Carta de bistrot: preus alineats sense tabuladors

// ═══ Postext Cookbook · Nº 052 · Bistro menu: prices aligned without tab stops ═══════
// https://postext.dev/en/cookbook/bistro-menu
// Code: MIT · Text: original, in French (CC BY 4.0) · Drawings: generated in code (CC BY 4.0)
// Fonts: Limelight, Noticia Text, Josefin Sans (SIL OFL 1.1) · Needs postext ≥ 1.4.1
// The autumn menu of an imaginary Paris bistro: two sides of one card, every price column a
// table with its rules switched off.
import { buildDocument, renderPageToCanvas, clearMeasurementCache, registerResourceImage,
  parseTSV, mergeCells } from 'https://esm.sh/postext';

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

// ─── 1 · Design ─────────────────────────────────────────────────────────────
const palette = { ink: '#1f2a24', paper: '#f6efdf', // green-black text on cream card
  wine: '#6d1f2c', brass: '#a9823a', // the name, heads and labels; rules and the drawings' metal
  straw: '#e8d4a8', bottle: '#2f4235', sage: '#8a9a78', // awning stripes and labels; glass
  muted: '#6b6457' }; // the colophon
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
// The engine's defaults link to 'main-color' (#295aa3, a blue); this palette makes it the wine red.
const colorPalette = Object.entries({ ...palette, 'main-color': palette.wine })
  .map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } }));
const [TEXT, DISPLAY, LABEL] = ['Noticia Text', 'Limelight', 'Josefin Sans'];
const [BODY, LEAD] = [10.5, 14.5]; // pt: the text, and the leading every table row keeps

// #region answer: dish on the left, price flush right: a two-column table with no rules
// Postext has no tab stops, so each course is a table. The document's tableStyle turns off
// every rule and fill, so nothing on the page shows that a table is there. The wine list's head
// row and merged region rows are in #region wines.
const tableStyle = { rules: 'none', cellPadding: pt(LEAD / 4), // a dish: 2½ lines of LEAD
  bodyFontFamily: TEXT, bodyFontSize: pt(BODY), bodyColor: col('ink'),
  headerFontFamily: LABEL, headerFontSize: pt(8.5), headerColor: col('wine'),
  headerBackgroundEnabled: false }; // header cells: the wine list's labels
// The kitchen keeps the menu as TSV: course · dish · the dish in the reader's language · price.
function course(id, tsv) {
  const rows = parseTSV(tsv).rows.filter(([c]) => c.content === id)
    .map(([, dish, translation, price]) => [
      { content: `${dish.content}\n*${translation.content}*` }, // one cell, two lines
      // Both cells start at the top of the row, so the price shares the dish's first baseline.
      { content: `**${price.content}**`, align: 'right' },
    ]);
  // columnWidths are weights: the price column takes 1/7 of the 158 mm measure, 22.6 mm.
  return piece(id, 'table', { table: { model: { rows, columnWidths: [6, 1] } } });
}
// #endregion

// #region type: one resource type for the whole card: set where it stands, never numbered
// No caption prefix and no caption, so no 'Table 1' line prints under a course. Placement
// 'here' sets each piece at its ::resource line; such a table never splits, so a course that
// outgrows the page moves to the next one whole (gotcha: here-table-no-split).
const resourceTypes = [{ id: 'menu', name: 'Menu', shortLabel: 'Menu', captionPrefix: '',
  numberingTemplate: '{n}', resetOn: 'never', counterFormat: 'decimal',
  defaultPlacement: { position: 'here' } }];
const piece = (id, kind, body) => ({ id, typeId: 'menu', kind, createdAt: 0, updatedAt: 0,
  ...body });
// #endregion

// #region wines: region rows merged across the three columns, prices under their labels
function wineList(tsv) {
  let m = { ...parseTSV(tsv), headerRowCount: 1, columnWidths: [5, 1, 1] };
  m.rows = m.rows.map((row, r) => row.map((cell, c) => (c === 0 ? cell : { align: 'right',
    content: r > 0 && cell.content ? `**${cell.content}**` : cell.content }))); // as the dishes'
  m.rows.forEach(([first, ...rest], r) => { // a line with one field names a region
    if (r === 0 || !first.content || rest.some((cell) => cell.content)) return;
    // One cell across the table, centred on the card like the course heads; a label centred
    // in the first column alone would sit 22.6 mm left of them. The label face is the header's.
    m.rows[r][0] = { ...first, isHeader: true, align: 'center' };
    // mergeCells marks the two cells it covers hiddenBy (gotcha: merged-cells-hiddenby).
    m = mergeCells(m, { start: { row: r, col: 0 }, end: { row: r, col: 2 } });
  });
  return piece('wines', 'table', { table: { model: m } });
}
// #endregion

// #region heads: a course head: its title centred, a brass rule anchored to each side of it
// The title has no width, so it shrink-wraps its text, and 'top' centres it on the column. Each
// rule hangs off one edge of the title ('left-of', 'right-of'), 4 mm away, and 'fill' runs it
// to the column's edge: 66.7 mm beside PLATS, 56.2 mm beside the longer LE COMPTOIR.
const rule = (edge, x) => ({ kind: 'rule', id: `rule-${edge}`, color: col('brass'),
  thickness: pt(0.75), // required in 1.4.1: a rule without it paints nothing
  placement: { anchor: { to: '#title', edge },
    size: { width: 'fill' }, // to the column's edge
    offset: { x: mm(x), y: pt(6) } } }); // 6 pt down: the middle of Limelight's capitals
const courseHead = { enabled: true, slot: { elements: [
  { kind: 'text', id: 'title', content: '{titleText}', fontFamily: DISPLAY, fontSize: pt(15),
    lineHeight: 0.96, // a multiple (gotcha: design-lineheight-multiple): 14.4 pt, one line
    textTransform: 'uppercase', color: col('wine'),
    placement: { anchor: { to: 'container', edge: 'top' } } },
  rule('left-of', -4), rule('right-of', 4),
] } };
// #endregion

// #region badges: dietary badges as chips, explained in small type under the desserts
// A chip is a box around inline text: the V disc is filled, the SG pill only outlined. A chip
// takes the weight of the text around it, so without bold the V is set in 400, a weight not loaded.
const badge = { fontFamily: LABEL, fontSize: pt(7.5), bold: true, // Josefin Sans 700
  borderRadius: pt(8), paddingY: em(0.1), gap: em(0.6) }; // radius clamped to a half-height
const chipStyles = [
  // V: paddingX makes the box as wide as it is tall, a disc. borderWidth 0 removes the default
  // outline, 0.5 pt of main-color, which would ring the green in wine red.
  { id: 'veg', name: 'Vegetarian', ...badge, paddingX: em(0.3), borderWidth: pt(0),
    background: col('bottle'), color: col('paper') },
  { id: 'gf', name: 'Gluten-free', ...badge, paddingX: em(0.45), backgroundEnabled: false,
    borderColor: col('bottle'), borderWidth: pt(0.6), color: col('bottle') },
];
// The notes under the desserts and the colophon on the back: smaller, on the card's axis.
// marginTop gives the line of air that a table set 'here' does not leave below itself.
const paragraphStyles = [
  { id: 'notes', name: 'Notes', fontSize: pt(9), marginTop: pt(LEAD) },
  { id: 'colophon', name: 'Colophon', fontSize: pt(7.5), color: col('muted'),
    marginTop: pt(LEAD) },
];
// #endregion

// #region centred: one axis for the card: the name, the course heads and the notes centred
// bodyText (in config) centres the lines under the name and the notes; only the tables keep a
// left edge. A centred line is never hyphenated (gotcha: ragged-no-hyphenation), so the config
// sets no locale: French patterns would change nothing on this card.
const headings = { fontFamily: DISPLAY, fontWeight: 400, color: col('wine'), textAlign: 'center',
  levels: [ // Limelight ships one weight, 400, and no italic
    // Any headings object drops the H1 break (gotcha: headings-drop-h1-break). Stated off, since
    // a break before an H1 would part the name from the awning and La Cave from its bottles.
    { level: 1, fontSize: pt(48), lineHeight: pt(3 * LEAD), breakBefore: { enabled: false },
      marginTop: pt(LEAD), marginBottom: pt(0) }, // three grid lines, one of air above
    { level: 2, lineHeight: pt(LEAD), advancedDesign: courseHead, // one line; #region heads
      marginTop: pt(LEAD), marginBottom: pt(0) }, // the table below adds a line of its own
  ] };
// #endregion

// #region art: a striped awning over the name, a shelf of bottles over the wine list
function awning() { // 158 × 20 mm; the canopy narrows 6 % toward the wall
  const [W, N, ROD, DROP, HEM, INSET] = [1660, 19, 12, 104, 46, 50];
  const s = W / N, top = (i) => INSET + i * (W - 2 * INSET) / N, bottom = (i) => i * s;
  const shade = { [palette.wine]: mix(palette.wine, palette.ink, 0.25), // the valance: each
    [palette.straw]: mix(palette.straw, palette.brass, 0.4) }; // stripe a shade darker
  let shapes = '';
  for (let i = 0; i < N; i++) {
    const fill = i % 2 ? palette.straw : palette.wine, y = ROD + DROP;
    shapes += `<path d="M${top(i)} ${ROD}H${top(i + 1)}L${bottom(i + 1)} ${y}H${bottom(i)}Z" `
      + `fill="${fill}"/><path d="M${bottom(i)} ${y}h${s}v${HEM}a${s / 2} ${s / 2} 0 0 1 `
      + `${-s} 0Z" fill="${shade[fill]}"/>`;
  }
  shapes += `<rect x="${INSET - 16}" y="0" width="${W - 2 * INSET + 32}" height="${ROD}" rx="6" `
    + `fill="${palette.brass}"/><rect x="0" y="${ROD + DROP - 3}" width="${W}" height="6" `
    + `fill="${palette.brass}"/>`; // the rod on the wall, a brass bead along the front edge
  return `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${W} 212" width="${W}" `
    + `height="212">${shapes}</svg>`;
}
function mix(a, b, t) { // a blend of two palette colours, t of the way from a to b
  const rgb = (hex) => [1, 3, 5].map((i) => parseInt(hex.slice(i, i + 2), 16));
  const [x, y] = [rgb(a), rgb(b)];
  return `#${x.map((v, i) => Math.round(v + (y[i] - v) * t).toString(16).padStart(2, '0'))
    .join('')}`;
}
function bottles() { // 158 × 29 mm: glasses, bottles and a carafe on a brass shelf
  const [W, H, BASE] = [1660, 300, 286];
  const glass = (x) => // a tulip glass, a third full
    `<path d="M${x - 34} ${BASE - 170}C${x - 36} ${BASE - 110} ${x - 20} ${BASE - 88} ${x} `
      + `${BASE - 86}C${x + 20} ${BASE - 88} ${x + 36} ${BASE - 110} ${x + 34} ${BASE - 170}Z" `
      + `fill="none" stroke="${palette.bottle}" stroke-width="4"/>`
      + `<path d="M${x - 33} ${BASE - 132}C${x - 30} ${BASE - 104} ${x - 16} ${BASE - 91} ${x} `
      + `${BASE - 90}C${x + 16} ${BASE - 91} ${x + 30} ${BASE - 104} ${x + 33} ${BASE - 132}Z" `
      + `fill="${palette.wine}"/>`
      + `<rect x="${x - 2.5}" y="${BASE - 88}" width="5" height="82" fill="${palette.bottle}"/>`
      + `<ellipse cx="${x}" cy="${BASE - 5}" rx="30" ry="5" fill="${palette.bottle}"/>`;
  const bottle = (x, h, w, shoulder, body, foil) => { // straight or sloping shoulders
    const neck = 13, top = BASE - h, sh = BASE - h * 0.62;
    return `<path d="M${x - w} ${BASE}V${sh}C${x - w} ${sh - shoulder} `
      + `${x - neck} ${sh - shoulder} ${x - neck} ${sh - shoulder * 1.6}`
      + `V${top + 6}Q${x - neck} ${top} ${x - neck + 6} ${top}`
      + `H${x + neck - 6}Q${x + neck} ${top} ${x + neck} ${top + 6}V${sh - shoulder * 1.6}`
      + `C${x + neck} ${sh - shoulder} ${x + w} ${sh - shoulder} ${x + w} ${sh}V${BASE}Z" `
      + `fill="${body}"/>`
      + `<rect x="${x - neck - 1}" y="${top}" width="${2 * neck + 2}" height="${h * 0.16}" `
      + `rx="4" fill="${foil}"/>`
      + `<rect x="${x - w + 8}" y="${BASE - h * 0.44}" width="${2 * w - 16}" height="${h * 0.26}" `
      + `fill="${palette.straw}"/>`
      + `<rect x="${x - w + 8}" y="${BASE - h * 0.3}" width="${2 * w - 16}" height="6" `
      + `fill="${foil}"/>`;
  };
  const carafe = (x) => `<path d="M${x - 16} ${BASE - 200}H${x + 16}V${BASE - 150}`
    + `C${x + 70} ${BASE - 120} ${x + 76} ${BASE - 20} ${x + 44} ${BASE}H${x - 44}`
    + `C${x - 76} ${BASE - 20} ${x - 70} ${BASE - 120} ${x - 16} ${BASE - 150}Z" fill="none" `
    + `stroke="${palette.bottle}" stroke-width="4"/>`
    + `<path d="M${x - 64} ${BASE - 74}C${x - 70} ${BASE - 30} ${x - 58} ${BASE - 8} ${x - 42} `
    + `${BASE - 4}H${x + 42}C${x + 58} ${BASE - 8} ${x + 70} ${BASE - 30} ${x + 64} ${BASE - 74}Z" `
    + `fill="${palette.wine}"/>`;
  const C = W / 2;
  const art = glass(C - 330) + bottle(C - 225, 250, 38, 12, palette.bottle, palette.wine)
    + bottle(C - 125, 262, 42, 34, palette.sage, palette.brass) + carafe(C)
    + bottle(C + 125, 256, 44, 36, palette.bottle, palette.brass)
    + bottle(C + 225, 250, 38, 12, palette.bottle, palette.wine) + glass(C + 330)
    + `<rect x="${C - 420}" y="${BASE}" width="840" height="6" fill="${palette.brass}"/>`;
  return `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${W} ${H}" width="${W}" `
    + `height="${H}">${art}</svg>`;
}
// #endregion

const config = () => ({ // a factory, never a shared object (gotcha: config-cache-identity)
  colorPalette, tableStyle, resourceTypes,
  page: { sizePreset: 'custom', width: mm(230), height: mm(310), dpi: 150,
    backgroundColor: col('paper'), // one card, printed both sides: margins are not mirrored
    margins: { top: mm(22), bottom: mm(20), left: mm(36), right: mm(36) } },
  layout: { layoutType: 'single' },
  bodyText: { fontFamily: TEXT, fontSize: pt(BODY), lineHeight: pt(LEAD), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), // both default to main-color, the wine red
    textAlign: 'center', firstLineIndent: mm(0) }, // the lines under the name and the notes
  headings, // the card's axis (#region centred)
  chipStyles, paragraphStyles, // the badges and the small print (#region badges)
  header: { elements: [] }, footer: { elements: [] }, // a menu has no running heads or folios
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Mostra en Markdown · 46 línies · content.es.md
title: "Les Tanneurs"
---

::resource{id="awning"}

# Les Tanneurs

*Bistrot parisien depuis 1931*

Carte d’automne 2026 · *carta de otoño*

## Entrées

::resource{id="entrees"}

## Plats

::resource{id="plats"}

## Desserts

::resource{id="desserts"}

:::paragraphs{style="notes"}
:chip[V]{style="veg"} Plat végétarien · *vegetariano* · :chip[SG]{style="gf"} Sans gluten · *sin gluten*

Bœuf d’origine France · *vacuno francés* · Prix nets, service compris · *servicio incluido*
:::

:::pagebreak

::resource{id="bottles"}

# La Cave

Vins au verre et à la bouteille · *vinos por copa y por botella*

::resource{id="wines"}

## Le Comptoir

::resource{id="counter"}

:::paragraphs{style="colophon"}
Compuesto en Limelight, Noticia Text y Josefin Sans (SIL OFL) · Les Tanneurs es un bistró imaginario · Texto y dibujos CC BY 4.0
:::
`; // the two sides of the card, in French
const dishes = String.raw`entrees	**Œuf mayonnaise**, cornichons de la maison :chip[V]{style="veg"} :chip[SG]{style="gf"}	Huevo con mayonesa, pepinillos de la casa	7
Mostra en Markdown · 15 línies · content.carte.es.md
entrees	**Velouté de potimarron**, crème crue, noisettes torréfiées :chip[V]{style="veg"} :chip[SG]{style="gf"}	Crema de calabaza, nata fresca, avellanas tostadas	9
entrees	**Terrine de campagne** au poivre vert, pain grillé	Terrina de campaña a la pimienta verde, pan tostado	11
entrees	**Poireaux vinaigrette**, œuf mimosa :chip[V]{style="veg"} :chip[SG]{style="gf"}	Puerros a la vinagreta, huevo mimosa	10
plats	**Blanquette de veau** à l’ancienne, riz pilaf	Blanqueta de ternera a la antigua, arroz pilaf	24
plats	**Paleron de bœuf** braisé au vin rouge, carottes fondantes	Aguja de vacuno guisada al vino tinto, zanahorias melosas	26
plats	**Filet de lieu jaune**, beurre blanc, poireaux fondus :chip[SG]{style="gf"}	Filete de abadejo, beurre blanc, puerros pochados	27
plats	**Risotto aux cèpes**, mascarpone et sauge :chip[V]{style="veg"} :chip[SG]{style="gf"}	Risotto de boletus, mascarpone y salvia	22
desserts	**Tarte fine aux pommes**, crème fraîche	Tarta fina de manzana, crème fraîche	10
desserts	**Mousse au chocolat noir**	Mousse de chocolate negro	9
desserts	**Île flottante**, pralines roses	Isla flotante, garrapiñadas rosas	9
desserts	**Trois fromages affinés**, confiture de cerises noires	Tres quesos curados, confitura de cereza negra	12
counter	**Kir** au vin blanc et cassis	Vino blanco con licor de grosella negra	6
counter	**Pastis**, carafe d’eau fraîche	Pastís con una jarra de agua fría	5
counter	**Bière à la pression**, 25 cl	Cerveza de barril, 25 cl	5
counter	**Café**, noisette ou allongé	Café solo, cortado o largo	3
`; // TSV: course · dish · translation · price
const wines = String.raw`Appellation · cépage	12 cl	75 cl
Mostra en Markdown · 16 línies · content.cave.en.md
BULLES
**Crémant de Loire** brut · *chenin blanc*	9	44

BLANCS
**Muscadet Sèvre-et-Maine** sur lie 2023 · *melon de Bourgogne*	7	32
**Mâcon-Villages** 2022 · *chardonnay*	9	40
**Sancerre** 2023 · *sauvignon blanc*	11	52
**Chablis** 2022 · *chardonnay*	12	58

ROUGES
**Côtes-du-Rhône** 2022 · *grenache, syrah*	7	32
**Saumur-Champigny** 2022 · *cabernet franc*	9	42
**Morgon** 2022 · *gamay*	10	46
**Bordeaux supérieur** 2020 · *merlot, cabernet sauvignon*	8	38
**Saint-Joseph** 2021 · *syrah*	12	56
**Saint-Émilion grand cru** 2018 · *merlot, cabernet franc*	—	78
`; // TSV: head row, regions, wines; one file for both editions
const resources = [
  piece('awning', 'svg', { svg: { fileId: 'awning.svg', width: 1660, height: 212 },
    altText: 'A striped wine-red and straw awning on a brass rod.' }),
  piece('bottles', 'svg', { svg: { fileId: 'bottles.svg', width: 1660, height: 300 },
    altText: 'Two glasses of red wine, four bottles and a carafe on a brass shelf.' }),
  course('entrees', dishes), course('plats', dishes), course('desserts', dishes),
  wineList(wines), course('counter', dishes),
];

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
// Every face the pages paint, loaded before the first build (gotcha: fonts-first).
const FONTS = { 'Noticia Text': ['400', '400i', '700'], Limelight: ['400'],
  'Josefin Sans': ['700'] };

// ─── 4 · Build & show ───────────────────────────────────────────────────────
const allText = markdown + dishes + wines;
await loadFonts(FONTS, allText);
await loadSvg('awning.svg', awning());
await loadSvg('bottles.svg', bottles());
const doc = await buildWithFonts(() => buildDocument({ markdown, resources }, config()), allText);
showPages(doc, { title: t({ en: 'Les Tanneurs: autumn menu',
  es: 'Les Tanneurs: carta de otoño' }) });

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 ───────────────────────────────────────────────────────────────────────