Configuration window UI reorg + Plot Builder polish

Devices tab split into Physical Devices (left) / Signals (right); Channels
tab now hosts the Namespace browser (left) alongside Channels (right,
larger by default). Plot Builder panes gain drag-to-reorder (same mechanics
as ControlPanel's widget list, adapted for the editable pane title via a
dedicated grip icon), "+ Add Channel" moved beside Size for a more compact
row, and Min/Max/Size/line-width spin boxes widened so values no longer
overlap the up/down arrows.

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

2 files changed, 154 insertions, 15 deletions

diff --git a/ui/windows/config_window.py b/ui/windows/config_window.py
index a31397e..3bd3dc6 100644
--- a/ui/windows/config_window.py
+++ b/ui/windows/config_window.py
@@ -34,7 +34,7 @@ from ui.windows.devices_window import DeviceRow, ChannelsTab
 from ui.windows.channels_window import PipelineTab, _slug_id, _dedupe_name
 from ui.windows.plot_window import (
     PlotWindow, LayoutConfig, LayoutCanvas, PaneBlock,
-    build_default_layout,
+    build_default_layout, _PlotDropContainer,
 )
 from ui.namespace_panel import NamespacePanel
 
@@ -242,7 +242,7 @@ class _PlotTab(PlotWindow):
 
         scroll = QScrollArea(); scroll.setWidgetResizable(True)
         scroll.setObjectName("deviceScroll")
-        self._cont = QWidget()
+        self._cont = _PlotDropContainer(self)
         self._blay = QVBoxLayout(self._cont)
         self._blay.setContentsMargins(10, 10, 10, 10); self._blay.setSpacing(12)
         self._blay.addStretch()
diff --git a/ui/windows/plot_window.py b/ui/windows/plot_window.py
index dc1617b..93ce776 100644
--- a/ui/windows/plot_window.py
+++ b/ui/windows/plot_window.py
@@ -28,8 +28,8 @@ from PyQt6.QtWidgets import (
     QCheckBox, QComboBox, QColorDialog, QToolButton,
     QFileDialog, QMessageBox, QDialog, QDialogButtonBox,
 )
-from PyQt6.QtCore import Qt, pyqtSignal, QPoint, QRect
-from PyQt6.QtGui import QColor, QCloseEvent, QPainter, QPen
+from PyQt6.QtCore import Qt, pyqtSignal, QPoint, QRect, QMimeData
+from PyQt6.QtGui import QColor, QCloseEvent, QPainter, QPen, QDrag
 
 from devices.device_registry import DeviceRegistry
 from core.signal_processor import SignalProcessor
@@ -301,7 +301,7 @@ class TraceRow(QFrame):
         lay.addWidget(self._sty)
         self._w = QDoubleSpinBox(); self._w.setObjectName("traceWidthSpin")
         self._w.setRange(0.5,6.0); self._w.setSingleStep(0.5)
-        self._w.setValue(self.tr.width); self._w.setFixedWidth(56)
+        self._w.setValue(self.tr.width); self._w.setMinimumWidth(68)
         self._w.valueChanged.connect(lambda v: setattr(self.tr,"width",v))
         lay.addWidget(self._w)
         up = QToolButton(); up.setText("▲"); up.setObjectName("traceRemoveBtn")
@@ -375,6 +375,85 @@ class TraceChannelPickerDialog(QDialog):
 
 
 # ══════════════════════════════════════════════════════════════════════════════
+#  Drag-to-reorder — same mechanics as ControlPanel (ui/control_panel.py):
+#  a small drag handle starts a QDrag carrying the source index, the config
+#  list container accepts the drop and reorders. The pane title here is an
+#  editable QLineEdit (unlike ControlPanel's static label), so the whole
+#  header can't be made transparent-for-mouse — a dedicated grip is used
+#  instead of the whole header.
+# ══════════════════════════════════════════════════════════════════════════════
+
+class _PaneDragHandle(QLabel):
+    def __init__(self):
+        super().__init__("⠿")
+        self._owner = None
+        self._block = None
+        self.setObjectName("paneDragHandle")
+        self.setFixedWidth(18)
+        self.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        self.setCursor(Qt.CursorShape.OpenHandCursor)
+        self.setToolTip("Drag to reorder")
+
+    def set_drag_source(self, owner: "PlotWindow", block: "PaneBlock"):
+        self._owner = owner
+        self._block = block
+
+    def mousePressEvent(self, event):
+        if event.button() == Qt.MouseButton.LeftButton and self._owner is not None:
+            drag = QDrag(self)
+            mime = QMimeData()
+            mime.setText(str(self._owner._blocks.index(self._block)))
+            drag.setMimeData(mime)
+            drag.exec(Qt.DropAction.MoveAction)
+        super().mousePressEvent(event)
+
+
+class _PlotDropContainer(QWidget):
+    """Holds the pane config blocks; drops reorder them — same drag-to-reorder
+    mechanics as ControlPanel's _DropContainer."""
+
+    def __init__(self, owner: "PlotWindow"):
+        super().__init__()
+        self._owner = owner
+        self._indicator_y = None
+        self.setAcceptDrops(True)
+
+    def dragEnterEvent(self, event):
+        if event.mimeData().hasText():
+            event.acceptProposedAction()
+            self._show_indicator(event.position().y())
+
+    def dragMoveEvent(self, event):
+        event.acceptProposedAction()
+        self._show_indicator(event.position().y())
+
+    def dragLeaveEvent(self, event):
+        self._indicator_y = None
+        self.update()
+
+    def dropEvent(self, event):
+        self._indicator_y = None
+        self.update()
+        try:
+            src_idx = int(event.mimeData().text())
+        except ValueError:
+            return
+        self._owner._reorder_panes(src_idx, self._owner._drop_index(event.position().y()))
+        event.acceptProposedAction()
+
+    def _show_indicator(self, y: float):
+        self._indicator_y = self._owner._indicator_y_for(self._owner._drop_index(y))
+        self.update()
+
+    def paintEvent(self, event):
+        if self._indicator_y is not None:
+            painter = QPainter(self)
+            painter.setPen(QPen(QColor("#3b82f6"), 2))
+            painter.drawLine(6, self._indicator_y, self.width() - 6, self._indicator_y)
+            painter.end()
+
+
+# ══════════════════════════════════════════════════════════════════════════════
 #  Pane block
 # ══════════════════════════════════════════════════════════════════════════════
 
@@ -395,6 +474,8 @@ class PaneBlock(QFrame):
 
         hdr = QWidget(); hdr.setObjectName("plotBlockHeader"); hdr.setFixedHeight(32)
         hl = QHBoxLayout(hdr); hl.setContentsMargins(8,0,6,0); hl.setSpacing(4)
+        self._drag_handle = _PaneDragHandle()
+        hl.addWidget(self._drag_handle)
         self._title = QLineEdit(self.spec.title); self._title.setObjectName("plotBlockTitle")
         self._title.textChanged.connect(lambda t: (
             setattr(self.spec, "title", t),
@@ -442,14 +523,14 @@ class PaneBlock(QFrame):
 
         sl.addWidget(QLabel("Min:"))
         self._ymin = QDoubleSpinBox(); self._ymin.setRange(-1e9,1e9)
-        self._ymin.setValue(self.spec.y_min); self._ymin.setFixedWidth(72)
+        self._ymin.setValue(self.spec.y_min); self._ymin.setMinimumWidth(92)
         self._ymin.setEnabled(not self.spec.y_auto)
         self._ymin.valueChanged.connect(lambda v: setattr(self.spec,"y_min",v))
         sl.addWidget(self._ymin)
 
         sl.addWidget(QLabel("Max:"))
         self._ymax = QDoubleSpinBox(); self._ymax.setRange(-1e9,1e9)
-        self._ymax.setValue(self.spec.y_max); self._ymax.setFixedWidth(72)
+        self._ymax.setValue(self.spec.y_max); self._ymax.setMinimumWidth(92)
         self._ymax.setEnabled(not self.spec.y_auto)
         self._ymax.valueChanged.connect(lambda v: setattr(self.spec,"y_max",v))
         sl.addWidget(self._ymax)
@@ -460,20 +541,23 @@ class PaneBlock(QFrame):
 
         sl.addWidget(QLabel("Size:"))
         self._wt = QSpinBox(); self._wt.setRange(1,10); self._wt.setValue(self.spec.weight)
-        self._wt.setFixedWidth(44); self._wt.setToolTip("Relative pane size")
+        self._wt.setMinimumWidth(56); self._wt.setToolTip("Relative pane size")
         self._wt.valueChanged.connect(lambda v: setattr(self.spec,"weight",v))
-        sl.addWidget(self._wt); sl.addStretch()
+        sl.addWidget(self._wt)
+
+        # Right-aligned — "+ Add Channel" lives here instead of its own row
+        # below the trace list, saving vertical space.
+        sl.addStretch()
+        ab = QPushButton("＋ Add Channel"); ab.setObjectName("addTraceBtn")
+        ab.clicked.connect(self._on_add)
+        sl.addWidget(ab)
         outer.addWidget(sett)
 
         tr_w = QWidget(); tr_w.setObjectName("plotBlockTraces")
         self._tlay = QVBoxLayout(tr_w)
         self._tlay.setContentsMargins(4,2,4,4); self._tlay.setSpacing(2)
         for tr in self.spec.traces: self._add_row(tr)
-
-        pick_row = QHBoxLayout()
-        ab = QPushButton("＋ Add Channel"); ab.setObjectName("addTraceBtn")
-        ab.clicked.connect(self._on_add); pick_row.addWidget(ab); pick_row.addStretch()
-        self._tlay.addLayout(pick_row)
+        self._tlay.addStretch()
         outer.addWidget(tr_w)
 
     def _add_row(self, tr: TraceSpec):
@@ -991,7 +1075,7 @@ class PlotWindow(QWidget):
 
         scroll = QScrollArea(); scroll.setWidgetResizable(True)
         scroll.setObjectName("deviceScroll")
-        self._cont = QWidget()
+        self._cont = _PlotDropContainer(self)
         self._blay = QVBoxLayout(self._cont)
         self._blay.setContentsMargins(10,10,10,10); self._blay.setSpacing(12)
         self._blay.addStretch()
@@ -1025,6 +1109,7 @@ class PlotWindow(QWidget):
         blk.removed.connect(self._rm)
         blk.changed.connect(self._maybe_live)
         blk.title_changed.connect(self._on_tile_title)
+        blk._drag_handle.set_drag_source(self, blk)
         self._blocks.append(blk)
         self._blay.insertWidget(self._blay.count()-1, blk)
 
@@ -1063,6 +1148,60 @@ class PlotWindow(QWidget):
         self._canvas.sync_panes(self.cfg.panes, self.cfg.tree)
         self._maybe_live()
 
+    def _drop_index(self, y: float) -> int:
+        """Insertion index for a drop at container-relative y."""
+        n = self._blay.count() - 1   # exclude trailing stretch
+        for i in range(n):
+            w = self._blay.itemAt(i).widget()
+            if y < w.y() + w.height() / 2:
+                return i
+        return n
+
+    def _indicator_y_for(self, idx: int) -> int:
+        """Container-relative y for the drop-line at insertion index idx."""
+        n = self._blay.count() - 1   # exclude trailing stretch
+        spacing = self._blay.spacing()
+        if n == 0:
+            return self._blay.contentsMargins().top()
+        if idx <= 0:
+            w = self._blay.itemAt(0).widget()
+            return w.y() - spacing // 2
+        if idx >= n:
+            w = self._blay.itemAt(n - 1).widget()
+            return w.y() + w.height() + spacing // 2
+        prev = self._blay.itemAt(idx - 1).widget()
+        nxt  = self._blay.itemAt(idx).widget()
+        return (prev.y() + prev.height() + nxt.y()) // 2
+
+    def _reorder_panes(self, src_idx: int, dst_idx: int):
+        """Move the pane at src_idx to dst_idx (drop-target index, pre-removal)
+        — same semantics as ControlPanel._reorder(). Also walks the BSP tree's
+        leaf pane-index labels through the same chain of adjacent swaps so
+        each grid tile keeps showing the same pane content after the move."""
+        if dst_idx > src_idx:
+            dst_idx -= 1
+        if dst_idx == src_idx:
+            return
+
+        spec = self.cfg.panes.pop(src_idx)
+        self.cfg.panes.insert(dst_idx, spec)
+
+        if self.cfg.tree:
+            step = 1 if dst_idx > src_idx else -1
+            idx = src_idx
+            while idx != dst_idx:
+                nxt_idx = idx + step
+                self.cfg.tree = _tree_swap(self.cfg.tree, idx, nxt_idx)
+                idx = nxt_idx
+
+        blk = self._blocks.pop(src_idx)
+        self._blocks.insert(dst_idx, blk)
+        self._blay.removeWidget(blk)
+        self._blay.insertWidget(dst_idx, blk)
+
+        self._canvas.sync_panes(self.cfg.panes, self.cfg.tree)
+        self._maybe_live()
+
     def _maybe_live(self):
         if self._live.isChecked():
             self.layout_applied.emit(deepcopy(self.cfg))