Refactoring: one file per node, consistent comments, shared helpers, split large modules

- Graph: nodes.ts split into nodes/<category>/<Type>.ts (62 files) with
  shared.ts factories and index.ts registry; NodeContext/values/NodeRegistry
  separated, writeTyped() replaces duplicated typed writes
- Comments: one style (JSDoc on non-obvious exports, // for decisions and
  traps), wrong/stale comments fixed or removed, ids.ts now real 10 base-36 chars
- Core: chainOf, shared worldPosition/editorPosition core, commands/require.ts,
  commands/naming.ts, util/list.ts, setBagValue/toPosition/propDef; dead code
  removed (isBehaviorAsset, SCENE_OBJECT_SCHEMA, CommandStack.subscribe,
  Input.axis, setMode, titleText, World.worldPosition, unused ctor params)
- Editor: Inspector split into inspector/ sections, App.ts into Editor.ts +
  debugHook.ts + shortcuts.ts, Viewport into items.ts + symbols.ts, shared
  "Add collider" action, unified type labels/swatches
- UI toolkit: Widget.trackHover/onPointerRelease, drawControlBox, math helpers,
  Popup.openBelow, Menu/Dialog/ColorPicker/ListRow in own files, named Theme sizes
- Tools: seed-demo/smoke-demo and demo-check project removed, tools/lib
  (harness, projects, builders), e2e.mjs as runner over tools/e2e/*.mjs sections
- Tests: tests/helpers.ts replaces copied fixtures and NodeContext doubles

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

src/runtime/systems/BehaviorSystem.ts

@@ -42,6 +42,11 @@ export class BehaviorSystem implements System {
     this.syncInstances(world);
   }
 
+  stop(): void {
+    this.instances = [];
+    this.world = null;
+  }
+
   /**
    * One instance per behavior entity: entities that appeared (placed while playing) get an
    * interpreter and their `On start`; instances whose entity is gone are dropped. A behavior
@@ -56,7 +61,10 @@ export class BehaviorSystem implements System {
       if (!asset || asset.type !== 'behavior') continue;
       const trace: Trace = { edges: new Map(), nodes: new Map() };
       const interpreter = new GraphInterpreter(asset.graph);
-      interpreter.trace = this.traceListener(trace, world);
+      interpreter.trace = {
+        onEdge: (id) => trace.edges.set(id, world.time),
+        onNode: (id) => trace.nodes.set(id, world.time),
+      } satisfies TraceListener;
       const instance = { entity, interpreter, trace };
       this.instances.push(instance);
       this.run(instance, (i, ctx) => i.fire('OnStart', ctx), 0);
@@ -117,22 +125,21 @@ export class BehaviorSystem implements System {
     fire('OnCollisionExit', this.collisions.exits);
   }
 
-  stop(): void {
-    this.instances = [];
-    this.world = null;
-  }
-
   /** Live highlight data for the graph editor: merged over all instances of the asset. */
   traceFor(assetId: string): Trace {
     const merged: Trace = { edges: new Map(), nodes: new Map() };
+    const latest = (into: Map<string, number>, from: Map<string, number>) => {
+      for (const [id, t] of from) into.set(id, Math.max(t, into.get(id) ?? -Infinity));
+    };
     for (const instance of this.instances) {
       if (instance.entity.assetId !== assetId) continue;
-      for (const [id, t] of instance.trace.edges) merged.edges.set(id, Math.max(t, merged.edges.get(id) ?? -Infinity));
-      for (const [id, t] of instance.trace.nodes) merged.nodes.set(id, Math.max(t, merged.nodes.get(id) ?? -Infinity));
+      latest(merged.edges, instance.trace.edges);
+      latest(merged.nodes, instance.trace.nodes);
     }
     return merged;
   }
 
+  /** Runs graph code for one instance; an exception stops play and is logged, never thrown. */
   private run(instance: Instance, body: (interpreter: GraphInterpreter, ctx: NodeContext) => void, dt: number): void {
     const world = this.world;
     if (!world) return;
@@ -146,6 +153,9 @@ export class BehaviorSystem implements System {
   }
 
   private context(entity: Entity, world: World, dt: number): NodeContext {
+    // Handles arriving from the graph are the entities themselves, or test doubles with the same id.
+    const resolve = (handle: EntityHandle | null): Entity | undefined =>
+      handle ? world.entities.find((e) => e === handle || e.id === handle.id) : undefined;
     return {
       self: entity,
       owner: entity.parent,
@@ -156,16 +166,16 @@ export class BehaviorSystem implements System {
       isKeyDown: (key) => this.input.isDown(key),
       pointer: world.pointer,
       hitTest: (target, x, y) => {
-        const found = world.entities.find((e) => e === target || e.id === target.id);
+        const found = resolve(target);
         return Boolean(found && world.hitTest(found, x, y));
       },
       isTouching: (a, b) => {
-        const ea = world.entities.find((e) => e === a || e.id === a.id);
-        const eb = world.entities.find((e) => e === b || e.id === b.id);
+        const ea = resolve(a);
+        const eb = resolve(b);
         return Boolean(this.collisions && ea && eb && this.collisions.touching(world, ea, eb));
       },
       moveAndSlide: (target, dx, dy) => {
-        const found = world.entities.find((e) => e === target || e.id === target.id);
+        const found = resolve(target);
         if (!found) return { blockedX: false, blockedY: false };
         if (this.collisions) return this.collisions.moveAndSlide(world, found, dx, dy);
         found.x += dx;
@@ -176,12 +186,9 @@ export class BehaviorSystem implements System {
         world.log.push(message);
         console.log(`[behavior ${entity.name}]`, message);
       },
-      spawn: (assetId, position, parent) => {
-        const parentEntity = parent ? world.entities.find((e) => e === parent || e.id === parent.id) ?? null : null;
-        return world.spawn(assetId, position, parentEntity);
-      },
-      destroy: (target: EntityHandle) => {
-        const found = world.entities.find((e) => e === target || e.id === target.id);
+      spawn: (assetId, position, parent) => world.spawn(assetId, position, resolve(parent) ?? null),
+      destroy: (target) => {
+        const found = resolve(target);
         if (found) world.remove(found);
       },
       stop: () => {
@@ -192,11 +199,4 @@ export class BehaviorSystem implements System {
       },
     };
   }
-
-  private traceListener(trace: Trace, world: World): TraceListener {
-    return {
-      onEdge: (id) => trace.edges.set(id, world.time),
-      onNode: (id) => trace.nodes.set(id, world.time),
-    };
-  }
 }