Catàleg de venda per correu amb imatges a les cel·les

// ═══ Postext Cookbook · Nº 036 · Mail-order catalogue with pictures in cells ═══════
// https://postext.dev/en/cookbook/seed-catalogue
// Code: MIT · Text: original (CC BY 4.0) · Pictures: diffusion models
// Fonts: Gelasio, Alfa Slab One, Cabin Condensed (SIL OFL 1.1) · Needs postext ≥ 1.4.1
// A fictional seed farm's spring list: a table read from TSV, a packet pictured in each row.
import { buildDocument, renderPageToCanvas, clearMeasurementCache, registerResourceImage,
  parseTSV, mergeCells, setAlignment, setCellBackground, setCellContent, setCellImage,
} from 'https://esm.sh/postext';

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

// ─── 1 · Design ─────────────────────────────────────────────────────────────
const palette = { // eight named colours; every colour in the config links to one of them
  ink: '#2d2620', paper: '#f0e2c4', // brown-black text on buff
  cream: '#fcf7ea', tomato: '#c23b22', // cells to write in; the accent: bands, titles, NEW
  basil: '#2f6b3b', sun: '#e8b53a', // rules, ORGANIC, the form's head; the cover's banner
  rule: '#c7ae86', muted: '#6d5f50', // hairlines; running heads and notes
};
// 1.4.1 designs read the hex, not paletteId: col() sets both (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' } }));

const TRIM = { w: 190, h: 250 }; // mm: a stapled mail-order booklet
const MARGIN = { top: 22, bottom: 20, inner: 18, outer: 15 }; // mm, mirrored: 157 mm wide
const LEAD = 13; // pt: the body leading, the grid the headings keep to
const TEXT = 'Gelasio', DISPLAY = 'Alfa Slab One', LABEL = 'Cabin Condensed';
const PACKET = 0.55; // the packet picture's share of its cell's inner width
const caps = (size, fontWeight = 600) => ({ fontFamily: LABEL, fontSize: pt(size), fontWeight,
  letterSpacing: pt(size * 0.18), textTransform: 'uppercase' });
const on = (to, edge, x, y, size) => ({ anchor: { to, edge }, offset: { x: mm(x), y: mm(y) },
  ...(size && { size }) });
const text = (id, content, placement, style) => ({ kind: 'text', id, content, placement,
  overflow: 'wrap', ...style }); // not '…' (gotcha: overflow-ellipsis-default)
const chip = (id, size, ink, box) => ({ id, fontFamily: LABEL, bold: true, fontSize: em(size),
  color: col(ink), borderRadius: pt(1.2), ...box });
const rule = (id, below, gap, thickness) => ({ kind: 'rule', id, direction: 'horizontal',
  thickness: pt(thickness), color: col('basil'),
  placement: { ...on(`#${below}`, 'below', 0, gap), size: { width: 'fill' } } });

// #region answer: a price list from TSV: a packet in each variety's cell, kinds merged down
const at = (row, c) => ({ row, col: c });
const slug = (name) => name.toLowerCase().replace(/\W+/g, '-'); // 'Gold Medal' → 'gold-medal'
function priceList(tsv) { // Kind · Variety · Description · Packet · Ounce, under one head row
  let m = { ...parseTSV(tsv), headerRowCount: 1, columnWidths: [20, 40, 63, 17, 17] }; // mm
  for (const c of [0, 1]) m = setAlignment(m, at(0, c), 'center'); // each head over its column
  for (const c of [3, 4]) m = setAlignment(m, at(0, c), 'right');
  for (let r = 1; r < m.rows.length; r++) {
    // The picture is a resource of its own; the cell sets it at the top, centred, with the
    // variety's name under it, and the row grows to hold both.
    const variety = m.rows[r][1].content;
    m = setCellImage(m, at(r, 1), { resourceId: slug(variety), width: PACKET });
    m = setCellContent(m, at(r, 1), `**${variety}**`);
    m = setAlignment(m, at(r, 1), 'center');
    for (const c of [3, 4]) { // prices in the label face: lining figures, flush right, and a
      // bare $, since a cell prints the backslash of \$ (gotcha: cell-dollar-backslash)
      m = setCellContent(m, at(r, c), `:chip[$${m.rows[r][c].content}]{style="price"}`);
      m = setAlignment(m, at(r, c), 'right');
    }
    if (!m.rows[r][0].content) continue; // an empty Kind goes on with the one above
    let end = r;
    while (m.rows[end + 1] && !m.rows[end + 1][0].content) end++;
    // One cell down the rows of its kind; mergeCells leaves the covered cells in the grid,
    // marked hiddenBy (gotcha: merged-cells-hiddenby). A split never cuts through it.
    m = mergeCells(m, { start: at(r, 0), end: at(end, 0) });
    m = setAlignment(m, at(r, 0), 'center', 'middle');
    m = setCellBackground(m, at(r, 0), col('cream'));
  }
  return m;
}
// The letter on page 1 cites the list, so it floats to the first free slot after the
// letter, page 2, and is cut between rows where the page ends; span 'page' gives it the
// full 157 mm, not a 75 mm column. Only a float splits (gotcha: here-table-no-split).
const vegetableList = (tsv) => ({ id: 'vegetables', typeId: 'list', kind: 'table',
  caption: '**Vegetable Seeds**', placement: { span: 'page' },
  note: 'A packet holds about 30 tomato or pepper seeds, 40 beans or 12 squash seeds.',
  table: { model: priceList(tsv) }, createdAt: 0, updatedAt: 0 });
// #endregion

// #region split: the list's style says what a continued part prints; the forms have their own
const tableStyle = { bodyFontSize: pt(9), headerFontFamily: LABEL, // body cells in Gelasio
  headerFontSize: pt(7.5), headerColor: col('paper'), headerBackground: col('ink'),
  rules: 'horizontal', borderColor: col('rule'), borderWidth: pt(0.5), cellPadding: mm(1.5),
  // 'split' is the default, written out as the key to change: 'clip' keeps the rows that fit
  // page 2 and drops the rest, 'hide' drops the whole list. Suffix and marker label the parts.
  overflow: 'split', continuedSuffix: '(continued)',
  continuesMarker: 'Continued on the facing page' };
const tableStyles = [{ id: 'form', rules: 'grid', borderRadius: mm(2.5), // a card to write on
  borderColor: col('muted'), borderWidth: pt(0.6), headerBackground: col('basil'),
  bodyFontFamily: LABEL, bodyFontSize: pt(8.5),
  bodyBackgroundEnabled: true, bodyBackground: col('cream'), cellPadding: mm(1.6) }];
// The caption sits above the table on a tomato band and is repeated on every part. Its note
// and the marker take the caption's face, so the caption keeps the body's Gelasio, which has
// the italic the suffix and the marker are set in; Cabin Condensed has none.
const captionStyle = { fontSize: pt(12), color: col('cream'),
  position: 'above', backgroundEnabled: true, background: col('tomato'), padding: mm(2),
  gap: mm(0), note: { fontSize: pt(7.8), color: col('muted') } };
// #endregion

const run = (id, content, parity, edge, x, extra) => ({ kind: 'text', id, content, parity,
  pages: 'body', ...caps(7.5), color: col('muted'), placement: on('page', edge, x, 12.5),
  ...extra });
const folio = { fontWeight: 700, color: col('ink') };
const header = { elements: [ // folios outside, the booklet's name on the verso, its issue opposite
  run('verso-folio', '{pageNumber}', 'even', 'top-left', MARGIN.outer, folio),
  run('verso-title', '{title}', 'even', 'top-left', MARGIN.outer + 6),
  run('recto-title', '{subtitle}', 'odd', 'top-right', -(MARGIN.outer + 6)),
  run('recto-folio', '{pageNumber}', 'odd', 'top-right', -MARGIN.outer, folio),
] };
const footer = { elements: [{ ...run('drop-folio', '{pageNumber}', 'all', 'bottom', 0, folio),
  pages: 'opener', placement: on('page', 'bottom', 0, -11) }] };

// #region cover: the frontmatter and the heading set the type; the painting fills the middle
const ART = { w: 150, h: 104, y: 60 }; // mm: the cover painting, and its top on the page
const FRAME = 8; // mm: the cover's frame, in from the trim
const AIR = 10; // mm: at least this much between the painting and the letter
const SINK = Math.ceil((ART.y + ART.h + AIR - MARGIN.top) / (LEAD * 25.4 / 72)); // lines
const cover = { id: 'cover', span: 'page', footer: { elements: [] },
  // A style's header replaces the document's on every page of its section, so it carries
  // the running heads too. The frame is drawn there: in the design it would count as
  // reserved height down to the page's foot, more than the column holds, and 1.4.1 then
  // drops the reservation and sets the letter over the painting (gotcha:
  // opener-reserves-anchored).
  header: { elements: [...header.elements, { kind: 'box', id: 'frame', pages: 'opener',
    style: { borderColor: col('basil'), borderWidth: pt(1.2) },
    placement: on('page', 'top-left', FRAME, FRAME,
      { width: mm(TRIM.w - 2 * FRAME), height: mm(TRIM.h - 2 * FRAME) }) }] },
  // The painting is an image, and images do not count towards the height an opener
  // reserves (gotcha: opener-image-no-reserve): minHeight holds the letter under it.
  advancedDesign: { enabled: true, minHeight: pt(SINK * LEAD), slot: { elements: [
    text('publisher', '{title}', on('page', 'top', 0, 17), { ...caps(9.5), color: col('basil') }),
    text('title', '{titleText}', on('page', 'top', 0, 23), { fontFamily: DISPLAY,
      fontSize: pt(58), lineHeight: 1, color: col('tomato') }),
    text('issue', '{subtitle}', on('page', 'top', 0, 49), { ...caps(8.5, 700), color: col('ink'),
      box: { backgroundColor: col('sun'), padding: { top: mm(1.3), bottom: mm(1.1),
        left: mm(4), right: mm(4) } } }),
    { kind: 'image', id: 'art', resourceId: 'cover-art',
      placement: on('page', 'top', 0, ART.y, { width: mm(ART.w) }) },
  ] } },
};
// #endregion

// #region heads: slab-serif section heads over a basil double rule, and the order sheet
const h2 = { level: 2, marginTop: pt(0), marginBottom: pt(0), advancedDesign: { // both open a
  enabled: true, minHeight: pt(2 * LEAD), slot: { elements: [ // column: no space above
    text('title', '{titleText}', on('container', 'top-left', 0, 0), { fontFamily: DISPLAY,
      fontSize: pt(14), lineHeight: 1.1, color: col('tomato') }),
    rule('thick', 'title', 1.4, 1.2), rule('thin', 'thick', 0.7, 0.4),
  ] } } };
const order = { id: 'order', span: 'page', layout: { layoutType: 'single' }, // one wide column
  advancedDesign: { enabled: true, slot: { elements: [
    text('address', '{attr.address}', on('container', 'top-left', 0, 0),
      { ...caps(8), color: col('basil') }),
    text('title', '{titleText}', on('#address', 'below', 0, 1.5), { fontFamily: DISPLAY,
      fontSize: pt(34), lineHeight: 1, color: col('tomato') }),
    rule('thick', 'title', 2.2, 1.6), rule('thin', 'thick', 0.8, 0.5),
    text('how', '{attr.how}', { ...on('#thin', 'below', 0, 3), size: { width: mm(150) } },
      { fontFamily: TEXT, italic: true, fontSize: pt(10.5), lineHeight: 1.35, align: 'left',
        color: col('ink') }),
  ] } } };
// #endregion

const config = () => ({ // a factory: configs are cached by identity (gotcha: config-cache-identity)
  colorPalette,
  page: { width: mm(TRIM.w), height: mm(TRIM.h), dpi: 150, backgroundColor: col('paper'),
    margins: { top: mm(MARGIN.top), bottom: mm(MARGIN.bottom), left: mm(MARGIN.inner),
      right: mm(MARGIN.outer), mirror: true } },
  layout: { layoutType: 'double', gutterWidth: mm(7) }, // two 75 mm columns of letter text
  bodyText: { fontFamily: TEXT, fontSize: pt(9.5), lineHeight: pt(LEAD), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceBold: false, referenceItalic: true,
    firstLineIndent: mm(4), indentAfterHeading: false, // ~48 characters to a 75 mm column, so
    maxWordSpacing: 1.6 }, // a cap under the default 2; Knuth–Plass can exceed it, so reword to fit
  headings: { fontFamily: DISPLAY, fontWeight: 400, levels: [
    // Restated: any headings object drops the H1 break (gotcha: headings-drop-h1-break).
    { level: 1, breakBefore: { enabled: true, parity: 'any' }, marginBottom: pt(0) }, h2] },
  headingStyles: [cover, order],
  paragraphStyles: [
    { id: 'signature', textAlign: 'right', firstLineIndent: pt(0) },
    { id: 'colophon', fontSize: pt(7.5), lineHeight: pt(10), color: col('muted'),
      textAlign: 'center', firstLineIndent: pt(0), marginTop: pt(LEAD) },
  ],
  chipStyles: [ // a price is a bare chip: the label face, bold, a little larger than the text
    chip('price', 1.12, 'ink', { backgroundEnabled: false, borderWidth: pt(0), paddingX: pt(0) }),
    chip('new', 0.8, 'cream', { background: col('tomato'), borderWidth: pt(0) }),
    chip('organic', 0.8, 'basil', { backgroundEnabled: false, borderColor: col('basil'),
      borderWidth: pt(0.6) })],
  resourceTypes: [{ id: 'list', name: 'Price list', shortLabel: 'List', captionPrefix: '',
    numberingTemplate: '{n}', resetOn: 'never', counterFormat: 'decimal' }], // no prefix: the
  // caption is the list's name alone, with no "Table 1".
  tableStyle, tableStyles, captionStyle, header, footer,
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Mostra en Markdown · 35 línies · content.en.md
title: "Brindlewood Seed Co."
subtitle: "Catalog No. 12 · Spring 2027"
---

# Spring Seeds {style="cover"}

## To Our Growers

This is our twelfth spring catalog, and it lists only the vegetables we grew out ourselves last summer at Brindlewood Farm, nine of them, each tested for germination in the packing shed this January. You will find each of them, with a picture of its packet, in :ref{id="vegetables" text="the price list"} on the next two pages.

Tomatoes open the list, as they have done since our first catalog in 2016. Two varieties are new to it this spring and carry a red :chip[NEW]{style="new"} tag, while four were grown on the certified organic field behind the barn and are marked :chip[ORGANIC]{style="organic"}. The rest came from farms we have bought seed from for years, and each one was grown out beside our own before we listed it.

Order early. Last spring the Brandywine and the Jimmy Nardello were sold out by March. We mail seed three days a week from February 1 to May 31. The order sheet is on the back page; tear it out, or copy it by hand and keep the catalog whole.

:::paragraphs{style="signature"}
*Ada Brindle and Tom Okafor*

Brindlewood Farm, Marrow Creek
:::

## From Our Trial Garden

Every variety on these pages spent last summer in our trial rows. We set out twenty plants of each and score them for how quickly they come up, how long they bear and whether the fruit comes true to type. A tomato that throws odd fruit on two of its twenty plants is dropped from the list.

Each lot was tested in January: a hundred seeds on damp paper in a warm room, counted after one week and again after two, and the figure is printed on the packet. Stored cool and dry in a sealed jar, tomato and squash seed stays good for four years, bean seed for three and pepper seed for two. Onion and parsnip seed keeps for only one year, which is why this list carries neither.

# Order Sheet {style="order" address="Mail to Brindlewood Seed Co. · Box 12 · Marrow Creek" how="Write one line for each variety: its number, its name and how many packets or ounces you want. Add the postage, and mail the sheet with a check or money order."}

::resource{id="ship-to"}

::resource{id="order"}

:::paragraphs{style="colophon"}
Set in Gelasio, Alfa Slab One and Cabin Condensed (SIL OFL) · Text: CC BY 4.0 · Pictures: generated · A fictional seed house
:::
`; // the letter, the trial notes and the order sheet
const list = String.raw`KIND	VARIETY	DESCRIPTION	PACKET	OUNCE
Mostra en Markdown · 9 línies · content.list.en.md
**Heirloom tomatoes**	Brandywine	*No. 101 · 90 days.* The pink beefsteak a Philadelphia seed house first listed in 1889. Fruit of a pound or more on tall, potato-leaved vines, sweet but with enough bite to taste of tomato. Stake the vines well. :chip[ORGANIC]{style="organic"}	3.95	42.00
	Cherokee Purple	*No. 102 · 80 days.* Dusky rose fruit of 10 to 12 ounces with green shoulders and brick-red flesh, kept by a Tennessee family long before it reached seed lists in the 1990s. Rich and smoky; slice it thick.	3.95	42.00
	Gold Medal	*No. 103 · 85 days.* A yellow beefsteak streaked red inside and out, so every slice comes out marbled. Mild and low in acid. Give it the longest season you have. :chip[NEW]{style="new"}	4.25	46.00
	Amish Paste	*No. 104 · 80 days.* Heart-shaped fruit of 8 to 12 ounces, meaty enough for sauce and juicy enough to eat off the vine. A paste tomato holds less water and fewer seeds, so it cooks down faster.	3.95	38.00
**Frying pepper**	Jimmy Nardello	*No. 201 · 80 days.* A long, thin-walled Italian frying pepper, sweet and red when ripe; fry it whole in olive oil. Brought from Basilicata to Connecticut in 1887 by the Nardello family. :chip[ORGANIC]{style="organic"}	4.25	48.00
**Beans**	Kentucky Wonder	*No. 301 · 65 days.* Pole bean. Meaty green pods 7 to 9 inches long, stringless if you pick them young, and in American gardens since the 1870s. Give it a pole or a fence 6 feet tall. :chip[ORGANIC]{style="organic"}	3.50	4.75
	Dragon Tongue	*No. 302 · 60 days.* A bush bean from the Netherlands. Flat, pale yellow pods streaked violet, tender up to 7 inches long. Cooking turns them plain yellow. :chip[NEW]{style="new"}	3.75	5.25
**Squash**	Black Beauty	*No. 401 · 50 days.* Zucchini. Glossy green-black fruit on an open bush that is easy to pick over. Cut them at 6 to 8 inches, every other day in July, and the plants keep bearing. On seed lists since the 1920s.	3.50	9.50
	Waltham Butternut	*No. 402 · 100 days.* Winter squash of 4 to 5 pounds with sweet orange flesh. Its hard, solid stems resist the vine borer that kills other squash, and it keeps until March in a cool room. :chip[ORGANIC]{style="organic"}	3.75	11.00
`; // the price list: TSV, as a spreadsheet exports it

// #region forms: the order sheet: empty rows to write in, labels on buff, totals merged
function form(id, widths, rows, merges, note) { // an empty cell still takes a line's height
  let m = { headerRowCount: 1, columnWidths: widths, rows: rows.map((row, r) =>
    widths.map((_, c) => ({ content: row[c] ?? '', isHeader: r === 0 }))) };
  for (const [r, c0, c1] of merges) m = mergeCells(m, { start: at(r, c0), end: at(r, c1) });
  m.rows.forEach((row, r) => row.forEach((cell, c) => { // a label takes the paper's buff
    if (r === 0 || !cell.content || cell.hiddenBy) return;
    m = setCellBackground(m, at(r, c), col('paper'));
    if (cell.colSpan > 1) m = setAlignment(m, at(r, c), 'right'); // the totals' labels
  }));
  return { id, typeId: 'list', kind: 'table', note, placement: { position: 'here' },
    table: { model: m, styleId: 'form' }, createdAt: 0, updatedAt: 0 };
}
const shipTo = form('ship-to', [24, 60, 24, 49], [['Ship to'], ['Name'], ['Street or box'],
  ['Town', '', 'State and ZIP']], [[0, 0, 3], [1, 1, 3], [2, 1, 3]]);
const lines = Array.from({ length: 11 }, () => []); // eleven varieties to a sheet
const orderForm = form('order', [16, 73, 20, 20, 28], [['No.', 'Variety', 'Packets', 'Ounces',
  'Amount'], ...lines, ['Seeds total'], ['Postage: free on orders of $40 or more, otherwise $4.50'],
['**Total enclosed**']], [1, 2, 3].map((k) => [lines.length + k, 0, 3]),
'We guarantee every packet to grow. If a variety fails to come up in your garden, write to '
  + 'us before August 1 and we will send a new packet or refund what you paid for it.');
// #endregion

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = { // every face the pages use, loaded before the build (gotcha: fonts-first)
  Gelasio: ['400', '400i', '700'], // text, captions, notes and the list
  'Alfa Slab One': ['400'], // display: the cover, section heads, the order sheet
  'Cabin Condensed': ['400', '600', '700'], // labels: heads, prices, chips, the forms
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
// #region pictures: every picture is a resource of its own, a JPEG in assets/ at its pixels
// Nothing cites the pictures, so none is numbered or placed: the cover design and the cells
// draw them by id, and their typeId is never looked up.
const picture = (id, fileId, [w, h], altText) => ({ id, typeId: 'figure', kind: 'bitmap',
  altText, bitmap: { fileId, format: 'jpeg', width: w, height: h }, createdAt: 0, updatedAt: 0 });
const varieties = parseTSV(list).rows.slice(1).map((row) => row[1].content);
const resources = [vegetableList(list), shipTo, orderForm,
  picture('cover-art', 'cover-1500.jpg', [1500, 1040], // the cover's 150 × 104 mm
    'A sunflower and a staked tomato plant in a ploughed field.'),
  ...varieties.map((name) => picture(slug(name), `${slug(name)}-360.jpg`, [360, 480], // 3 : 4
    `Seed packet of ${name}.`))];
await loadFonts(FONTS, markdown + list);
await Promise.all(resources.flatMap(({ bitmap }) => bitmap
  ? [loadImage(bitmap.fileId, asset(bitmap.fileId))] : []));
// #endregion
const doc = await buildWithFonts(() => buildDocument({ markdown, resources }, config()),
  markdown + list);
showPages(doc, { title: 'Brindlewood Seed Co. · Spring 2027' });

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