Channels tab drag-to-reorder, Namespace absolute references, fix stale Channel ID renames

Generalized the Plot pane drag-to-reorder (_PaneDragHandle/_PlotDropContainer
-> _DragHandle/_DragReorderContainer) and reused it for the Channels tab's
derived-channel list; reordering also updates SignalProcessor's evaluation
order (list order matters for chained Channels) via new reorder_derived().

Namespace panel: added an ID column (bare channel_id, matching the actual
channels.get(...) script convention) and fixed the Source column for
Channels to show resolved absolute references (dev_id/ch_id for a Signal,
bare id for a chained Channel) instead of the operation kind, so a chain
is traceable by eye.

Fixed a real bug this surfaced: renaming a Channel's ID never propagated
to other Channels' sources, leaving dangling ("derived", old_id)
references that silently stopped updating. Added
SignalProcessor.rename_derived() to fix up sources plus carry the ring
buffer/latest-value cache to the new key, wired to DerivedBlock's Apply.

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

1 files changed, 35 insertions, 13 deletions

diff --git a/ui/namespace_panel.py b/ui/namespace_panel.py
index 7d8c42d..44750c6 100644
--- a/ui/namespace_panel.py
+++ b/ui/namespace_panel.py
@@ -28,10 +28,11 @@ from core.signal_processor import SignalProcessor
 _VARS_POLL_MS = 400
 
 _C_KIND   = 0
-_C_NAME   = 1
-_C_DIR    = 2
-_C_VALUE  = 3
-_C_SOURCE = 4
+_C_ID     = 1
+_C_NAME   = 2
+_C_DIR    = 3
+_C_VALUE  = 4
+_C_SOURCE = 5
 
 
 def _fmt_value(v) -> str:
@@ -42,6 +43,16 @@ def _fmt_value(v) -> str:
     return str(v)
 
 
+def _fmt_ref(dev_id: str, ch_id: str) -> str:
+    """Absolute reference for a source — device_id/channel_id for a Signal
+    (device_id is stable across machines even when the COM/tty port isn't,
+    see ProfileManager.apply()'s port re-detection), or the bare channel_id
+    for another Channel (derived channels have no device to qualify with)."""
+    if dev_id == "derived":
+        return ch_id
+    return f"{dev_id}/{ch_id}"
+
+
 class NamespacePanel(QWidget):
     def __init__(self, registry: DeviceRegistry, processor: SignalProcessor):
         super().__init__()
@@ -73,13 +84,14 @@ class NamespacePanel(QWidget):
 
         self._table = QTableWidget()
         self._table.setObjectName("channelTable")
-        self._table.setColumnCount(5)
+        self._table.setColumnCount(6)
         self._table.setHorizontalHeaderLabels(
-            ["Kind", "Name", "Dir", "Value", "Source"]
+            ["Kind", "ID", "Name", "Dir", "Value", "Source"]
         )
         hdr = self._table.horizontalHeader()
         hdr.setSectionResizeMode(_C_SOURCE, QHeaderView.ResizeMode.Stretch)
         hdr.setSectionResizeMode(_C_KIND,   QHeaderView.ResizeMode.ResizeToContents)
+        hdr.setSectionResizeMode(_C_ID,     QHeaderView.ResizeMode.ResizeToContents)
         hdr.setSectionResizeMode(_C_NAME,   QHeaderView.ResizeMode.ResizeToContents)
         hdr.setSectionResizeMode(_C_DIR,    QHeaderView.ResizeMode.ResizeToContents)
         hdr.setSectionResizeMode(_C_VALUE,  QHeaderView.ResizeMode.ResizeToContents)
@@ -122,23 +134,33 @@ class NamespacePanel(QWidget):
             ch  = dev.get_channel(ch_id) if dev else None
             name  = ch.name if ch else ch_id
             is_wr = bool(ch and ch.writable)
-            self._set_row(row, "Signal", name, "WRITE" if is_wr else "READ",
-                          None, f"{dev_id}/{ch_id}")
+            self._set_row(row, "Signal", ch_id, name, "WRITE" if is_wr else "READ",
+                          None, _fmt_ref(dev_id, ch_id))
         elif kind == "channel":
             _, channel_id = key
             dc = next((d for d in self.processor.get_derived()
                        if d.channel_id == channel_id), None)
             name = dc.name if dc else channel_id
-            src  = dc.kind if dc else ""
-            self._set_row(row, "Channel", name, "READ", None, src)
+            if dc and dc.sources:
+                # Absolute reference(s) this Channel is chained from — same
+                # format as another row's ID column, so a chain (Channel 1 ->
+                # Channel 2 -> Channel 3) can be traced by eye: Channel 3's
+                # Source literally matches Channel 2's ID.
+                src = ", ".join(_fmt_ref(d, c) for d, c in dc.sources)
+            else:
+                src = dc.kind if dc else ""
+            self._set_row(row, "Channel", channel_id, name, "READ", None, src)
         else:  # var
             _, name = key
             val = self.processor.get_var(name, None)
-            self._set_row(row, "var", name, "R/W", val, "shared (vars)")
+            self._set_row(row, "var", name, name, "R/W", val, "shared (vars)")
 
-    def _set_row(self, row: int, kind: str, name: str, direction: str,
-                 value, source: str):
+    def _set_row(self, row: int, kind: str, id_ref: str, name: str,
+                 direction: str, value, source: str):
         self._table.setItem(row, _C_KIND, QTableWidgetItem(kind))
+        id_item = QTableWidgetItem(id_ref)
+        id_item.setForeground(QColor("#94a3b8"))
+        self._table.setItem(row, _C_ID, id_item)
         self._table.setItem(row, _C_NAME, QTableWidgetItem(name))
         dir_item = QTableWidgetItem(direction)
         dir_item.setForeground(_dir_color(direction))