Tier 0: render what the services already decided, honestly

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

config/dot/quickshell/modules/quicksettings/BluetoothList.qml

@@ -6,6 +6,7 @@ import Quickshell
 import Quickshell.Widgets
 import Quickshell.Bluetooth
 import qs.config
+import qs.services
 
 Item {
     id: root
@@ -16,7 +17,15 @@ Item {
     property alias maxHeight: list.maxHeight
 
     readonly property var adapter: Bluetooth.defaultAdapter
-    property bool discoveryOwned: false
+
+    // Discovery is held, not switched. This picker and the settings page both
+    // list the same adapter, and each writing adapter.discovering from its own
+    // visibility flag meant the last one to change its mind decided for both --
+    // closing the settings page stopped discovery under this panel, which then
+    // said "Searching…" over a radio that had stopped. Connectivity counts the
+    // holds, owns the BlueZ write, and never stops a scan it did not start;
+    // nothing here touches the adapter.
+    readonly property string scanHold: "quicksettings-bluetooth"
 
     implicitHeight: list.implicitHeight
 
@@ -32,29 +41,14 @@ Item {
         return list;
     }
 
-    function syncDiscovery(): void {
-        if (!root.adapter)
-            return;
-        const shouldDiscover = root.active && root.adapter.enabled;
-        if (shouldDiscover && !root.adapter.discovering) {
-            root.adapter.discovering = true;
-            root.discoveryOwned = true;
-        } else if (!shouldDiscover && root.discoveryOwned && root.adapter.discovering) {
-            root.adapter.discovering = false;
-            root.discoveryOwned = false;
-        }
-    }
-
-    onActiveChanged: root.syncDiscovery()
-    onAdapterChanged: {
+    onActiveChanged: {
         if (root.active)
-            root.syncDiscovery();
+            Connectivity.acquireDiscovery(root.scanHold);
+        else
+            Connectivity.releaseDiscovery(root.scanHold);
     }
 
-    Component.onDestruction: {
-        if (root.adapter && root.discoveryOwned && root.adapter.discovering)
-            root.adapter.discovering = false;
-    }
+    Component.onDestruction: Connectivity.releaseDiscovery(root.scanHold)
 
     function stateText(device): string {
         if (device.pairing)