fix(video): send the model default for fal settings a frame change invalidates

Attaching or removing a start frame switches a fal model between its
text-to-video and image-to-video endpoints, and the settings picked for
one can be invalid on the other (Seedance 2.5 takes 16:9 from a prompt
but only auto from a frame). The V3 block now drops any stored setting
the selected endpoint does not accept, so the run uses the model
default instead of failing validation.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: myxamediyar

apps/sim/blocks/blocks/video_generator.ts

@@ -140,6 +140,33 @@ const LEGACY_FAL_SETTING_KEYS: Record<string, keyof FalVideoSettings> = {
   promptOptimizer: 'promptOptimizer',
 }
 
+/**
+ * Drops stored settings the endpoint a run calls does not accept, so the model default applies.
+ * Attaching or removing a start frame switches endpoints without clearing the settings chosen for
+ * the other one: Seedance 2.5 takes `16:9` from a prompt but only `auto` from a start frame.
+ */
+function keepFalSettingsAllowed(
+  params: Record<string, unknown>,
+  settings: FalVideoSettings | undefined
+) {
+  const { duration, aspectRatio, resolution } = params
+  const durations = settings?.durations?.map((value) => Number.parseFloat(String(value)))
+  return {
+    ...params,
+    duration: typeof duration === 'number' && durations?.includes(duration) ? duration : undefined,
+    aspectRatio:
+      typeof aspectRatio === 'string' && settings?.aspectRatios?.includes(aspectRatio)
+        ? aspectRatio
+        : undefined,
+    resolution:
+      typeof resolution === 'string' && settings?.resolutions?.includes(resolution)
+        ? resolution
+        : undefined,
+    generateAudio: settings?.audioField ? params.generateAudio : undefined,
+    promptOptimizer: settings?.promptOptimizer ? params.promptOptimizer : undefined,
+  }
+}
+
 function withFalVideoCatalog(subBlocks: SubBlockConfig[]): SubBlockConfig[] {
   return subBlocks.flatMap((subBlock) => {
     const condition = subBlock.condition
@@ -1998,16 +2025,12 @@ export const VideoGeneratorV3Block: BlockConfig = {
       params: (params) => {
         if (params.provider === 'falai') {
           const falParams = VideoGeneratorV2Block.tools.config?.params?.(params) ?? params
-          if (!getFalVideoModel(params.model)?.image || !falParams.visualReference)
-            return { ...falParams, visualReference: undefined }
-          const image = getFalVideoVariant(params.model, true)
+          const model = getFalVideoModel(params.model)
+          if (!model) return { ...falParams, visualReference: undefined }
+          const withImage = Boolean(model.image && falParams.visualReference)
           return {
-            ...falParams,
-            duration: image?.durations ? falParams.duration : undefined,
-            aspectRatio: image?.aspectRatios ? falParams.aspectRatio : undefined,
-            resolution: image?.resolutions ? falParams.resolution : undefined,
-            generateAudio: image?.audioField ? falParams.generateAudio : undefined,
-            promptOptimizer: image?.promptOptimizer ? falParams.promptOptimizer : undefined,
+            ...keepFalSettingsAllowed(falParams, getFalVideoVariant(params.model, withImage)),
+            visualReference: withImage ? falParams.visualReference : undefined,
           }
         }
         const visualReference =

apps/sim/serializer/field-analysis.test.ts

@@ -16,6 +16,7 @@ vi.mock('@/blocks', () => ({
 
 import { videoToolBodySchema } from '@/lib/api/contracts/tools/media/video'
 import { buildDirectVideoRequest } from '@/lib/internal/video/direct-request'
+import { buildFalVideoRequest } from '@/lib/internal/video/fal-request'
 import { VideoGeneratorV3Block } from '@/blocks/blocks/video_generator'
 import { collectBlockFieldIssues, extractBlockParams } from '@/serializer/index'
 import { getToolMetadata, getToolParams } from '@/tools/metadata'
@@ -208,6 +209,59 @@ describe('extractBlockParams', () => {
     expect(request.body).toMatchObject(payload)
   })
 
+  it.each([
+    {
+      name: 'a frame is attached after picking a prompt-only aspect ratio',
+      model: 'bytedance/seedance-2.5/text-to-video',
+      aspectRatio: '16:9',
+      frame: true,
+      endpoint: 'bytedance/seedance-2.5/image-to-video',
+    },
+    {
+      name: 'the frame is removed after picking a frame-only aspect ratio',
+      model: 'fal-ai/bytedance/seedance/v1/pro/text-to-video',
+      aspectRatio: 'auto',
+      frame: false,
+      endpoint: 'fal-ai/bytedance/seedance/v1/pro/text-to-video',
+    },
+  ])(
+    'sends the model default for a fal setting the endpoint rejects when $name',
+    ({ model, aspectRatio, frame, endpoint }) => {
+      svcConfig.value = VideoGeneratorV3Block
+      const frameFile = {
+        id: 'f',
+        name: 'frame.png',
+        url: '',
+        size: 3,
+        type: 'image/png',
+        key: 'k',
+      }
+      const values = {
+        provider: 'falai',
+        apiKey: 'test-key',
+        model,
+        prompt: 'A cinematic sunrise',
+        falAspectRatio: aspectRatio,
+        ...(frame ? { visualReferenceInput: frameFile } : {}),
+      }
+      const params = extractBlockParams(
+        block({
+          type: 'svc',
+          subBlocks: Object.fromEntries(
+            Object.entries(values).map(([id, value]) => [id, { id, type: 'short-input', value }])
+          ),
+        })
+      )
+      const mapped = VideoGeneratorV3Block.tools.config?.params?.(params)
+      const request = buildFalVideoRequest({
+        ...videoToolBodySchema.parse(mapped),
+        provider: 'falai',
+      })
+      expect(request.endpoint).toBe(endpoint)
+      expect(request.body).not.toHaveProperty('aspect_ratio')
+    }
+  )
+
   it('resolves a canonical pair to its canonical id (advanced value wins when basic empty)', () => {
     svcConfig.value = config([
       {