fix(video): drop only settings a start frame change made stale

Runway models also switch endpoints when a start frame is attached, and
their stored settings can be valid on one and not the other (Kling 4
takes 1920:1080 from a prompt but only auto ratios from a frame).
Both fal and direct providers now drop a setting only when the selected
endpoint rejects it and the model's other endpoint accepts it. Values
neither endpoint lists still reach the request builder, which maps
legacy Runway ratios such as 16:9 and rejects anything else.

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

Author: myxamediyar

apps/sim/blocks/blocks/video_generator.ts

@@ -141,27 +141,34 @@ const LEGACY_FAL_SETTING_KEYS: Record<string, keyof FalVideoSettings> = {
 }
 
 /**
- * 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.
+ * Drops a stored setting the endpoint a run calls rejects but the model's other endpoint accepts,
+ * so the model default applies. Attaching or removing a start frame switches endpoints without
+ * clearing settings picked for the other one: Seedance 2.5 takes `16:9` from a prompt but only
+ * `auto` from a start frame. Any other value passes through to the request's own legacy mapping
+ * and validation.
  */
+function dropStaleSetting(
+  value: unknown,
+  allowed: readonly (number | string)[] | undefined,
+  otherAllowed: readonly (number | string)[] | undefined,
+  numeric = false
+) {
+  const normalize = (choice: unknown) => (numeric ? Number.parseFloat(String(choice)) : choice)
+  const accepts = (choices?: readonly (number | string)[]) =>
+    choices?.some((choice) => normalize(choice) === normalize(value)) ?? false
+  return value !== undefined && !accepts(allowed) && accepts(otherAllowed) ? undefined : value
+}
+
 function keepFalSettingsAllowed(
   params: Record<string, unknown>,
-  settings: FalVideoSettings | undefined
+  settings: FalVideoSettings | undefined,
+  other: 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,
+    duration: dropStaleSetting(params.duration, settings?.durations, other?.durations, true),
+    aspectRatio: dropStaleSetting(params.aspectRatio, settings?.aspectRatios, other?.aspectRatios),
+    resolution: dropStaleSetting(params.resolution, settings?.resolutions, other?.resolutions),
     generateAudio: settings?.audioField ? params.generateAudio : undefined,
     promptOptimizer: settings?.promptOptimizer ? params.promptOptimizer : undefined,
   }
@@ -2029,7 +2036,11 @@ export const VideoGeneratorV3Block: BlockConfig = {
           if (!model) return { ...falParams, visualReference: undefined }
           const withImage = Boolean(model.image && falParams.visualReference)
           return {
-            ...keepFalSettingsAllowed(falParams, getFalVideoVariant(params.model, withImage)),
+            ...keepFalSettingsAllowed(
+              falParams,
+              getFalVideoVariant(params.model, withImage),
+              getFalVideoVariant(params.model, !withImage)
+            ),
             visualReference: withImage ? falParams.visualReference : undefined,
           }
         }
@@ -2038,21 +2049,35 @@ export const VideoGeneratorV3Block: BlockConfig = {
             ? normalizeFileInput(params.visualReference, { single: true })
             : undefined
         const model = getDirectVideoModel(params.provider, params.model, Boolean(visualReference))
+        const other = getDirectVideoModel(params.provider, params.model, !visualReference)?.settings
         const setting = (key: string, supported: unknown, fallbackKey?: string) => {
           if (!supported) return undefined
           const value = params[key] ?? (fallbackKey ? params[fallbackKey] : undefined)
           return value === FAL_MODEL_DEFAULT.id ? undefined : value
         }
-        const duration = setting('duration', model?.settings?.durations)
+        const duration = dropStaleSetting(
+          setting('duration', model?.settings?.durations),
+          model?.settings?.durations,
+          other?.durations,
+          true
+        )
         return {
           provider: params.provider,
           model: params.model,
           apiKey: params.apiKey,
           prompt: params.prompt,
           visualReference,
           duration: duration ? Number(duration) : undefined,
-          aspectRatio: setting('aspectRatio', model?.settings?.aspectRatios),
-          resolution: setting('resolution', model?.settings?.resolutions),
+          aspectRatio: dropStaleSetting(
+            setting('aspectRatio', model?.settings?.aspectRatios),
+            model?.settings?.aspectRatios,
+            other?.aspectRatios
+          ),
+          resolution: dropStaleSetting(
+            setting('resolution', model?.settings?.resolutions),
+            model?.settings?.resolutions,
+            other?.resolutions
+          ),
           generateAudio: parseOptionalBooleanInput(
             setting('directGenerateAudio', model?.settings?.audio, 'generateAudio')
           ),

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

@@ -262,6 +262,33 @@ describe('extractBlockParams', () => {
     }
   )
 
+  it('sends the model default for a Runway setting the start frame endpoint rejects', () => {
+    svcConfig.value = VideoGeneratorV3Block
+    const frameFile = { id: 'f', name: 'frame.png', url: '', size: 3, type: 'image/png', key: 'k' }
+    const values = {
+      provider: 'runway',
+      apiKey: 'test-key',
+      model: 'kling_4',
+      prompt: 'A cinematic sunrise',
+      aspectRatio: '1920:1080',
+      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 = buildDirectVideoRequest({
+      ...videoToolBodySchema.parse(mapped),
+      provider: 'runway',
+    })
+    expect(request.body).not.toHaveProperty('ratio')
+  })
+
   it('resolves a canonical pair to its canonical id (advanced value wins when basic empty)', () => {
     svcConfig.value = config([
       {