带书眉检字的中文字典页

// ═══ Postext Cookbook · Nº 086 · A Chinese dictionary page with guide words ═════════
// https://postext.dev/en/cookbook/chinese-dictionary-page
// Code: MIT · Text: 康熙字典 (1716), Wikisource transcription, CC BY-SA 4.0 · Pinyin: CC BY 4.0
// Fonts: Noto Serif TC, Noto Sans TC, LXGW WenKai TC (SIL OFL 1.1) · Needs postext ≥ 1.9.0
import { buildDocument, renderPageToCanvas, clearMeasurementCache } from 'https://esm.sh/postext';
import { renderToPdf, decompressWoff2 } from 'https://esm.sh/postext-pdf';

const LANG = 'en'; // @lang: the language of the sample document ('en' | 'es')
const RECIPE = 'chinese-dictionary-page';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: black and one cinnabar, the second ink of a two-colour dictionary
const palette = {
  ink: '#1f1b17', // text, guide words
  cinnabar: '#a52f28', // headwords, their readings, sense numbers, the thumb tab
  rule: '#bab2a4', // the column rule
  muted: '#5c554d', // folios, colophon
  paper: '#fbf8f2', // the page, and the letter reversed out of the tab
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
// The engine's defaults link to 'main-color': point it at the cinnabar.
const colorPalette = Object.entries({ ...palette, 'main-color': palette.cinnabar })
  .map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } }));
// #endregion
const [SONG, HEI, KAI] = ['Noto Serif TC', 'Noto Sans TC', 'LXGW WenKai TC'];
const PT = 25.4 / 72; // mm in a point
const [BODY, LEAD] = [9, 15]; // pt: 小五 on a 15 pt line, the grid both columns share
const [CHARS, LINES] = [17, 31]; // characters to a column's line, lines to a column
const TRIM = { width: 140, height: 203 }; // mm: 大32开
const MIN = { top: 20, bottom: 16, side: 12 }; // mm: minimums the grid grows to centre the area
// The type area the grid sets (two columns and a 2-em gutter) and the margins it leaves.
const AREA = { width: (2 * CHARS + 2) * BODY * PT, height: LINES * LEAD * PT }; // 114.3 × 164
const SIDE = (TRIM.width - AREA.width) / 2; // 12.85 mm
const TOP = MIN.top + (TRIM.height - MIN.top - MIN.bottom - AREA.height) / 2; // 21.5 mm

// #region answer: the first and the last headword of each page in its running head
// Each headword is a level-2 heading, '## {天|tiān}'. {firstMark.h2} prints the text of the
// first one that starts on the page, without its reading, and {lastMark.h2} the last; a
// page on which none starts repeats the one in force. They stand at the outer corner, the
// folio outside them, over a hairline as wide as the type area.
const HEAD_Y = 11; // mm from the top edge to the top of the guide words
const [GUIDE, FOLIO] = [10.5, 8]; // pt
const head = (id, content, parity, x, size, extra) => ({ kind: 'text', id, content, parity,
  fontFamily: HEI, fontWeight: 700, fontSize: pt(size), lineHeight: 1, color: col('ink'),
  // A design line puts its baseline 0.8 of its height down: the folio drops to share it.
  placement: { anchor: { to: 'page', edge: parity === 'even' ? 'top-left' : 'top-right' },
    offset: { x: mm(parity === 'even' ? x : -x), y: mm(HEAD_Y + 0.8 * (GUIDE - size) * PT) } },
  ...extra });
const folio = { color: col('muted') };
const guideWords = [
  head('verso-folio', '{pageNumber}', 'even', SIDE, FOLIO, folio),
  head('verso-guide', '{firstMark.h2}—{lastMark.h2}', 'even', SIDE + 8, GUIDE),
  head('recto-guide', '{firstMark.h2}—{lastMark.h2}', 'odd', SIDE + 8, GUIDE),
  head('recto-folio', '{pageNumber}', 'odd', SIDE, FOLIO, folio),
  { kind: 'rule', id: 'hairline', direction: 'horizontal', thickness: pt(0.5), color: col('ink'),
    placement: { anchor: { to: 'page', edge: 'top-left' },
      offset: { x: mm(SIDE), y: mm(HEAD_Y + 5.5) }, size: { width: mm(AREA.width) } } },
];
// #endregion

// #region tab: the initial T on the fore-edge, 19th of the 23 that start a pinyin syllable
const INITIALS = 'ABCDEFGHJKLMNOPQRSTWXYZ'; // no pinyin syllable starts with I, U or V
const STEP = AREA.height / INITIALS.length; // mm: 7.13, the 23 tabs fill the type area's height
const tab = (parity) => {
  const edge = parity === 'odd' ? 'top-right' : 'top-left'; // the fore-edge
  const at = (x, width) => ({ anchor: { to: 'page', edge },
    offset: { x: mm(parity === 'odd' ? x : -x), y: mm(TOP + INITIALS.indexOf('T') * STEP + 0.3) },
    size: { width: mm(width), height: mm(STEP - 0.6) } });
  // 6 mm inside the trim and 3 mm past it: the page cuts the tab square at the fore-edge
  // (a print file with cutLines prints the 3 mm in its bleed); the letter on the 6 mm.
  return [
    { kind: 'box', id: `tab-${parity}`, parity, placement: at(3, 9),
      style: { backgroundColor: col('cinnabar'), borderRadius: mm(1.2) } },
    { kind: 'text', id: `tab-letter-${parity}`, parity, content: 'T', fontFamily: HEI,
      fontWeight: 700, fontSize: pt(9), lineHeight: 1, color: col('paper'), align: 'center',
      verticalAlign: 'middle', placement: at(0, 6) },
  ];
};
// #endregion

// #region headwords: 15 pt Song Black in cinnabar, the pinyin over it in the line gap
// A heading with no design of its own keeps its reading: '## {天|tiān}' sets tiān over 天.
// Two grid lines hold the headword and a 7.5 pt reading, so every entry stays on the grid.
// A Latin reading stands clear of its base by its descenders: the g of tīng stays off 汀.
const cjk = {
  grid: { enabled: true, charsPerLine: CHARS, linesPerPage: LINES },
  // The regular Song, not the heading's Black: a reading takes the face of its base.
  ruby: { fontFamily: SONG, fontSize: em(0.5), color: col('cinnabar') },
};
const headword = { level: 2, fontSize: pt(15), lineHeight: pt(2 * LEAD), marginTop: pt(0),
  marginBottom: pt(0) };
// #endregion

// #region senses: one paragraph to an entry, the sense numbers ① ② in cinnabar
// As the Kangxi Dictionary sets an entry: the rhyme-book readings (反切), then the senses
// run in, each after its number. '**②**' marks a number, and the text prints its bold in
// cinnabar: the only bold on these pages. A word joiner (U+2060, invisible) follows each
// number in the Markdown: no line ends on a number, away from the sense it opens.
const bodyText = { fontFamily: SONG, fontSize: pt(BODY), lineHeight: pt(LEAD), color: col('ink'),
  boldColor: col('cinnabar'), italicColor: col('ink'), referenceColor: col('ink'),
  textAlign: 'justify', firstLineIndent: pt(0) }; // no indent: the headword opens the entry
// #endregion
// The colophon: a sentence of Chinese in the Kai, then the credits in the Song's Latin letters.
const colophon = { fontSize: pt(7.5), lineHeight: pt(11), color: col('muted'),
  firstLineIndent: pt(0), textAlign: 'left' };
const paragraphStyles = [
  { id: 'colophon-zh', ...colophon, fontFamily: KAI, marginTop: pt(LEAD) },
  { id: 'colophon', ...colophon, fontFamily: SONG, marginTop: pt(3) },
];

const config = () => ({ // a factory: the engine caches resolved configs per object
  // Taiwan's rules: full-width punctuation, centred in Noto Serif TC, and the basic
  // line breaking. Written out, never LANG (gotcha: cjk-locale-tag).
  locale: 'zh-Hant',
  colorPalette,
  page: { width: mm(TRIM.width), height: mm(TRIM.height), dpi: 150,
    backgroundColor: col('paper'),
    margins: { top: mm(MIN.top), bottom: mm(MIN.bottom), left: mm(MIN.side),
      right: mm(MIN.side), mirror: true } },
  layout: { layoutType: 'double', gutterWidth: pt(2 * BODY),
    columnRule: { enabled: true, color: col('rule'), lineWidth: pt(0.4) } },
  cjk,
  bodyText,
  headings: { fontFamily: SONG, fontWeight: 900, color: col('cinnabar'), textAlign: 'left',
    // Every entry follows the one before with no line between them. Column balancing would
    // open lines above some headwords to bring a short column down to the foot; off, a column
    // that cannot take the next headword and two lines of its text ends short instead.
    balancing: { enabled: false },
    levels: [
      // No letter opens in these pages; restated all the same, since any headings object
      // drops the H1 break (gotcha: headings-drop-h1-break).
      { level: 1, breakBefore: { enabled: true, parity: 'any' } },
      headword,
    ] },
  paragraphStyles,
  header: { elements: [...guideWords, ...tab('even'), ...tab('odd')] },
  footer: { elements: [] },
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Markdown样例 · 130行 · content.en.md
title: "康熙字典選讀"
---

## {天|tiān}

《唐韻》《正韻》他前切，《集韻》《韻會》他年切。**①**⁠《說文》顛也。至高在上，从一大也。《易·說卦》乾為天。**②**⁠星名。《爾雅·釋天》天根，氐也。**③**⁠地名。《蜀地志》蜀邛僰山後四野，無晴日，曰漏天。《杜甫詩》地近漏天終歲雨。**④**⁠姓。漢長社令天高，見《姓苑》。

## {添|tiān}

《唐韻》《集韻》《韻會》《正韻》並他兼切，音沾。**①**⁠《玉篇》益也。**②**⁠《集韻》他念切，味益也。**③**⁠《李翊俗名小錄》呼下酒具為添。

## {田|tián}

《唐韻》待年切，《集韻》《韻會》《正韻》亭年切，並音闐。**①**⁠《說文》陳也。樹穀曰田，象四口。十，阡陌之制也。《正韻》土已耕曰田。《易·乾卦》見龍在田。**②**⁠獵也，與畋、佃通。《易·恆卦》田无禽。《詩·鄭風》叔于田。**③**⁠姓。《五音集韻》出北平，敬仲自陳適齊，後改田氏。《史記·田敬仲完世家註》敬仲奔齊，以陳田二字聲相近，遂為田氏。**④**⁠鼓名。《詩·周頌》應田縣鼓。《傳》田，大鼓也。**⑤**⁠蓮葉貌。《江南曲》江南可採蓮，蓮葉何田田。

## {恬|tián}

《唐韻》《集韻》《韻會》《正韻》並徒兼切，音甜。**①**⁠《說文》安也。从心，甜省聲。《書·梓材》引養引恬。**②**⁠靜也。《莊子·繕性篇》以恬養志。

## {填|tián}

《廣韻》徒年切，《集韻》《韻會》《正韻》亭年切，並音田。**①**⁠《說文》塞也。《博物志》炎帝女溺死東海中，化為鳥，曰精衛，常取西山之木石，以填東海。**②**⁠鼓聲。《孟子》填然鼓之。

## {闐|tián}

《唐韻》待年切，《集韻》《韻會》《正韻》亭年切，並音田。**①**⁠《說文》盛也。**②**⁠《博雅》闐闐，聲也。《詩·小雅》振旅闐闐。《左思·蜀都賦》車馬雷駭，轟轟闐闐。**③**⁠《增韻》滿也。《史記·汲鄭傳》始翟公為廷尉，賓客闐門。

## {忝|tiǎn}

《唐韻》《集韻》《韻會》《正韻》並他點切。**①**⁠《說文》辱也。《詩·小雅》無忝爾所生。

## {殄|tiǎn}

《唐韻》《集韻》《韻會》《正韻》並徒典切，填上聲。**①**⁠《說文》盡也。一曰絕也。《書·畢命》商俗靡靡，餘風未殄。**②**⁠與腆同。《儀禮·燕禮》寡君有不腆之酒。《鄭註》古文腆皆作殄。

## {腆|tiǎn}

《唐韻》《集韻》《韻會》《正韻》並他典切。**①**⁠《說文》設膳腆腆多也。《玉篇》厚也。《書·酒誥》自洗腆致用酒。《註》洗以致其潔，腆以致其厚。**②**⁠《廣韻》善也。《禮·郊特牲》幣必誠，辭無不腆。

## {佻|tiāo}

《廣韻》徒聊切，《集韻》《韻會》《正韻》田聊切，並音條。**①**⁠《爾雅·釋言》佻，偷也。《屈原·離騷》余猶惡其佻巧。**②**⁠行不耐勞苦貌。《詩·小雅》佻佻公子，行彼周行。**③**⁠竊取名。《周語》佻天以為己力。

## {挑|tiāo}

《唐韻》吐彫切，《集韻》《韻會》《正韻》他彫切，並音祧。**①**⁠《說文》撓也。**②**⁠《增韻》杖荷也。俗謂肩荷曰挑。**③**⁠取也。今揀選人物亦謂之挑。

## {迢|tiáo}

《唐韻》徒聊切，《集韻》《韻會》《正韻》田聊切，並音條。**①**⁠《說文》迢遰也。《正字通》遠不相通也。**②**⁠《集韻》迢迢，高貌。

## {條|tiáo}

《廣韻》徒聊切，《集韻》《韻會》田聊切，並音迢。**①**⁠《說文》小枝也。《詩·周南》伐其條枚。《傳》枝曰條，榦曰枚。**②**⁠條理也。《書·盤庚》若網在綱，有條而不紊。**③**⁠條例。顏師古曰：凡言條者，一一而疏舉之，若木條焉。**④**⁠八風之一。《易緯通卦驗》東北曰條風。

## {蜩|tiáo}

《唐韻》徒聊切，《集韻》《韻會》《正韻》田聊切，並音迢。**①**⁠《玉篇》蟬也。《詩·豳風》五月鳴蜩。《傳》蜩，蟬也。螗，蝘也。**②**⁠蜩甲，蟬蛻也。《莊子·寓言篇》予蜩甲也。

## {調|tiáo}

《唐韻》徒遼切，《集韻》《韻會》《正韻》田聊切，並音迢。**①**⁠《說文》和也。《詩·小雅》弓矢既調。《禮·月令》仲夏調竽笙竾簧。**②**⁠《韻會》揉伏也。《史記·秦本紀》大費佐舜調馴鳥獸。**③**⁠《正字通》嘲笑也。《世說》王丞相每調之。

## {髫|tiáo}

《唐韻》徒聊切，《集韻》《韻會》《正韻》田聊切，並音迢。**①**⁠《說文》小兒垂結也。《後漢·伏湛傳》髫髮厲志。《註》髫髮謂童子垂髮也。《干祿字書》俗作齠。

## {挑|tiǎo}

《唐韻》《集韻》《韻會》並徒了切，音窕。**①**⁠引也，撥也。《史記·項羽紀》願與漢王挑戰，決雌雄。《前漢·司馬相如傳》相如以琴心挑之。《註》寄心於琴聲，以挑動之也。**②**⁠亦與誂通。誘也，戲也。

## {窕|tiǎo}

《唐韻》《韻會》《正韻》並徒了切，掉上聲。**①**⁠深極也，閒也。《詩·周南》窈窕淑女。《傳》窈窕，幽閒也。**②**⁠山水深亦曰窈窕。《杜甫詩》煙生窈窕溪。**③**⁠細也。《左傳·昭二十一年》小者不窕。

## {眺|tiào}

《唐韻》《集韻》《韻會》《正韻》並他弔切，音糶。**①**⁠《說文》目不正也。《潘岳·射雉賦》邪眺旁剔。《註》視瞻不正，常驚惕也。**②**⁠《玉篇》眺望也。《類篇》遠視也。《禮·月令》可以遠眺望。

## {跳|tiào}

《廣韻》徒聊切，《集韻》《韻會》《正韻》田聊切，並音迢。**①**⁠《說文》蹶也。一曰躍也。《莊子·逍遙遊》東西跳梁。《史記·司馬相如傳》馳波跳沫。**②**⁠《集韻》徒刀切，音陶。與逃通。《前漢·高帝紀》漢王跳。《註》謂走也。

## {糶|tiào}

《廣韻》《集韻》《韻會》《正韻》並他弔切，音眺。**①**⁠《說文》出穀也。《史記·貨殖傳》糶二十病農，九十病末。**②**⁠《集韻》徒弔切，音調。姓也。晉有糶裁。

## {帖|tiē}

《唐韻》他叶切，《集韻》《韻會》託協切，《正韻》他協切，並音貼。**①**⁠《廣雅》服也。**②**⁠《增韻》妥帖，定也。《王逸·楚辭序》義多乖異，事不妥帖。《陸機·文賦》或妥帖而易施。

## {貼|tiē}

《廣韻》《正韻》他協切，《集韻》《韻會》托協切，並音帖。**①**⁠《說文》以物為質也。**②**⁠《增韻》裨也，依附也，黏置也。

## {鐵|tiě}

〔古文〕銕《唐韻》天結切，《集韻》《韻會》《正韻》他結切，並天入聲。**①**⁠《說文》黑金也。《書·禹貢》厥貢璆鐵銀鏤砮磬。《史記·貨殖傳》邯鄲郭縱以冶鐵成業。**②**⁠《禮·月令》孟冬駕鐵驪。《註》鐵驪，色如鐵。**③**⁠姓。《正字通》宋鐵南仲，明鐵鉉。

## {餮|tiè}

《廣韻》《集韻》《韻會》《正韻》並他結切，音鐵。**①**⁠《玉篇》貪食也。《左傳·文十八年》縉雲氏有不才子，貪於飲食，冒於貨賄，天下謂之饕餮。《註》貪財為饕，貪食為餮。

## {汀|tīng}

《唐韻》他丁切，《集韻》《韻會》湯丁切，《正韻》他經切。**①**⁠《說文》平也。謂水際平地。《謝靈運詩》汀曲舟已隱。**②**⁠洲渚。《楚辭·九歌》搴汀洲兮杜若。

## {聽|tīng}

《廣韻》《集韻》《韻會》《正韻》並他定切，音侹。**①**⁠《說文》聆也。《書·太甲》聽德惟聰。**②**⁠《廣韻》待也。**③**⁠從也。《左傳·昭二十六年》姑慈婦聽。**④**⁠斷也。《禮·王制》司寇正刑明辟，以聽獄訟。

## {廳|tīng}

《廣韻》他丁切，《集韻》湯丁切，《正韻》他經切，並音汀。**①**⁠《廣韻》屋也。**②**⁠《集韻》古者治官處，謂之聽事。《增韻》漢晉皆作聽，六朝以來，乃始加广。

## {亭|tíng}

《唐韻》特丁切，《集韻》《韻會》《正韻》唐丁切，並音庭。**①**⁠《說文》民所安定也。《釋名》停也。道路所舍，人停集也。**②**⁠亭長。《後漢·百官志》十里一亭，十亭一鄉。**③**⁠平也，均也。《前漢·酷吏傳》張湯平亭疑法。**④**⁠亭亭，聳立貌。《黃庭經》九原之山何亭亭。

## {庭|tíng}

《唐韻》特丁切，《集韻》《韻會》《正韻》唐丁切，並音亭。**①**⁠《說文》宮中也。《玉篇》堂階前也。《易·節卦》不出戶庭，无咎。**②**⁠《爾雅·釋詁》直也。《詩·小雅》播厥百穀，既庭且碩。**③**⁠洞庭，湖名。《楚辭·九歌》洞庭波兮木葉下。

:::paragraphs{style="colophon-zh"}
據維基文庫本《康熙字典》選錄三十條，依漢語拼音排序，拼音與義項編號為編者所加。
:::

:::paragraphs{style="colophon"}
Entries from the Kangxi Dictionary (1716) in the Wikisource transcription (CC BY-SA 4.0); pinyin readings and sense numbers added by the editors. Set in Noto Serif TC, Noto Sans TC and LXGW WenKai TC (SIL OFL).
:::
`; // content.<lang>.md, inlined by the Cookbook

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = { // every face the pages use, loaded before the build (gotcha: fonts-first)
  'Noto Serif TC': ['400', '700', '900'], // SONG: the entries, readings, credits; the headwords
  'Noto Sans TC': ['700'], // HEI: guide words, folios, the tab
  'LXGW WenKai TC': ['400'], // KAI: the colophon's sentence of Chinese
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
// #region voices: each face loads the files of the characters it sets
// Fontsource cuts a Chinese face into about a hundred files (gotcha: cjk-fonts-slices).
// The regular Song sets the whole sample; each other voice gets only its own text.
const all = (re) => [...markdown.matchAll(re)].map((m) => m[1]).join('');
const heads = all(/^## \{(.+?)\|/gm);
await loadFonts(FONTS, markdown);
await loadCjkFonts({ [SONG]: ['400'] }, markdown);
await loadCjkFonts({ [SONG]: ['700'] }, all(/\*\*(.+?)\*\*/g));
await loadCjkFonts({ [SONG]: ['900'] }, heads);
await loadCjkFonts({ [HEI]: ['700'] }, `${heads}—0123456789T`);
await loadCjkFonts({ [KAI]: ['400'] }, all(/style="colophon-zh"\}\n(.+)\n/g));
// #endregion
// Pages 634 to 637 of the dictionary: page 1 is a verso, so the four lie as two spreads.
const continuation = { pageIndexOffset: 633, pageNumbering: { startAt: 634 } };
const doc = await buildWithFonts(
  () => buildDocument({ markdown, continuation }, config()), markdown);
showPages(doc, { title: t({ en: 'A Chinese dictionary page',
  es: 'Una página de diccionario chino' }) });
offerPdf(() => renderToPdf(doc, { fontProvider: cjkPdfProvider }), `${RECIPE}.pdf`);

工具包 · core, fonts, viewer, pdf, cjk：每道食谱都相同 · 422行
// ─── Kit ── helpers shared by every Cookbook recipe · postext.dev/cookbook ─────

// ─── Kit · core v1 ── the same in every recipe · postext.dev/cookbook ─────────
function mm(value) { return { value, unit: 'mm' }; }
function pt(value) { return { value, unit: 'pt' }; }
function em(value) { return { value, unit: 'em' }; }
/** The sample language's string: t({ en: 'Figure', es: 'Figura' }). */
function t(strings) { return strings[LANG] ?? Object.values(strings)[0]; }
/** A file in this recipe's assets folder, served from the Postext repo by jsDelivr. */
function asset(file) { return `https://cdn.jsdelivr.net/gh/drnachio/postext@main/cookbook/${RECIPE}/assets/${file}`; }

// ─── Kit · fonts v1 ── the same in every recipe · postext.dev/cookbook ────────
// Postext measures text with the faces the browser has loaded, and caches the
// widths, so every face must be ready before the first build. Faces come from
// Fontsource: the same static files the PDF embeds, so screen and PDF agree.

/** faces = { 'Family Name': ['400', '400i', '700'] }. `text` is the sample:
 *  letters beyond Latin-1 (č, ł, ő…) also load the latin-ext files. With
 *  `optional`, a face Fontsource does not ship is skipped instead of failing.
 *  Resolves to the number of faces added. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = {
    latin: 'U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,'
      + 'U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD',
    'latin-ext': 'U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,'
      + 'U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF',
  };
  const subsets = /[Ā-˿Ḁ-ỿ]/.test(text) ? ['latin', 'latin-ext'] : ['latin'];
  const jobs = [];
  let added = 0;
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const meta = optional ? await fontsourceMeta(family) : null;
    for (const spec of new Set(specs)) {
      const weight = parseInt(spec, 10);
      const style = spec.endsWith('i') ? 'italic' : 'normal';
      if (hasFace(family, weight, style)) continue;
      if (optional && !(meta?.weights.includes(weight) && meta.styles.includes(style))) continue;
      for (const subset of subsets) {
        const url = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-${subset}-${weight}-${style}.woff2`;
        const face = new FontFace(family, `url(${url}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: ranges[subset] });
        jobs.push(face.load().then((ready) => { document.fonts.add(ready); added++; }, () => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return added;
}

/** Runs `build` (a buildDocument or buildBundle call) and checks the faces
 *  the pages use. A regular face missing from FONTS is loaded with a warning;
 *  bold and italic variants are loaded when the family ships them. Then the
 *  measurement caches are cleared and the build runs again. */
async function buildWithFonts(build, text = '') {
  const tried = new Set();
  for (let round = 0; round < 3; round++) {
    kitStatus('Laying out…');
    await new Promise(requestAnimationFrame);          // let the status paint first
    const result = await Promise.resolve().then(build).catch((error) => { kitFail(error); throw error; });
    const wanted = { base: {}, variants: {} };
    for (const { font, base } of [result].flat().flatMap(fontStringsOf)) {
      const { family, weight, style } = parseFont(font);
      const key = `${family}|${weight}|${style}`;
      if (tried.has(key) || hasFace(family, weight, style)) continue;
      tried.add(key);
      (wanted[base ? 'base' : 'variants'][family] ??= []).push(`${weight}${style === 'italic' ? 'i' : ''}`);
    }
    if (Object.keys(wanted.base).length) {
      console.warn(`[cookbook] FONTS does not list ${JSON.stringify(wanted.base)}: loading them.`);
    }
    const added = await loadFonts(wanted.base, text) + await loadFonts(wanted.variants, text, { optional: true });
    if (added === 0) return result;
    clearMeasurementCache();
  }
  throw new Error('The fonts did not settle after three builds.');
}

/** Every font string of the layout. `base` marks a block's own face; its
 *  bold, italic and bold-italic variants are listed whether or not used. */
function fontStringsOf(doc) {
  const found = new Map();
  const walk = (node) => {
    if (!node || typeof node !== 'object') return;
    if (Array.isArray(node)) { node.forEach(walk); return; }
    for (const [key, value] of Object.entries(node)) {
      if (typeof value === 'string' && /fontString$/i.test(key)) {
        found.set(value, found.get(value) || key === 'fontString');
      } else if (value && typeof value === 'object') walk(value);
    }
  };
  walk(doc.pages);
  walk(doc.blocks);
  return [...found].map(([font, base]) => ({ font, base }));
}

/** '700 37.5px Open Sans' / 'italic 400 13px "Source Serif 4"' → { family, weight, style }.
 *  A string with no weight ('95.8px Young Serif', from a design text) is 400. */
function parseFont(font) {
  const m = /^(?:(italic|oblique)\s+)?(?:small-caps\s+)?(?:(\d+|bold|normal)\s+)?[\d.]+px\s+(.+)$/.exec(font.trim());
  if (!m) throw new Error(`Unexpected font string: ${font}`);
  const weight = m[2] === 'bold' ? 700 : !m[2] || m[2] === 'normal' ? 400 : Number(m[2]);
  return { family: m[3].replace(/^["']|["']$/g, ''), weight, style: m[1] ? 'italic' : 'normal' };
}

/** True when a loaded FontFace covers exactly this family, weight and style
 *  (document.fonts.check() is also true for families nobody declared). */
function hasFace(family, weight, style) {
  for (const face of document.fonts) {
    if (face.status !== 'loaded' || face.style !== style) continue;
    if (face.family.replace(/^["']|["']$/g, '') !== family) continue;
    const [low, high = low] = face.weight.split(' ').map(Number);
    if (weight >= low && weight <= high) return true;
  }
  return false;
}

/** Fontsource's id for a family: 'Source Serif 4' → 'source-serif-4'. */
function fontsourceId(family) { return family.toLowerCase().replace(/\s+/g, '-'); }

/** The weights and styles a family ships ({ weights: [400, 700], styles: ['normal', 'italic'] }), or null. */
function fontsourceMeta(family) {
  fontsourceMeta.cache ??= new Map();
  const id = fontsourceId(family);
  if (!fontsourceMeta.cache.has(id)) {
    fontsourceMeta.cache.set(id, fetch(`https://api.fontsource.org/v1/fonts/${id}`)
      .then((res) => (res.ok ? res.json() : null), () => null));
  }
  return fontsourceMeta.cache.get(id);
}

// ─── Kit · viewer v1 ── the same in every recipe · postext.dev/cookbook ───────
/** Shows the pages as facing spreads on a dark desk: the first page is a
 *  recto on its own, then verso | recto pairs, as in a bound book. Pages
 *  are painted when they scroll near the screen. */
function showPages(docs, { title, width = 460 } = {}) {
  const root = viewer(title);
  const pages = [docs].flat().flatMap((doc) =>
    doc.pages.map((page) => ({ doc, page, n: (doc.pageIndexOffset ?? 0) + page.index })));
  const spreads = [];
  let verso = null;
  for (const p of pages) {
    if (p.n % 2 === 1) { if (verso) spreads.push([verso, null]); verso = p; }
    else { spreads.push([verso, p]); verso = null; }
  }
  if (verso) spreads.push([verso, null]);
  const density = Math.min(window.devicePixelRatio || 1, 2);
  showPages.painter?.disconnect();
  const painter = new IntersectionObserver((entries) => {
    for (const { isIntersecting, target } of entries) {
      if (!isIntersecting) continue;
      painter.unobserve(target);
      const { doc, page } = target.postext;
      renderPageToCanvas(page, doc, target, { scale: (width * density) / page.width });
    }
  }, { rootMargin: '800px' });
  showPages.painter = painter;
  root.replaceChildren(...spreads.map((pair) => {
    const spread = document.createElement('div');
    spread.className = 'pt-spread';
    for (const p of pair) {
      const figure = document.createElement('figure');
      if (p) {
        const label = p.page.pageLabel || String(p.n + 1);
        const canvas = document.createElement('canvas');
        canvas.postext = p;
        canvas.style.aspectRatio = `${p.page.width} / ${p.page.height}`;
        canvas.setAttribute('role', 'img');
        canvas.setAttribute('aria-label', `Page ${label}`);
        const folio = document.createElement('figcaption');
        folio.textContent = label;
        figure.append(canvas, folio);
        painter.observe(canvas);
      } else figure.className = 'pt-blank';
      spread.append(figure);
    }
    return spread;
  }));
  kitStatus(`${pages.length} ${pages.length === 1 ? 'page' : 'pages'}`);
  document.documentElement.dataset.postext = 'ready';
  return pages.length;
}

/** The desk, the bar and the error reporting, created once. */
function viewer(title) {
  if (!document.getElementById('pt-kit')) {
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit">
      :root { color-scheme: dark; }
      body { margin: 0; background: #0e1014; color: #b9bcc4; font: 13px/1.45 system-ui, sans-serif; }
      #pt-bar { position: sticky; top: 0; z-index: 1; display: flex; flex-wrap: wrap; align-items: center;
        gap: 6px 16px; padding: 10px 16px; background: rgb(14 16 20 / .92); backdrop-filter: blur(6px);
        border-bottom: 1px solid #23262d; }
      #pt-bar strong { color: #f4f1ea; font-weight: 600; }
      #pt-actions { display: flex; gap: 12px; margin-left: auto; }
      #pt-actions a, #pt-actions button { color: #d8a21a; font: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
      #pages { display: grid; justify-items: center; gap: 48px; padding: 32px 16px 72px; }
      .pt-spread { display: flex; }
      .pt-spread figure { margin: 0; width: min(460px, 44vw); }
      .pt-spread canvas { display: block; width: 100%; background: #fff;
        box-shadow: 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figure:first-child canvas { box-shadow: inset -14px 0 14px -14px rgb(0 0 0 / .18), 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figcaption { margin-top: 10px; text-align: center; font: 600 10px/1 system-ui, sans-serif;
        letter-spacing: .18em; text-transform: uppercase; color: #6c7079; }
      .pt-blank { visibility: hidden; }
      @media (max-width: 760px) {
        .pt-spread { flex-direction: column; gap: 32px; }
        .pt-spread figure { width: min(460px, 92vw); }
        .pt-blank { display: none; }
      }
    </style>`);
    document.body.insertAdjacentHTML('afterbegin',
      '<header id="pt-bar"><strong id="pt-title"></strong><span id="pt-status" role="status"></span><span id="pt-actions"></span></header>');
    document.getElementById('pt-title').textContent = document.title || 'Postext';
    addEventListener('error', (event) => kitFail(event.error ?? event.message));
    addEventListener('unhandledrejection', (event) => kitFail(event.reason));
  }
  if (title) document.getElementById('pt-title').textContent = title;
  return document.getElementById('pages')
    ?? document.body.appendChild(Object.assign(document.createElement('main'), { id: 'pages' }));
}

function kitStatus(text) {
  viewer();
  document.getElementById('pt-status').textContent = text;
}

function kitFail(error) {
  document.documentElement.dataset.postext = 'error';
  kitStatus(`Error: ${error?.message ?? error}`);
}

// ─── Kit · pdf v1 ── the same in every recipe that exports a PDF ──────────────
/** postext-pdf embeds TrueType bytes. Fetch the Fontsource file the screen
 *  used, snapping to a weight the family ships and falling back to upright
 *  when it has no italic: the PDF asks for every face a block could use. */
async function fontsourceProvider(family, weight, style) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  const weights = meta?.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && meta && !meta.styles.includes('italic') ? 'normal' : style;
  const res = await fetch(`https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-latin-${w}-${s}.woff2`);
  if (!res.ok) throw new Error(`Fontsource has no ${family} ${w} ${s} (${res.status})`);
  return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
}

/** A "Build the PDF" button in the bar. Once built: "Open the PDF" (a new
 *  tab, since CodePen's preview frame cannot show PDFs) and a download link. */
function offerPdf(makePdf, filename) {
  viewer();
  const button = Object.assign(document.createElement('button'), { type: 'button', textContent: 'Build the PDF' });
  button.dataset.postextPdf = filename;
  button.addEventListener('click', async () => {
    button.disabled = true;
    button.textContent = 'Building the PDF…';
    try {
      const bytes = await makePdf();
      const url = URL.createObjectURL(new Blob([bytes], { type: 'application/pdf' }));
      const size = `${Math.max(1, Math.round(bytes.length / 1024))} KB`;
      button.replaceWith(
        Object.assign(document.createElement('a'), { href: url, target: '_blank', rel: 'noopener', textContent: 'Open the PDF ↗' }),
        Object.assign(document.createElement('a'), { href: url, download: filename, textContent: `Download ${filename} · ${size}` }));
    } catch (error) {
      button.disabled = false;
      button.textContent = 'Build the PDF';
      kitFail(error);
    }
  });
  document.getElementById('pt-actions').append(button);
}

// ─── Kit · cjk v1 ── Chinese, Japanese and Korean books · postext.dev/cookbook ─
// Fontsource ships a CJK family as about a hundred files per weight, each
// declared in its stylesheet with the unicode-range it covers. The screen
// loads the files the sample touches; the PDF gets the same files for the
// characters its pages set in each face, and embeds each as a subset.
// A book bound on the right (vertical text) is shown with its spreads
// mirrored: page 1 alone on the left of the spine, then [3 | 2].

/** The files of a Fontsource face, read from its stylesheet: { url, range,
 *  ranges }, the last declared first (the order the browser tries them in). */
function cjkSlices(family, weight, style) {
  cjkSlices.cache ??= new Map();
  const id = fontsourceId(family);
  const css = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/${weight}${style === 'italic' ? '-italic' : ''}.css`;
  if (!cjkSlices.cache.has(css)) {
    cjkSlices.cache.set(css, fetch(css)
      .then((res) => {
        if (!res.ok) throw new Error(`Fontsource has no ${family} ${weight} ${style} (${res.status})`);
        return res.text();
      })
      .then((text) => [...text.matchAll(/@font-face\s*{([^}]*)}/g)].map(([, rule]) => {
        const range = /unicode-range:\s*([^;]+);/.exec(rule)?.[1].trim() ?? 'U+0-10FFFF';
        const ranges = range.split(',').map((part) => {
          const [lo, hi = lo] = part.trim().slice(2).split('-');
          return [parseInt(lo, 16), parseInt(hi, 16)];
        });
        return { url: new URL(/url\(([^)]+?\.woff2)\)/.exec(rule)[1], css).href, range, ranges };
      }).reverse()));
  }
  return cjkSlices.cache.get(css);
}

/** The file of `slices` that holds code point `cp`, if any. */
function cjkSliceFor(slices, cp) {
  return slices.find((slice) => slice.ranges.some(([lo, hi]) => cp >= lo && cp <= hi));
}

/** Whether Fontsource serves `family` as a Chinese, Japanese or Korean
 *  family (its subsets name the script). Fails when the API does not
 *  answer: a CJK face taken for a Latin one would paint in a system face. */
async function isCjkFamily(family) {
  const meta = await fontsourceMeta(family);
  if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
  return !!meta.subsets?.some((subset) => /^(chinese|japanese|korean)/.test(subset));
}

/** faces = { 'Noto Serif TC': ['400', '700'] }, as for loadFonts: the
 *  whole FONTS object may be passed, its other families are left to
 *  loadFonts. Adds one FontFace per file of each CJK face with its
 *  unicodeRange, then loads the files `text` touches. `text` is what the
 *  faces set: the sample for the text face; a book in several voices calls
 *  it once per voice (loadCjkFonts({ 'LXGW WenKai TC': ['400'] }, quotes)),
 *  so the heading and quotation faces fetch and check only their own
 *  characters. Fails when a character of `text` is in no file of a face.
 *  List every weight the pages use: a weight left to buildWithFonts gets
 *  the latin file only. With { vertical: true } it also loads each
 *  family's vertical forms (brackets, quotes, pause marks) for the canvas,
 *  which needs loadVerticalAlternates imported from postext. Resolves to
 *  the number of files loaded. */
async function loadCjkFonts(faces, text, { vertical = false } = {}) {
  kitStatus('Loading fonts…');
  let loaded = 0;
  try {
    if (vertical && typeof loadVerticalAlternates !== 'function') {
      throw new Error('loadCjkFonts(…, { vertical: true }) needs loadVerticalAlternates imported from postext');
    }
    for (const [family, specs] of Object.entries(faces)) {
      if (!(await isCjkFamily(family))) continue;
      const twin = [];
      for (const spec of new Set(specs)) {
        const weight = parseInt(spec, 10);
        const style = spec.endsWith('i') ? 'italic' : 'normal';
        const slices = await cjkSlices(family, weight, style);
        const missing = [...new Set(text)].filter((ch) => /\S/.test(ch) && !cjkSliceFor(slices, ch.codePointAt(0)));
        if (missing.length) {
          throw new Error(`${family} ${spec} has no file for ${missing.slice(0, 12).join(' ')}: `
            + `give each face the text it sets (loadCjkFonts({ '${family}': ['${spec}'] }, text))`);
        }
        for (const slice of slices) {
          document.fonts.add(new FontFace(family, `url(${slice.url}) format('woff2')`,
            { weight: String(weight), style, unicodeRange: slice.range }));
          twin.push({ source: slice.url, weight: String(weight), style, unicodeRange: slice.range });
        }
        const font = `${style === 'italic' ? 'italic ' : ''}${weight} 16px "${family}"`;
        loaded += (await document.fonts.load(font, text)).length;
        if (!document.fonts.check(font, text)) throw new Error(`${family} ${spec} did not load for the sample`);
      }
      // The same files under a twin name with the `vert` feature on: the
      // canvas paints the punctuation of vertical lines with it.
      if (vertical && twin.length) await loadVerticalAlternates(family, twin);
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return loaded;
}

/** The PDF font provider for recipes with CJK faces: a family whose
 *  Fontsource subsets are Chinese, Japanese or Korean gets the files that
 *  hold the characters its pages set (`request.codePoints`); any other
 *  family goes to fontsourceProvider (the "pdf" block). */
async function cjkPdfProvider(family, weight, style, request) {
  if (!(await isCjkFamily(family))) return fontsourceProvider(family, weight, style);
  const meta = await fontsourceMeta(family);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const slices = await cjkSlices(family, w, s);
  const picked = new Set();
  for (const cp of request?.codePoints ?? []) {
    const slice = cjkSliceFor(slices, cp);
    if (slice) picked.add(slice);
  }
  if (!picked.size) picked.add(slices[0]);
  return Promise.all(slices.filter((slice) => picked.has(slice)).map(async (slice) => {
    const res = await fetch(slice.url);
    if (!res.ok) throw new Error(`Fontsource file ${slice.url} (${res.status})`);
    return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
  }));
}

/** showPages for a book bound on either edge. A right-bound book (the
 *  document says so: doc.binding is 'right' for page.binding 'right' and
 *  for vertical text) lies on the desk as it opens: page 1 alone on the
 *  left of the spine, then [3 | 2], the spine shade on each page's inner
 *  edge. `binding` ('left' | 'right') overrides the document's. */
function showBook(docs, { binding, ...options } = {}) {
  const count = showPages(docs, options);
  const right = (binding ?? [docs].flat()[0]?.binding) === 'right';
  if (!document.getElementById('pt-kit-cjk')) {
    // The pages keep direction ltr: a canvas draws text in the direction its
    // element inherits, and under rtl each run would end where the engine
    // starts it, its brackets mirrored.
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit-cjk">
      .pt-spread[dir="rtl"] canvas { direction: ltr; }
      .pt-spread[dir="rtl"] figure:first-child canvas { box-shadow: inset 14px 0 14px -14px rgb(0 0 0 / .18),
        0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
    </style>`);
  }
  // Each pair stays [verso, recto] in the page; right to left, the verso
  // sits on the right. Phones stack the pages in reading order either way.
  for (const spread of document.querySelectorAll('#pages > .pt-spread')) spread.dir = right ? 'rtl' : 'ltr';
  document.getElementById('pages').dataset.binding = right ? 'right' : 'left';
  return count;
}

// ─── /Kit ───────────────────────────────────────────────────────────────────────