feat(frontend): 编辑器内「续写」——读本章前文生成多候选，点选插入正文

Phase 1（写作工作台重构）：编辑器「续写」按钮复用 continue 生成器（with_prior_chapter
自动读该章已写正文承接），每次产出一条候选并累加成多候选（useContinue，已单测），
「再来一个」可多生成几版；作者点某条「插入正文」才追加到章末（HITL，不静默写入）。
续写前 flush 自动保存，确保读到最新草稿。润色/续写结果卡互斥不并占。

apps/web/components/workbench/ContinuePanel.tsx

@@ -0,0 +1,104 @@
+"use client";
+
+import { useEffect, useRef } from "react";
+import { Check, Plus, X } from "lucide-react";
+
+import { ThinkingIndicator } from "@/components/ThinkingIndicator";
+import { Button } from "@/components/ui/Button";
+import { SectionHeader } from "@/components/ui/SectionHeader";
+import { StatusNote } from "@/components/ui/StatusNote";
+import { useContinue } from "@/lib/workbench/useContinue";
+
+interface ContinuePanelProps {
+  projectId: string;
+  chapterNo: number;
+  // 插入选中候选到正文（追加到章末）。
+  onInsert: (text: string) => void;
+  onClose: () => void;
+}
+
+// 续写结果卡（内联，非模态）：打开即读该章前文续写一条候选；可「再来一个」累加多候选，
+// 作者点某条「插入正文」才落回草稿（HITL，不静默写入）。
+export function ContinuePanel({
+  projectId,
+  chapterNo,
+  onInsert,
+  onClose,
+}: ContinuePanelProps) {
+  const { status, candidates, generate } = useContinue();
+  const ranRef = useRef(false);
+
+  useEffect(() => {
+    if (ranRef.current) return;
+    ranRef.current = true;
+    void generate(projectId, chapterNo);
+  }, [projectId, chapterNo, generate]);
+
+  const busy = status === "generating";
+
+  return (
+    <div className="border-b border-line bg-panel px-4 py-3 sm:px-6">
+      <div className="flex items-center justify-between gap-3">
+        <SectionHeader
+          title="续写候选"
+          description="承接本章前文续写；点「再来一个」多生成几版，选中意的插入正文。"
+        />
+        <Button onClick={onClose} variant="ghost" size="icon" aria-label="关闭续写">
+          <X className="h-4 w-4" aria-hidden="true" />
+        </Button>
+      </div>
+
+      {candidates.length === 0 && busy ? (
+        <div className="mt-3">
+          <ThinkingIndicator label="续写中" className="text-xs text-cinnabar" />
+        </div>
+      ) : null}
+
+      {candidates.length === 0 && status === "error" ? (
+        <StatusNote variant="danger" className="mt-3 text-xs" title="续写失败">
+          <button
+            type="button"
+            onClick={() => void generate(projectId, chapterNo)}
+            className="mt-1 inline-flex items-center gap-1 text-cinnabar hover:underline"
+          >
+            重试
+          </button>
+        </StatusNote>
+      ) : null}
+
+      <ul className="mt-3 space-y-2">
+        {candidates.map((text, i) => (
+          <li
+            key={i}
+            className="rounded border border-line bg-bg p-3"
+          >
+            <div className="mb-1 flex items-center justify-between gap-2">
+              <span className="text-2xs text-ink-soft">候选 {i + 1}</span>
+              <Button
+                onClick={() => onInsert(text)}
+                variant="primary"
+                size="sm"
+              >
+                <Check className="h-4 w-4" aria-hidden="true" />
+                插入正文
+              </Button>
+            </div>
+            <p className="whitespace-pre-wrap text-sm text-ink">{text}</p>
+          </li>
+        ))}
+      </ul>
+
+      <div className="mt-3">
+        <Button
+          onClick={() => void generate(projectId, chapterNo)}
+          disabled={busy}
+          variant="secondary"
+          size="sm"
+        >
+          <Plus className="h-4 w-4" aria-hidden="true" />
+          再来一个候选
+        </Button>
+      </div>
+    </div>
+  );
+}

apps/web/components/workbench/Workbench.tsx

@@ -13,6 +13,7 @@ import {
   PenLine,
   Square,
   Wand2,
+  WrapText,
 } from "lucide-react";
 
 import { AppShell } from "@/components/AppShell";
@@ -38,6 +39,7 @@ import { ChapterList, ChapterListContent } from "./ChapterList";
 import { ChapterAssistant, AssistantContent } from "./ChapterAssistant";
 import { Editor, type EditorSelection } from "./Editor";
 import { RefinePanel } from "./RefinePanel";
+import { ContinuePanel } from "./ContinuePanel";
 
 interface WorkbenchProps {
   project: ProjectResponse;
@@ -71,6 +73,7 @@ export function Workbench({
   // 选区级 AI 动作（润色/再沟通）：编辑器上报的最新选区 + 结果卡开合。
   const [selection, setSelection] = useState<EditorSelection | null>(null);
   const [refineOpen, setRefineOpen] = useState(false);
+  const [continueOpen, setContinueOpen] = useState(false);
   const toast = useToast();
   const autosave = useAutosave(project.id, chapterNo, initialText);
   const stream = useDraftStream();
@@ -131,6 +134,28 @@ export function Workbench({
     setSelection(null);
   };
 
+  // 打开润色/续写互斥，避免两张结果卡同时占位。
+  const openRefine = (): void => {
+    setContinueOpen(false);
+    setRefineOpen(true);
+  };
+
+  // 续写前先 flush 自动保存，确保 continue 读到的是最新草稿（with_prior_chapter 读库）。
+  const openContinue = (): void => {
+    autosave.flush();
+    setRefineOpen(false);
+    setContinueOpen(true);
+  };
+
+  // 插入续写候选：追加到章末（续写语义），落回草稿。
+  const onInsertContinuation = (candidate: string): void => {
+    const base = text.trimEnd();
+    const next = base.length > 0 ? `${base}\n\n${candidate}` : candidate;
+    setText(next);
+    autosave.onChange(next);
+    setContinueOpen(false);
+  };
+
   // 字数统计非空白字符（与中文读者直觉一致：标点/空格不计入正文体量）。
   const wordCount = text.replace(/\s+/g, "").length;
   const closePanel = (): void => setMobilePanel(null);
@@ -189,6 +214,14 @@ export function Workbench({
               onClose={() => setRefineOpen(false)}
             />
           ) : null}
+          {continueOpen ? (
+            <ContinuePanel
+              projectId={project.id}
+              chapterNo={chapterNo}
+              onInsert={onInsertContinuation}
+              onClose={() => setContinueOpen(false)}
+            />
+          ) : null}
           <div className="flex-1 overflow-auto px-6 py-8">
             <Editor
               value={text}
@@ -209,7 +242,8 @@ export function Workbench({
             onWrite={onWrite}
             onStop={stream.stop}
             canRefine={canRefine}
-            onRefineSelection={() => setRefineOpen(true)}
+            onRefineSelection={openRefine}
+            onContinue={openContinue}
           />
         </section>
 
@@ -400,6 +434,8 @@ interface ToolbarProps {
   // 选区级润色：有非空选区时可用；点击打开润色/再沟通结果卡。
   canRefine: boolean;
   onRefineSelection: () => void;
+  // 续写：读本章前文续写候选。
+  onContinue: () => void;
 }
 
 function Toolbar({
@@ -415,6 +451,7 @@ function Toolbar({
   onStop,
   canRefine,
   onRefineSelection,
+  onContinue,
 }: ToolbarProps) {
   return (
     <div className="sticky bottom-0 z-10 border-t border-line bg-panel/95 px-4 py-2 backdrop-blur sm:px-6 sm:py-3">
@@ -433,6 +470,11 @@ function Toolbar({
           </Button>
         )}
         {!streaming ? (
+          <>
+            <Button onClick={onContinue} variant="secondary" size="sm">
+              <WrapText className="h-4 w-4" aria-hidden="true" />
+              续写
+            </Button>
             <Button
               onClick={onRefineSelection}
               disabled={!canRefine}
@@ -443,6 +485,7 @@ function Toolbar({
               <Wand2 className="h-4 w-4" aria-hidden="true" />
               润色选段
             </Button>
+          </>
         ) : null}
         {streaming ? (
           // ThinkingIndicator 自带 role=status，开始时播报一次「生成中」；

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

@@ -0,0 +1,106 @@
+// @vitest-environment jsdom
+import { act, renderHook } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { useContinue } from "./useContinue";
+
+const post = vi.fn();
+const toast = vi.fn();
+vi.mock("@/lib/api/client", () => ({
+  api: { POST: (...a: unknown[]) => post(...a) },
+}));
+vi.mock("@/components/Toast", () => ({ useToast: () => toast }));
+
+const GEN_PATH = "/projects/{project_id}/skills/{tool_key}/generate";
+
+describe("useContinue", () => {
+  beforeEach(() => {
+    post.mockReset();
+    toast.mockReset();
+  });
+  afterEach(() => vi.clearAllMocks());
+
+  it("初始为 idle，无候选", () => {
+    const { result } = renderHook(() => useContinue());
+    expect(result.current.status).toBe("idle");
+    expect(result.current.candidates).toEqual([]);
+  });
+
+  it("续写：调 continue 生成器（读该章前文），产出一条候选，status=ready", async () => {
+    post.mockResolvedValue({
+      data: { output_kind: "ContinuationResult", preview: { text: "续写正文一" } },
+      error: null,
+    });
+
+    const { result } = renderHook(() => useContinue());
+    await act(async () => {
+      await result.current.generate("p1", 3);
+    });
+
+    expect(post).toHaveBeenCalledWith(GEN_PATH, {
+      params: { path: { project_id: "p1", tool_key: "continue" } },
+      body: { brief: "", chapter_no: 3 },
+    });
+    expect(result.current.status).toBe("ready");
+    expect(result.current.candidates).toEqual(["续写正文一"]);
+  });
+
+  it("多候选：再次生成累加候选，不覆盖前一条", async () => {
+    post
+      .mockResolvedValueOnce({ data: { preview: { text: "候选一" } }, error: null })
+      .mockResolvedValueOnce({ data: { preview: { text: "候选二" } }, error: null });
+
+    const { result } = renderHook(() => useContinue());
+    await act(async () => {
+      await result.current.generate("p1", 1);
+    });
+    await act(async () => {
+      await result.current.generate("p1", 1);
+    });
+
+    expect(result.current.candidates).toEqual(["候选一", "候选二"]);
+  });
+
+  it("产出为空：不加候选、提示重试、status=ready", async () => {
+    post.mockResolvedValue({ data: { preview: { text: "" } }, error: null });
+    const { result } = renderHook(() => useContinue());
+    await act(async () => {
+      await result.current.generate("p1", 1);
+    });
+    expect(result.current.candidates).toEqual([]);
+    expect(result.current.status).toBe("ready");
+    expect(toast).toHaveBeenCalledWith(expect.any(String), "info");
+  });
+
+  it("后端返回 error：status=error、弹错误 toast、候选不变", async () => {
+    post.mockResolvedValue({ data: null, error: { detail: "配额不足" } });
+    const { result } = renderHook(() => useContinue());
+    await act(async () => {
+      await result.current.generate("p1", 1);
+    });
+    expect(result.current.status).toBe("error");
+    expect(result.current.candidates).toEqual([]);
+    expect(toast).toHaveBeenCalledWith(expect.any(String), "error");
+  });
+
+  it("请求抛异常：status=error、弹网络异常 toast", async () => {
+    post.mockRejectedValue(new Error("network down"));
+    const { result } = renderHook(() => useContinue());
+    await act(async () => {
+      await result.current.generate("p1", 1);
+    });
+    expect(result.current.status).toBe("error");
+    expect(toast).toHaveBeenCalledWith("续写请求异常，请检查网络。", "error");
+  });
+
+  it("reset 清回 idle 与空候选", async () => {
+    post.mockResolvedValue({ data: { preview: { text: "候选" } }, error: null });
+    const { result } = renderHook(() => useContinue());
+    await act(async () => {
+      await result.current.generate("p1", 1);
+    });
+    act(() => result.current.reset());
+    expect(result.current.status).toBe("idle");
+    expect(result.current.candidates).toEqual([]);
+  });
+});

apps/web/lib/workbench/useContinue.ts

@@ -0,0 +1,72 @@
+"use client";
+
+import { useCallback, useState } from "react";
+
+import { api } from "@/lib/api/client";
+import { useToast } from "@/components/Toast";
+import { generationErrorMessage } from "@/lib/generation/cards";
+
+// 编辑器「续写」：复用 continue 生成器（with_prior_chapter，自动读该章已写正文承接），
+// 每次生成一条候选并累加成多候选，作者点选某条插入正文（HITL，不静默写入）。
+export type ContinueStatus = "idle" | "generating" | "ready" | "error";
+
+export interface UseContinue {
+  status: ContinueStatus;
+  candidates: string[];
+  // 生成一条续写候选（累加，不覆盖）；chapterNo 指定承接哪一章。
+  generate: (projectId: string, chapterNo: number) => Promise<void>;
+  reset: () => void;
+}
+
+function extractText(preview: unknown): string {
+  if (preview && typeof preview === "object" && "text" in preview) {
+    const text = (preview as { text: unknown }).text;
+    return typeof text === "string" ? text : "";
+  }
+  return "";
+}
+
+export function useContinue(): UseContinue {
+  const [status, setStatus] = useState<ContinueStatus>("idle");
+  const [candidates, setCandidates] = useState<string[]>([]);
+  const toast = useToast();
+
+  const generate = useCallback<UseContinue["generate"]>(
+    async (projectId, chapterNo) => {
+      setStatus("generating");
+      try {
+        const { data, error } = await api.POST(
+          "/projects/{project_id}/skills/{tool_key}/generate",
+          {
+            params: { path: { project_id: projectId, tool_key: "continue" } },
+            body: { brief: "", chapter_no: chapterNo },
+          },
+        );
+        if (error || !data) {
+          setStatus("error");
+          toast(generationErrorMessage(error), "error");
+          return;
+        }
+        const text = extractText(data.preview).trim();
+        if (text.length === 0) {
+          setStatus("ready");
+          toast("本次未生成有效续写，请再试一次。", "info");
+          return;
+        }
+        setCandidates((prev) => [...prev, text]);
+        setStatus("ready");
+      } catch {
+        setStatus("error");
+        toast("续写请求异常，请检查网络。", "error");
+      }
+    },
+    [toast],
+  );
+
+  const reset = useCallback((): void => {
+    setStatus("idle");
+    setCandidates([]);
+  }, []);
+
+  return { status, candidates, generate, reset };
+}