diff --git a/web/src/SignalTree.tsx b/web/src/SignalTree.tsx
index dd0f69a..37b6b68 100644
--- a/web/src/SignalTree.tsx
+++ b/web/src/SignalTree.tsx
@@ -117,17 +117,48 @@ export default function SignalTree({ onDragStart, width, panelId, statevars, onS
   const [showAddLocal, setShowAddLocal] = useState(false);
   const [localOpen, setLocalOpen] = useState(true);
   const [lvName, setLvName] = useState('');
-  const [lvType, setLvType] = useState<'number' | 'bool' | 'string'>('number');
+  const [lvType, setLvType] = useState<'number' | 'bool' | 'string' | 'array'>('number');
   const [lvInitial, setLvInitial] = useState('0');
+  // array-specific fields (mirror LogicEditor LocalVars)
+  const [lvElem, setLvElem] = useState<'number' | 'bool' | 'array'>('number');
+  const [lvSizing, setLvSizing] = useState<'dynamic' | 'capped' | 'fixed'>('dynamic');
+  const [lvCapacity, setLvCapacity] = useState('100');
+  const [lvJsonErr, setLvJsonErr] = useState('');
+
+  function handleLvTypeChange(t: 'number' | 'bool' | 'string' | 'array') {
+    setLvType(t);
+    setLvInitial(t === 'array' ? '[]' : t === 'bool' ? 'false' : t === 'string' ? '' : '0');
+    setLvJsonErr('');
+  }
+
+  function handleLvInitialChange(v: string) {
+    setLvInitial(v);
+    if (lvType === 'array') {
+      try { JSON.parse(v); setLvJsonErr(''); }
+      catch (e: any) { setLvJsonErr(e.message); }
+    }
+  }
 
   function addLocal() {
     const name = lvName.trim();
     if (!name || !onStateVarsChange) return;
+    if (lvType === 'array' && lvJsonErr) return;
+    const base: StateVar = { name, type: lvType, initial: lvInitial };
+    if (lvType === 'array') {
+      base.elem = lvElem;
+      base.sizing = lvSizing;
+      if (lvSizing !== 'dynamic') base.capacity = parseInt(lvCapacity, 10) || 100;
+    }
     const next = (statevars ?? []).filter(v => v.name !== name);
-    next.push({ name, type: lvType, initial: lvInitial });
+    next.push(base);
     onStateVarsChange(next);
     setLvName('');
     setLvInitial('0');
+    setLvType('number');
+    setLvElem('number');
+    setLvSizing('dynamic');
+    setLvCapacity('100');
+    setLvJsonErr('');
     setShowAddLocal(false);
   }
 
@@ -324,20 +355,56 @@ export default function SignalTree({ onDragStart, width, panelId, statevars, onS
                         class="prop-select"
                         style="font-size: 0.7rem; height: 1.6rem; padding: 0 4px;"
                         value={lvType}
-                        onChange={(e) => setLvType((e.target as HTMLSelectElement).value as any)}
+                        onChange={(e) => handleLvTypeChange((e.target as HTMLSelectElement).value as any)}
                       >
                         <option value="number">number</option>
                         <option value="bool">bool</option>
                         <option value="string">string</option>
+                        <option value="array">array</option>
                       </select>
+                      {lvType === 'array' && (
+                        <Fragment>
+                          <select
+                            class="prop-select"
+                            style="font-size: 0.7rem; height: 1.6rem; padding: 0 4px;"
+                            value={lvElem}
+                            onChange={(e) => setLvElem((e.target as HTMLSelectElement).value as any)}
+                          >
+                            <option value="number">elem: number</option>
+                            <option value="bool">elem: bool</option>
+                            <option value="array">elem: array</option>
+                          </select>
+                          <select
+                            class="prop-select"
+                            style="font-size: 0.7rem; height: 1.6rem; padding: 0 4px;"
+                            value={lvSizing}
+                            onChange={(e) => setLvSizing((e.target as HTMLSelectElement).value as any)}
+                          >
+                            <option value="dynamic">sizing: dynamic</option>
+                            <option value="capped">sizing: capped</option>
+                            <option value="fixed">sizing: fixed</option>
+                          </select>
+                          {lvSizing !== 'dynamic' && (
+                            <input
+                              class="signal-add-input"
+                              type="number"
+                              style="width: 5rem;"
+                              placeholder="capacity"
+                              value={lvCapacity}
+                              onInput={(e) => setLvCapacity((e.target as HTMLInputElement).value)}
+                            />
+                          )}
+                        </Fragment>
+                      )}
                       <input
-                        class="signal-add-input"
+                        class={`signal-add-input${lvJsonErr ? ' prop-input-error' : ''}`}
                         style="flex: 1;"
-                        placeholder="initial"
+                        placeholder={lvType === 'array' ? 'initial (JSON)' : 'initial'}
                         value={lvInitial}
-                        onInput={(e) => setLvInitial((e.target as HTMLInputElement).value)}
+                        onInput={(e) => handleLvInitialChange((e.target as HTMLInputElement).value)}
                         onKeyDown={(e: KeyboardEvent) => { if (e.key === 'Enter') addLocal(); }}
                       />
+                      {lvJsonErr && <p class="wizard-error" style="flex-basis: 100%; margin: 0;">{lvJsonErr}</p>}
                       <button class="icon-btn" title="Add" onClick={addLocal}>✓</button>
                       <button class="icon-btn" title="Cancel" onClick={() => setShowAddLocal(false)}>✕</button>
                     </div>