One presentation for every formatter

// apps/docs/examples/format/presentation-switcher.tsx'use client';
import {useId, useState} from 'react';
import {  composePresentationContext,  formatByteSize,  formatCurrency,  formatDateOnly,  formatDateTime,  formatFractionAsPercent,  formatList,  formatNumber,  toIanaTimeZone,  type DateNotationPreset,  type NumberNotationPreset,  type PresentationProfileConfig,  type TimeNotationPreset,} from '@workspace/active-format';import {  Field,  FieldLabel,} from '@workspace/active-ui/components/primitives/field';import {  NativeSelect,  NativeSelectOption,} from '@workspace/active-ui/components/primitives/native-select';import {  Table,  TableBody,  TableCell,  TableRow,} from '@workspace/active-ui/components/primitives/table';
// Fixed values, so every reader sees the same input.const CALENDAR_DAY = '2026-03-09';const INSTANT = '2026-03-09T20:18:05Z';const LANGUAGES = ['en', 'nl', 'de', 'fr', 'es', 'ja', 'ar-EG'];const CURRENCIES = ['EUR', 'USD', 'GBP', 'JPY', 'KWD'];const TIME_ZONES = [  'Europe/Amsterdam',  'America/New_York',  'Asia/Tokyo',  'UTC',];
type Choice<T> = T | 'language';
// What each notation choice shows. The value stays the preset name the// profile takes; the label says what it does, short enough to read in full// in a field on a narrow screen.const CHOICE_LABELS: Record<string, string> = {  language: 'From the language',  DMY_NUMERIC: 'Day, month, year',  MDY_NUMERIC: 'Month, day, year',  ISO_NUMERIC: 'Year, month, day (ISO)',  H24: '24-hour clock',  H12: '12-hour clock',  DOT_DECIMAL_COMMA_GROUP: 'Decimal point, comma groups',  COMMA_DECIMAL_DOT_GROUP: 'Decimal comma, point groups',  COMMA_DECIMAL_SPACE_GROUP: 'Decimal comma, space groups',};
/** One presentation, composed from language, profile and zone, feeding every formatter. */export default function PresentationSwitcher() {  const [language, setLanguage] = useState('en');  const [currency, setCurrency] = useState('EUR');  const [timeZone, setTimeZone] = useState('Europe/Amsterdam');  const [dateFormat, setDateFormat] =    useState<Choice<DateNotationPreset>>('language');  const [timeFormat, setTimeFormat] =    useState<Choice<TimeNotationPreset>>('language');  const [numberFormat, setNumberFormat] =    useState<Choice<NumberNotationPreset>>('language');
  // A profile field that is absent means "not configured": the language's own  // convention applies.  const profile: PresentationProfileConfig = {    ...(dateFormat === 'language' ? {} : {dateFormat}),    ...(timeFormat === 'language' ? {} : {timeFormat}),    ...(numberFormat === 'language' ? {} : {numberFormat}),  };  const presentation = composePresentationContext(    language,    profile,    toIanaTimeZone(timeZone),  );
  const rows: [string, string][] = [    ['formatDateOnly', formatDateOnly(CALENDAR_DAY, 'long', presentation)],    [      'formatDateTime',      formatDateTime(INSTANT, 'numeric-datetime', presentation),    ],    ['formatNumber', formatNumber(1234567.891, 'decimal-2', presentation)],    [      'formatCurrency',      formatCurrency({amount: 1234.5, currency}, presentation),    ],    [      'formatFractionAsPercent',      formatFractionAsPercent(0.125, 'decimal-1', presentation),    ],    [      'formatByteSize',      formatByteSize(1_536_000, presentation, {system: 'decimal'}),    ],    ['formatList', formatList(['Amsterdam', 'Utrecht', 'Delft'], presentation)],  ];
  // The stage centres its content, which sizes a plain root to its widest  // child: `w-full min-w-0` keeps the demo to the width there is, so the  // fields wrap and only the result table scrolls, in its own named region.  return (    <div className="flex w-full min-w-0 flex-col gap-4">      {/* Columns follow the width the demo has, not the screen: beside the          sidebar a three-column row at `sm` left each field too narrow for          its longest choice. */}      <div className="grid grid-cols-[repeat(auto-fill,minmax(min(100%,15rem),1fr))] gap-3">        <Select          label="Language"          value={language}          onChange={setLanguage}          options={LANGUAGES}        />        <Select          label="Currency"          value={currency}          onChange={setCurrency}          options={CURRENCIES}        />        <Select          label="Time zone"          value={timeZone}          onChange={setTimeZone}          options={TIME_ZONES}        />        <Select          label="Date notation"          value={dateFormat}          onChange={(value) =>            setDateFormat(value as Choice<DateNotationPreset>)          }          options={['language', 'DMY_NUMERIC', 'MDY_NUMERIC', 'ISO_NUMERIC']}        />        <Select          label="Clock"          value={timeFormat}          onChange={(value) =>            setTimeFormat(value as Choice<TimeNotationPreset>)          }          options={['language', 'H24', 'H12']}        />        <Select          label="Number notation"          value={numberFormat}          onChange={(value) =>            setNumberFormat(value as Choice<NumberNotationPreset>)          }          options={[            'language',            'DOT_DECIMAL_COMMA_GROUP',            'COMMA_DECIMAL_DOT_GROUP',            'COMMA_DECIMAL_SPACE_GROUP',          ]}        />      </div>      <Table scrollLabel="Results, scrolls sideways">        <TableBody>          {rows.map(([name, text]) => (            <TableRow key={name}>              <TableCell className="text-muted-foreground font-mono text-xs">                {name}              </TableCell>              <TableCell>                <output suppressHydrationWarning>{text}</output>              </TableCell>            </TableRow>          ))}        </TableBody>      </Table>    </div>  );}
function Select({  label,  value,  onChange,  options,}: {  label: string;  value: string;  onChange: (value: string) => void;  options: readonly string[];}) {  const id = useId();  return (    <Field className="min-w-0">      <FieldLabel htmlFor={id}>{label}</FieldLabel>      <NativeSelect        id={id}        className="w-full"        value={value}        onChange={(event) => onChange(event.target.value)}      >        {options.map((option) => (          <NativeSelectOption key={option} value={option}>            {CHOICE_LABELS[option] ?? option}          </NativeSelectOption>        ))}      </NativeSelect>    </Field>  );}