Keep PwNode objects out of the audio panel's Repeater models

The panel handed its three Repeaters snapshots of live PwNode objects, and Quickshell deletes a node the moment PipeWire drops it. Qt then dereferences that row without a null check in VDMListDelegateDataType::createMissingProperties (qqmldmlistaccessordata_p.h:222, unchanged in 6.11.2), so any teardown that emptied the graph with the panel open segfaulted the shell: a USB DAC unplugged, a Bluetooth profile switch, omarchy-restart-audio, a WirePlumber restart, or a laptop suspend.

Rows now carry the node's id and name rather than the node, and each delegate resolves its own PwNode through nodeFor(), so labels, glyphs and stream volumes stay live. The name is what pins a row to the node it came from, since PipeWire reuses object ids; it is CONSTANT on PwNode for as long as the node exists. This is the projection the bluetooth panel already uses against the same crash class.

Filtering the snapshot instead does not work, which is worth recording because it is the obvious thing to reach for: the node is usually alive when the snapshot is taken and dies while Qt is incubating the delegate, so nothing visible at snapshot time identifies the row that will dangle.

Co-Authored-By: Codex XHigh <codex@openai.com>

shell/plugins/panels/audio/Model.js

@@ -18,8 +18,31 @@ function isAudioSource(node) {
     || mediaClass.indexOf("Source") !== -1
 }
 
-function listSnapshot(list) {
-  return list && list.slice ? list.slice() : []
+// Project a node list to the primitive rows a Repeater model can hold. A row
+// holding the PwNode itself is a QObject that Qt dereferences without a null
+// check while it builds the delegate, and PipeWire deletes nodes outright, so a
+// graph teardown segfaults the shell. Primitives cannot dangle, which is what
+// closes that race -- not the check below, since the node usually dies after the
+// snapshot is taken. That is also why filtering the list here never worked.
+//
+// The name rides along because PipeWire reuses object ids: without it a row
+// could resolve to whatever inherited its id. PwNode.name is CONSTANT, so it
+// identifies the node it was taken from for as long as that node lives.
+function nodeRow(node) {
+  if (!node) return null
+  var id = node.id
+  if (id === undefined || id === null) return null
+  return { id: id, name: String(node.name || "") }
+}
+
+function rowSnapshot(list) {
+  var values = list && list.length ? list : []
+  var rows = []
+  for (var i = 0; i < values.length; i++) {
+    var row = nodeRow(values[i])
+    if (row) rows.push(row)
+  }
+  return rows
 }
 
 function outputVolumeName(volume, muted) {
@@ -237,7 +260,8 @@ if (typeof module !== "undefined") {
   module.exports = {
     isPlaybackStream: isPlaybackStream,
     isAudioSource: isAudioSource,
-    listSnapshot: listSnapshot,
+    nodeRow: nodeRow,
+    rowSnapshot: rowSnapshot,
     outputVolumeName: outputVolumeName,
     parseSinkAvailability: parseSinkAvailability,
     friendlyDeviceLabel: friendlyDeviceLabel,

shell/plugins/panels/audio/Panel.qml

@@ -100,11 +100,13 @@ Panel {
     return list
   }
 
-  // Feed Repeaters with panel-local snapshots instead of the live PipeWire
-  // model. PipeWire can remove nodes while Quickshell is dispatching the
-  // removal signal; rebuilding a Repeater from that signal path has crashed
-  // in Quickshell's PipeWire service. The snapshot timer lets that mutation
-  // settle first, and closed panels keep their repeaters detached entirely.
+  // Feed Repeaters with panel-local snapshots of primitives instead of the live
+  // PipeWire model. PipeWire can remove nodes while Quickshell is dispatching
+  // the removal signal, and a row still holding the PwNode is a QObject Qt
+  // dereferences without a null check, which segfaults the shell. Rows carry id
+  // and name only; every delegate resolves its own node through nodeFor(). The
+  // snapshot timer lets the mutation settle first, and closed panels keep their
+  // repeaters detached entirely.
   property var displayAudioSinks: []
   property var displayAudioSources: []
   property var displayAudioStreams: []
@@ -281,7 +283,7 @@ Panel {
       return
     }
     if (focusSection === "streams" && selectedIndex >= 0 && selectedIndex < displayAudioStreams.length) {
-      var s = displayAudioStreams[selectedIndex]
+      var s = nodeFor(displayAudioStreams[selectedIndex])
       if (s && s.audio) s.audio.volume = Math.max(0, Math.min(1.5, s.audio.volume + delta))
     }
   }
@@ -291,18 +293,18 @@ Panel {
     if (focusSection === "header") { toggleAllMuted(); return }
     if (focusSection === "output") {
       if (selectedIndex === -1) { toggleOutputMute(); return }
-      var sink = displayAudioSinks[selectedIndex]
+      var sink = nodeFor(displayAudioSinks[selectedIndex])
       if (sink) setDefaultSink(sink)
       return
     }
     if (focusSection === "input") {
       if (selectedIndex === -1) { toggleInputMute(); return }
-      var src = displayAudioSources[selectedIndex]
+      var src = nodeFor(displayAudioSources[selectedIndex])
       if (src) setDefaultSource(src)
       return
     }
     if (focusSection === "streams" && selectedIndex >= 0) {
-      var st = displayAudioStreams[selectedIndex]
+      var st = nodeFor(displayAudioStreams[selectedIndex])
       if (st && st.audio) st.audio.muted = !st.audio.muted
     }
   }
@@ -324,15 +326,26 @@ Panel {
   onAudioSourcesChanged: scheduleDisplayAudioModelRefresh()
   onAudioStreamsChanged: scheduleDisplayAudioModelRefresh()
 
-  function listSnapshot(list) {
-    return Model.listSnapshot(list)
+  function rowSnapshot(list) {
+    return Model.rowSnapshot(list)
+  }
+
+  // A row that outlives its node resolves to null, and every binding below
+  // already guards for that; a row that never held the node cannot dangle.
+  function nodeFor(row) {
+    if (!row) return null
+    for (var i = 0; i < nodes.length; i++) {
+      var n = nodes[i]
+      if (n && n.id === row.id && String(n.name || "") === row.name) return n
+    }
+    return null
   }
 
   function refreshDisplayAudioModels() {
     if (!opened) return
-    displayAudioSinks = listSnapshot(audioSinks)
-    displayAudioSources = listSnapshot(audioSources)
-    displayAudioStreams = listSnapshot(audioStreams)
+    displayAudioSinks = rowSnapshot(audioSinks)
+    displayAudioSources = rowSnapshot(audioSources)
+    displayAudioStreams = rowSnapshot(audioStreams)
     clampCursor()
   }
 
@@ -559,15 +572,18 @@ Panel {
     // Spotify exposes its PipeWire stream as "audio-src". For generic stream
     // names, use the one MPRIS player not already represented by another audio
     // stream (e.g. Chromium, or ALSA apps like cliamp).
-    return Model.unmatchedMprisStreamLabel(label, mprisPlayers, displayAudioStreams)
+    return Model.unmatchedMprisStreamLabel(label, mprisPlayers, audioStreams)
   }
 
+  // These read the other streams' node properties, so they take the live list --
+  // displayAudioStreams carries primitives now, and resolving each row back
+  // would only rebuild what audioStreams already is.
   function streamLabel(node) {
-    return Model.streamLabel(node, mprisPlayers, displayAudioStreams)
+    return Model.streamLabel(node, mprisPlayers, audioStreams)
   }
 
   function streamRepresentsPlayer(node, player) {
-    return Model.streamRepresentsPlayer(node, player, mprisPlayers, displayAudioStreams)
+    return Model.streamRepresentsPlayer(node, player, mprisPlayers, audioStreams)
   }
 
   implicitWidth: button.implicitWidth
@@ -675,7 +691,7 @@ Panel {
           if (!root.cursorActive) return
           if (root.focusSection === "streams" && root.selectedIndex >= 0
               && root.selectedIndex < root.displayAudioStreams.length) {
-            var s = root.displayAudioStreams[root.selectedIndex]
+            var s = root.nodeFor(root.displayAudioStreams[root.selectedIndex])
             if (s && s.audio) s.audio.muted = !s.audio.muted
           } else if (root.focusSection === "input") {
             root.toggleInputMute()
@@ -854,7 +870,7 @@ Panel {
                 required property var modelData
                 required property int index
                 width: panelColumn.width
-                node: modelData
+                node: root.nodeFor(modelData)
                 rowIndex: index
               }
             }
@@ -961,7 +977,7 @@ Panel {
                 required property var modelData
                 required property int index
                 width: panelColumn.width
-                node: modelData
+                node: root.nodeFor(modelData)
                 rowIndex: index
               }
             }
@@ -991,7 +1007,7 @@ Panel {
                 required property var modelData
                 required property int index
                 width: panelColumn.width
-                node: modelData
+                node: root.nodeFor(modelData)
                 rowIndex: index
               }
             }