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, 14 insertions, 1 deletions

diff --git a/ui/strip_chart.py b/ui/strip_chart.py
index b295a8c..e77c092 100644
--- a/ui/strip_chart.py
+++ b/ui/strip_chart.py
@@ -180,7 +180,7 @@ class StripChartWidget(QWidget):
                 pen   = pg.mkPen(color="#6b7280" if missing else tr.color, width=tr.width,
                                   style=Qt.PenStyle.DashLine if missing
                                         else _STYLES.get(tr.style, Qt.PenStyle.SolidLine))
-                label = tr.label or tr.channel_id
+                label = tr.label or self._lookup_channel_name(tr.device_id, tr.channel_id)
                 curve = plot.plot([], [], pen=pen,
                                    name=f"{label} (missing)" if missing else label)
                 key   = (tr.device_id, tr.channel_id)
@@ -216,6 +216,19 @@ class StripChartWidget(QWidget):
         dev = self.registry.get_instance(device_id)
         return dev is None or dev.get_signal(channel_id) is None
 
+    def _lookup_channel_name(self, device_id: str, channel_id: str) -> str:
+        """Live display name for a trace with no user-typed label, so a
+        Signal/Channel rename shows up on the chart without re-adding the
+        trace — mirrors _lookup_channel_unit()."""
+        if device_id == "derived":
+            for dc in self.processor.get_derived():
+                if dc.channel_id == channel_id:
+                    return dc.name
+            return channel_id
+        dev = self.registry.get_instance(device_id)
+        ch = dev.get_signal(channel_id) if dev else None
+        return (ch.name if ch and ch.name else channel_id)
+
     def _lookup_channel_unit(self, device_id: str, channel_id: str) -> str:
         if device_id == "derived":
             for dc in self.processor.get_derived():