fix(design): connect video preparation and playable history

shared/image-workspace.ts

@@ -16,11 +16,24 @@ export type DesignProvenance =
   | 'restored'
   | 'legacy_import';
 
+export type DesignGenerationOptions = {
+  available: boolean;
+  supportedAspectRatios: string[];
+  supportedDurationSeconds: number[];
+  maxOutputCount: number;
+  requiresFirstFrame: boolean;
+  supportedReferenceRoles: string[];
+};
+
 export type DesignCapabilities = {
   conversation: boolean;
   generation: boolean;
   image: boolean;
   video: boolean;
+  generationOptions: {
+    image: DesignGenerationOptions;
+    video: DesignGenerationOptions;
+  };
 };
 
 export type DesignFieldDecision = {
@@ -353,6 +366,7 @@ export type DesignUserFieldOperation =
 
 export type DesignUserInput =
   | { kind: 'direct_edit'; operations: DesignUserFieldOperation[] }
+  | { kind: 'prepare_generation'; operations?: DesignUserFieldOperation[] }
   | { kind: 'chat'; message: string }
   | {
     kind: 'prompt_resolution';