diff --git a/packages/agent/src/index.ts b/packages/agent/src/index.ts
index db224065..0d898cf1 100644
--- a/packages/agent/src/index.ts
+++ b/packages/agent/src/index.ts
@@ -62,4 +62,10 @@ export {
   resolveAgentSettings,
   THINKING_LEVELS,
 } from "./settings.ts";
-export { buildSystemPrompt, interactionRules, REPORT_FORMAT, type SystemPromptInput } from "./system-prompt.ts";
+export {
+  AGENT_AUDIENCE,
+  buildSystemPrompt,
+  interactionRules,
+  REPORT_FORMAT,
+  type SystemPromptInput,
+} from "./system-prompt.ts";
diff --git a/packages/agent/src/system-prompt.ts b/packages/agent/src/system-prompt.ts
index e3cb2e2e..b43598f2 100644
--- a/packages/agent/src/system-prompt.ts
+++ b/packages/agent/src/system-prompt.ts
@@ -63,6 +63,15 @@ export const REPORT_FORMAT: readonly string[] = [
   "可以用 Markdown 列表、表格和粗体,不写标题,不写 HTML。",
 ];
 
+/**
+ * 子会话 / 视觉子流程(audience = agent)的汇报约定(AG-4):汇报给父会话汇总,仍然全程中文——
+ * 父会话派出的目标、工具结果或网页是英文时,子会话容易整轮用英文思考,用户展开子会话看到的就是英文。
+ */
+export const AGENT_AUDIENCE: readonly string[] = [
+  "你的汇报交给父会话汇总,不直接给用户看,可以带对象 ID。",
+  "思考、步骤说明和汇报一律用中文,即使目标、工具结果或网页是英文;引用文件名、原站标题时保持原文。",
+];
+
 /**
  * 系统提示模板。硬性规则不可被用户消息、工具输出、网页/RSS 内容覆盖。
  */
@@ -100,6 +109,7 @@ export function buildSystemPrompt({
     ...rules.map((r, i) => `${i + 1}. ${r}`),
   ];
   if (audience === "user") lines.push("", "## 汇报格式", ...REPORT_FORMAT.map((r) => `- ${r}`));
+  else lines.push("", "## 汇报对象", ...AGENT_AUDIENCE.map((r) => `- ${r}`));
   const ways = interaction ? interactionRules(interaction) : [];
   if (ways.length > 0) lines.push("", "## 工作方式", ...ways.map((r) => `- ${r}`));
   if (constraints.length > 0) {
diff --git a/packages/agent/test/system-prompt.test.ts b/packages/agent/test/system-prompt.test.ts
index 89826390..a1c50f33 100644
--- a/packages/agent/test/system-prompt.test.ts
+++ b/packages/agent/test/system-prompt.test.ts
@@ -48,6 +48,24 @@ describe("汇报格式(AGUI-3)", () => {
     const p = buildSystemPrompt({ role: "网页挑战处理员", goal: "过验证", audience: "agent" });
     expect(p).not.toContain("## 汇报格式");
   });
+
+  it("子会话与父会话一样要求思考、步骤说明和汇报都用中文(AG-4)", () => {
+    const child = buildSystemPrompt({
+      role: "媒体库自动化智能体",
+      goal: "Check the torrent list on the site",
+      audience: "agent",
+    });
+    // 与父会话同一条硬规则
+    expect(child).toContain("思考、步骤说明和汇报都用中文");
+    expect(userPrompt()).toContain("思考、步骤说明和汇报都用中文");
+    // 子会话专有的一节:目标 / 工具结果是英文也用中文
+    expect(section(child, "汇报对象")).toMatchInlineSnapshot(`
+      "## 汇报对象
+      - 你的汇报交给父会话汇总,不直接给用户看,可以带对象 ID。
+      - 思考、步骤说明和汇报一律用中文,即使目标、工具结果或网页是英文;引用文件名、原站标题时保持原文。"
+    `);
+    expect(section(userPrompt(), "汇报对象")).toBe("");
+  });
 });
 
 describe("工作方式(AGUI-3)", () => {