Add asset reaping

types/engine.d.ts

@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+/**
+ * Controls over the engine main loop.
+ */
+interface EngineNamespace {
+  /**
+   * Whether the engine main loop is still running (read-only).
+   * Becomes `false` after `Engine.exit()` is called.
+   *
+   * @example
+   * while (Engine.running) { ... }
+   */
+  readonly running: boolean;
+
+  /**
+   * Requests an orderly shutdown of the engine.
+   * Sets the internal running flag to `false`; the main loop exits at the end
+   * of the current tick.
+   *
+   * @example
+   * Engine.exit();
+   */
+  exit(): void;
+}
+
+/** Engine lifecycle controls. */
+declare var Engine: EngineNamespace;