feat(frontend): 整章「再沟通/重写」面板——给意见流式重写整章，版本栈迭代，接受替换正文

WFW-8 整章级再沟通（前端）。底栏新增「整章重写」→ ChapterRewritePanel：
- 作者给意见 → useChapterRewrite 消费 POST .../rewrite 的 SSE 流（复用 lib/stream/sse
  帧解析），流式 live 展示新一版；
- 每轮完成压入版本栈，「再改一版」以最新版为 prior_draft + 新意见迭代（多轮对话式）；
- 接受某版才「替换整章正文」落草稿（HITL，AI 绝不静默覆盖）；停/错误/网络异常均归一处理。
四张 AI 结果卡（润色/续写/工具箱/整章重写）互斥。gen:api 重生成 TS 客户端。
门禁绿：tsc/lint/vitest 636（+7 useChapterRewrite）/build/coverage 95.36%。

apps/web/lib/workbench/useChapterRewrite.test.ts

@@ -0,0 +1,162 @@
+// @vitest-environment jsdom
+import { act, renderHook } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { useChapterRewrite } from "./useChapterRewrite";
+
+// fetch（SSE 流）是 hook 的外部副作用边界，单测一律 stub 全局 fetch。
+const fetchMock = vi.fn();
+
+function sseStream(chunks: string[]): ReadableStream<Uint8Array> {
+  const enc = new TextEncoder();
+  return new ReadableStream({
+    start(c) {
+      for (const ch of chunks) c.enqueue(enc.encode(ch));
+      c.close();
+    },
+  });
+}
+
+function sseResponse(chunks: string[]): Response {
+  return new Response(sseStream(chunks), {
+    status: 200,
+    headers: { "Content-Type": "text/event-stream" },
+  });
+}
+
+describe("useChapterRewrite", () => {
+  beforeEach(() => {
+    fetchMock.mockReset();
+    vi.stubGlobal("fetch", fetchMock);
+  });
+  afterEach(() => {
+    vi.unstubAllGlobals();
+    vi.clearAllMocks();
+  });
+
+  it("初始为 idle、无版本", () => {
+    const { result } = renderHook(() => useChapterRewrite());
+    expect(result.current.state.phase).toBe("idle");
+    expect(result.current.versions).toEqual([]);
+    expect(result.current.latest).toBeNull();
+  });
+
+  it("重写完成（token+done）：流式累积正文并压入版本栈（带作者意见）", async () => {
+    fetchMock.mockResolvedValue(
+      sseResponse([
+        'event:token\ndata:{"text":"新版"}\n\n',
+        'event:token\ndata:{"text":"正文"}\n\n',
+        'event:done\ndata:{"length":4}\n\n',
+      ]),
+    );
+
+    const { result } = renderHook(() => useChapterRewrite());
+    await act(async () => {
+      await result.current.send("p1", 3, "节奏太慢", "旧草稿");
+    });
+
+    // POST body 带 feedback + prior_draft（snake_case）。
+    const call = fetchMock.mock.calls[0];
+    expect(call?.[0]).toContain("/projects/p1/chapters/3/rewrite");
+    expect(JSON.parse((call?.[1]?.body as string) ?? "")).toEqual({
+      feedback: "节奏太慢",
+      prior_draft: "旧草稿",
+    });
+    expect(result.current.state.phase).toBe("done");
+    expect(result.current.versions).toEqual([
+      { feedback: "节奏太慢", text: "新版正文" },
+    ]);
+    expect(result.current.latest?.text).toBe("新版正文");
+  });
+
+  it("多轮迭代：第二轮再压一版，latest 为最新版", async () => {
+    fetchMock
+      .mockResolvedValueOnce(
+        sseResponse([
+          'event:token\ndata:{"text":"第一版"}\n\n',
+          'event:done\ndata:{"length":3}\n\n',
+        ]),
+      )
+      .mockResolvedValueOnce(
+        sseResponse([
+          'event:token\ndata:{"text":"第二版"}\n\n',
+          'event:done\ndata:{"length":3}\n\n',
+        ]),
+      );
+
+    const { result } = renderHook(() => useChapterRewrite());
+    await act(async () => {
+      await result.current.send("p1", 1, "意见一", "原草稿");
+    });
+    await act(async () => {
+      await result.current.send("p1", 1, "意见二", "第一版");
+    });
+
+    expect(result.current.versions).toHaveLength(2);
+    expect(result.current.latest).toEqual({ feedback: "意见二", text: "第二版" });
+  });
+
+  it("error 帧：phase=error 且不入版本栈", async () => {
+    fetchMock.mockResolvedValue(
+      sseResponse([
+        'event:error\ndata:{"code":"RATE_LIMIT","message":"配额不足"}\n\n',
+      ]),
+    );
+
+    const { result } = renderHook(() => useChapterRewrite());
+    await act(async () => {
+      await result.current.send("p1", 1, "改", "草稿");
+    });
+
+    expect(result.current.state.phase).toBe("error");
+    expect(result.current.state.error).toMatchObject({ code: "RATE_LIMIT" });
+    expect(result.current.versions).toEqual([]);
+  });
+
+  it("流前错误（!res.ok）：解析 JSON 信封提取错误码", async () => {
+    fetchMock.mockResolvedValue(
+      new Response(
+        JSON.stringify({ error: { code: "LLM_UNAVAILABLE", message: "无可用凭据" } }),
+        { status: 503 },
+      ),
+    );
+
+    const { result } = renderHook(() => useChapterRewrite());
+    await act(async () => {
+      await result.current.send("p1", 1, "改", "草稿");
+    });
+
+    expect(result.current.state.error).toMatchObject({ code: "LLM_UNAVAILABLE" });
+    expect(result.current.versions).toEqual([]);
+  });
+
+  it("网络抛异常（非 Abort）：phase=error 且 code=NETWORK", async () => {
+    fetchMock.mockRejectedValue(new Error("connection reset"));
+
+    const { result } = renderHook(() => useChapterRewrite());
+    await act(async () => {
+      await result.current.send("p1", 1, "改", "草稿");
+    });
+
+    expect(result.current.state.error).toMatchObject({
+      code: "NETWORK",
+      message: "connection reset",
+    });
+  });
+
+  it("reset 清回 idle 与空版本栈", async () => {
+    fetchMock.mockResolvedValue(
+      sseResponse([
+        'event:token\ndata:{"text":"x"}\n\n',
+        'event:done\ndata:{"length":1}\n\n',
+      ]),
+    );
+    const { result } = renderHook(() => useChapterRewrite());
+    await act(async () => {
+      await result.current.send("p1", 1, "改", "草稿");
+    });
+    act(() => result.current.reset());
+    expect(result.current.state.phase).toBe("idle");
+    expect(result.current.versions).toEqual([]);
+  });
+});