fix: fallback to asset metadata/name when filename missing (#8302)

## Summary

Fix model node creation failing when `user_metadata.filename` is missing
by falling back to `asset.metadata.filename` or `asset.name`.

## Changes

- Add fallback chain for filename: `userMetadata.filename ||
validAsset.metadata?.filename || validAsset.name`

## Testing

Manual testing with assets that have filename in different metadata
locations.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8302-fix-fallback-to-asset-metadata-name-when-filename-missing-2f36d73d365081478299e2f2c1abde81)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>

src/platform/assets/utils/createModelNodeFromAsset.test.ts

@@ -226,6 +226,30 @@ describe('createModelNodeFromAsset', () => {
       expect(result.success).toBe(true)
       expect(vi.mocked(app).canvas.graph!.add).toHaveBeenCalledWith(mockNode)
     })
+    it('should fallback to asset.metadata.filename when user_metadata.filename missing', async () => {
+      const asset = createMockAsset({
+        user_metadata: {},
+        metadata: { filename: 'models/checkpoints/from-metadata.safetensors' }
+      })
+      const mockNode = await createMockNode()
+      await setupMocks({ createdNode: mockNode })
+      const result = createModelNodeFromAsset(asset)
+      expect(result.success).toBe(true)
+      expect(mockNode.widgets?.[0].value).toBe(
+        'models/checkpoints/from-metadata.safetensors'
+      )
+    })
+    it('should fallback to asset.name when both filename sources missing', async () => {
+      const asset = createMockAsset({
+        user_metadata: {},
+        metadata: undefined
+      })
+      const mockNode = await createMockNode()
+      await setupMocks({ createdNode: mockNode })
+      const result = createModelNodeFromAsset(asset)
+      expect(result.success).toBe(true)
+      expect(mockNode.widgets?.[0].value).toBe('test-model.safetensors')
+    })
     it('should add node to active subgraph when present', async () => {
       const asset = createMockAsset()
       const mockNode = await createMockNode()
@@ -253,27 +277,28 @@ describe('createModelNodeFromAsset', () => {
     })
     it.each([
       {
-        case: 'missing user_metadata',
-        overrides: { user_metadata: undefined },
+        case: 'missing user_metadata with no fallback',
+        overrides: { user_metadata: undefined, metadata: undefined, name: '' },
         expectedCode: 'INVALID_ASSET' as const,
-        errorPattern: /missing required user_metadata/
-      },
-      {
-        case: 'missing filename property',
-        overrides: { user_metadata: {} },
-        expectedCode: 'INVALID_ASSET' as const,
-        errorPattern:
-          /Invalid filename.*expected non-empty string, got undefined/
+        errorPattern: /Invalid filename.*expected non-empty string/
       },
       {
         case: 'non-string filename',
-        overrides: { user_metadata: { filename: 123 } },
+        overrides: {
+          user_metadata: { filename: 123 },
+          metadata: undefined,
+          name: ''
+        },
         expectedCode: 'INVALID_ASSET' as const,
         errorPattern: /Invalid filename.*expected non-empty string, got number/
       },
       {
-        case: 'empty filename',
-        overrides: { user_metadata: { filename: '' } },
+        case: 'empty filename with no fallback',
+        overrides: {
+          user_metadata: { filename: '' },
+          metadata: undefined,
+          name: ''
+        },
         expectedCode: 'INVALID_ASSET' as const,
         errorPattern: /Invalid filename.*expected non-empty string/
       }

src/platform/assets/utils/createModelNodeFromAsset.ts

@@ -69,20 +69,10 @@ export function createModelNodeFromAsset(
 
   const validAsset = validatedAsset.data
 
-  const userMetadata = validAsset.user_metadata
-  if (!userMetadata) {
-    console.error(`Asset ${validAsset.id} missing required user_metadata`)
-    return {
-      success: false,
-      error: {
-        code: 'INVALID_ASSET',
-        message: 'Asset missing required user_metadata',
-        assetId: validAsset.id
-      }
-    }
-  }
+  const userMetadata = validAsset.user_metadata ?? {}
 
-  const filename = userMetadata.filename
+  const filename =
+    userMetadata.filename || validAsset.metadata?.filename || validAsset.name
   if (typeof filename !== 'string' || filename.length === 0) {
     console.error(
       `Asset ${validAsset.id} has invalid user_metadata.filename (expected non-empty string, got ${typeof filename})`