Fix Signal name reset and orphaned references on device reconfigure

Apply & Reconnect rebuilt a device's whole Signal list from hardware
defaults on every call, silently discarding user/profile-set names,
units, and colors even when pins hadn't changed. Add
merge_signal_metadata() and call it from ArduinoDevice.remap_pins()
and SerialDevice.reconfigure() to reapply the same fields
ProfileManager already treats as user overrides, keyed by signal_id.

Also close a related gap: removing a pin that a Channel/Plot/Control
still referenced left it silently dangling, and SignalProcessor never
pruned its latest-value cache, so a derived Channel kept computing off
a permanently frozen stale reading. Add SignalProcessor.
on_device_reconfigured() to purge that cache, reference_registry.
find_references() for a console breadcrumb, and live "missing source"
indicators on Plot traces and Channel blocks reusing ControlWidget's
existing stale/QSS pattern. Also fixes ControlWidget._write() still
enqueuing writes to a channel that no longer exists.

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

1 files changed, 17 insertions, 0 deletions

diff --git a/devices/base_device.py b/devices/base_device.py
index e3eed65..ae7f438 100644
--- a/devices/base_device.py
+++ b/devices/base_device.py
@@ -104,3 +104,20 @@ class BaseDevice(ABC):
 
     def __repr__(self):
         return f"<{self.__class__.__name__} id={self.info.device_id} status={self.status.value}>"
+
+
+def merge_signal_metadata(old_signals: List[SignalConfig], new_signals: List[SignalConfig]) -> List[SignalConfig]:
+    """Reapply user-customized Signal metadata (name/unit/enabled/color) onto a
+    freshly rebuilt signal list, keyed by signal_id. Mirrors exactly the fields
+    ProfileManager treats as user overrides (core/profile.py capture/apply) so
+    identity set at profile-load time survives a later device reconfigure too —
+    otherwise a device's own reconfigure()/remap_pins() rebuilding info.signals
+    from scratch silently resets names back to hardware defaults. Signal ids
+    not present in old_signals (new pins) keep their fresh defaults; ids no
+    longer in new_signals (removed pins) are simply dropped."""
+    old_by_id = {s.signal_id: s for s in old_signals}
+    for sig in new_signals:
+        old = old_by_id.get(sig.signal_id)
+        if old is not None:
+            sig.name, sig.unit, sig.enabled, sig.color = old.name, old.unit, old.enabled, old.color
+    return new_signals