Autotiles are a new asset type with a tab that shows every tile of the floor (2x3) or wall (2x2) block and an animated sample pattern (#118)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/core/commands/require.ts

@@ -1,7 +1,7 @@
 /** Lookups that throw a `CommandError` when the target does not exist. */
 import { findNode, type Graph, type GraphEdge, type GraphNode } from '../graph/Graph';
 import { type NodeDef, nodeDef } from '../graph/NodeRegistry';
-import type { Asset, BehaviorAsset, StateMachineAsset, VariablesAsset } from '../model/Asset';
+import type { Asset, AutotileAsset, BehaviorAsset, StateMachineAsset, VariablesAsset } from '../model/Asset';
 import { findObject, type ObjectTree } from '../model/hierarchy';
 import { isTemplateContent, objectRef, type ObjectRef } from '../model/instance';
 import {
@@ -79,6 +79,12 @@ export function requireVariableOwner(project: Project, assetId: string): Behavio
   return asset;
 }
 
+export function requireAutotile(project: Project, assetId: string): AutotileAsset {
+  const asset = findAssetOf(project, assetId, 'autotile');
+  if (!asset) throw new CommandError(`Autotile ${assetId} not found`);
+  return asset;
+}
+
 export function requireStateMachine(project: Project, assetId: string): StateMachineAsset {
   const asset = findAssetOf(project, assetId, 'statemachine');
   if (!asset) throw new CommandError(`State machine ${assetId} not found`);