feat(logic): round-trip array statevar attributes in panel XML

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/lib/xml.ts

@@ -73,6 +73,11 @@ export function serializeInterface(iface: Interface): string {
     if (sv.unit) attrs.push(`unit="${xmlEsc(sv.unit)}"`);
     if (sv.low !== undefined) attrs.push(`low="${sv.low}"`);
     if (sv.high !== undefined) attrs.push(`high="${sv.high}"`);
+    if (sv.type === 'array') {
+      if (sv.elem) attrs.push(`elem="${sv.elem}"`);
+      if (sv.sizing) attrs.push(`sizing="${sv.sizing}"`);
+      if (sv.capacity !== undefined) attrs.push(`capacity="${sv.capacity}"`);
+    }
     lines.push(`  <statevar ${attrs.join(' ')}/>`);
   }
   if (iface.logic && (iface.logic.nodes.length > 0 || iface.logic.wires.length > 0)) {
@@ -213,13 +218,21 @@ export function parseInterface(xml: string): Interface {
     const low = el.getAttribute('low');
     const high = el.getAttribute('high');
     const unit = el.getAttribute('unit');
+    const elem = el.getAttribute('elem');
+    const sizing = el.getAttribute('sizing');
+    const capacityAttr = el.getAttribute('capacity');
+    const svType: StateVar['type'] =
+      type === 'bool' || type === 'string' || type === 'array' ? type : 'number';
     statevars.push({
       name,
-      type: type === 'bool' || type === 'string' ? type : 'number',
+      type: svType,
       initial: el.getAttribute('initial') ?? '',
       ...(unit ? { unit } : {}),
       ...(low !== null ? { low: parseFloat(low) } : {}),
       ...(high !== null ? { high: parseFloat(high) } : {}),
+      ...(elem ? { elem: elem as StateVar['elem'] } : {}),
+      ...(sizing ? { sizing: sizing as StateVar['sizing'] } : {}),
+      ...(capacityAttr !== null ? { capacity: Number(capacityAttr) } : {}),
     });
   }