device("block")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp123"
+        mock_dispvm.devices_denied = ""
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = AttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+        mock_dispvm.run_service.assert_not_called()
+
+
+class TestDetachAndAttachDisposableWidget:
+
+    def test_block_device_opens_file_manager(self, mock_qapp):
+        """run_service is called for block device on detach+attach"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_device = make_mock_device("block")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp456"
+        mock_dispvm.log = Mock()
+        mock_dispvm.devices_denied = ""
+
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = DetachAndAttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+
+        mock_dispvm.run_service.assert_called_once_with(
+            "qubes.StartApp+qubes-open-file-manager",
+            wait=False,
+        )
+
+    def test_file_manager_exception_logged(self, mock_qapp):
+        """QubesException from run_service is logged via dispvm.log"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_device = make_mock_device("block")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp456"
+        mock_dispvm.log = Mock()
+        mock_dispvm.devices_denied = ""
+        mock_dispvm.run_service.side_effect = exc.QubesException("failed")
+
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = DetachAndAttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+
+        mock_dispvm.log.exception.assert_called_once()
+
+    def test_feature_flag_disables_file_manager(self, mock_qapp):
+        """run_service is NOT called when feature flag is disabled"""
+        mock_vm = make_mock_vm(mock_qapp)
+        mock_vm.vm_object.features["device-open-file-manager-on-attach"] = ""
+        mock_device = make_mock_device("block")
+        mock_dispvm = Mock()
+        mock_dispvm.name = "disp456"
+        mock_dispvm.devices_denied = ""
+        with patch("qubesadmin.vm.DispVM.from_appvm", return_value=mock_dispvm):
+            widget = DetachAndAttachDisposableWidget(mock_vm, mock_device)
+            asyncio.run(widget.widget_action())
+        mock_dispvm.run_service.assert_not_called()