Rework channel labeling and add source picker to virtual-channel creation

Relabel every channel picker/header to "NAME (DEVICE/SIGNAL)" instead of
the previous "DEVICE/SIGNAL (NAME)" ordering, consistently across
channels_window.py (_channel_combo, ChannelPickerDialog,
ChannelPipelineBlock header), plot_builder.py, plot_config.py,
control_editor.py, and plot_window.py.

While touching each of those pickers, added the missing `.enabled`
filter that _make_picker()/_x_cb/_build_channel_picker lacked (the
default-layout builders already filtered disabled channels; these
manual "add channel to pane" pickers didn't).

Devices window Signals tab: removed the separate "Signal ID" column
(folded into the existing non-editable Device column instead of the
editable Name column, to avoid corrupting the in-place channel rename
feature that column already supports).

Channels window Virtual Channels pane: added a "Source" dropdown next
to "+ Add Channel" — picking a source pre-seeds the new derived
channel with it via DerivedBlock._add_src(); leaving it on the default
"none" entry keeps today's behavior of creating an empty channel.

Note: docs/ToDo.md's "Channels window UI" items referred to the *live*
UI (this window's PipelineTab + the Devices window's Signals tab), not
SignalsListTab in this same file, which its own module docstring flags
as dead/unused code kept only for old-profile compatibility — verified
by grepping for any instantiation of it (none exist).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

3 files changed, 37 insertions, 24 deletions

diff --git a/ui/windows/channels_window.py b/ui/windows/channels_window.py
index 381800a..38d477b 100644
--- a/ui/windows/channels_window.py
+++ b/ui/windows/channels_window.py
@@ -74,7 +74,7 @@ def _channel_combo(registry: DeviceRegistry,
         for ch in dev.info.channels:
             if not ch.enabled:
                 continue
-            label = f"{dev.info.device_id} / {ch.channel_id}  ({ch.name})"
+            label = f"{ch.name}  ({dev.info.device_id}/{ch.channel_id})"
             if show_unit and ch.unit:
                 label += f"  [{ch.unit}]"
             cb.addItem(label, userData=(dev.info.device_id, ch.channel_id))
@@ -115,7 +115,7 @@ class ChannelPickerDialog(QDialog):
                 if (dev.info.device_id, ch.channel_id) in already_shown:
                     continue
                 any_available = True
-                label = f"{dev.info.device_id} / {ch.channel_id}  ({ch.name})"
+                label = f"{ch.name}  ({dev.info.device_id}/{ch.channel_id})"
                 if ch.unit:
                     label += f"  [{ch.unit}]"
                 chk = QCheckBox(label)
@@ -236,7 +236,7 @@ class ChannelPipelineBlock(QFrame):
         # Header
         hdr = QWidget(); hdr.setObjectName("plotBlockHeader"); hdr.setFixedHeight(32)
         hl  = QHBoxLayout(hdr); hl.setContentsMargins(8, 0, 6, 0)
-        title = f"{self.dev_id} / {self.ch_id}  ({ch_name})"
+        title = f"{ch_name}  ({self.dev_id}/{self.ch_id})"
         if unit:
             title += f"  [{unit}]"
         self._title_lbl = QLabel(title); self._title_lbl.setObjectName("traceSource")
@@ -307,7 +307,7 @@ class ChannelPipelineBlock(QFrame):
         self._body.setVisible(False)
 
     def _refresh_title(self):
-        title = f"{self.dev_id} / {self.ch_id}  ({self._ch_name})"
+        title = f"{self._ch_name}  ({self.dev_id}/{self.ch_id})"
         if self._unit:
             title += f"  [{self._unit}]"
         self._title_lbl.setText(title)
@@ -444,7 +444,12 @@ class PipelineTab(QWidget):
         virt_bar = QWidget(); virt_bar.setObjectName("cfgGlobalBar")
         vb_lay = QHBoxLayout(virt_bar); vb_lay.setContentsMargins(10, 7, 10, 7); vb_lay.setSpacing(6)
         vb_lbl = QLabel("Channels"); vb_lbl.setObjectName("devWindowTitle")
-        vb_lay.addWidget(vb_lbl, 1)
+        vb_lay.addWidget(vb_lbl)
+        self._src_cb = _channel_combo(self.registry, self.processor, include_derived=True)
+        self._src_cb.setObjectName("channelPickerCb")
+        self._src_cb.insertItem(0, "Source: none (empty channel)", userData=None)
+        self._src_cb.setCurrentIndex(0)
+        vb_lay.addWidget(self._src_cb, 1)
         add_virt = QPushButton("＋ Add Channel"); add_virt.setObjectName("addTraceBtn")
         add_virt.clicked.connect(self._add_virtual)
         vb_lay.addWidget(add_virt)
@@ -579,6 +584,11 @@ class PipelineTab(QWidget):
                             kind="expression", color=color)
         blk = self._make_derived_block(dc)
         self._virt_inner.insertWidget(self._virt_inner.count() - 1, blk)
+        # Pre-seed the source picked in the bar above, if any — otherwise the
+        # channel is created empty and sources can be added manually.
+        src = self._src_cb.currentData()
+        if src:
+            blk._add_src(src)
 
     def _make_derived_block(self, dc: DerivedChannel) -> DerivedBlock:
         blk = DerivedBlock(dc, self.registry, self.processor)
diff --git a/ui/windows/devices_window.py b/ui/windows/devices_window.py
index ac9d13c..3b193b2 100644
--- a/ui/windows/devices_window.py
+++ b/ui/windows/devices_window.py
@@ -124,12 +124,11 @@ class ChannelsTab(QWidget):
 
     # Col indices
     _C_DEVICE  = 0
-    _C_CH_ID   = 1
-    _C_ENABLED = 2
-    _C_NAME    = 3
-    _C_UNIT    = 4
-    _C_MIN     = 5
-    _C_MAX     = 6
+    _C_ENABLED = 1
+    _C_NAME    = 2
+    _C_UNIT    = 3
+    _C_MIN     = 4
+    _C_MAX     = 5
 
     def __init__(self, registry: DeviceRegistry):
         super().__init__()
@@ -142,14 +141,13 @@ class ChannelsTab(QWidget):
 
         self._table = QTableWidget()
         self._table.setObjectName("channelTable")
-        self._table.setColumnCount(7)
+        self._table.setColumnCount(6)
         self._table.setHorizontalHeaderLabels(
-            ["Device", "Signal ID", "On", "Name", "Unit", "Min", "Max"]
+            ["Device", "On", "Name", "Unit", "Min", "Max"]
         )
         hdr = self._table.horizontalHeader()
         hdr.setSectionResizeMode(self._C_NAME,    QHeaderView.ResizeMode.Stretch)
         hdr.setSectionResizeMode(self._C_DEVICE,  QHeaderView.ResizeMode.ResizeToContents)
-        hdr.setSectionResizeMode(self._C_CH_ID,   QHeaderView.ResizeMode.ResizeToContents)
         hdr.setSectionResizeMode(self._C_ENABLED, QHeaderView.ResizeMode.ResizeToContents)
         self._table.setSelectionBehavior(QAbstractItemView.SelectionBehavior.SelectRows)
         self._table.setAlternatingRowColors(True)
@@ -165,16 +163,13 @@ class ChannelsTab(QWidget):
             for ch in dev.info.channels:
                 self._table.insertRow(row)
 
-                dev_item = QTableWidgetItem(f"{dev.info.icon} {dev.info.device_id}")
+                # Device + signal ID folded into one non-editable column —
+                # the separate "Signal ID" column was removed as redundant.
+                dev_item = QTableWidgetItem(f"{dev.info.icon} {dev.info.device_id} / {ch.channel_id}")
                 dev_item.setFlags(dev_item.flags() & ~Qt.ItemFlag.ItemIsEditable)
                 dev_item.setForeground(QColor("#64748b"))
                 self._table.setItem(row, self._C_DEVICE, dev_item)
 
-                ch_item = QTableWidgetItem(ch.channel_id)
-                ch_item.setFlags(ch_item.flags() & ~Qt.ItemFlag.ItemIsEditable)
-                ch_item.setForeground(QColor(ch.color))
-                self._table.setItem(row, self._C_CH_ID, ch_item)
-
                 # Enabled checkbox — centred in cell
                 chk_container = QWidget()
                 chk_lay = QHBoxLayout(chk_container)
diff --git a/ui/windows/plot_window.py b/ui/windows/plot_window.py
index 9edf046..f311e9e 100644
--- a/ui/windows/plot_window.py
+++ b/ui/windows/plot_window.py
@@ -355,10 +355,14 @@ class PaneBlock(QFrame):
         self._x_cb.addItem("⏱  Time (elapsed s)", userData="time")
         for dev in self.registry.all_instances():
             for ch in dev.info.channels:
-                self._x_cb.addItem(f"{dev.info.device_id}/{ch.channel_id}  ({ch.name})",
+                if not ch.enabled:
+                    continue
+                self._x_cb.addItem(f"{ch.name}  ({dev.info.device_id}/{ch.channel_id})",
                                    userData=f"{dev.info.device_id}/{ch.channel_id}")
         for dc in self.processor.get_derived():
-            self._x_cb.addItem(f"[virtual] {dc.channel_id}",
+            if not dc.enabled:
+                continue
+            self._x_cb.addItem(f"{dc.name}  ([virtual]/{dc.channel_id})",
                                userData=f"derived/{dc.channel_id}")
         for i in range(self._x_cb.count()):
             if self._x_cb.itemData(i) == self.spec.x_source:
@@ -417,10 +421,14 @@ class PaneBlock(QFrame):
         cb = QComboBox(); cb.setObjectName("channelPickerCb")
         for dev in self.registry.all_instances():
             for ch in dev.info.channels:
-                cb.addItem(f"{dev.info.device_id} / {ch.channel_id}  ({ch.name})",
+                if not ch.enabled:
+                    continue
+                cb.addItem(f"{ch.name}  ({dev.info.device_id}/{ch.channel_id})",
                            userData=(dev.info.device_id, ch.channel_id, ch.name, ch.color))
         for dc in self.processor.get_derived():
-            cb.addItem(f"[virtual] {dc.channel_id}  ({dc.name})",
+            if not dc.enabled:
+                continue
+            cb.addItem(f"{dc.name}  ([virtual]/{dc.channel_id})",
                        userData=("derived", dc.channel_id, dc.name, dc.color))
         return cb