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, 102 insertions, 12 deletions

diff --git a/ui/windows/channels_window.py b/ui/windows/channels_window.py
index 31d1458..cc83b3b 100644
--- a/ui/windows/channels_window.py
+++ b/ui/windows/channels_window.py
@@ -431,8 +431,18 @@ class PipelineTab(QWidget):
         phys_bar = QWidget(); phys_bar.setObjectName("cfgGlobalBar")
         pb_lay = QHBoxLayout(phys_bar); pb_lay.setContentsMargins(10, 7, 10, 7); pb_lay.setSpacing(6)
         pb_lbl = QLabel("Signals"); pb_lbl.setObjectName("devWindowTitle")
-        pb_lay.addWidget(pb_lbl, 1)
+        pb_lay.addWidget(pb_lbl)
+        self._src_cb = _channel_combo(self.registry, self.processor, include_derived=True)
+        self._src_cb.setObjectName("channelPickerCb")
+        self._src_cb.insertItem(0, "Signal: none (empty channel)", userData=None)
+        self._src_cb.setCurrentIndex(0)
+        pb_lay.addWidget(self._src_cb, 1)
+        add_virt = QPushButton("＋ New Channel"); add_virt.setObjectName("addTraceBtn")
+        add_virt.setToolTip("Create a Channel from the selected Signal")
+        add_virt.clicked.connect(self._add_virtual)
+        pb_lay.addWidget(add_virt)
         add_btn = QPushButton("＋ Add"); add_btn.setObjectName("addTraceBtn")
+        add_btn.setToolTip("Add an existing Signal to this list")
         add_btn.clicked.connect(self._on_add_channel)
         pb_lay.addWidget(add_btn)
         phys_l.addWidget(phys_bar)
@@ -458,15 +468,7 @@ 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)
-        self._src_cb = _channel_combo(self.registry, self.processor, include_derived=True)
-        self._src_cb.setObjectName("channelPickerCb")
-        self._src_cb.insertItem(0, "Signal: 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)
+        vb_lay.addWidget(vb_lbl, 1)
         virt_l.addWidget(virt_bar)
 
         div2 = QFrame(); div2.setFrameShape(QFrame.Shape.HLine)
@@ -861,15 +863,45 @@ class ChannelBlock(QFrame):
         outer.addWidget(hdr)
         hdr.mousePressEvent = lambda e: self._toggle()
 
+        # Subtitle — always visible (collapsed or expanded): what this
+        # Channel is currently wired to, plus a one-click rebind for the
+        # common single-source case. Lets a rewire be fixed (or a channel
+        # proactively repointed at a different Signal) without expanding
+        # the block or hunting for the per-source combo in the editor body.
+        sub = QWidget(); sub.setObjectName("plotBlockSubtitle")
+        sub_lay = QHBoxLayout(sub)
+        sub_lay.setContentsMargins(30, 0, 6, 4); sub_lay.setSpacing(6)
+        self._src_lbl = QLabel(""); self._src_lbl.setObjectName("traceSource")
+        sub_lay.addWidget(self._src_lbl, 1)
+        self._reconnect_cb = _channel_combo(self.registry, include_derived=False)
+        self._reconnect_cb.setFixedWidth(220)
+        sub_lay.addWidget(self._reconnect_cb)
+        self._reconnect_btn = QPushButton("↺ Reconnect")
+        self._reconnect_btn.setObjectName("addTraceBtn")
+        self._reconnect_btn.setToolTip("Point this channel at a different physical Signal")
+        self._reconnect_btn.clicked.connect(self._do_reconnect)
+        sub_lay.addWidget(self._reconnect_btn)
+        outer.addWidget(sub)
+
         # Body
         body = QWidget(); body.setObjectName("plotBlockSettings")
         bl = QVBoxLayout(body); bl.setContentsMargins(10, 8, 10, 10); bl.setSpacing(6)
 
-        # ID / unit row
+        # ID / unit row — the id is auto-derived from the name at creation
+        # (_slug_id()) and normally never needs to be seen, let alone typed;
+        # tucked behind a toggle so Name is the only identity field most
+        # users ever interact with.
         meta = QHBoxLayout()
-        meta.addWidget(QLabel("ID:"))
+        self._id_toggle = QToolButton(); self._id_toggle.setText("ID ▸")
+        self._id_toggle.setObjectName("traceRemoveBtn"); self._id_toggle.setCheckable(True)
+        self._id_toggle.setToolTip(f"Technical id: {self.dc.channel_id} — only needed to "
+                                    f"reference this channel from an expression/script by id, "
+                                    f"or to rename it. Click to edit.")
+        self._id_toggle.toggled.connect(self._toggle_id_box)
+        meta.addWidget(self._id_toggle)
         self._id = QLineEdit(self.dc.channel_id)
         self._id.setObjectName("traceLabel"); self._id.setFixedWidth(100)
+        self._id.setVisible(False)
         self._id.textChanged.connect(lambda t: setattr(self.dc, "channel_id", t))
         meta.addWidget(self._id)
         meta.addWidget(QLabel("Unit:"))
@@ -1023,6 +1055,58 @@ class ChannelBlock(QFrame):
         self._update_vars_hint()
         self._update_visibility()
         self.refresh_missing_sources()
+        self._refresh_source_subtitle()
+
+    def _refresh_source_subtitle(self):
+        """Update the always-visible '← wired-to' line and show/hide the
+        inline quick-reconnect control — only offered for the unambiguous
+        single-source case; multi-source channels use the per-source combos
+        in the expanded editor instead."""
+        names = [f"{_channel_display_name(self.registry, self.processor, d, c)}  ({d}/{c})"
+                 for d, c in self.dc.sources]
+        self._src_lbl.setText("← " + ", ".join(names) if names else "no source")
+        single = len(self.dc.sources) == 1
+        self._reconnect_cb.setVisible(single)
+        self._reconnect_btn.setVisible(single)
+        # Pre-select the actual current source — otherwise the combo always
+        # shows whatever landed first in registry iteration order, which
+        # looks like that's what's connected even when it isn't.
+        if single:
+            cur = self.dc.sources[0]
+            self._reconnect_cb.blockSignals(True)
+            for i in range(self._reconnect_cb.count()):
+                if self._reconnect_cb.itemData(i) == cur:
+                    self._reconnect_cb.setCurrentIndex(i)
+                    break
+            else:
+                self._reconnect_cb.setCurrentIndex(-1)
+            self._reconnect_cb.blockSignals(False)
+
+    def _do_reconnect(self):
+        """Inline one-click rebind: point this channel's sole source at
+        whatever Signal is currently selected in the quick-reconnect combo —
+        no need to expand the block or use the per-source editor combos."""
+        new_src = self._reconnect_cb.currentData()
+        if not new_src or len(self.dc.sources) != 1:
+            return
+        self.dc.sources = [new_src]
+        self.dc.source_names = [_channel_display_name(self.registry, self.processor, *new_src)]
+        if self._src_combos:
+            cb = self._src_combos[0]
+            for i in range(cb.count()):
+                if cb.itemData(i) == new_src:
+                    cb.setCurrentIndex(i)
+                    break
+        err = self.processor.add_derived(self.dc)
+        self._refresh_source_subtitle()
+        self.refresh_missing_sources()
+        if err:
+            self._st.setText(f"⚠ {err[:100]}")
+            self._st.setStyleSheet("color:#ef4444;")
+        else:
+            self._st.setText("✓ Reconnected")
+            self._st.setStyleSheet("color:#22c55e;")
+            self.applied.emit(self.dc)
 
     def refresh_missing_sources(self):
         """Update the header warning icon for a source signal that no longer
@@ -1046,6 +1130,10 @@ class ChannelBlock(QFrame):
         self._body.setVisible(self._expanded)
         self._toggle_btn.setText("▼" if self._expanded else "▶")
 
+    def _toggle_id_box(self, checked: bool):
+        self._id.setVisible(checked)
+        self._id_toggle.setText("ID ▾" if checked else "ID ▸")
+
     def _add_src(self, src=None):
         row = QHBoxLayout()
         cb = _channel_combo(self.registry, self.processor,
@@ -1247,6 +1335,8 @@ class ChannelBlock(QFrame):
         elif self.dc.kind in ("function", "custom_script"):
             self.dc.script = self._code.toPlainText()
         err = self.processor.add_derived(self.dc)
+        self._refresh_source_subtitle()
+        self.refresh_missing_sources()
         # Emitted regardless of whether this channel's own expression/script
         # compiles — propagate_rename() (via id_renamed) still needs to run
         # so other channels' sources / plot traces / controls don't dangle.