预设兼容：按真实抓包对齐装配与包装层，补上声明式工具与预设正则。

- 装配只认 prompt_order.enabled；squash_system_messages 只合并相邻 system（新增 system 档，连接符按酒馆用单换行）
- 包装层：new_chat_prompt、示例对话（new_example_chat_prompt + <START> 切段 + name）、角色卡三块与 personality_format/scenario_format、{{user}}/{{char}} 取值、任务契约并进预设条目
- 工具协议：按 ToolBindings / 伪工具协议数据声明真 tools（presetToolPolicy=preset），工具描述用到的条目不再重复作为消息发出
- 正则：promptOnly 作用于对话历史（含 depth 过滤）、写入时脚本改写回复；{{//}} 注释按配平扫描
- tools/st-request-diff：真假上游抓包对比工具、三份预设的机制结论与实测报告

tests/preset-wrapper.test.ts

@@ -1,4 +1,19 @@
-import { describe, expect, it } from "vitest";
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+import { mkdtempSync, rmSync } from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+// 这些用例只测夹心与整形，不该被本机 ~/.writing-agent/settings.json 里的
+// messageSquash / presetToolPolicy 覆盖，跑的时候给一份干净的临时数据目录。
+let isolatedDataDir = "";
+beforeAll(() => {
+  isolatedDataDir = mkdtempSync(path.join(os.tmpdir(), "wa-preset-wrapper-"));
+  process.env.WRITING_AGENT_DATA_DIR = isolatedDataDir;
+});
+afterAll(() => {
+  delete process.env.WRITING_AGENT_DATA_DIR;
+  if (isolatedDataDir) rmSync(isolatedDataDir, { recursive: true, force: true });
+});
 import type {
   ChatMessage,
   CompleteResult,
@@ -25,6 +40,8 @@ const samplePreset: PresetPackage = {
   ],
   promptOrder: [{ promptId: "sys", enabled: true, orderIndex: 0 }],
   generation: { temperature: 0.91, maxOutputTokens: 1234, reasoningEffort: "max" },
+  // 这组用例测的是夹心，不是整形；整形单独有用例。
+  messagePolicy: { squash: "none" },
   unsupported: [],
   importedAt: "2026-01-01T00:00:00.000Z",
 };
@@ -163,4 +180,18 @@ describe("wrapLlmForSession", () => {
     await llm.complete([{ role: "user", content: "TASK" }]);
     expect(received[0].messages[0].content).toBe("称呼 @玩家");
   });
+
+  it("defaults to strict squash when the preset says nothing", async () => {
+    const preset: PresetPackage = { ...samplePreset };
+    delete (preset as { messagePolicy?: unknown }).messagePolicy;
+    const { provider, received } = recordingProvider();
+    const llm = wrapLlmForSession(provider, undefined, () => preset);
+
+    await llm.complete([{ role: "user", content: "TASK" }]);
+
+    // strict：system 折进 user，首条为 user
+    expect(received[0].messages.map((m) => m.role)).toEqual(["user"]);
+    expect(received[0].messages[0]!.content).toContain("PRESET_RULES");
+    expect(received[0].messages[0]!.content).toContain("TASK");
+  });
 });