Ein Satz Panels, drei Seitenaufteilungen

// ═══ Postext Cookbook · Nº 144 · One set of panels, three page splits ═══════════════
// https://postext.dev/en/cookbook/comic-page-splitters
// Code: MIT · Text: original (CC BY 4.0) · Pictures: generated with diffusion models
// Fonts: Comic Neue, Bangers and the faces of five editions (OFL) · Needs postext ≥ 1.25.0
//
// A layout proof for one page of a comic: the same five pictures and the same lines of
// dialogue laid out under three `split` trees. Each picture carries a safe area, so its subject
// stays in view whether its cell is wide, tall or square, and the lettering is placed again
// around the speakers' anchors on every page and in every language.
import {
  buildDocument, withLoadedFonts, renderPageToCanvas, registerResourceImage, loadVerticalAlternates,
} from 'https://esm.sh/postext';
import { renderToPdf, decompressWoff2 } from 'https://esm.sh/postext-pdf';

const LANG = 'de'; // @lang: 'en' | 'es' | 'ca' | 'zh' | 'ar' | 'ja' | 'pt' | 'fr' | 'de' | 'it'
const RECIPE = 'comic-page-splitters';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: the night sea, the lighthouse red and the yellow of the captions
const palette = {
  ink: '#1b2430', // panel borders, lettering and text: a blue-black
  accent: '#b8322a', // the lighthouse red: the proof's labels
  caption: '#f4e7bf', // caption boxes, an old-paper yellow
  muted: '#5f6873', // folios and the imprint
  paper: '#fdfbf6',
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
const colorPalette = [
  ...Object.entries(palette).map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } })),
  { id: 'main-color', name: 'accent (defaults)', value: { hex: palette.accent, model: 'hex' } },
];
// #endregion

// #region editions: one comic, six editions, each lettered in faces for its script
// The lettering and sound-effect faces of each edition: the engine's defaults, but for Chinese
// two ZCOOL faces drawn for cartoons instead of Noto Sans SC. content.<lang>.md holds the words
// of each edition under the same speaker ids; Japanese balloons are set vertically, and the
// Japanese and Arabic editions, read right to left, mirror the order of the panels in every row.
const [LETTERING, SFX] = t({
  en: ['Comic Neue', 'Bangers'], es: ['Comic Neue', 'Bangers'], ca: ['Comic Neue', 'Bangers'],
  ja: ['Zen Antique', 'Dela Gothic One'], zh: ['ZCOOL KuaiLe', 'ZCOOL QingKe HuangYou'],
  ar: ['Playpen Sans Arabic', 'Lalezar'], pt: ['Comic Neue', 'Bangers'],
  fr: ['Comic Neue', 'Bangers'], de: ['Comic Neue', 'Bangers'], it: ['Comic Neue', 'Bangers'],
});
// #endregion

// #region answer: the comic: a frame, gutters, a panel border, and a page per split
// Every :::page fills the type area; its split attribute cuts it into cells and its ::panel
// lines fill them in reading order (rows top to bottom, columns from the start side):
//   :::page{split="30 / 35 [* | * | *] / *"}    three tiers, the middle one in three
//   :::page{split="60 [* / *] | * [* / * / *]"} two columns, then each column in tiers
//   :::page{split="30 [30 | 20 | *] / *"}       a 30 % tier cut 30 | 20 | rest, then the rest
// A size is a percentage of the parent cell, * shares what is left, [ … ] cuts that cell
// on the other axis. A panel with inset="x y w h" sits over the panel before it.
const comics = {
  gutter: { horizontal: mm(4), vertical: mm(3) }, // between tiers, between panels in a tier
  panel: { borderWidth: pt(1), borderColor: col('ink'), background: col('paper') },
  lettering: { fontFamily: LETTERING, fontSize: pt(8), color: col('ink'), inset: mm(1) },
  balloonStyles: [
    { id: 'speech', stroke: col('ink') },
    { id: 'caption', fill: col('caption'), stroke: col('ink') },
    { id: 'sfx', fontFamily: SFX, color: col('accent'), haloColor: col('paper') },
  ],
  runningHeads: true, // a comic page has no running head unless asked: here, its folio
};
// #endregion

const LABEL = { fontFamily: LETTERING, fontSize: pt(7.5), color: col('muted') };
const footer = { elements: [{ kind: 'text', id: 'folio', content: '{pageNumber}', ...LABEL,
  align: 'center', placement: { anchor: { to: 'page', edge: 'bottom' },
    offset: { x: mm(0), y: mm(-8) } } }] };

const config = () => ({
  locale: t({ en: 'en-us', es: 'es', ca: 'ca', ja: 'ja', zh: 'zh-Hans', ar: 'ar',
    pt: 'pt-BR', fr: 'fr', de: 'de', it: 'it' }),
  colorPalette, comics,
  // The trim of an American comic book, 6⅝ × 10³⁄₁₆ in; the type area is the panel frame.
  page: { sizePreset: 'custom', width: mm(168), height: mm(259), dpi: 150,
    backgroundColor: col('paper'),
    margins: { top: mm(14), bottom: mm(18), left: mm(13), right: mm(11), mirror: true } },
  layout: { layoutType: 'single' },
  // The proof's cover sheet is set in the lettering face of the edition.
  bodyText: { fontFamily: LETTERING, fontSize: pt(10.5), lineHeight: pt(15), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
    textAlign: 'left', firstLineIndent: pt(0), paragraphSpacing: true,
    hyphenation: { enabled: false } },
  headings: { fontFamily: SFX, color: col('accent'), fontWeight: 400,
    levels: [
      // The cover sheet's title opens a page, on either side.
      { level: 1, fontSize: pt(34), lineHeight: pt(38), breakBefore: { enabled: true,
        parity: 'any' }, marginTop: mm(30), marginBottom: pt(15) },
      { level: 2, fontFamily: LETTERING, fontSize: pt(10.5), fontWeight: 700,
        color: col('accent'), marginTop: pt(15), marginBottom: pt(0) },
    ] },
  paragraphStyles: [
    { id: 'split', fontSize: pt(10.5), color: col('accent'), textAlign: 'left' }, // the attribute
    { id: 'imprint', fontSize: pt(7.5), lineHeight: pt(10), color: col('muted'),
      marginTop: pt(30) },
  ],
  header: { elements: [] }, footer,
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`# Eine Seite, drei Varianten
Markdown-Beispiel · 74 Zeilen · content.de.md

## Der Leuchtturm von Porthcove · Seite 12 · Layoutentwurf

Drei Pläne für dieselbe Seite, unter denen der Autor wählen kann. Jeder enthält dieselben fünf Bilder und dieselben Dialogzeilen; nur die Aufteilung der Seite ändert sich, und Bildausschnitte und Sprechblasen folgen ihr.

**Plan A, Seite 2.** Drei Streifen, der mittlere in drei Panels geteilt.

:::paragraphs{style="split" dir=ltr}
split="30 / 35 [\* | \* | \*] / \*"
:::

**Plan B, Seite 3.** Zwei Spalten, die linke in zwei Panels, die rechte in drei.

:::paragraphs{style="split" dir=ltr}
split="60 [\* / \*] | \* [\* / \* / \*]"
:::

**Plan C, Seite 4.** Ein Streifen von 30 % der Höhe, geteilt in 30 | 20 | den Rest, über einem hohen Panel; die Katze ist ein Einschub in Mayas Panel.

:::paragraphs{style="split" dir=ltr}
split="30 [30 | 20 | \*] / \*"
:::

:::paragraphs{style="imprint"}
Geschichte und Lettering für das Postext-Rezeptbuch. Bilder mit Diffusionsmodellen erzeugt. Gelettert in Comic Neue und Bangers (SIL OFL).
:::

:::page{split="30 / 35 [* | * | *] / *"}
::panel{art=lh-arrive}
caption: Jeden Sommer verbrachte Maya eine Woche am Leuchtturm.
maya: Opa! Ich bin da!
::panel{art=lh-radio}
tomas: Gerade rechtzeitig. Das Funkgerät ist taub,
tomas: und ein Sturm zieht auf.
::panel{art=lh-maya}
maya: Opa… ich glaube, ich weiß, woran es liegt.
::panel{art=lh-biscuit}
sfx{rotate=-6}: schnurrr
::panel{art=lh-beam}
tomas: Funk geht, Lampe brennt.
maya: Und Biscuit hat ein neues Bett gefunden.
:::

:::page{split="60 [* / *] | * [* / * / *]"}
::panel{art=lh-arrive}
caption: Jeden Sommer verbrachte Maya eine Woche am Leuchtturm.
maya: Opa! Ich bin da!
::panel{art=lh-radio}
tomas: Gerade rechtzeitig. Das Funkgerät ist taub,
tomas: und ein Sturm zieht auf.
::panel{art=lh-maya}
maya: Opa… ich glaube, ich weiß, woran es liegt.
::panel{art=lh-biscuit}
sfx{rotate=-6}: schnurrr
::panel{art=lh-beam}
tomas: Funk geht, Lampe brennt.
maya: Und Biscuit hat ein neues Bett gefunden.
:::

:::page{split="30 [30 | 20 | *] / *"}
::panel{art=lh-arrive}
caption: Jeden Sommer verbrachte Maya eine Woche am Leuchtturm.
maya: Opa! Ich bin da!
::panel{art=lh-radio}
tomas{break}: Gerade rechtzeitig. Das Funkgerät ist taub,
tomas: und ein Sturm zieht auf.
::panel{art=lh-maya}
maya: Opa… ich glaube, ich weiß, woran es liegt.
::panel{art=lh-biscuit inset="50 50 46 46"}
sfx{rotate=-6}: schnurrr
::panel{art=lh-beam}
tomas: Funk geht, Lampe brennt.
maya: Und Biscuit hat ein neues Bett gefunden.
:::
`; // content.<lang>.md, inlined by the Cookbook

// #region art: the five pictures: safe area, speakers' anchors and avoid zones
// From the art manifest; fractions of each picture, the same in every language. The safe
// area is what every crop keeps: Tomás alone, not his radio, so a cell a fifth of the page
// wide still shows him; the lighthouse and the gallery, not the boat, so a tall cell holds them.
const ART = {
  'lh-arrive': { width: 1100, height: 733, safeArea: { x: 0.22, y: 0.08, width: 0.4, height: 0.64 },
    anchors: [{ id: 'maya', x: 0.29, y: 0.52, head: { x: 0.27, y: 0.47 },
      face: { x: 0.22, y: 0.42, width: 0.12, height: 0.16 } },
    { id: 'biscuit', x: 0.4, y: 0.68, face: { x: 0.37, y: 0.64, width: 0.07, height: 0.08 } }],
    avoid: [{ x: 0.51, y: 0.09, width: 0.1, height: 0.43 }],
    alt: t({ en: 'A girl in a yellow raincoat walks up a coastal path towards a red-and-white '
      + 'lighthouse, a fat orange cat ahead of her.',
      es: 'Una niña con chubasquero amarillo sube por un camino de costa hacia un faro rojo y '
        + 'blanco, con un gato naranja gordo delante.',
      ca: 'Una nena amb impermeable groc puja per un camí de costa cap a un far vermell i blanc, '
        + 'amb un gat taronja gras al davant.',
      zh: '一个穿黄色雨衣的女孩沿着海边小路走向红白相间的灯塔，一只胖胖的橘猫走在前面。',
      ar: 'فتاة بمعطف مطر أصفر تصعد دربًا ساحليًا نحو منارة حمراء وبيضاء، وأمامها قط برتقالي سمين.',
      ja: '黄色いレインコートの女の子が、赤と白の灯台へ続く海辺の小道をのぼっていく。前を太ったオレンジ色の猫が歩く。',
      pt: 'Uma menina de capa de chuva amarela sobe um caminho à beira-mar rumo a um farol '
        + 'vermelho e branco, com um gato laranja gordo à frente.',
      fr: 'Une fillette en ciré jaune monte un sentier côtier vers un phare rouge et blanc, '
        + 'précédée d’un gros chat roux.',
      de: 'Ein Mädchen in gelbem Regenmantel geht einen Küstenpfad zu einem rot-weißen '
        + 'Leuchtturm hinauf, eine dicke rote Katze vor ihr.',
      it: 'Una bambina con l’impermeabile giallo sale per un sentiero costiero verso un faro '
        + 'bianco e rosso, preceduta da un grosso gatto rosso.' }) },
  'lh-radio': { width: 1000, height: 1000,
    safeArea: { x: 0.27, y: 0.38, width: 0.24, height: 0.3 },
    anchors: [{ id: 'tomas', x: 0.345, y: 0.52, head: { x: 0.38, y: 0.44 },
      face: { x: 0.29, y: 0.4, width: 0.16, height: 0.18 } }],
    avoid: [{ x: 0, y: 0.44, width: 0.22, height: 0.26 }],
    alt: t({ en: 'The old keeper, white-bearded, in a navy sweater and cap, taps a valve radio '
      + 'with the microphone in his hand.',
      es: 'El viejo farero, de barba blanca, jersey azul marino y gorra, golpea una radio de '
        + 'válvulas con el micrófono en la mano.',
      ca: 'El vell faroner, de barba blanca, jersei blau marí i gorra, pica una ràdio de vàlvules '
        + 'amb el micròfon a la mà.',
      zh: '白胡子的老守塔人穿着藏青色毛衣、戴着帽子，手握话筒，敲着一台电子管收音机。',
      ar: 'حارس المنارة العجوز بلحيته البيضاء وكنزته الكحلية وقبعته ينقر على مذياع قديم '
        + 'والميكروفون في يده.',
      ja: '白いひげの老灯台守が、紺のセーターに帽子姿でマイクを握り、真空管ラジオをたたいている。',
      pt: 'O velho faroleiro, de barba branca, suéter azul-marinho e boné, dá batidinhas num '
        + 'rádio valvulado com o microfone na mão.',
      fr: 'Le vieux gardien, barbe blanche, pull bleu marine et casquette, tapote une radio à '
        + 'lampes, le micro à la main.',
      de: 'Der alte Wärter mit weißem Bart, marineblauem Pullover und Mütze klopft auf ein '
        + 'Röhrenradio, das Mikrofon in der Hand.',
      it: 'Il vecchio guardiano, barba bianca, maglione blu e berretto, picchietta su una radio a '
        + 'valvole con il microfono in mano.' }) },
  'lh-maya': { width: 1100, height: 1100, safeArea: { x: 0.25, y: 0.27, width: 0.41, height: 0.68 },
    anchors: [{ id: 'maya', x: 0.54, y: 0.565, head: { x: 0.5, y: 0.3 },
      face: { x: 0.4, y: 0.33, width: 0.24, height: 0.29 } }],
    avoid: [{ x: 0.27, y: 0.73, width: 0.25, height: 0.22 }],
    alt: t({ en: 'Close-up of Maya frowning at the floor and pointing down.',
      es: 'Primer plano de Maya, que frunce el ceño mirando al suelo y señala hacia abajo.',
      ca: 'Primer pla de la Maya, que arrufa les celles mirant a terra i assenyala avall.',
      zh: '玛雅的特写：她皱着眉头看着地板，手指向下指。',
      ar: 'لقطة قريبة لمايا وهي تعقد حاجبيها ناظرةً إلى الأرض وتشير إلى أسفل.',
      ja: 'マヤのアップ。眉をひそめて床を見つめ、下を指さしている。',
      pt: 'Close de Maya, de testa franzida, olhando para o chão e apontando para baixo.',
      fr: 'Gros plan sur Maya, sourcils froncés, qui fixe le sol et pointe le doigt vers le '
        + 'bas.',
      de: 'Nahaufnahme von Maya, die mit gerunzelter Stirn auf den Boden blickt und nach unten '
        + 'zeigt.',
      it: 'Primo piano di Maya, accigliata, che fissa il pavimento e indica in basso.' }) },
  'lh-biscuit': { width: 1000, height: 1000,
    safeArea: { x: 0.58, y: 0.25, width: 0.42, height: 0.33 },
    anchors: [{ id: 'biscuit', x: 0.72, y: 0.355, head: { x: 0.73, y: 0.32 },
      face: { x: 0.64, y: 0.27, width: 0.2, height: 0.18 } }],
    avoid: [{ x: 0.93, y: 0.28, width: 0.07, height: 0.24 },
      { x: 0, y: 0.72, width: 0.4, height: 0.1 }],
    alt: t({ en: 'Under the desk the fat orange cat sleeps on his back, right on top of the black '
      + 'radio cable.',
      es: 'Bajo la mesa, el gato naranja gordo duerme panza arriba justo encima del cable negro '
        + 'de la radio.',
      ca: 'Sota la taula, el gat taronja gras dorm panxa enlaire just a sobre del cable negre de '
        + 'la ràdio.',
      zh: '桌子底下，胖橘猫四脚朝天地睡着，正好压在收音机的黑色电线上。',
      ar: 'تحت المكتب ينام القط البرتقالي السمين على ظهره فوق سلك المذياع الأسود تمامًا.',
      ja: '机の下で、太ったオレンジ色の猫がラジオの黒いコードの真上にあおむけで眠っている。',
      pt: 'Debaixo da mesa, o gato laranja gordo dorme de barriga para cima bem em cima do cabo '
        + 'preto do rádio.',
      fr: 'Sous le bureau, le gros chat roux dort sur le dos, juste sur le câble noir de la '
        + 'radio.',
      it: 'Sotto la scrivania, il grosso gatto rosso dorme a pancia in su, proprio sopra il cavo '
        + 'nero della radio.',
      de: 'Unter dem Schreibtisch schläft die dicke rote Katze auf dem Rücken, genau auf dem '
        + 'schwarzen Kabel des Funkgeräts.' }) },
  'lh-beam': { width: 1200, height: 800, safeArea: { x: 0.15, y: 0.01, width: 0.25, height: 0.3 },
    anchors: [{ id: 'maya', x: 0.235, y: 0.15,
      face: { x: 0.21, y: 0.11, width: 0.05, height: 0.07 } },
      { id: 'tomas', x: 0.3, y: 0.145, face: { x: 0.28, y: 0.11, width: 0.04, height: 0.06 } }],
    avoid: [{ x: 0.79, y: 0.55, width: 0.08, height: 0.09 }],
    alt: t({ en: 'Night: the beam sweeps over a dark sea; Maya and her grandfather stand on the '
      + 'lantern gallery and a fishing boat shows its lights far out.',
      es: 'De noche, el haz barre un mar oscuro; Maya y su abuelo están en la galería de la '
        + 'linterna y a lo lejos se ven las luces de un pesquero.',
      ca: 'De nit, el feix escombra un mar fosc; la Maya i el seu avi són a la galeria de la '
        + 'llanterna i lluny es veuen els llums d’un pesquer.',
      zh: '夜里，灯塔的光束扫过漆黑的海面；玛雅和外公站在灯室外的回廊上，远处一艘渔船亮着灯。',
      ar: 'ليلًا يمسح الشعاع بحرًا مظلمًا، ومايا وجدّها واقفان على شرفة الفانوس، وفي البعيد قارب '
        + 'صيد بأضوائه.',
      ja: '夜。光の帯が暗い海をなでる。マヤと祖父は灯室の回廊に立ち、沖には漁船の明かりが見える。',
      pt: 'À noite, o facho varre um mar escuro; Maya e o avô estão na galeria da lanterna e, ao '
        + 'longe, aparecem as luzes de um barco de pesca.',
      fr: 'La nuit, le faisceau balaie une mer sombre ; Maya et son grand-père se tiennent sur '
        + 'la galerie de la lanterne et, au large, un bateau de pêche montre ses feux.',
      de: 'Nacht: Der Lichtstrahl streicht über ein dunkles Meer; Maya und ihr Großvater stehen '
        + 'auf der Galerie der Laterne, und weit draußen zeigt ein Fischerboot seine Lichter.',
      it: 'Di notte il fascio di luce spazza un mare scuro; Maya e suo nonno sono sulla balconata '
        + 'della lanterna e, al largo, si vedono le luci di un peschereccio.' }) },
};
// #endregion

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
// Every face of the six editions; each edition loads the latin files of all of them and the
// Japanese, Chinese or Arabic files of its own two.
const FONTS = {
  'Comic Neue': ['400', '400i', '700', '700i'],
  Bangers: ['400'],
  'Zen Antique': ['400'],
  'Dela Gothic One': ['400'],
  'ZCOOL KuaiLe': ['400'],
  'ZCOOL QingKe HuangYou': ['400'],
  'Playpen Sans Arabic': ['400', '700'],
  Lalezar: ['400'],
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
const faces = { [LETTERING]: FONTS[LETTERING], [SFX]: FONTS[SFX] };
await loadFonts(FONTS, markdown);
await loadCjkFonts(faces, markdown, { vertical: LANG === 'ja' }); // ja balloons are vertical
await loadArabicFonts(faces, markdown);
await loadComicFonts(faces, markdown); // the bold and italic the faces do not ship
const resources = await Promise.all([
  comicPanel('lh-arrive', asset('lh-arrive.jpg'), ART['lh-arrive']),
  comicPanel('lh-radio', asset('lh-radio.jpg'), ART['lh-radio']),
  comicPanel('lh-maya', asset('lh-maya.jpg'), ART['lh-maya']),
  comicPanel('lh-biscuit', asset('lh-biscuit.jpg'), ART['lh-biscuit']),
  comicPanel('lh-beam', asset('lh-beam.jpg'), ART['lh-beam']),
]);
const doc = await withLoadedFonts(() => buildDocument({ markdown, resources }, config()),
  { ...kitFonts(FONTS), text: markdown });
showBook(doc, { title: t({ en: 'One set of panels, three page splits',
  es: 'Las mismas viñetas en tres divisiones de página',
  pt: 'Os mesmos quadros em três divisões de página',
  fr: 'Les mêmes cases en trois découpages de page',
  de: 'Dieselben Panels in drei Seitenaufteilungen',
  it: 'Le stesse vignette in tre suddivisioni della pagina' }) });
offerPdf(() => renderToPdf(doc, { fontProvider: comicPdfProvider, resourceBytes: imageBytes }),
  `${RECIPE}.pdf`);

Kit · core, fonts, viewer, pdf, images, cjk, arabic, comics: in jedem Rezept gleich · 740 Zeilen
// ─── 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 v3 ── the same in every recipe · postext.dev/cookbook
// Postext loads the faces a config asks for before layout (prepareFonts,
// buildDocumentWithFonts) and asks the kit for the files: Fontsource's, the
// files the PDF embeds too.

/** The options of buildDocumentWithFonts / prepareFonts / withLoadedFonts:
 *  the Fontsource resolver, and the faces of FONTS loaded with the ones the
 *  config names. FONTS = { 'Family Name': ['400', '400i', '700'] }. */
function kitFonts(FONTS = {}) {
  const faces = Object.entries(FONTS).flatMap(([family, specs]) => specs.map((spec) =>
    ({ family, weight: parseInt(spec, 10), style: spec.endsWith('i') ? 'italic' : 'normal' })));
  return { resolve: fontsourceResolver, faces };
}

/** A face's Fontsource files, in a fixed order: latin, then latin-ext and greek
 *  when `text` needs them and the family ships them (kitSubsetsFor), each with
 *  its unicode-range. Null for a weight or slant Fontsource does not ship. */
async function fontsourceResolver(family, weight, style, { text = '' } = {}) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  if (meta && !(meta.weights.includes(weight) && meta.styles.includes(style))) return null;
  kitStatus('Loading fonts…');
  const at = await fontsourceAt(id);
  return ['latin', ...kitSubsetsFor(text, meta)].map((subset) => ({
    source: `${at}files/${id}-${subset}-${weight}-${style}.woff2`,
    unicodeRange: kitRanges()[subset],
  }));
}

/** The unicode-range of each Fontsource file the kit loads (a function: the
 *  kit is inlined after the pen's code, which runs before a const would be set). */
function kitRanges() {
  return {
    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',
    greek: 'U+0370-03FF',
  };
}

/** For the cjk, arabic and comics blocks, which add their own files: the
 *  faces of `faces` = { 'Family Name': ['400', '400i', '700'] }. `text` is the sample:
 *  č ł † α χ also load latin-ext and greek files (kitSubsetsFor). With
 *  `optional`, a face Fontsource does not ship is skipped instead of failing.
 *  The files are added once all have loaded, in the order asked (latin, then
 *  latin-ext, then greek), whatever order they arrive in: the last one added
 *  wins a character two files hold. Resolves to the number of faces added. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = kitRanges();
  const jobs = [];
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const todo = [...new Set(specs)].map((spec) => [parseInt(spec, 10), spec.endsWith('i') ? 'italic' : 'normal'])
      .filter(([weight, style]) => !hasFace(family, weight, style)); // before any await
    const at = fontsourceAt(id);
    const meta = optional || /[^\0-ÿ]/u.test(text) ? await fontsourceMeta(family) : null;
    const subsets = ['latin', ...kitSubsetsFor(text, meta)];
    for (const [weight, style] of todo) {
      if (optional && !(meta?.weights.includes(weight) && meta.styles.includes(style))) continue;
      for (const subset of subsets) {
        const url = `${await at}files/${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().catch(() => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  const ready = await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return ready.filter((face) => face && document.fonts.add(face)).length;
}

/** A loaded FontFace covers this family, weight and style (fonts.check() would
 *  also say yes 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;
}

/** The files beyond latin `text` needs that `meta`'s family ships. */
function kitSubsetsFor(text, meta) {
  return [[/[Ā-˿ᴀ-ᶿḀ-ỿ†ℓⱠ-Ɀ꜠-ꟿ]/u, 'latin-ext'], [/[Ͱ-Ͽ]/u, 'greek']]
    .filter(([re, x]) => re.test(text) && meta?.subsets?.includes(x)).map(([, x]) => x);
}

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

/** A package's folder at the one version @5 names now (#766). */
function fontsourceAt(id, u = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@`) {
  return (fontsourceAt.c ??= {})[id] ??= fetch(u + '5/package.json').then((r) => r.json())
    .then((p) => p.version || 5, () => 5).then((v) => `${u}${v}/`);
}

/** The family's Fontsource metadata (weights, styles, subsets), 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 v2 ── the same in every recipe · postext.dev/cookbook
/** The pages as spreads on a dark desk, page 1 alone, then verso | recto,
 *  each painted when it scrolls near. Other options go to renderPageToCanvas. */
function showPages(docs, { title, width = 460, ...render } = {}) {
  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, { ...render, 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 v3 ── the same in every recipe that exports a PDF
/** The Fontsource files the screen used, as TrueType, with their range and
 *  place: the nearest weight the family ships, upright with no italic;
 *  latin, then what its letters need (kitSubsetsFor). */
async function fontsourceProvider(family, weight, style, request) {
  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 text = String.fromCodePoint(...(request?.codePoints ?? []));
  const files = await Promise.all(['latin', ...kitSubsetsFor(text, meta)].map(async (subset, order) => {
    const res = await fetch(`${await fontsourceAt(id)}files/${id}-${subset}-${w}-${s}.woff2`);
    if (!res.ok) throw new Error(`Fontsource has no ${family} ${w} ${s} ${subset}`);
    return Object.assign(await decompressWoff2(new Uint8Array(await res.arrayBuffer())),
      { unicodeRange: kitRanges()[subset], order });
  }));
  return files.length === 1 ? files[0] : files;
}

/** A "Build the PDF" button; then "Open the PDF" (a new tab: CodePen's frame
 *  shows no 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 · images v3 ── recipes with pictures · postext.dev/cookbook
/** Registers a photo or PNG for the canvas and keeps its bytes for the PDF.
 *  fetch → ImageBitmap never taints the canvas (a plain cross-origin <img> would). */
async function loadImage(fileId, url) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Image not found (${res.status}): ${url}`);
  const bytes = new Uint8Array(await res.arrayBuffer());
  registerResourceImage(fileId, await createImageBitmap(new Blob([bytes])));
  (loadImage.bytes ??= new Map()).set(fileId, bytes);
}

/** Registers SVG markup as a vector image, its fonts inside (inlineSvgFonts, ≥ 1.25).
 *  `options` go to registerResourceImage: { singleInk: true } tints it on the canvas. */
async function loadSvg(fileId, svg, options) {
  if (typeof inlineSvgFonts === 'function') svg = await inlineSvgFonts(svg, svgFaces);
  const img = new Image();
  img.src = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svg)}`;
  await img.decode();
  registerResourceImage(fileId, img, options);
  (loadImage.bytes ??= new Map()).set(fileId, new TextEncoder().encode(svg));
}

/** A face's Fontsource files: nearest weight; latin + what the SVG sets. */
async function svgFaces(family, weight, style, { codePoints = [] } = {}) {
  const [id, m] = [fontsourceId(family), await fontsourceMeta(family)];
  const w = m?.weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a)) ?? weight;
  const s = m?.styles.includes(style) === false ? 'normal' : style;
  return Promise.all(['latin', ...kitSubsetsFor(String.fromCodePoint(...codePoints), m)].map(async (x) => new Uint8Array(
    await (await fetch(`${await fontsourceAt(id)}files/${id}-${x}-${w}-${s}.woff2`)).arrayBuffer())));
}

/** renderToPdf({ resourceBytes: imageBytes }) */
function imageBytes(fileId) { return loadImage.bytes?.get(fileId); }

/** renderToHtml({ resourceImageUrl: imageUrl }) */
function imageUrl(fileId) {
  const bytes = imageBytes(fileId);
  if (!bytes) return undefined;
  imageUrl.urls ??= new Map();
  if (!imageUrl.urls.has(fileId)) {
    const type = /\.svg$/i.test(fileId) ? 'image/svg+xml' : /\.png$/i.test(fileId) ? 'image/png' : 'image/jpeg';
    imageUrl.urls.set(fileId, URL.createObjectURL(new Blob([bytes], { type })));
  }
  return imageUrl.urls.get(fileId);
}

// ─── Kit · cjk v2 ── 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 = `${id}/${weight}${style === 'italic' ? '-italic' : ''}.css`;
  if (!cjkSlices.cache.has(css)) {
    let at;
    cjkSlices.cache.set(css, fontsourceAt(id).then((a) => fetch(at = a + css.slice(id.length + 1)))
      .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], at).href, range, ranges };
      }).reverse()));
  }
  return cjkSlices.cache.get(css);
}

/** The file of `slices` the screen sets code point `cp` in, if any: the
 *  last one loadCjkFonts adds whose range holds it. A numbered file that
 *  repeats a letter of latin is added after latin, and wins it. */
function cjkSliceFor(slices, cp) {
  const holds = (slice) => slice.ranges.some(([lo, hi]) => cp >= lo && cp <= hi);
  return slices.reduce((last, slice) => (holds(slice) ? slice : last), undefined);
}

/** 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 the engine's later round
 *  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 the
 *  screen set its pages' characters in (`request.codePoints`), each marked
 *  with its unicode-range and its place in the order loadCjkFonts added
 *  them: postext-pdf sets a character two files hold in the one added
 *  last, as the browser does. Any other family gets the latin file
 *  fontsourceProvider fetches (the "pdf" block) and, when the face sets
 *  letters only latin-ext has, that file too. */
async function cjkPdfProvider(family, weight, style, request) {
  if (!(await isCjkFamily(family))) return cjkLatinPdfFiles(family, weight, style, request);
  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.map(async (slice, order) => {
    if (!picked.has(slice)) return null;
    const res = await fetch(slice.url);
    if (!res.ok) throw new Error(`Fontsource file ${slice.url} (${res.status})`);
    const bytes = await decompressWoff2(new Uint8Array(await res.arrayBuffer()));
    return Object.assign(bytes, { unicodeRange: slice.range, order });
  })).then((files) => files.filter(Boolean));
}

/** A Latin family set next to the CJK faces: its latin file, then its
 *  latin-ext file when the face sets letters only latin-ext has (ō ū in
 *  Hepburn rōmaji, ǎ in pinyin), the file loadFonts adds on screen for
 *  them, each marked with its unicode-range and its place in that order:
 *  the PDF sets a character in the file the browser took it from. A face
 *  Fontsource ships without latin-ext, or whose file does not come, gets
 *  latin alone, and the PDF names the letters it lacks. */
async function cjkLatinPdfFiles(family, weight, style, request) {
  const meta = await fontsourceMeta(family);
  const beyond = [...(request?.codePoints ?? [])].some(cjkLatinExtOnly);
  if (!beyond || !meta?.subsets?.includes('latin-ext')) return fontsourceProvider(family, weight, style);
  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 id = fontsourceId(family);
  const url = `${await fontsourceAt(id)}files/${id}-latin-ext-${w}-${s}.woff2`;
  const [latin, ext] = await Promise.all([fontsourceProvider(family, weight, style), fetch(url)
    .then(async (res) => (res.ok ? decompressWoff2(new Uint8Array(await res.arrayBuffer())) : null), () => null)]);
  const ranges = kitRanges();
  return ext ? [Object.assign(latin, { unicodeRange: ranges.latin, order: 0 }),
    Object.assign(ext, { unicodeRange: ranges['latin-ext'], order: 1 })] : latin;
}

/** Whether code point `cp` is in Fontsource's latin-ext file and not in
 *  its latin file: Latin Extended-A and -B, IPA, the spacing modifiers and
 *  Latin Extended Additional (loadFonts's test for latin-ext), less the
 *  few latin holds too (ı Œ œ ʻ ʼ ˆ ˚ ˜). */
function cjkLatinExtOnly(cp) {
  if (!((cp >= 0x100 && cp <= 0x2ff) || (cp >= 0x1e00 && cp <= 0x1eff))) return false;
  return ![0x131, 0x152, 0x153, 0x2bb, 0x2bc, 0x2c6, 0x2da, 0x2dc].includes(cp);
}

/** 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 · arabic v2 ── Arabic-script faces · postext.dev/cookbook
// Fontsource ships an Arabic family as one file per subset and weight: the
// `arabic` file holds the letters, the harakat, the Arabic-Indic digits, the
// Arabic punctuation and the presentation forms; `latin` and `latin-ext`
// hold the rest. loadFonts loads the latin files; this block adds the arabic
// file of every Arabic family, for the canvas and for the PDF, which shapes
// the letters with HarfBuzz from the same bytes.

/** The code points of Fontsource's `arabic` subset, as its stylesheets
 *  declare them (the same unicode-range the browser picks the file by). A
 *  function, not a const: the kit is inlined after the recipe's top-level
 *  awaits, and a const read before its line throws, where a function
 *  declaration is hoisted. */
function arabicRange() {
  return 'U+0600-06FF,U+0750-077F,U+0870-088E,U+0890-0891,U+0897-08E1,U+08E3-08FF,'
    + 'U+200C-200E,U+2010-2011,U+204F,U+2E41,U+FB50-FDFF,U+FE70-FE74,U+FE76-FEFC,U+102E0-102FB,'
    + 'U+10E60-10E7E,U+10EC2-10EC4,U+10EFC-10EFF,U+1EE00-1EEFF';
}

/** Whether code point `cp` is in the arabic file. */
function inArabicRange(cp) {
  inArabicRange.ranges ??= arabicRange().split(',').map((part) => {
    const [lo, hi = lo] = part.slice(2).split('-');
    return [parseInt(lo, 16), parseInt(hi, 16)];
  });
  return inArabicRange.ranges.some(([lo, hi]) => cp >= lo && cp <= hi);
}

/** Whether Fontsource serves `family` with an `arabic` subset. Fails when
 *  the API does not answer: an Arabic face taken for a Latin one would set
 *  its letters in a system face. */
async function isArabicFamily(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?.includes('arabic');
}

/** The arabic file of a face. */
async function arabicFileUrl(family, weight, style) {
  const id = fontsourceId(family);
  return `${await fontsourceAt(id)}files/${id}-arabic-${weight}-${style}.woff2`;
}

/** faces = { Amiri: ['400', '700'] }, as for loadFonts, after it: the whole
 *  FONTS object may be passed, its families without an arabic subset are
 *  left alone. Adds the arabic file of every listed weight of each Arabic
 *  family (the latin files come from loadFonts) and loads it. `text` is
 *  the sample: fails when it holds an Arabic-script character the arabic
 *  file does not cover. List every weight the pages set in Arabic: a weight
 *  left to the engine's later round gets the latin file only, and its Arabic letters
 *  fall back to a system face. Resolves to the number of files loaded. */
async function loadArabicFonts(faces, text = '') {
  kitStatus('Loading fonts…');
  let loaded = 0;
  try {
    const outside = [...new Set(text)].filter((ch) => /\p{Script=Arabic}/u.test(ch) && !inArabicRange(ch.codePointAt(0)));
    if (outside.length) throw new Error(`Fontsource's arabic files have no ${outside.slice(0, 12).join(' ')}`);
    for (const [family, specs] of Object.entries(faces)) {
      if (!(await isArabicFamily(family))) continue;
      for (const spec of new Set(specs)) {
        const weight = parseInt(spec, 10);
        const style = spec.endsWith('i') ? 'italic' : 'normal';
        const face = new FontFace(family, `url(${await arabicFileUrl(family, weight, style)}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: arabicRange() });
        document.fonts.add(await face.load().catch(() => {
          throw new Error(`Fontsource has no arabic file for ${family} ${weight} ${style}`);
        }));
        loaded++;
      }
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return loaded;
}

/** The PDF font provider for recipes with Arabic faces: a family with an
 *  arabic subset gets its arabic file when its pages set Arabic letters
 *  (`request.codePoints`), then its latin file, and its latin-ext file for
 *  the letters beyond latin (transliteration: ā ḥ ʿ), each marked with its
 *  unicode-range and its place in the order the screen added them (latin
 *  and latin-ext by loadFonts, then arabic): the arabic file also has a
 *  space and brackets, which the browser takes from latin, the file whose
 *  range holds them, and postext-pdf follows it. Any other family goes to
 *  fontsourceProvider (the "pdf" block). */
async function arabicPdfProvider(family, weight, style, request) {
  if (!(await isArabicFamily(family))) return fontsourceProvider(family, weight, style, request);
  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 wanted = [...(request?.codePoints ?? [])];
  const id = fontsourceId(family);
  const subsets = !wanted.length || wanted.some(inArabicRange) ? ['arabic', 'latin'] : ['latin'];
  if (meta.subsets.includes('latin-ext') && wanted.some((cp) => /[Ā-˿Ḁ-ỿ]/u.test(String.fromCodePoint(cp)))) {
    subsets.push('latin-ext');
  }
  const at = await fontsourceAt(id);
  return Promise.all(subsets.map(async (subset) => {
    const url = `${at}files/${id}-${subset}-${w}-${s}.woff2`;
    const res = await fetch(url);
    if (!res.ok) throw new Error(`Fontsource file ${url} (${res.status})`);
    const bytes = await decompressWoff2(new Uint8Array(await res.arrayBuffer()));
    return Object.assign(bytes, { unicodeRange: subset === 'arabic' ? arabicRange() : kitRanges()[subset],
      order: ['latin', 'latin-ext', 'greek', 'arabic'].indexOf(subset) });
  }));
}

// ─── Kit · comics v2 ── comic pages · postext.dev/cookbook
// The engine letters a comic in a face per language (defaultComicFont:
// Comic Neue, Zen Antique for Japanese, Noto Sans SC, LXGW WenKai TC,
// Playpen Sans Arabic; defaultComicSfxFont: Bangers, Dela Gothic One,
// ZCOOL KuaiLe, Lalezar) and asks for the bold of a shout or a sound effect
// and the italic of an inner voice. Most of these faces ship one weight and
// no italic: this block declares the file Fontsource does ship for those
// variants, so the canvas measures and paints the letters the PDF embeds
// (the providers snap to the shipped file) and not a bold or a slant the
// browser makes up. It also turns the art manifest into panel resources.

/** faces = { 'Comic Neue': ['400', '700'], Bangers: ['400'] }, as for
 *  loadFonts, after it (and after loadCjkFonts or loadArabicFonts for the
 *  faces of those scripts); the whole FONTS object may be passed. List in
 *  FONTS only what Fontsource ships (Bangers: ['400']): loadFonts fails on
 *  the rest. For each family, the regular, bold, italic and bold italic it
 *  lacks are declared with its nearest file (the regular for the bold, the
 *  upright for the italic) and loaded for `text`. A CJK face needs the cjk
 *  block; an Arabic face setting Arabic, the arabic block. Resolves to the
 *  number of variants added. */
async function loadComicFonts(faces, text = '') {
  kitStatus('Loading fonts…');
  let added = 0;
  try {
    for (const family of Object.keys(faces)) {
      const meta = await fontsourceMeta(family);
      if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
      const weights = meta.weights?.length ? meta.weights : [400, 700];
      const styles = meta.styles?.length ? meta.styles : ['normal'];
      for (const [weight, style] of [[400, 'normal'], [700, 'normal'], [400, 'italic'], [700, 'italic']]) {
        if ((weights.includes(weight) && styles.includes(style)) || hasFace(family, weight, style)) continue;
        const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
        const s = style === 'italic' && styles.includes('italic') ? 'italic' : 'normal';
        for (const { url, range } of await comicFaceFiles(family, w, s, meta, text)) {
          document.fonts.add(new FontFace(family, `url(${url}) format('woff2')`,
            { weight: String(weight), style, unicodeRange: range }));
        }
        await document.fonts.load(`${style === 'italic' ? 'italic ' : ''}${weight} 16px "${family}"`, text || 'A');
        added++;
      }
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return added;
}

/** The files of a shipped face ({ url, range }): a CJK face's slices (the
 *  cjk block reads them from its stylesheet), else latin, the latin-ext
 *  and greek files `text` needs, and the arabic file when `text` holds
 *  Arabic. */
async function comicFaceFiles(family, weight, style, meta, text) {
  if (meta.subsets?.some((subset) => /^(chinese|japanese|korean)/.test(subset))) {
    if (typeof cjkSlices !== 'function') throw new Error(`${family} is a CJK face: list the cjk kit block`);
    return (await cjkSlices(family, weight, style)).map(({ url, range }) => ({ url, range }));
  }
  const id = fontsourceId(family);
  const at = await fontsourceAt(id);
  const file = (subset) => `${at}files/${id}-${subset}-${weight}-${style}.woff2`;
  const files = ['latin', ...kitSubsetsFor(text, meta)].map((subset) => ({ url: file(subset), range: comicRange(subset) }));
  if (meta.subsets?.includes('arabic') && /\p{Script=Arabic}/u.test(text)) {
    if (typeof arabicRange !== 'function') throw new Error(`${family} sets Arabic: list the arabic kit block`);
    files.unshift({ url: file('arabic'), range: arabicRange() });
  }
  return files;
}

/** The unicode-range loadFonts gives a Fontsource file. A function, not a
 *  const: the kit is inlined after the recipe's top-level awaits. */
function comicRange(subset) {
  return {
    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',
    greek: 'U+0370-03FF',
  }[subset];
}

/** The PDF font provider of a comic in any script: a CJK face goes to
 *  cjkPdfProvider, an Arabic face to arabicPdfProvider, any other to
 *  fontsourceProvider (the "pdf" block). Each embeds the shipped weight
 *  and style nearest to the one asked for, the file loadComicFonts
 *  declared for the canvas. */
async function comicPdfProvider(family, weight, style, request) {
  const subsets = (await fontsourceMeta(family))?.subsets ?? [];
  if (subsets.some((subset) => /^(chinese|japanese|korean)/.test(subset))) {
    if (typeof cjkPdfProvider !== 'function') throw new Error(`${family} is a CJK face: list the cjk kit block`);
    return cjkPdfProvider(family, weight, style, request);
  }
  if (subsets.includes('arabic') && typeof arabicPdfProvider === 'function') {
    return arabicPdfProvider(family, weight, style, request);
  }
  return fontsourceProvider(family, weight, style, request);
}

/** A panel picture as a resource for art= (and pop=): loads `url`
 *  (write asset('lh-arrive.jpg') in the call, so the lint checks the file)
 *  and declares it with `meta`, its entry in the art manifest:
 *  { width, height, alt, safeArea, anchors, avoid, faces }. The safe area
 *  is what every crop keeps, the anchors the speakers' mouths, heads and
 *  faces, the avoid zones what no balloon covers unless a panel has no
 *  other room, and `faces` the faces of the people who do not speak, which
 *  no balloon ever covers; all in fractions of the picture, the same in
 *  every language. Without width and height, the picture's own size. Needs
 *  the images block. Resolves to the resource. */
async function comicPanel(id, url, meta = {}) {
  const fileId = decodeURIComponent(url.split('/').pop());
  await loadImage(fileId, url);
  let { width, height } = meta;
  if (!width || !height) {
    const bitmap = await createImageBitmap(new Blob([imageBytes(fileId)]));
    ({ width, height } = bitmap);
    bitmap.close();
  }
  return {
    id, typeId: meta.typeId ?? 'figure', kind: 'bitmap', createdAt: 0, updatedAt: 0,
    bitmap: { fileId, format: /\.png$/i.test(fileId) ? 'png' : 'jpeg', width, height },
    ...(meta.alt && { altText: meta.alt }),
    ...(meta.safeArea && { safeArea: meta.safeArea }),
    ...(meta.anchors?.length && { anchors: meta.anchors }),
    ...(meta.avoid?.length && { avoid: meta.avoid }),
    ...(meta.faces?.length && { faces: meta.faces }),
  };
}

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