Castellà justificat en una novel·la de butxaca

// ═══ Postext Cookbook · Nº 016 · Justified Spanish in a pocket novel ═════════════════
// https://postext.dev/en/cookbook/spanish-pocket-novel
// Code: MIT · Text: B. Pérez Galdós, Marianela, 1878 (PD, Gutenberg #17340) · Map: drawn in code
// Fonts: Gentium Book Plus, Libre Bodoni, Marcellus SC (SIL OFL 1.1) · Needs postext ≥ 1.12.2
import { buildDocument, renderPageToCanvas, clearMeasurementCache, defaultResourceTypes,
  registerResourceImage } from 'https://esm.sh/postext';

const LANG = 'es'; // @lang: the language of the sample document (this recipe is Spanish only)
const RECIPE = 'spanish-pocket-novel';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
const palette = {
  ink: '#1e1b18', // text: a warm near-black
  oxblood: '#8b2e2a', // the one accent: chapter label, rule, initial, asterisks, route
  muted: '#6d645a', // running heads, the map's paths, the caption's credit
  paper: '#f7f2e8', // an ivory book paper
  slag: '#c8553d', moss: '#6f7a4f', water: '#58707f', // the map: mined earth, woods, river
};
// Each colour names its palette entry and carries its hex (gotcha: palette-skips-designs).
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: 'oxblood (defaults)', value: { hex: palette.oxblood, model: 'hex' } },
];
const TEXT = 'Gentium Book Plus'; // the text face
const DISPLAY = 'Libre Bodoni'; // the chapter's title and the initial
const LABEL = 'Marcellus SC'; // small capitals: chapter label, running heads, map names
const [BODY, LEAD] = [10, 13.8]; // pt: the body size, and its leading: the grid's pitch
const smallCaps = { fontFamily: LABEL, fontSize: pt(9), letterSpacing: pt(1.6), // 2 labels
  color: col('oxblood'), align: 'center' };

// #region page: a pocket paperback; the text block holds 30 whole lines
const TRIM = { width: 115, height: 180 }; // mm: 11.5 × 18 cm
const [TOP, INNER, OUTER] = [16, 15, 14]; // mm: a pocket page keeps its margins tight
const LINES = 30; // lines of LEAD per page, so every full page ends on the same line
const MEASURE = TRIM.width - INNER - OUTER; // 86 mm: about 57 characters of Gentium at 10 pt
const page = {
  width: mm(TRIM.width), height: mm(TRIM.height), dpi: 150, backgroundColor: col('paper'),
  margins: { top: mm(TOP), bottom: mm(TRIM.height - TOP - (LINES * LEAD * 25.4) / 72),
    left: mm(INNER), right: mm(OUTER), mirror: true }, // left is inner on a recto
};
// #endregion

// #region answer: Spanish syllables, word spaces under 1.7×, captions that say Figura
const LOCALE = 'es'; // config().locale; 'es-ES' gets US breaks (gotcha: hyphenation-locales)
const bodyText = { // config().bodyText
  fontFamily: TEXT, fontSize: pt(BODY), lineHeight: pt(LEAD), color: col('ink'),
  boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
  referenceBold: false, // '[fig. 1]' reads in roman, like the words around it
  firstLineIndent: mm(4), indentAfterHeading: false, // the lead's paragraph goes on flush
  // The defaults justify, hyphenate, break by Knuth–Plass and keep widows and orphans out.
  // Long Spanish words on an 86 mm measure need two more settings. Spaces under 1.7×: at
  // the default 2×, eight lines here open past 1.6×; at 1.7 it hyphenates hie-rro, ca-lles.
  // A last line under 26 space widths is a runt; at 20, 'siem- / pre adelante.' got through.
  maxWordSpacing: 1.7, runtMinCharacters: 26,
};
// config().resourceTypes, as the locale leaves captions in English (gotcha:
// resource-types-locale): 'Figura' and 'Fig.', numbered through the book, Figura 1.
const resourceTypes = defaultResourceTypes(LOCALE)
  .map((type) => ({ ...type, numberingTemplate: '{n}', resetOn: 'never' }));
// #endregion

// #region opener: the chapter spelled out, its title, and the lead under a raised initial
const [LABEL_Y, RULE_Y, TITLE_Y] = [4, 10.5, 13.5]; // mm below the top of the text block
const SINK = 8; // lines of LEAD above the lead: the chapter drops a quarter of the page
const INITIAL = 3 * LEAD; // pt: the initial's size, three leads
// Design text is set ragged (gotcha: design-text-ragged): the lead is the one line beside
// the initial, fitted flush by the gap; the paragraph goes on in the Markdown.
const INITIAL_GAP = 0.55; // mm: the line ends 0.1 mm short of the measure
const centred = (y) => ({ anchor: { to: 'container', edge: 'top' }, offset: { y: mm(y) } });
const opener = {
  enabled: true,
  slot: { elements: [
    // Numbering templates print numerals only (1, 01, I, i, A, a); a number in words comes
    // from the heading's own attribute: # Perdido {ordinal="primero" lead="Se puso el sol. …"}
    { kind: 'text', id: 'chapter', content: 'capítulo {attr.ordinal}', ...smallCaps,
      placement: centred(LABEL_Y) },
    { kind: 'rule', id: 'rule', direction: 'horizontal', thickness: pt(0.6),
      color: col('oxblood'), placement: { ...centred(RULE_Y), size: { width: mm(9) } } },
    { kind: 'text', id: 'title', content: '{titleText}', fontFamily: DISPLAY, italic: true,
      fontSize: pt(26), lineHeight: 1.1, color: col('ink'), align: 'center',
      overflow: 'wrap', // longer titles wrap, not '…' (gotcha: overflow-ellipsis-default)
      placement: centred(TITLE_Y) },
    { kind: 'text', id: 'lead', content: '{attr.lead}', fontFamily: TEXT, fontSize: pt(BODY),
      lineHeight: LEAD / BODY, // a multiple, never a pt (gotcha: design-lineheight-multiple)
      color: col('ink'), align: 'left', overflow: 'wrap', // a dropCap needs wrapping text
      dropCap: { lines: 1, fontFamily: DISPLAY, fontWeight: 700, fontSize: pt(INITIAL),
        color: col('oxblood'), gap: mm(INITIAL_GAP) }, // lines: 1, a raised initial
      placement: { anchor: { to: 'container', edge: 'top-left' },
        offset: { y: pt(SINK * LEAD) }, size: { width: mm(MEASURE) } } },
  ] },
};
// The break restated (gotcha: headings-drop-h1-break): the next page, as pocket books do.
// marginBottom replaces the level's default, a blank line of its own: the text goes on
// on the line under the lead.
const chapter = { level: 1, breakBefore: { enabled: true, parity: 'any' },
  marginBottom: pt(0), advancedDesign: opener };
// #endregion

// #region heads: the author on the verso, the title on the recto; a drop folio on the opener
const [HEAD_Y, DROP_Y] = [9, -10]; // mm: heads from the top edge, drop folio from the foot
const head = (id, content, parity, edge, x, y = HEAD_Y, pages = 'body') => ({
  kind: 'text', id, content, parity, pages, // running heads skip the openers
  fontFamily: LABEL, fontSize: pt(8), letterSpacing: pt(1.2), color: col('muted'),
  placement: { anchor: { to: 'page', edge }, offset: { x: mm(x), y: mm(y) } },
});
const SHIFT = (INNER - OUTER) / 2; // mm: the text block's centre is off the page's centre
// Folios in the text face (Marcellus SC's 1 and 0 read as I and O), on the heads' baseline.
const folio = { fontFamily: TEXT, letterSpacing: pt(0), color: col('ink') };
const header = { elements: [
  { ...head('verso-folio', '{pageNumber}', 'even', 'top-left', OUTER), ...folio },
  head('verso-author', '{author}', 'even', 'top', -SHIFT),
  head('recto-title', '{title}', 'odd', 'top', SHIFT),
  { ...head('recto-folio', '{pageNumber}', 'odd', 'top-right', -OUTER), ...folio },
] };
const drop = (parity, x) => ({ ...head(`drop-${parity}`, '{pageNumber}', parity, 'bottom', x,
  DROP_Y, 'opener'), ...folio }); // a chapter can open on either side of the spread
const footer = { elements: [drop('odd', SHIFT), drop('even', -SHIFT)] };
// #endregion

// #region figure: the map faces chapter I as Figura 1; the text cites it as [fig. 1]
const MAP_H = 112; // mm: a frontispiece map, the measure wide
const resources = [{
  id: 'plano', typeId: 'figure', kind: 'svg', createdAt: 0, updatedAt: 0,
  svg: { fileId: 'plano.svg', width: MEASURE, height: MAP_H }, // the ratio: set column-wide
  placement: { position: 'here' }, // where ::resource{id="plano"} stands, not a float
  caption: 'El camino de Golfín: de Villafangosa, por la pasadera y el cerro, al talud de '
    + 'las minas de Socartes.',
  note: 'Plano conjetural dibujado para esta edición a partir del capítulo primero.',
  altText: 'Plano: abajo, la villa, el río y la pasadera; en medio, un cerro arbolado; arriba, '
    + 'las minas en gradas. Un punteado lleva de la villa al talud de las minas.',
}];
// The plate's heading, # Las minas de Socartes {style="lamina"}, opens a page the heads skip.
const frontispiece = {
  id: 'lamina', // its own break, or it takes the chapter's (gotcha: style-inherits-break)
  breakBefore: { enabled: true, parity: 'any' }, marginBottom: pt(0),
  footer: { elements: [] }, // no drop folio
  advancedDesign: { enabled: true, slot: { elements: [{ kind: 'text', id: 'name',
    content: '{titleText}', ...smallCaps, // a line down: the plate centres on the page
    placement: { anchor: { to: 'container', edge: 'top' }, offset: { y: pt(LEAD) } } }] } },
};
const captionStyle = { fontFamily: TEXT, fontSize: pt(8.3), gap: mm(2),
  labelColor: col('oxblood'), descriptionItalic: true, note: { color: col('muted') } };
// #endregion

// #region styles: the asterisks that close the excerpt, the edition's note, the colophon
const paragraphStyles = [
  { id: 'asterismo', fontFamily: DISPLAY, fontSize: pt(11), color: col('oxblood'),
    textAlign: 'center' },
  // In ink, not muted: a style has no italic colour (gotcha: style-italic-colour).
  { id: 'nota', fontSize: pt(8.3), lineHeight: pt(LEAD * 0.8), firstLineIndent: pt(0),
    marginTop: pt(LEAD) },
  { id: 'colofon', fontSize: pt(7.5), color: col('muted'), textAlign: 'center',
    firstLineIndent: pt(0), marginTop: pt(LEAD / 2) },
];
// #endregion

const config = () => ({ // a factory: the engine caches resolved configs per object
  locale: LOCALE,
  resourceTypes,
  colorPalette,
  page,
  layout: { layoutType: 'single' },
  bodyText,
  headings: {
    fontFamily: DISPLAY, // the designs paint the titles; this keeps Open Sans unloaded
    levels: [chapter],
  },
  headingStyles: [frontispiece],
  paragraphStyles,
  captionStyle,
  header,
  footer,
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Mostra en Markdown · 45 línies · content.es.md
title: "Marianela"
author: "Benito Pérez Galdós"
---

# Las minas de Socartes {style="lamina"}

::resource{id="plano"}

# Perdido {ordinal="primero" lead="Se puso el sol. Tras el breve crepúsculo vino tranquila"}

y oscura la noche, en cuyo negro seno murieron poco a poco los últimos rumores de la tierra soñolienta, y el viajero siguió adelante en su camino, apresurando su paso a medida que avanzaba la noche. Iba por angosta vereda, de esas que sobre el césped traza el constante pisar de hombres y brutos, y subía sin cansancio por un cerro en cuyas vertientes se alzaban pintorescos grupos de guinderos, hayas y robles. (Ya se ve que estamos en el Norte de España.)

Era un hombre de mediana edad, de complexión recia, buena talla, ancho de espaldas, resuelto de ademanes, firme de andadura, basto de facciones, de mirar osado y vivo, ligero a pesar de su regular obesidad, y (dígase de una vez aunque sea prematuro) excelente persona por doquiera que se le mirara. Vestía el traje propio de los señores acomodados que viajan en verano, con el redondo sombrerete, que debe a su fealdad el nombre de hongo, gemelos de campo pendientes de una correa, y grueso bastón que, entre paso y paso, le servía para apalear las zarzas cuando extendían sus ramas llenas de afiladas uñas para atraparle la ropa.

Detúvose, y mirando a todo el círculo del horizonte, parecía impaciente y desasosegado. Sin duda no tenía gran confianza en la exactitud de su itinerario y aguardaba el paso de algún aldeano que le diese buenos informes topográficos para llegar pronto y derechamente a su destino.

—No puedo equivocarme —murmuró—. Me dijeron que atravesara el río por la pasadera… así lo hice. Después que marchara adelante, siempre adelante. En efecto, allá, detrás de mí queda esa apreciable villa, a quien yo llamaría *Villafangosa* por el buen surtido de lodos que hay en sus calles y caminos… De modo que por aquí, adelante, siempre adelante (me gusta esta frase, y si yo tuviera escudo no le pondría otra divisa) he de llegar a las famosas minas de Socartes [:ref{id="plano" case="lower"}].

Después de andar largo trecho, añadió:

—Me he perdido, no hay duda de que me he perdido… Aquí tienes, Teodoro Golfín, el resultado de tu «adelante, siempre adelante». Estos palurdos no conocen el valor de las palabras. O han querido burlarse de ti, o ellos mismos ignoran dónde están las minas de Socartes. Un gran establecimiento minero ha de anunciarse con edificios, chimeneas, ruido de arrastres, resoplido de hornos, relincho de caballos, trepidación de máquinas, y yo no veo, ni huelo, ni oigo nada… Parece que estoy en un desierto… ¡qué soledad! Si yo creyera en brujas, pensaría que mi destino me proporcionaba esta noche el honor de ser presentado a ellas… ¡Demonio!, ¿pero no hay gente en estos lugares?… Aún falta media hora para la salida de la luna. ¡Ah!, bribona, tú tienes la culpa de mi extravío… Si al menos pudiera conocer el sitio donde me encuentro… ¿Pero qué más da? (Al decir esto, hizo un gesto propio del hombre esforzado que desprecia los peligros). Golfín, tú que has dado la vuelta al mundo, ¿te acobardarás ahora?… ¡Ah!, los aldeanos tenían razón: adelante, siempre adelante. La ley universal de la locomoción no puede fallar en este momento.

Y puesta denodadamente en ejecución aquella osada ley, recorrió un kilómetro, siguiendo a capricho las veredas que le salían al paso y se cruzaban y se quebraban en ángulos mil, cual si quisiesen engañarle y confundirle más. Por grande que fuera su resolución e intrepidez, al fin tuvo que pararse. Las veredas, que al principio subían, luego empezaron a bajar, enlazándose; y al fin bajaron tanto, que nuestro viajero hallose en un talud, por el cual solo habría podido descender echándose a rodar.

—¡Bonita situación! —exclamó sonriendo y buscando en su buen humor lenitivo a la enojosa contrariedad—. ¿En dónde estás, querido Golfín? Esto parece un abismo. ¿Ves algo allá abajo? Nada, absolutamente nada… pero el césped ha desaparecido, el terreno está removido. Todo es aquí pedruscos y tierra sin vegetación, teñida por el óxido de hierro… Sin duda estoy en las minas… pero ni alma viviente, ni chimeneas humeantes, ni ruido, ni un tren que murmure a lo lejos, ni siquiera un perro que ladre… ¿Qué haré?, hay por aquí una vereda que vuelve a subir. ¿Seguirela? ¿Desandaré lo andado?… ¡Retroceder! ¡Qué absurdo! O yo dejo de ser quien soy, o llegaré esta noche a las famosas minas de Socartes y abrazaré a mi querido hermano. Adelante, siempre adelante.

Dio un paso y hundiose en la frágil tierra movediza.

—¿Esas tenemos, señor planeta?… ¿Conque quiere usted tragarme?… Si ese holgazán satélite quisiera alumbrar un poco, ya nos veríamos las caras usted y yo… Y a fe que por aquí abajo no hemos de ir a ningún paraíso. Parece esto el cráter de un volcán apagado… Hay que andar suavemente por tan delicioso precipicio. ¿Qué es esto? ¡Ah! Una piedra; magnífico asiento para echar un cigarro, esperando a que salga la luna.

El discreto Golfín se sentó tranquilamente como podría haberlo hecho en el banco de un paseo; y ya se disponía a fumar, cuando sintió una voz… sí, indudablemente era una voz humana que lejos sonaba, un quejido patético, mejor dicho, melancólico canto, formado de una sola frase, cuya última cadencia se prolongaba apianándose en la forma que los músicos llamaban *morendo*, y que se apagaba al fin en el plácido silencio de la noche, sin que el oído pudiera apreciar su vibración postrera.

:::space{lines=2}

:::paragraphs{style="asterismo"}
\*  \*  \*
:::

:::paragraphs{style="nota"}
⁠1878. Galdós publica *Marianela* en Madrid, en la Imprenta y Litografía de La Guirnalda. Seguimos el comienzo de su capítulo primero en el texto de dominio público de Project Gutenberg (eBook 17340), con la ortografía y la puntuación actuales: raya en los diálogos y comillas latinas para la consigna del viajero, que se vuelven inglesas cuando la cita va dentro de otra: «el resultado de tu “adelante, siempre adelante”». Los corchetes señalan lo que añade el editor.
:::

:::paragraphs{style="colofon"}
Compuesto en Gentium Book Plus, Libre Bodoni y Marcellus SC (SIL OFL)
:::
`; // content.es.md, inlined by the Cookbook

// #region art: the map of Socartes, in millimetres at its printed size, in the palette
function mulberry32(seed) { // a seeded PRNG: the same drawing on every run
  return () => {
    seed = (seed + 0x6d2b79f5) | 0;
    let r = Math.imul(seed ^ (seed >>> 15), 1 | seed);
    r = (r + Math.imul(r ^ (r >>> 7), 61 | r)) ^ r;
    return ((r ^ (r >>> 14)) >>> 0) / 4294967296;
  };
}
const mix = (hex, other, k) => `#${[1, 3, 5].map((i) => Math.round(
  parseInt(hex.slice(i, i + 2), 16) * (1 - k) + parseInt(other.slice(i, i + 2), 16) * k)
  .toString(16).padStart(2, '0')).join('')}`;
const n2 = (v) => +v.toFixed(2);
// A smooth path through the points (Catmull-Rom as cubic Béziers), open or closed.
function smooth(list, close = false) {
  const p = close ? [list.at(-1), ...list, list[0], list[1]] : [list[0], ...list, list.at(-1)];
  let d = `M${n2(p[1][0])} ${n2(p[1][1])}`;
  for (let i = 1; i < p.length - 2; i++) {
    const [a, b, c, e] = [p[i - 1], p[i], p[i + 1], p[i + 2]];
    d += `C${n2(b[0] + (c[0] - a[0]) / 6)} ${n2(b[1] + (c[1] - a[1]) / 6)} `
      + `${n2(c[0] - (e[0] - b[0]) / 6)} ${n2(c[1] - (e[1] - b[1]) / 6)} ${n2(c[0])} ${n2(c[1])}`;
  }
  return close ? `${d}Z` : d;
}
async function labelFace() { // Marcellus SC inside the SVG (gotcha: svg-no-webfonts)
  const url = 'https://cdn.jsdelivr.net/npm/@fontsource/marcellus-sc@5/files/'
    + 'marcellus-sc-latin-400-normal.woff2';
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Label face not found (${res.status}): ${url}`);
  const bytes = new Uint8Array(await res.arrayBuffer());
  let bin = '';
  for (let i = 0; i < bytes.length; i += 8192) {
    bin += String.fromCharCode(...bytes.subarray(i, i + 8192));
  }
  return `@font-face{font-family:L;src:url(data:font/woff2;base64,${btoa(bin)}) format('woff2')}`;
}
function drawMap(face, W, H) { // drawn for W 86 × H 112: the mines above, the town below
  const rnd = mulberry32(1878);
  const C = {
    ground: mix(palette.paper, palette.moss, 0.16), hill: mix(palette.moss, palette.paper, 0.45),
    wood: palette.moss, shade: mix(palette.moss, palette.ink, 0.35),
    earth: mix(palette.slag, palette.paper, 0.3), bench: palette.slag,
    deep: mix(palette.slag, palette.ink, 0.2), pit: mix(palette.slag, palette.ink, 0.45),
    edge: mix(palette.slag, palette.ink, 0.5),
    water: palette.water, ink: palette.ink, path: palette.muted, route: palette.oxblood,
    stream: mix(palette.water, palette.ink, 0.3), // the river's name: 5.7:1 on the ground
  };
  const out = [`<rect width="${W}" height="${H}" fill="${C.ground}"/>`];
  const fill = (d, color) => out.push(`<path d="${d}" fill="${color}"/>`);
  const stroke = (d, color, w, extra = '') => out.push(`<path d="${d}" fill="none" `
    + `stroke="${color}" stroke-width="${w}" stroke-linecap="round" `
    + `stroke-linejoin="round"${extra}/>`);
  // The names, set first so that no tree grows over them.
  const labels = [[33, 30.5, 'minas de', 'end'], [33, 34, 'Socartes', 'end'],
    [34.4, 19, 'talleres', 'end'],
    [43.6, 52.4, 'talud', 'end', C.route], [12, 70.5, 'cerro', 'middle'],
    [25.5, 96.4, 'pasadera'], [70, 94.5, 'río', 'middle', C.stream],
    [3, 109.6, 'Villafangosa'], [5, 11.4, 'N', 'middle']];
  const box = ([x, y, text, anchor = 'start']) => {
    const w = text.length * 1.45;
    const left = anchor === 'end' ? x - w : anchor === 'middle' ? x - w / 2 : x;
    return [left - 0.8, y - 2.6, left + w + 0.8, y + 0.8];
  };
  const clear = (x, y) => labels.map(box).every(([a, b, c, d]) => x < a || x > c || y < b || y > d);
  // The mines: iron-stained earth cut in benches down to the pit, the "extinct crater".
  const mine = [[40, 6], [58, 3], [76, 5], [84, 17], [83, 35], [74, 47], [58, 52], [45, 50],
    [36, 40], [35, 20]];
  [[1, C.earth], [0.76, C.bench], [0.52, C.deep], [0.28, C.pit]].forEach(([k, color], i) => {
    const [cx, cy] = [60 + i * 1.6, 27 - i * 1.4]; // each bench deeper, the pit off-centre
    const ring = mine.map(([x, y]) => [cx + (x - 60) * k + (rnd() - 0.5) * 2.4 * k,
      cy + (y - 27) * k + (rnd() - 0.5) * 2.4 * k]);
    out.push(`<path d="${smooth(ring, true)}" fill="${color}" stroke="${C.edge}" `
      + 'stroke-width="0.25"/>');
  });
  fill('M28.4 11.6h6.5v3.2h-6.5zM33 7h0.9v4.7h-0.9z', C.ink); // workshops, chimney, by the rim
  // The hill of cherry, beech and oak, and the paths that cross it at a thousand angles.
  out.push(`<path d="${smooth([[19, 73], [23, 61], [36, 56], [50, 59], [55, 72], [49, 85],
    [35, 90], [23, 84]], true)}" fill="${C.hill}" stroke="${C.shade}" stroke-width="0.25"/>`);
  for (let i = 0; i < 100; i++) {
    const a = rnd() * Math.PI * 2;
    const r = Math.sqrt(rnd()) * 16;
    const [x, y] = [37 + Math.cos(a) * r, 73 + Math.sin(a) * r];
    const [size, shade] = [0.55 + rnd() * 0.55, rnd() < 0.3 ? C.shade : C.wood];
    if (clear(x, y)) {
      out.push(`<circle cx="${n2(x)}" cy="${n2(y)}" r="${n2(size)}" fill="${shade}"/>`);
    }
  }
  [[[22, 80], [30, 74], [28, 64], [38, 58]], [[26, 62], [36, 70], [46, 64], [52, 70]],
    [[27, 87], [33, 79], [42, 82], [50, 76]], [[38, 57], [40, 67], [33, 76], [37, 89]]]
    .forEach((path) => stroke(smooth(path), C.path, 0.3, ' stroke-dasharray="1 0.8"'));
  // The river, the footbridge, and the town the traveller left behind.
  stroke(smooth([[0, 92], [12, 93], [22, 99], [34, 100], [50, 96], [66, 98], [W + 1, 102]]),
    C.water, 2.4);
  stroke('M20.4 95.2L18.6 101.2', C.ink, 0.7);
  for (let i = 0; i < 18; i++) {
    const [x, y] = [3 + (i % 6) * 2.2 + rnd() * 0.5, 98.6 + Math.floor(i / 6) * 2.3 + rnd() * 0.5];
    fill(`M${n2(x)} ${n2(y)}h1.5v1.2h-1.5z`, C.ink);
  }
  fill('M5.2 94.4h1v2.4h-1zM4 96.2h3.4v2h-3.4z', C.ink); // the church
  // Golfín's walk: over the footbridge, up the hill by its paths, down to the edge.
  stroke(smooth([[12, 101], [17, 99.4], [21, 94], [25, 88], [31, 84], [27, 78], [33, 72],
    [40, 75], [45, 68], [40, 62], [45.3, 53.6]]), C.route, 0.75,
  ' stroke-dasharray="0.05 1.3"');
  out.push(`<circle cx="46.4" cy="51.6" r="1.4" fill="none" stroke="${C.route}" `
    + 'stroke-width="0.6"/>');
  // North, up: a half-inked arrowhead over an N.
  fill('M5 3.2L6.6 8.2L5 7.2Z', C.ink);
  out.push(`<path d="M5 3.2L3.4 8.2L5 7.2Z" fill="none" stroke="${C.ink}" stroke-width="0.2"/>`);
  labels.forEach(([x, y, text, anchor = 'start', color = C.ink]) => out.push(`<text x="${x}" `
    + `y="${y}" text-anchor="${anchor}" fill="${color}">${text}</text>`));
  out.push(`<rect x="0.2" y="0.2" width="${W - 0.4}" height="${H - 0.4}" fill="none" `
    + `stroke="${C.ink}" stroke-width="0.4"/>`);
  return `<svg xmlns="http://www.w3.org/2000/svg" width="${W}mm" height="${H}mm" `
    + `viewBox="0 0 ${W} ${H}"><style>${face}text{font-family:L;font-size:2.35px}</style>`
    + `${out.join('')}</svg>`;
}
// #endregion

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = { // every face the pages use, loaded before the build (gotcha: fonts-first)
  'Gentium Book Plus': ['400', '400i', '700'], // text, captions (700: 'Figura 1.'), the note
  'Libre Bodoni': ['400', '400i', '700'], // asterisks, the chapter's title, the initial
  'Marcellus SC': ['400'], // chapter label, plate name, running heads
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
await loadFonts(FONTS, markdown);
await loadSvg('plano.svg', drawMap(await labelFace(), MEASURE, MAP_H));
// The map is book page 8, a verso, facing chapter I: folios and parity follow the book.
const continuation = { pageIndexOffset: 7, pageNumbering: { startAt: 8 } };
const doc = await buildWithFonts(
  () => buildDocument({ markdown, resources, continuation }, config()), markdown);
showPages(doc, { title: 'Español justificado en una novela de bolsillo' });

Kit · core, fonts, viewer, images: igual a totes les receptes · 270 línies
// ─── 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 · images v1 ── 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 (drawn in code, or fetched) as a vector image. */
async function loadSvg(fileId, svg) {
  const img = new Image();
  img.src = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svg)}`;
  await img.decode();
  registerResourceImage(fileId, img);
  (loadImage.bytes ??= new Map()).set(fileId, new TextEncoder().encode(svg));
}

/** 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 ───────────────────────────────────────────────────────────────────────