Make Channel the single source of truth for a reading's name

Device tab stays hardware-only (pins, wiring, may vary per workstation);
the Channels window owns the profile-facing identity. Concretely:

- Fix a real regression: SerialDevice generic-format Apply & Reconnect
  nulled out custom channel_names/units every time (no fallback, unlike
  every other optional field in reconfigure()), silently reverting to
  sig0/sig1/... ids.
- Plot legend now live-tracks the current Signal/Channel name instead of
  freezing tr.label at add-time, so a rename shows up without re-adding
  the trace.
- Add an inline quick-reconnect (combo + button, pre-selects the actual
  current source) directly on each Channel block in the Channels window,
  for the common single-source case — rewiring hardware no longer means
  touching every Plot/pipeline that referenced it.
- Collapse the Channel ID field behind an "ID ▸" advanced toggle;
  channel_id is already auto-derived from the name (_slug_id) and rarely
  needs to be seen.
- Devices tab's Signal "Name" column relabeled "Label" with a tooltip —
  de-emphasized now that Channel name is the real identity.
- Move "create a Channel from this Signal" from a column on the Devices
  tab's signal table to a ⊕ button on each Signal row in the Channels
  tab's Namespace panel — the action now lives where the identity is
  created, not on the hardware tab. Only that instance opts in
  (on_create_channel); the read-only Namespace dock on the main window
  is unaffected.
- Floor the Namespace panel's width at its columns' natural size so
  dragging the Channels-tab splitter narrower can't push the ⊕ column
  behind the horizontal scrollbar.
- Breadcrumb log when a profile-saved Signal override can't be applied
  because the signal_id no longer exists.

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

1 files changed, 47 insertions, 8 deletions

diff --git a/ui/namespace_panel.py b/ui/namespace_panel.py
index 9616db7..e2b8809 100644
--- a/ui/namespace_panel.py
+++ b/ui/namespace_panel.py
@@ -5,19 +5,24 @@ NAMESPACE panel — dockable, live browser of everything referenceable in a
 script: Signals (raw device endpoints), Channels (processed/derived
 values), and vars (the shared dict bridging Control Panel On Action
 Scripts and Channel scripts). Read-only reference, not an editor — editing
-still happens in Configuration > Channels.
+still happens in Configuration > Channels — with one narrow exception:
+when constructed with `on_create_channel`, each Signal row gets a ⊕
+button to create a passthrough Channel from it directly. Only
+ConfigWindow's Channels-tab instance opts into this (config_window.py);
+the dockable instance on the main window (ui/main_window.py) does not
+pass a callback, so it stays exactly the plain read-only reference.
 
 Docked opposite the Control Panel (ui/main_window.py), built the same way:
 a QDockWidget you can drag, float, redock, or close.
 """
 
 from __future__ import annotations
-from typing import Dict, Tuple
+from typing import Callable, Dict, Optional, Tuple
 
 from PyQt6.QtWidgets import (
     QWidget, QVBoxLayout, QHBoxLayout, QLabel,
     QTableWidget, QTableWidgetItem, QHeaderView, QAbstractItemView,
-    QApplication,
+    QToolButton, QApplication,
 )
 from PyQt6.QtCore import QTimer, pyqtSlot
 from PyQt6.QtGui import QColor
@@ -33,6 +38,7 @@ _C_NAME   = 2
 _C_DIR    = 3
 _C_VALUE  = 4
 _C_SOURCE = 5
+_C_CREATE = 6   # only present when on_create_channel is set
 
 
 def _fmt_value(v) -> str:
@@ -54,10 +60,14 @@ def _fmt_ref(dev_id: str, ch_id: str) -> str:
 
 
 class NamespacePanel(QWidget):
-    def __init__(self, registry: DeviceRegistry, processor: SignalProcessor):
+    def __init__(self, registry: DeviceRegistry, processor: SignalProcessor,
+                 on_create_channel: Optional[Callable[[str, str, str, str, str], None]] = None):
         super().__init__()
         self.registry  = registry
         self.processor = processor
+        # (dev_id, ch_id, name, unit, color) -> None, called when a Signal
+        # row's ⊕ button is clicked. None hides the column entirely.
+        self.on_create_channel = on_create_channel
         # row key -> row index. Keys:
         #   ("signal", dev_id, ch_id) | ("channel", channel_id) | ("var", name)
         self._row_index: Dict[Tuple, int] = {}
@@ -84,10 +94,11 @@ class NamespacePanel(QWidget):
 
         self._table = QTableWidget()
         self._table.setObjectName("channelTable")
-        self._table.setColumnCount(6)
-        self._table.setHorizontalHeaderLabels(
-            ["Kind", "ID", "Name", "Dir", "Value", "Source"]
-        )
+        labels = ["Kind", "ID", "Name", "Dir", "Value", "Source"]
+        if self.on_create_channel:
+            labels.append("")
+        self._table.setColumnCount(len(labels))
+        self._table.setHorizontalHeaderLabels(labels)
         hdr = self._table.horizontalHeader()
         hdr.setSectionResizeMode(_C_SOURCE, QHeaderView.ResizeMode.Stretch)
         hdr.setSectionResizeMode(_C_KIND,   QHeaderView.ResizeMode.ResizeToContents)
@@ -95,6 +106,8 @@ class NamespacePanel(QWidget):
         hdr.setSectionResizeMode(_C_NAME,   QHeaderView.ResizeMode.ResizeToContents)
         hdr.setSectionResizeMode(_C_DIR,    QHeaderView.ResizeMode.ResizeToContents)
         hdr.setSectionResizeMode(_C_VALUE,  QHeaderView.ResizeMode.ResizeToContents)
+        if self.on_create_channel:
+            hdr.setSectionResizeMode(_C_CREATE, QHeaderView.ResizeMode.ResizeToContents)
         self._table.setSelectionBehavior(QAbstractItemView.SelectionBehavior.SelectRows)
         self._table.setEditTriggers(QAbstractItemView.EditTrigger.NoEditTriggers)
         self._table.setAlternatingRowColors(True)
@@ -102,6 +115,17 @@ class NamespacePanel(QWidget):
         self._table.cellDoubleClicked.connect(self._on_double_clicked)
         lay.addWidget(self._table)
 
+    def _apply_min_width(self):
+        """Floor the panel's width at the sum of its columns' natural sizes
+        (Source gets a fixed placeholder rather than its live stretched
+        width, which would be circular) — so dragging the Channels-tab
+        splitter divider narrower can never push the ⊕ create-channel
+        column (or any other column) behind the horizontal scrollbar."""
+        total = 0
+        for i in range(self._table.columnCount()):
+            total += 80 if i == _C_SOURCE else self._table.columnWidth(i)
+        self.setMinimumWidth(total + 24)
+
     # ── Row-set (structural) rebuild — devices/channels/vars added or removed ──
 
     def _desired_keys(self):
@@ -125,9 +149,13 @@ class NamespacePanel(QWidget):
         for row, key in enumerate(keys):
             self._row_index[key] = row
             self._paint_row(row, key)
+        self._apply_min_width()
 
     def _paint_row(self, row: int, key: Tuple):
         kind = key[0]
+        if self.on_create_channel:
+            self._table.removeCellWidget(row, _C_CREATE)   # row's kind may have
+                                                             # changed since last paint
         if kind == "signal":
             _, dev_id, ch_id = key
             dev = self.registry.get_instance(dev_id)
@@ -136,6 +164,17 @@ class NamespacePanel(QWidget):
             is_wr = bool(ch and ch.writable)
             self._set_row(row, "Signal", ch_id, name, "WRITE" if is_wr else "READ",
                           None, _fmt_ref(dev_id, ch_id))
+            if self.on_create_channel and ch is not None:
+                btn = QToolButton()
+                btn.setText("⊕")
+                btn.setObjectName("addTraceBtn")
+                btn.setFixedSize(24, 22)
+                btn.setToolTip("Create a Channel from this Signal")
+                btn.clicked.connect(
+                    lambda _=False, d=dev_id, c=ch_id, n=ch.name, u=ch.unit, col=ch.color:
+                        self.on_create_channel(d, c, n, u, col)
+                )
+                self._table.setCellWidget(row, _C_CREATE, btn)
         elif kind == "channel":
             _, channel_id = key
             dc = next((d for d in self.processor.get_derived()