feat(commands): adopt unified command envelope — msg.origin provenance

Resolve command origin via msg.origin (registry-stamped, default parent) with a
legacy fallback to the previous payload.source/msg.source field. Feeds the
existing mode/allowedSources arbitration unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/commands/handlers.js

@@ -9,6 +9,16 @@ function _logger(source, ctx) {
   return ctx?.logger || source?.logger || null;
 }
 
+// Resolve the command origin (control authority: parent | GUI | fysical).
+// The shared commandRegistry stamps msg.origin (default 'parent'); legacy flows
+// carried it as payload.source. Prefer the legacy field when present so existing
+// flows keep working, otherwise use the registry-stamped msg.origin.
+function _origin(msg) {
+  const p = msg && msg.payload;
+  if (p && typeof p === 'object' && typeof p.source === 'string' && p.source) return p.source;
+  return (typeof msg?.origin === 'string' && msg.origin) ? msg.origin : 'parent';
+}
+
 exports.setMode = (source, msg) => {
   source.setMode(msg.payload);
 };
@@ -31,25 +41,18 @@ exports.registerChild = (source, msg, ctx) => {
 };
 
 exports.execSequence = async (source, msg) => {
-  const { source: seqSource, action: seqAction, parameter } = msg.payload || {};
-  await source.handleInput(seqSource, seqAction, parameter);
+  const { action: seqAction, parameter } = msg.payload || {};
+  await source.handleInput(_origin(msg), seqAction, parameter);
 };
 
 exports.totalFlowChange = async (source, msg) => {
   const payload = msg.payload || {};
-  if (payload && typeof payload === 'object' && Object.prototype.hasOwnProperty.call(payload, 'source')) {
-    const src = payload.source || 'parent';
-    const action = payload.action || 'totalFlowChange';
-    await source.handleInput(src, action, payload);
-    return;
-  }
-  await source.handleInput('parent', 'totalFlowChange', payload);
+  const action = payload.action || 'totalFlowChange';
+  await source.handleInput(_origin(msg), action, payload);
 };
 
 exports.emergencyStop = async (source, msg) => {
-  const payload = msg.payload || {};
-  const src = payload.source || 'parent';
-  await source.handleInput(src, 'emergencystop');
+  await source.handleInput(_origin(msg), 'emergencystop');
 };
 
 exports.setReconcileInterval = (source, msg) => {