引入游玩回合与开场收口，抽出可替换 agent 司机并支持运行中止；完善预设洞位、世界书拼装与试跑，并打磨会话运行时与 Web 交互。

Co-authored-by: Cursor <cursoragent@cursor.com>

src/preset/play-frame.ts

@@ -0,0 +1,24 @@
+import type { ChatMessage } from "../llm/client.js";
+import type { PresetPackage } from "../types/preset.js";
+import { assemblePresetMessages } from "./assembler.js";
+import { applyExtendedMarkers } from "./markers.js";
+import {
+  resolveWorldInfoMarker,
+  type WorldInfoPack,
+} from "./world-info-pack.js";
+
+/**
+ * Play worker：system 契约 + 按扩展 prompt_order 填洞。
+ * 不要再把同一份 context-order 正文叠成第二包 user。
+ */
+export function assemblePlayWorkerMessages(params: {
+  systemPrompt: string;
+  preset: PresetPackage;
+  pack: WorldInfoPack;
+}): ChatMessage[] {
+  const framed = applyExtendedMarkers(params.preset);
+  const filled = assemblePresetMessages(framed, (id) =>
+    resolveWorldInfoMarker(params.pack, id),
+  );
+  return [{ role: "system", content: params.systemPrompt }, ...filled];
+}