统一在预设包装层做提示词夹心，并修正探针实际发信路径。

让所有模型请求与界面预览共用同一套夹心，避免探针与运行时行为分叉。

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

tests/play-frame.test.ts

@@ -51,9 +51,11 @@ describe("assemblePlayWorkerMessages", () => {
     });
 
     expect(messages.map((m) => [m.role, m.content])).toEqual([
-      ["system", "SKILL"],
       ["system", "MAIN"],
-      ["system", "### 舞台\n\n古镇夜雨"],
+      [
+        "system",
+        "### 任务契约\n\nSKILL\n\n### 舞台\n\n古镇夜雨",
+      ],
       ["system", "用户：昨天来过"],
       ["system", "### 变量\n\nHP 3"],
       ["user", "我推门"],
@@ -62,6 +64,57 @@ describe("assemblePlayWorkerMessages", () => {
     ]);
   });
 
+  it("does not emit any message before the first preset order entry", () => {
+    const report = importSillyTavernPreset({
+      prompts: [
+        {
+          identifier: "wb-head",
+          name: "世界书首",
+          role: "system",
+          content: "<世界书>",
+        },
+        {
+          identifier: "chatHistory",
+          name: "History",
+          role: "system",
+          marker: true,
+        },
+        {
+          identifier: "wb-tail",
+          name: "世界书尾",
+          role: "system",
+          content: "</世界书>",
+        },
+      ],
+      prompt_order: [
+        {
+          character_id: 1,
+          order: [
+            { identifier: "wb-head", enabled: true },
+            { identifier: "chatHistory", enabled: true },
+            { identifier: "wb-tail", enabled: true },
+          ],
+        },
+      ],
+    });
+    const messages = assemblePlayWorkerMessages({
+      systemPrompt: "创作步骤契约",
+      preset: report.preset,
+      pack: {
+        worldBookBefore: [{ id: "lore", name: "设定", content: "港口" }],
+        history: "昨日对话",
+        worldBookAfter: [],
+        turn: "本轮",
+        postTurn: [],
+      },
+    });
+    expect(messages[0]).toEqual({ role: "system", content: "<世界书>" });
+    expect(messages.some((m) => m.content === "创作步骤契约")).toBe(false);
+    expect(
+      messages.some((m) => m.content.includes("### 任务契约\n\n创作步骤契约")),
+    ).toBe(true);
+  });
+
   it("does not fill ST charDescription even if resolver returns content", () => {
     const report = importSillyTavernPreset({
       prompts: [