hardware wallets: better handle label collision when selecting device

related: #5759

electrum/plugin.py

@@ -314,6 +314,9 @@ class HardwarePluginToScan(NamedTuple):
     exception: Optional[Exception]
 
 
+PLACEHOLDER_HW_CLIENT_LABELS = {"", " "}
+
+
 class DeviceMgr(ThreadJob):
     '''Manages hardware clients.  A client communicates over a hardware
     channel with the device.
@@ -507,7 +510,7 @@ class DeviceMgr(ThreadJob):
               'its seed (and passphrase, if any).  Otherwise all bitcoins you '
               'receive will be unspendable.').format(plugin.device))
 
-    def unpaired_device_infos(self, handler, plugin: 'HW_PluginBase', devices=None,
+    def unpaired_device_infos(self, handler, plugin: 'HW_PluginBase', devices: List['Device'] = None,
                               include_failing_clients=False):
         '''Returns a list of DeviceInfo objects: one for each connected,
         unpaired device accepted by the plugin.'''
@@ -537,7 +540,7 @@ class DeviceMgr(ThreadJob):
         return infos
 
     def select_device(self, plugin: 'HW_PluginBase', handler,
-                      keystore: 'Hardware_KeyStore', devices=None) -> 'DeviceInfo':
+                      keystore: 'Hardware_KeyStore', devices: List['Device'] = None) -> 'DeviceInfo':
         '''Ask the user to select a device to use if there is more than one,
         and return the DeviceInfo for the device.'''
         while True:
@@ -557,12 +560,21 @@ class DeviceMgr(ThreadJob):
             devices = None
         if len(infos) == 1:
             return infos[0]
-        # select device by label
-        for info in infos:
-            if info.label == keystore.label:
-                return info
+        # select device by label automatically;
+        # but only if not a placeholder label and only if there is no collision
+        device_labels = [info.label for info in infos]
+        if (keystore.label not in PLACEHOLDER_HW_CLIENT_LABELS
+                and device_labels.count(keystore.label) == 1):
+            for info in infos:
+                if info.label == keystore.label:
+                    return info
+        # ask user to select device
         msg = _("Please select which {} device to use:").format(plugin.device)
-        descriptions = [str(info.label) + ' (%s)'%(_("initialized") if info.initialized else _("wiped")) for info in infos]
+        descriptions = ["{label} ({init}, {transport})"
+                        .format(label=info.label,
+                                init=(_("initialized") if info.initialized else _("wiped")),
+                                transport=info.device.transport_ui_string)
+                        for info in infos]
         c = handler.query_choice(msg, descriptions)
         if c is None:
             raise UserCancelled()

electrum/plugins/hw_wallet/plugin.py

@@ -160,7 +160,12 @@ class HardwareClientBase:
         raise NotImplementedError()
 
     def label(self) -> str:
-        """The name given by the user to the device."""
+        """The name given by the user to the device.
+
+        Note: labels are shown to the user to help distinguish their devices,
+        and they are also used as a fallback to distinguish devices programmatically.
+        So ideally, different devices would have different labels.
+        """
         raise NotImplementedError()
 
     def has_usable_connection_with_device(self) -> bool: