feat(frontend): 写作工作台补齐三项——内容感知书名 / 上下文速查抽屉 / genre采集

写作工作台重构剩余 3 项（多 agent 并行构建各自新文件，主线统一集成）：

- WFW-5 内容感知书名（#6）：buildManuscriptExcerpt 取正文首尾摘录（硬上界控 token）；
  GeneratorRunner 加 manuscriptText，有 brief 字段时出现「用当前正文」按钮把摘录填入
  brief，让 book-title 等据正文反推。纯前端零后端；HITL——只填表单，生成仍需作者触发。
- WFW-6 上下文速查抽屉（#7）：ContextDrawer 视口无关右侧 slide-over，设定库/大纲完整
  只读速查 + 伏笔/规则/文风摘要跳链；底栏「速查」按钮触发。加法式、CONTEXT_DRAWER_ENABLED
  一键回滚、旧侧栏/全宽页路由全保留。
- WFW-7 genre 采集 + 无大纲降级：项目无题材时首次写章前弹 GenrePicker 采集（临时并入
  本次 directive 不落库）；chapters 为空时编辑器显式提示「尚无大纲，将按设定自由生成」。

各项 TDD：manuscriptExcerpt/useGenreGate/contextDrawer/useContextDrawer 共 32 新单测。
门禁全绿：vitest 629 / tsc / lint / build / coverage 95.43%。

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

@@ -0,0 +1,112 @@
+import { describe, expect, it } from "vitest";
+
+import type { OutlineChapterView, WorldEntityCardView } from "@/lib/api/types";
+import {
+  CONTEXT_TABS,
+  contextTabHref,
+  toCodexGroups,
+  toOutlineRows,
+} from "./contextDrawer";
+
+const entity = (
+  type: string,
+  name: string,
+  rules: string[] = [],
+): WorldEntityCardView => ({ type, name, rules });
+
+describe("contextTabHref", () => {
+  it("按 Tab key 拼出完整编辑页路由", () => {
+    // Arrange / Act / Assert
+    expect(contextTabHref("p1", "codex")).toBe("/projects/p1/codex");
+    expect(contextTabHref("p1", "foreshadow")).toBe("/projects/p1/foreshadow");
+    expect(contextTabHref("p1", "style")).toBe("/projects/p1/style");
+  });
+
+  it("五个 Tab 覆盖全部读为主入口", () => {
+    expect(CONTEXT_TABS.map((t) => t.key)).toEqual([
+      "codex",
+      "outline",
+      "foreshadow",
+      "rules",
+      "style",
+    ]);
+  });
+});
+
+describe("toCodexGroups", () => {
+  it("空列表返回空分组", () => {
+    expect(toCodexGroups([])).toEqual([]);
+  });
+
+  it("按 type 归组并保持首次出现顺序", () => {
+    const entities = [
+      entity("势力", "雾港议会"),
+      entity("地理", "北境"),
+      entity("势力", "红手会"),
+    ];
+
+    const groups = toCodexGroups(entities);
+
+    expect(groups.map((g) => g.type)).toEqual(["势力", "地理"]);
+    expect(groups[0]?.entities.map((e) => e.name)).toEqual([
+      "雾港议会",
+      "红手会",
+    ]);
+    expect(groups[1]?.entities.map((e) => e.name)).toEqual(["北境"]);
+  });
+
+  it("空白/缺省 type 归入「未分类」", () => {
+    const groups = toCodexGroups([entity("  ", "无名之物")]);
+    expect(groups[0]?.type).toBe("未分类");
+  });
+
+  it("不修改入参数组", () => {
+    const entities = [entity("势力", "甲"), entity("势力", "乙")];
+    const snapshot = [...entities];
+    toCodexGroups(entities);
+    expect(entities).toEqual(snapshot);
+  });
+});
+
+describe("toOutlineRows", () => {
+  const chapter = (
+    no: number,
+    volume: number,
+    beats: string[],
+    codes: string[] = [],
+  ): OutlineChapterView => ({
+    no,
+    volume,
+    beats,
+    foreshadow_windows: codes.map((code) => ({ code })),
+  });
+
+  it("空列表返回空数组", () => {
+    expect(toOutlineRows([])).toEqual([]);
+  });
+
+  it("按章号升序整形并抽出节拍与伏笔代号", () => {
+    const rows = toOutlineRows([
+      chapter(2, 1, ["决战"], ["F2"]),
+      chapter(1, 1, ["开场", "引入"], ["F1"]),
+    ]);
+
+    expect(rows.map((r) => r.no)).toEqual([1, 2]);
+    expect(rows[0]?.beats).toEqual(["开场", "引入"]);
+    expect(rows[0]?.foreshadowCodes).toEqual(["F1"]);
+    expect(rows[1]?.foreshadowCodes).toEqual(["F2"]);
+  });
+
+  it("缺省 beats / foreshadow_windows 回退为空数组", () => {
+    const rows = toOutlineRows([{ no: 1, volume: 1 }]);
+    expect(rows[0]?.beats).toEqual([]);
+    expect(rows[0]?.foreshadowCodes).toEqual([]);
+  });
+
+  it("不修改入参数组", () => {
+    const chapters = [chapter(2, 1, []), chapter(1, 1, [])];
+    const snapshot = chapters.map((c) => c.no);
+    toOutlineRows(chapters);
+    expect(chapters.map((c) => c.no)).toEqual(snapshot);
+  });
+});