feat(frontend): 五类交互接入 AI 对话留痕 + Workbench 抽屉入口（AC-3）

- RefinePanel/ChapterRewritePanel：结束后 append [author(意见/答复), ai(产出)]；
  clarify buffer-until-concluded——澄清 Q&A（原意见→反问→答复）缓冲，随最终产出批
  一起落库同 thread；纯放弃不记。refine ai 行 meta 存 version_no+原选段（每版重锚）。
- ContinuePanel：ai-only（续写无作者输入），每候选一条 ai 气泡 meta{candidate_index}。
- GeneratorRunner：成功后 append [author(字段摘要, meta{tool_key,input_fields}),
  ai(渲染预览, meta{tool_key,output_kind})]；空产物不记。lib/toolbox/aiSummary.ts 纯助手+单测。
- InlineToolbox→GeneratorRunner 透传 append+本章号；ToolboxPage 用 silent 直投项目级(chapter_no=null)。
- Workbench：挂 useAiConversation 单实例 + AiConversationDrawer + 底栏「AI 对话」入口（flag 灰度），
  三个 DRAFT-only 再接受回调（替换整章/插入正文/回填选段），成功关抽屉+toast、漂移不盲替换。

apps/web/components/workbench/ChapterRewritePanel.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useState } from "react";
+import { useRef, useState } from "react";
 import { Check, MessagesSquare, RotateCcw, Square, X } from "lucide-react";
 
 import { ThinkingIndicator } from "@/components/ThinkingIndicator";
@@ -12,6 +12,10 @@ import { friendlyError } from "@/lib/errors/messages";
 import { foldClarifications, needsClarifyGate } from "@/lib/workbench/clarify";
 import { useChapterRewrite } from "@/lib/workbench/useChapterRewrite";
 import { useRewriteClarify } from "@/lib/workbench/useRewriteClarify";
+import type {
+  AiTurnInput,
+  AiTurnMessage,
+} from "@/lib/workbench/useAiConversation";
 import { ChoiceChips } from "./ChoiceChips";
 
 // 门控阈值：整章意见 trim 后短于此字数才自动预检反问（清晰意见不交往返税）。
@@ -24,6 +28,8 @@ interface ChapterRewritePanelProps {
   currentDraft: string;
   // 接受某一版 → 替换整章正文（HITL，作者显式点选才落草稿）。
   onAccept: (text: string) => void;
+  // 留痕：每版重写记 [author(折后意见), ai(版本正文)]，含缓冲的 clarify Q&A；同 thread 迭代。
+  appendMessages: (turn: AiTurnInput) => void;
   onClose: () => void;
 }
 
@@ -34,12 +40,16 @@ export function ChapterRewritePanel({
   chapterNo,
   currentDraft,
   onAccept,
+  appendMessages,
   onClose,
 }: ChapterRewritePanelProps) {
   const rewrite = useChapterRewrite();
   const clarify = useRewriteClarify();
   const [feedback, setFeedback] = useState("");
   const [pendingFeedback, setPendingFeedback] = useState<string | null>(null);
+  // 本面板一次会话 = 一个 thread；多版迭代 + 澄清往复归此组，版本号本地累加。
+  const threadId = useRef(crypto.randomUUID()).current;
+  const versionNoRef = useRef(0);
 
   const hasVersions = rewrite.versions.length > 0;
   const clarifying = clarify.status === "checking";
@@ -51,12 +61,34 @@ export function ChapterRewritePanel({
   const priorDraft = rewrite.latest?.text ?? currentDraft;
   const err = rewrite.state.phase === "error" ? rewrite.state.error : null;
 
-  // 折入澄清答案（或原意见）后流式重写，并清理澄清态。
-  const runSend = (fb: string): void => {
+  // 折入澄清答案（或原意见）后流式重写，结束后留痕；clarifyTurns 非空时把缓冲 Q&A 一并落库。
+  const runSend = (fb: string, clarifyTurns: AiTurnMessage[] | null): void => {
     clarify.reset();
     setPendingFeedback(null);
     setFeedback("");
-    void rewrite.send(projectId, chapterNo, fb, priorDraft);
+    void (async () => {
+      const v = await rewrite.send(projectId, chapterNo, fb, priorDraft);
+      if (!v) return; // 停止/失败/空版：不留痕。
+      versionNoRef.current += 1;
+      const versionNo = versionNoRef.current;
+      const aiRow: AiTurnMessage = {
+        role: "ai",
+        content: v.text,
+        meta: { version_no: versionNo },
+      };
+      // clarify 分支：作者答复 IS 本轮 author 输入；否则记 author(折后意见, meta{version_no})。
+      const messages = clarifyTurns
+        ? [...clarifyTurns, aiRow]
+        : [
+            {
+              role: "author" as const,
+              content: fb,
+              meta: { version_no: versionNo },
+            },
+            aiRow,
+          ];
+      appendMessages({ threadId, kind: "rewrite", chapterNo, messages });
+    })();
   };
 
   // 「重写整章 / 再改一版」：意见含糊/极短（或 force）先预检反问；否则直接流式重写。
@@ -70,14 +102,32 @@ export function ChapterRewritePanel({
         return;
       }
     }
-    runSend(fb);
+    runSend(fb, null);
   };
 
-  // 作者答复澄清（点选 value 或自由输入）→ 折进意见 → 流式重写。
+  // 作者答复澄清（点选 value 或自由输入）→ 缓冲 Q&A（原意见→反问→答复）+ 折进意见 → 流式重写。
   const onClarifyAnswer = (answer: string): void => {
-    const question = clarify.decision?.questions[0]?.question ?? "";
+    const q = clarify.decision?.questions[0];
+    const question = q?.question ?? "";
     const base = pendingFeedback ?? feedback.trim();
-    runSend(foldClarifications(base, [{ question, answer }]));
+    const clarifyTurns: AiTurnMessage[] = [
+      { role: "author", content: base },
+      {
+        role: "ai",
+        content: question,
+        meta: {
+          parent_kind: "rewrite",
+          options: (q?.options ?? []).map((o) => ({
+            label: o.label,
+            value: o.value,
+          })),
+          allow_free_text: q?.allowFreeText ?? false,
+          verification: clarify.decision?.verification ?? "",
+        },
+      },
+      { role: "author", content: answer },
+    ];
+    runSend(foldClarifications(base, [{ question, answer }]), clarifyTurns);
   };
 
   return (