Unify Signals/Channels around auto-naming, plot-by-channel, and shared vars

Devices: auto-name from OS-reported port description (Device Manager /
udev string) instead of a generic label; default Serial #Channels 1;
consistent simulate-mode checkbox across backends; inline device rename.

Channels: calibration/filters move out of Signals into a Channel
"Operation" (adds Scale/Offset alongside the existing math kinds);
single-physical-source Channels get an embedded Filters block; new
Channels auto-name/auto-ID from their source and reject duplicate
names/IDs on apply; "Create Channel" button on each Signal row; renamed
"Sources" -> "Signals" in the Channels UI; Signals' READ/WRITE dir badge
(was silently-broken IN/OUT) now reflects the real writable flag.

Plot: default layout is one pane per Channel (not per device, not raw
Signals) titled by channel name; "+ Add Channel" is a checkbox dialog
instead of an inline dropdown; traces get up/down reorder; live unit
changes (e.g. a Mark-10 gauge switching lb/kgF/N/ozF) propagate to an
open pane's axis label without clobbering a manually-typed one.

Control Panel: hardware assignment now picks from the same writable-
Signals list instead of a separate device/channel combo with a
hardcoded Arduino pin list; stale visual indicator when a control's
target device/channel disconnects or disappears; documented the `vars`
bridge (Control Panel On Action Script <-> Channel scripts) in both
directions' help text and script templates.

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

1 files changed, 20 insertions, 0 deletions

diff --git a/ui/code_templates.py b/ui/code_templates.py
index ffa1662..2a3ff09 100644
--- a/ui/code_templates.py
+++ b/ui/code_templates.py
@@ -19,6 +19,15 @@ Namespace available in all kinds:
   math   — Python math module
   vars   — shared SignalProcessor._script_vars dict (read/write)
   state  — per-channel persistent dict (survives between evaluations)
+
+`vars` is the bridge from the Control Panel into Channel math: a button's
+"On Action Script" (ui/control_editor.py) and every Channel script here see
+the *same* `vars` dict. e.g. a "Zero" button sets
+    vars['zero'] = channels.get('force_raw', 0)
+and a Channel reads it back with `vars.get('zero', 0)` — see the
+"custom_script" template below. Same pattern for an operator-entered
+constant like specimen length: a Setpoint control's On Action Script sets
+`vars['specimen_length_cm'] = value`, and a Channel divides by it.
 """
 
 BUILTIN_TEMPLATES: dict = {
@@ -27,6 +36,14 @@ BUILTIN_TEMPLATES: dict = {
 result = x[0]
 """,
 
+    "scale_offset": """\
+# scale/offset also settable from a Control Panel button's On Action Script,
+# e.g. vars["offset"] = -x[0]  to zero the reading on press
+scale = vars.get("scale", 1.0)
+offset = vars.get("offset", 0.0)
+result = x[0] * scale + offset
+""",
+
     "derivative": """\
 prev_v = state.get("v", x[0])
 prev_t = state.get("t", t)
@@ -99,11 +116,14 @@ SCRIPT_TEMPLATES: dict = {
     "expression": "x[0]",
 
     "function": """\
+# "offset" can be set here or from a Control Panel button's On Action Script
+# (vars is the same dict on both sides)
 offset = vars.get("offset", 0)
 return x[0] - offset
 """,
 
     "custom_script": """\
+# Wire a "Zero" button to this: On Action Script -> vars["zero"] = channels.get("<signal_id>", 0)
 zero = vars.get("zero", 0)
 result = x[0] - zero
 """,