fix native and web screenshot rendering

frontend/tests/workflowSerialization.test.mjs

@@ -0,0 +1,91 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import { serializeWorkflowState } from '../src/workflowSerialization.js';
+
+test('serializeWorkflowState keeps only stable workflow fields needed for reload', () => {
+  const nodes = [
+    {
+      id: '1',
+      type: 'custom',
+      position: { x: 100, y: 200 },
+      dragHandle: '.node-header',
+      selected: true,
+      width: 320,
+      data: {
+        label: 'Demo Label',
+        className: 'DemoNode',
+        widgetValues: { threshold: 0.42, mode: 'fast' },
+        definition: { input: { required: { threshold: ['FLOAT', { default: 0.5 }] } } },
+        previewImage: 'data:image/png;base64,abc',
+        tableRows: [{ a: 1 }],
+        meshData: { vertices: [1, 2, 3] },
+        overlay: { active: true },
+      },
+    },
+    {
+      id: '2',
+      position: { x: 10, y: 20 },
+      data: {
+        className: 'NoLabelNode',
+      },
+    },
+  ];
+
+  const edges = [
+    {
+      id: 'e1-2',
+      source: '1',
+      sourceHandle: 'output::0::IMAGE',
+      target: '2',
+      targetHandle: 'input::image::IMAGE',
+      style: { stroke: '#fff', strokeWidth: 2 },
+      selected: true,
+      animated: true,
+    },
+  ];
+
+  const serialized = serializeWorkflowState(nodes, edges);
+
+  assert.deepEqual(serialized, {
+    version: 1,
+    nodes: [
+      {
+        id: '1',
+        type: 'custom',
+        position: { x: 100, y: 200 },
+        dragHandle: '.node-header',
+        data: {
+          label: 'Demo Label',
+          className: 'DemoNode',
+          widgetValues: { threshold: 0.42, mode: 'fast' },
+        },
+      },
+      {
+        id: '2',
+        type: 'custom',
+        position: { x: 10, y: 20 },
+        dragHandle: '.drag-handle',
+        data: {
+          label: 'NoLabelNode',
+          className: 'NoLabelNode',
+          widgetValues: {},
+        },
+      },
+    ],
+    edges: [
+      {
+        id: 'e1-2',
+        source: '1',
+        sourceHandle: 'output::0::IMAGE',
+        target: '2',
+        targetHandle: 'input::image::IMAGE',
+        style: { stroke: '#fff', strokeWidth: 2 },
+      },
+    ],
+  });
+
+  assert.equal('definition' in serialized.nodes[0].data, false);
+  assert.equal('previewImage' in serialized.nodes[0].data, false);
+  assert.equal('selected' in serialized.edges[0], false);
+});