fix: handle outputGallery nodes in image externalization

OutputGallery nodes were not being handled in externalizeWorkflowImages(),
causing their images arrays (which can contain dozens of high-res base64
images) to remain embedded in workflow JSON even when "Embed images as
base64" was disabled.

This caused workflow files to balloon to 500MB+ and hit JavaScript's
"Invalid string length" limit when saving.

Changes:
- Add outputGallery case to externalizeNodeImages() to clear images array
- Add outputGallery case to hydrateNodeImages() for consistency
- Add cleanup-workflow.js script for fixing existing affected workflows

OutputGallery content is display-only and regenerated on workflow execution,
so it doesn't need to be persisted.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

cleanup-workflow.js

@@ -0,0 +1,73 @@
+/**
+ * One-time script to clean up outputGallery nodes with embedded images
+ * This fixes workflows saved before the outputGallery externalization bug was fixed
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+const workflowPath = process.argv[2];
+
+if (!workflowPath) {
+  console.error('Usage: node cleanup-workflow.js <path-to-workflow.json>');
+  process.exit(1);
+}
+
+console.log(`Reading workflow: ${workflowPath}`);
+const workflow = JSON.parse(fs.readFileSync(workflowPath, 'utf8'));
+
+let cleaned = false;
+let totalSizeBefore = 0;
+let totalSizeAfter = 0;
+
+workflow.nodes.forEach((node, index) => {
+  if (node.type === 'outputGallery' && node.data.images && node.data.images.length > 0) {
+    const sizeBefore = JSON.stringify(node.data.images).length;
+    const imageCount = node.data.images.filter(img => img && img.startsWith('data:')).length;
+
+    if (imageCount > 0) {
+      console.log(`\nNode ${index} (${node.id}):`);
+      console.log(`  Found ${imageCount} embedded images`);
+      console.log(`  Size: ${(sizeBefore / 1024 / 1024).toFixed(2)} MB`);
+
+      node.data.images = [];
+      totalSizeBefore += sizeBefore;
+      cleaned = true;
+    }
+  }
+
+  if (node.type === 'output' && node.data.image && node.data.image.startsWith('data:')) {
+    const sizeBefore = node.data.image.length;
+    console.log(`\nNode ${index} (${node.id}):`);
+    console.log(`  Found embedded output image`);
+    console.log(`  Size: ${(sizeBefore / 1024 / 1024).toFixed(2)} MB`);
+
+    node.data.image = null;
+    node.data.imageRef = undefined;
+    if (node.data.video) {
+      node.data.video = null;
+    }
+    totalSizeBefore += sizeBefore;
+    cleaned = true;
+  }
+});
+
+if (cleaned) {
+  const backupPath = workflowPath.replace('.json', '.backup.json');
+  console.log(`\nCreating backup: ${backupPath}`);
+  fs.copyFileSync(workflowPath, backupPath);
+
+  console.log(`Writing cleaned workflow...`);
+  fs.writeFileSync(workflowPath, JSON.stringify(workflow, null, 2));
+
+  const finalSize = fs.statSync(workflowPath).size;
+  const originalSize = fs.statSync(backupPath).size;
+
+  console.log(`\n✅ Done!`);
+  console.log(`  Original size: ${(originalSize / 1024 / 1024).toFixed(2)} MB`);
+  console.log(`  New size: ${(finalSize / 1024 / 1024).toFixed(2)} MB`);
+  console.log(`  Saved: ${((originalSize - finalSize) / 1024 / 1024).toFixed(2)} MB`);
+  console.log(`\nBackup saved to: ${backupPath}`);
+} else {
+  console.log('\n✓ No embedded images found - workflow is already clean!');
+}

src/utils/imageStorage.ts

@@ -270,6 +270,14 @@ async function externalizeNodeImages(
       break;
     }
 
+    case "outputGallery": {
+      const d = data as import("@/types").OutputGalleryNodeData;
+      // OutputGallery content is regenerated on each workflow run
+      // Clear images array to keep workflow file small
+      newData = { ...d, images: [] };
+      break;
+    }
+
     case "splitGrid": {
       const d = data as import("@/types").SplitGridNodeData;
       // SplitGrid source is input content, save to inputs
@@ -510,6 +518,12 @@ async function hydrateNodeImages(
       break;
     }
 
+    case "outputGallery": {
+      // OutputGallery content is not persisted - it's regenerated on each workflow run
+      newData = data;
+      break;
+    }
+
     case "splitGrid": {
       const d = data as import("@/types").SplitGridNodeData;
       if (d.sourceImageRef && !d.sourceImage) {