Behaviors with Blueprint-style node graph, graph editor tab and BehaviorSystem

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/core/model/Asset.ts

@@ -1,3 +1,5 @@
+import type { Graph } from '../graph/Graph';
+import type { PropertyDef } from '../properties/PropertySchema';
 import type { AssetType } from './AssetTypes';
 import type { PropertyBag } from './Properties';
 import type { SceneObject } from './SceneObject';
@@ -24,8 +26,23 @@ export interface SceneAsset extends AssetBase {
   objects: SceneObject[];
 }
 
-export type Asset = SpriteAsset | CameraAsset | SceneAsset;
+/**
+ * A behavior is logic: a node graph plus the variables it declares. Variables are ordinary
+ * properties – `variables` is the asset's own property schema, `props` holds their default
+ * values, and placed instances override them like any other property.
+ */
+export interface BehaviorAsset extends AssetBase {
+  type: 'behavior';
+  variables: PropertyDef[];
+  graph: Graph;
+}
+
+export type Asset = SpriteAsset | CameraAsset | SceneAsset | BehaviorAsset;
 
 export function isSceneAsset(asset: Asset): asset is SceneAsset {
   return asset.type === 'scene';
 }
+
+export function isBehaviorAsset(asset: Asset): asset is BehaviorAsset {
+  return asset.type === 'behavior';
+}

src/core/model/AssetTypes.ts

@@ -1,5 +1,5 @@
-/** All asset types known in phase 1. Scenes are assets too, but cannot be placed in scenes. */
-export const ASSET_TYPES = ['scene', 'camera', 'sprite'] as const;
+/** All asset types. Scenes are assets too, but cannot be placed in scenes. */
+export const ASSET_TYPES = ['scene', 'camera', 'sprite', 'behavior'] as const;
 
 export type AssetType = (typeof ASSET_TYPES)[number];
 
@@ -13,3 +13,11 @@ export function isPlaceableType(type: AssetType): type is PlaceableAssetType {
 export function isAssetType(value: unknown): value is AssetType {
   return typeof value === 'string' && (ASSET_TYPES as readonly string[]).includes(value);
 }
+
+/**
+ * Types drawn as editor symbols (icon in the overlay layer) instead of as scene content.
+ * They exist in the scene for their position, not for their looks.
+ */
+export function isSymbolType(type: AssetType): boolean {
+  return type === 'camera' || type === 'behavior';
+}

src/core/model/SceneObject.ts

@@ -13,9 +13,21 @@ export interface SceneObject {
   /** World position plus draw order (`z`). */
   position: Position;
   overrides: PropertyBag;
+  /**
+   * Another object of the same scene this one acts on (used by behaviors: "the owner").
+   * Empty string = none. Any object may carry one, only behaviors interpret it.
+   */
+  ownerId: string;
 }
 
 /** Creates a scene object; `z` defaults to 0 when the caller only has a 2D point. */
 export function createSceneObject(id: string, assetId: string, position: Vec2 | Position): SceneObject {
-  return { id, assetId, name: '', position: { x: position.x, y: position.y, z: 'z' in position ? position.z : 0 }, overrides: {} };
+  return {
+    id,
+    assetId,
+    name: '',
+    position: { x: position.x, y: position.y, z: 'z' in position ? position.z : 0 },
+    overrides: {},
+    ownerId: '',
+  };
 }