From a3ff221496f58d67ac962bfa6d011cc3e9d6ad3d Mon Sep 17 00:00:00 2001
From: Christian Kolset <christian.kolset@gmail.com>
Date: Wed, 3 Jun 2026 17:11:41 -0600
Subject: Fix virtual channels not appearing in Plot Builder

Root cause: PlotWindow deepcopied _chart._cfg on init, so refresh_channels()
operated on a stale copy. Also, when _win_plot was None, _on_derived_changed
did nothing to prepare the config for when it opened.

Fix:
- refresh_channels() now owns the derived-pane sync: adds panes for new
  virtual channels (updating BSP tree), removes panes for deleted ones
- _open_plot always passes current _chart._cfg reference then calls
  refresh_channels() so derived panes sync on every open
- _on_derived_changed syncs cfg reference before calling refresh_channels()

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 ui/main_window.py         |  8 ++++++--
 ui/windows/plot_window.py | 43 +++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 47 insertions(+), 4 deletions(-)

(limited to 'ui')

diff --git a/ui/main_window.py b/ui/main_window.py
index 5078a60..ebc7463 100644
--- a/ui/main_window.py
+++ b/ui/main_window.py
@@ -352,9 +352,10 @@ class MainWindow(QMainWindow):
                                         self._chart._cfg, self)
             self._win_plot.layout_applied.connect(self._chart.apply_layout)
             self._win_plot.closed.connect(lambda: self._btn_plot.setChecked(False))
+            self._win_plot.refresh_channels()   # sync any derived channels
         else:
             self._win_plot.cfg = self._chart._cfg
-            self._win_plot._populate()
+            self._win_plot.refresh_channels()
         self._show_win(self._win_plot, "below")
 
     def _open_settings(self):
@@ -507,7 +508,10 @@ class MainWindow(QMainWindow):
 
     def _on_derived_changed(self):
         self._chart.refresh()
-        if self._win_plot: self._win_plot.refresh_channels()
+        if self._win_plot:
+            # Ensure plot window works on current chart cfg, then sync derived panes
+            self._win_plot.cfg = self._chart._cfg
+            self._win_plot.refresh_channels()
 
     # ── Run / Log ─────────────────────────────────────────────────────────
 
diff --git a/ui/windows/plot_window.py b/ui/windows/plot_window.py
index f929261..95b520c 100644
--- a/ui/windows/plot_window.py
+++ b/ui/windows/plot_window.py
@@ -357,7 +357,6 @@ 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:
-                if not ch.enabled: continue
                 self._x_cb.addItem(f"{dev.info.device_id}/{ch.channel_id}  ({ch.name})",
                                    userData=f"{dev.info.device_id}/{ch.channel_id}")
         for dc in self.processor.get_derived():
@@ -420,7 +419,6 @@ class PaneBlock(QFrame):
         cb = QComboBox(); cb.setObjectName("channelPickerCb")
         for dev in self.registry.all_instances():
             for ch in dev.info.channels:
-                if not ch.enabled: continue
                 cb.addItem(f"{dev.info.device_id} / {ch.channel_id}  ({ch.name})",
                            userData=(dev.info.device_id, ch.channel_id, ch.name, ch.color))
         for dc in self.processor.get_derived():
@@ -986,6 +984,47 @@ class PlotWindow(QWidget):
                 QMessageBox.critical(self, "Import failed", str(e))
 
     def refresh_channels(self):
+        """Sync virtual channel panes then rebuild UI."""
+        existing = {
+            tr.channel_id
+            for p in self.cfg.panes
+            for tr in p.traces if tr.device_id == "derived"
+        }
+        current_ids = {dc.channel_id for dc in self.processor.get_derived()}
+
+        # Add panes for new virtual channels
+        for dc in self.processor.get_derived():
+            if dc.channel_id not in existing:
+                new_idx = len(self.cfg.panes)
+                spec = PaneSpec(title=dc.name, y_label=dc.unit)
+                spec.traces.append(TraceSpec(
+                    device_id="derived", channel_id=dc.channel_id,
+                    label=dc.name, color=dc.color,
+                ))
+                self.cfg.panes.append(spec)
+                if self.cfg.tree is None:
+                    self.cfg.tree = {"kind": "leaf", "pane": 0}
+                else:
+                    self.cfg.tree = _tree_equalize_ratios({
+                        "kind": "vsplit", "ratio": 0.5,
+                        "first": self.cfg.tree,
+                        "second": {"kind": "leaf", "pane": new_idx},
+                    })
+
+        # Remove panes whose sole trace is a deleted virtual channel
+        removed = [
+            i for i, p in enumerate(self.cfg.panes)
+            if len(p.traces) == 1
+            and p.traces[0].device_id == "derived"
+            and p.traces[0].channel_id not in current_ids
+        ]
+        for i in reversed(removed):
+            self.cfg.panes.pop(i)
+            if self.cfg.tree:
+                self.cfg.tree = _tree_remove(self.cfg.tree, i)
+                if self.cfg.tree:
+                    self.cfg.tree = _tree_equalize_ratios(_tree_reindex(self.cfg.tree, i))
+
         self._populate()
 
     def closeEvent(self, e: QCloseEvent):
-- 
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