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.ts

@@ -0,0 +1,163 @@
+"use client";
+
+import { useCallback, useReducer, useRef, useState } from "react";
+
+import { API_BASE_PUBLIC } from "@/lib/api/config";
+import {
+  SseFrameBuffer,
+  initialStreamState,
+  reduceStream,
+  type StreamState,
+} from "@/lib/stream/sse";
+
+// 一轮整章重写的产出（作者意见 + 产出正文）。多轮迭代累积成版本栈。
+export interface RewriteVersion {
+  feedback: string;
+  text: string;
+}
+
+type Action =
+  | { type: "start" }
+  | { type: "events"; events: ReturnType<SseFrameBuffer["push"]> }
+  | { type: "abort" }
+  | { type: "fail"; code: string; message: string }
+  | { type: "reset" };
+
+function reducer(state: StreamState, action: Action): StreamState {
+  switch (action.type) {
+    case "start":
+      return { phase: "streaming", text: "", error: null };
+    case "events":
+      return action.events.reduce(reduceStream, state);
+    case "abort":
+      return { ...state, phase: "aborted" };
+    case "fail":
+      return {
+        ...state,
+        phase: "error",
+        error: { code: action.code, message: action.message },
+      };
+    case "reset":
+      return initialStreamState;
+    default:
+      return state;
+  }
+}
+
+export interface UseChapterRewrite {
+  // 当前流式状态（text = 正在生成/最新一版正文，供 live 展示）。
+  state: StreamState;
+  isStreaming: boolean;
+  // 已完成的版本栈（每轮一版）。
+  versions: RewriteVersion[];
+  latest: RewriteVersion | null;
+  // 发起一轮整章重写：作者意见 + 当前整章草稿 → 流式重写一版。
+  send: (
+    projectId: string,
+    chapterNo: number,
+    feedback: string,
+    priorDraft: string,
+  ) => Promise<void>;
+  stop: () => void;
+  reset: () => void;
+}
+
+// 整章再沟通/重写流：POST .../rewrite（feedback + prior_draft）→ 消费 SSE → 累积成新一版。
+// 每轮完成压入版本栈；下一轮以最新版正文为 prior_draft + 新意见迭代（HITL：接受才落草稿）。
+// 用 fetch+ReadableStream（EventSource 不支持 POST），复用 lib/stream/sse 的帧解析与归一。
+export function useChapterRewrite(): UseChapterRewrite {
+  const [state, dispatch] = useReducer(reducer, initialStreamState);
+  const [versions, setVersions] = useState<RewriteVersion[]>([]);
+  const controllerRef = useRef<AbortController | null>(null);
+  const textRef = useRef("");
+
+  const stop = useCallback(() => {
+    controllerRef.current?.abort();
+    controllerRef.current = null;
+    dispatch({ type: "abort" });
+  }, []);
+
+  const reset = useCallback(() => {
+    dispatch({ type: "reset" });
+    setVersions([]);
+  }, []);
+
+  const send = useCallback<UseChapterRewrite["send"]>(
+    async (projectId, chapterNo, feedback, priorDraft) => {
+      const controller = new AbortController();
+      controllerRef.current = controller;
+      textRef.current = "";
+      dispatch({ type: "start" });
+      try {
+        const res = await fetch(
+          `${API_BASE_PUBLIC}/projects/${projectId}/chapters/${chapterNo}/rewrite`,
+          {
+            method: "POST",
+            headers: {
+              Accept: "text/event-stream",
+              "Content-Type": "application/json",
+            },
+            body: JSON.stringify({ feedback, prior_draft: priorDraft }),
+            signal: controller.signal,
+          },
+        );
+        if (!res.ok || !res.body) {
+          // 流前错误（如无凭据 → 503 LLM_UNAVAILABLE，JSON 信封而非帧）。
+          let code = "STREAM_FAILED";
+          let message = `整章重写请求失败（${res.status}）`;
+          try {
+            const body = (await res.json()) as {
+              error?: { code?: string; message?: string };
+            };
+            if (body.error?.code) code = body.error.code;
+            if (body.error?.message) message = body.error.message;
+          } catch {
+            // 非 JSON 信封，沿用默认文案。
+          }
+          dispatch({ type: "fail", code, message });
+          return;
+        }
+        const reader = res.body.getReader();
+        const decoder = new TextDecoder();
+        const buffer = new SseFrameBuffer();
+        let done = false;
+        for (;;) {
+          const { value, done: readerDone } = await reader.read();
+          if (readerDone) break;
+          const events = buffer.push(decoder.decode(value, { stream: true }));
+          if (events.length > 0) {
+            dispatch({ type: "events", events });
+            for (const ev of events) {
+              if (ev.event === "token") textRef.current += ev.data.text;
+              if (ev.event === "done") done = true;
+            }
+          }
+        }
+        // 收到 done 且有正文 → 压入版本栈（未 done/空文本不入栈，避免脏版本）。
+        if (done && textRef.current.length > 0) {
+          const version: RewriteVersion = { feedback, text: textRef.current };
+          setVersions((prev) => [...prev, version]);
+        }
+      } catch (err: unknown) {
+        if (err instanceof DOMException && err.name === "AbortError") {
+          return; // 用户主动停止：state 已置 aborted。
+        }
+        const message = err instanceof Error ? err.message : "未知网络错误";
+        dispatch({ type: "fail", code: "NETWORK", message });
+      } finally {
+        controllerRef.current = null;
+      }
+    },
+    [],
+  );
+
+  return {
+    state,
+    isStreaming: state.phase === "streaming",
+    versions,
+    latest: versions.at(-1) ?? null,
+    send,
+    stop,
+    reset,
+  };
+}