# TokenStream
An agent answer card that reveals Markdown word by word, then settles with copy, retry and rating controls.
## 1. Setup
// npm install framer-motion
File: components-workspace/token-stream/index.tsx · 'use client' · export default function TokenStream(props: TokenStreamProps)
Tailwind CSS v4, with the dark: variant following your theme. Colors come from the component variables in THEME_VARS.
The @/app/_icons imports are the AI Canvas icon set. Without it, use any icon components that accept size, weight and SVG props, with a matching IconProps type.
import { memo, useCallback, useEffect, useLayoutEffect, useMemo, useRef, useState, useSyncExternalStore } from 'react'
import type * as React from 'react'
import { animate, AnimatePresence, motion, useMotionTemplate, useMotionValue } from 'framer-motion'
import { RotateCw } from '@/app/_icons/icons/rotate-cw'
import { RotateCcw } from '@/app/_icons/icons/rotate-ccw'
import { Check } from '@/app/_icons/icons/check'
import { Copy } from '@/app/_icons/icons/copy'
import { Play } from '@/app/_icons/icons/play'
import { Stop } from '@/app/_icons/icons/stop'
import { ThumbsDown } from '@/app/_icons/icons/thumbs-down'
import { ThumbsUp } from '@/app/_icons/icons/thumbs-up'
import { SparkleDuotone } from '@/app/_icons/icons/sparkle-duotone'
import { CircleCheckDuotone } from '@/app/_icons/icons/circle-check-duotone'
import { CircleStopDuotone } from '@/app/_icons/icons/circle-stop-duotone'
import { CircleMinusDuotone } from '@/app/_icons/icons/circle-minus-duotone'
## 2. Constants
export type Tuning = {
cardMaxW: number
firstPhraseMs: number
phraseMs: number
wordMs: number
commaPauseMs: number
sentencePauseMs: number
blockPauseMs: number
fenceOpenMs: number
lineEndMs: number
inkMs: number
risePx: number
paceJitter: number
flowCapMs: number
reducedChunk: number
reducedStepMs: number
codeHeaderH: number
codeLineH: number
codePadY: number
codeMaxLines: number
dotFieldH: number
dotPitch: number
waitMinH: number
hoverMs: number
stateMs: number
panelMs: number
lightMs: number
copiedMs: number
shimmerS: number
pressScale: number
growS: number
followS: number
tailRoomPx: number
blockHoldMs: number
holdMs: number
}
export const TUNING: Tuning = {
cardMaxW: 560,
firstPhraseMs: 1200,
phraseMs: 800,
wordMs: 35,
commaPauseMs: 70,
sentencePauseMs: 150,
blockPauseMs: 220,
fenceOpenMs: 260,
lineEndMs: 70,
inkMs: 260,
risePx: 4,
paceJitter: 0.45,
flowCapMs: 600,
reducedChunk: 8,
reducedStepMs: 180,
codeHeaderH: 36,
codeLineH: 20,
codePadY: 12,
codeMaxLines: 8,
dotFieldH: 64,
dotPitch: 6,
waitMinH: 28,
hoverMs: 150,
stateMs: 200,
panelMs: 280,
lightMs: 600,
copiedMs: 1500,
shimmerS: 2.6,
pressScale: 0.97,
growS: 0.35,
followS: 0.45,
tailRoomPx: 20,
blockHoldMs: 140,
holdMs: 8000,
}
const EASE = [0.23, 1, 0.32, 1] as const
const INK_EASE = `cubic-bezier(${EASE.join(', ')})`
export type TokenStreamStatus = 'waiting' | 'writing' | 'done' | 'stopped'
export type TokenStreamProps = {
markdown?: string
status?: TokenStreamStatus
waitingPhrases?: string[]
wordsPerSecond?: number
label?: string
onStop?: () => void
onContinue?: () => void
onRetry?: () => void
onFeedback?: (value: 'up' | 'down' | null) => void
elapsedMs?: number
className?: string
tuning?: Partial<Tuning>
}
// A number stays on the same line as its unit.
const NBSP = String.fromCharCode(160)
const FENCE = '```'
const DEMO_MARKDOWN = [
'### Rate limits',
'',
'Every request counts against a **per-key budget**. The budget refills on a rolling one-minute window, so a burst that fails at 12:00 can succeed at 12:01. Read `x-ratelimit-remaining` on every response.',
'',
'### What to do on a 429',
'',
'- Wait for the time in `retry-after`, not a fixed delay',
'- Back off with jitter so parallel workers do not retry together',
'- Stop after five attempts and surface the error',
'',
`${FENCE}ts`,
'for (let attempt = 1; attempt <= 5; attempt++) {',
' const res = await fetch(url, init)',
' if (res.status !== 429) return res',
" const secs = Number(res.headers.get('retry-after') ?? 1)",
' await sleep(secs * 1000 + Math.random() * 250)',
'}',
FENCE,
'',
'With this in place the burst at 12:00 drains instead of failing.',
].join('\n')
const DEMO_PHRASES = [`Searching 4${NBSP}sources`, 'Reading the rate limit docs']
const NO_PHRASES: string[] = []
type TokenKind = 'keyword' | 'string' | 'number' | 'comment' | 'ident' | 'fn' | 'punct'
type Token = { text: string; kind: TokenKind }
type ScanState = { block: boolean; template: boolean }
const KEYWORDS = new Set([
'abstract', 'any', 'as', 'async', 'await', 'bigint', 'boolean', 'break', 'case', 'catch',
'class', 'const', 'continue', 'declare', 'default', 'delete', 'do', 'else', 'enum', 'export',
'extends', 'finally', 'for', 'from', 'function', 'if', 'implements', 'import', 'in', 'infer',
'instanceof', 'interface', 'is', 'keyof', 'let', 'never', 'new', 'number', 'object', 'of',
'private', 'protected', 'public', 'readonly', 'return', 'satisfies', 'static', 'string',
'super', 'switch', 'symbol', 'this', 'throw', 'try', 'type', 'typeof', 'unknown', 'var',
'void', 'while', 'yield',
])
const LITERALS = new Set(['false', 'Infinity', 'NaN', 'null', 'true', 'undefined'])
function closingQuote(line: string, from: number, quote: string) {
for (let i = from; i < line.length; i += 1) {
if (line[i] === '\\') {
i += 1
continue
}
if (line[i] === quote) return i
}
return -1
}
function scanLine(line: string, state: ScanState, out: Token[]) {
let i = 0
while (i < line.length) {
if (state.block || state.template) {
const end = state.block ? line.indexOf('*/', i) : closingQuote(line, i, '`')
const kind: TokenKind = state.block ? 'comment' : 'string'
if (end === -1) {
out.push({ text: line.slice(i), kind })
return
}
const stop = state.block ? end + 2 : end + 1
out.push({ text: line.slice(i, stop), kind })
state.block = false
state.template = false
i = stop
continue
}
const ch = line[i]
if (ch === '/' && line[i + 1] === '/') {
out.push({ text: line.slice(i), kind: 'comment' })
return
}
if (ch === '/' && line[i + 1] === '*') {
state.block = true
out.push({ text: '/*', kind: 'comment' })
i += 2
continue
}
if (ch === '"' || ch === "'" || ch === '`') {
const end = closingQuote(line, i + 1, ch)
if (end === -1) {
out.push({ text: line.slice(i), kind: 'string' })
if (ch === '`') state.template = true
return
}
out.push({ text: line.slice(i, end + 1), kind: 'string' })
i = end + 1
continue
}
if (/[0-9]/.test(ch)) {
let j = i + 1
while (j < line.length && /[0-9a-fA-FxXoObBn._]/.test(line[j])) j += 1
out.push({ text: line.slice(i, j), kind: 'number' })
i = j
continue
}
if (/[A-Za-z_$]/.test(ch)) {
let j = i + 1
while (j < line.length && /[A-Za-z0-9_$]/.test(line[j])) j += 1
const word = line.slice(i, j)
let kind: TokenKind = 'ident'
if (KEYWORDS.has(word)) kind = 'keyword'
else if (LITERALS.has(word)) kind = 'number'
else if (line[j] === '(' && /^[a-z_$]/.test(word)) kind = 'fn'
out.push({ text: word, kind })
i = j
continue
}
let j = i + 1
while (j < line.length && !/[A-Za-z0-9_$"'`/]/.test(line[j])) j += 1
out.push({ text: line.slice(i, j), kind: 'punct' })
i = j
}
}
function tokenize(lines: string[]): Token[][] {
const state: ScanState = { block: false, template: false }
return lines.map((line) => {
const out: Token[] = []
scanLine(line, state, out)
return out
})
}
const TOKEN_CLASS: Record<TokenKind, string> = {
keyword: 'text-(color:--ts-ai)',
string: 'text-(color:--ts-success)',
number: 'text-(color:--ts-attention)',
comment: 'italic text-(color:--ts-muted)',
ident: 'text-(color:--ts-text)',
fn: 'font-semibold text-(color:--ts-text)',
punct: 'text-(color:--ts-body)',
}
// A unit never splits, so a line break is set once and settled text never reflows.
type PartKind = 'text' | 'bold' | 'italic' | 'bolditalic' | 'code' | 'link'
type Part = { text: string; kind: PartKind; href?: string }
type Unit = Part[]
// sig: the block's content as one string, so a re-parse of the same text compares equal.
type TextBlock = {
type: 'h' | 'p' | 'li' | 'oli'
first: number
count: number
units: Unit[]
level: number
num: number
sig: string
}
type RuleBlock = { type: 'hr'; first: number; count: 1; sig: string }
type Chunk = { line: number; from: number; to: number }
type CodeBlock = {
type: 'code'
first: number
count: number
lang: string
lines: string[]
tokens: Token[][]
chunks: Chunk[]
closed: boolean
sig: string
}
type Block = TextBlock | RuleBlock | CodeBlock
type Doc = { blocks: Block[]; total: number; wordsUpTo: number[] }
const TICK = '`'
const WORD_CHAR = /[A-Za-z0-9]/
function addPart(unit: Unit, part: Part) {
const last = unit[unit.length - 1]
if (last && last.kind === part.kind && last.href === part.href && part.kind !== 'link')
unit[unit.length - 1] = { ...last, text: last.text + part.text }
else unit.push(part)
}
function styleOf(bold: boolean, italic: boolean): PartKind {
if (bold) return italic ? 'bolditalic' : 'bold'
return italic ? 'italic' : 'text'
}
// Only http(s) and relative addresses become links; any other scheme stays plain text.
function safeHref(raw: string): string | undefined {
const first = raw.trim().split(/\s/)[0] ?? ''
const href = Array.from(first)
.filter((c) => c.charCodeAt(0) > 32)
.join('')
if (!href) return undefined
if (/^https?:\/\//i.test(href)) return href
if (/^[a-z][a-z0-9+.-]*:/i.test(href)) return undefined
return href
}
// A link whose address has not closed shows its text alone, so brackets never flash.
function linkAt(s: string, i: number, tail: boolean): { part: Part; end: number } | null {
const close = s.indexOf(']', i + 1)
const pending = (text: string) => (tail ? { part: { text, kind: 'link' as const }, end: s.length } : null)
if (close === -1) return pending(s.slice(i + 1))
const text = s.slice(i + 1, close)
if (close + 1 === s.length) return pending(text)
if (s[close + 1] !== '(') return null
const end = s.indexOf(')', close + 2)
if (end === -1) return pending(text)
return { part: { text, kind: 'link', href: safeHref(s.slice(close + 2, end)) }, end: end + 1 }
}
// tail: an open mark closes where the text ends, so half a mark never shows raw.
function inlineUnits(src: string, tail: boolean): Unit[] {
const s = tail && src.endsWith('*') && !src.endsWith('**') ? src.slice(0, -1) : src
const runs: Part[] = []
let bold = false
let italic = ''
let buf = ''
const flush = () => {
if (buf) runs.push({ text: buf, kind: styleOf(bold, !!italic) })
buf = ''
}
let i = 0
while (i < s.length) {
const ch = s[i]
if (s.startsWith('**', i)) {
flush()
bold = !bold
i += 2
continue
}
if (ch === '*' || ch === '_') {
const prev = s[i - 1] ?? ''
const next = s[i + 1] ?? ''
// An underscore inside a word (snake_case) is a letter, not a mark.
const closes = italic === ch && prev !== '' && !/\s/.test(prev) && (ch === '*' || !WORD_CHAR.test(next))
const opens = !italic && next !== '' && !/\s/.test(next) && (ch === '*' || !WORD_CHAR.test(prev))
if (closes || opens) {
flush()
italic = closes ? '' : ch
i += 1
continue
}
}
if (ch === TICK) {
flush()
const end = s.indexOf(TICK, i + 1)
const code = end === -1 ? s.slice(i + 1) : s.slice(i + 1, end)
if (code) runs.push({ text: code, kind: 'code' })
i = end === -1 ? s.length : end + 1
continue
}
if (ch === '[') {
const link = linkAt(s, i, tail)
if (link) {
flush()
if (link.part.text) runs.push(link.part)
i = link.end
continue
}
}
buf += ch
i += 1
}
flush()
const units: Unit[] = []
let cur: Unit | null = null
let spaced = false
for (const run of runs) {
const whole = run.kind === 'code' || run.kind === 'link'
const pieces = whole ? [run.text] : run.text.split(/(\s+)/).filter(Boolean)
for (const piece of pieces) {
if (!whole && /^\s+$/.test(piece)) {
if (cur) {
addPart(cur, { text: ' ', kind: run.kind })
spaced = true
}
continue
}
if (!cur || spaced) {
cur = []
units.push(cur)
spaced = false
}
addPart(cur, { ...run, text: piece })
}
}
return units
}
function chunksOf(lines: string[]): Chunk[] {
const out: Chunk[] = []
lines.forEach((line, n) => {
let first = true
for (const m of line.matchAll(/\S+\s*/g)) {
const at = m.index ?? 0
out.push({ line: n, from: first ? 0 : at, to: at + m[0].length })
first = false
}
if (first) out.push({ line: n, from: 0, to: line.length })
})
return out
}
const FENCE_OPEN = /^\s{0,3}```\s*([\w+-]*)\s*$/
const FENCE_CLOSE = /^\s{0,3}```\s*$/
const FENCE_PARTIAL = /^\s{0,3}`{1,2}$/
const MARK_PARTIAL = /^\s{0,3}(`{1,2}|#{1,6}|[-*+]|-{2}|\*{2}|_{1,2}|\d{1,9}[.)]?)\s*$/
const RULE = /^\s{0,3}([-*_])(?:\s*\1){2,}\s*$/
const HEAD = /^\s{0,3}(#{1,6})\s+(.*)$/
const ITEM = /^\s{0,3}[-*+]\s+(.*)$/
const ORDERED = /^\s{0,3}(\d{1,9})[.)]\s+(.*)$/
function parseDoc(src: string, open: boolean): Doc {
const lines = src.replace(/\r\n?/g, '\n').split('\n')
const lastLine = lines.length - 1
const blocks: Block[] = []
const isWord: boolean[] = []
let next = 0
let para: string[] = []
let paraEnd = -1
const pushText = (type: TextBlock['type'], text: string, tail: boolean, level = 0, num = 0) => {
const units = inlineUnits(text, open && tail)
if (!units.length) return
const sig = JSON.stringify([type, next, level, num, units])
blocks.push({ type, first: next, count: units.length, units, level, num, sig })
units.forEach(() => isWord.push(true))
next += units.length
}
const flush = () => {
if (para.length) pushText('p', para.join(' '), paraEnd === lastLine)
para = []
}
for (let i = 0; i < lines.length; i += 1) {
const line = lines[i]
const fence = FENCE_OPEN.exec(line)
if (fence) {
flush()
const body: string[] = []
let closed = false
for (i += 1; i < lines.length; i += 1) {
if (FENCE_CLOSE.test(lines[i])) {
closed = true
break
}
body.push(lines[i])
}
if (!closed && body.length && FENCE_PARTIAL.test(body[body.length - 1])) body.pop()
const chunks = chunksOf(body)
const count = 1 + chunks.length + (closed ? 1 : 0)
const lang = fence[1] || 'text'
blocks.push({
type: 'code',
first: next,
count,
lang,
lines: body,
tokens: tokenize(body),
chunks,
closed,
sig: JSON.stringify(['code', next, lang, closed, body]),
})
isWord.push(false)
chunks.forEach((c) => isWord.push(c.to > c.from))
if (closed) isWord.push(false)
next += count
continue
}
if (i === lastLine && MARK_PARTIAL.test(line)) continue
if (RULE.test(line)) {
flush()
blocks.push({ type: 'hr', first: next, count: 1, sig: `hr|${next}` })
isWord.push(false)
next += 1
continue
}
const head = HEAD.exec(line)
if (head) {
flush()
pushText('h', head[2], i === lastLine, head[1].length)
continue
}
const item = ITEM.exec(line)
if (item) {
flush()
pushText('li', item[1], i === lastLine)
continue
}
const ordered = ORDERED.exec(line)
if (ordered) {
flush()
pushText('oli', ordered[2], i === lastLine, 0, Number(ordered[1]))
continue
}
if (!line.trim()) {
flush()
continue
}
para.push(line.trim())
paraEnd = i
}
flush()
const wordsUpTo = [0]
isWord.forEach((w, i) => wordsUpTo.push(wordsUpTo[i] + (w ? 1 : 0)))
return { blocks, total: next, wordsUpTo }
}
const MARK: Partial<Record<PartKind, string>> = { bold: '**', italic: '*', bolditalic: '***' }
function inlineText(units: Unit[]) {
const runs: Part[] = []
for (const unit of units)
for (const p of unit) {
const last = runs[runs.length - 1]
if (last && last.kind === p.kind && p.kind !== 'code' && p.kind !== 'link')
runs[runs.length - 1] = { ...last, text: last.text + p.text }
else runs.push(p)
}
return runs
.map((p) => {
if (p.kind === 'code') return TICK + p.text + TICK
if (p.kind === 'link') return p.href ? `[${p.text}](${p.href})` : p.text
const mark = MARK[p.kind]
if (!mark) return p.text
const inner = p.text.trimEnd()
return mark + inner + mark + p.text.slice(inner.length)
})
.join('')
.trimEnd()
}
function docText(doc: Doc, shown: number) {
let out = ''
let prev: Block['type'] | null = null
for (const b of doc.blocks) {
if (b.first >= shown) break
const local = Math.min(b.count, shown - b.first)
let text: string
if (b.type === 'code') {
const lines: string[] = []
b.chunks.slice(0, Math.max(0, local - 1)).forEach((c) => {
lines[c.line] = (lines[c.line] ?? '') + b.lines[c.line].slice(c.from, c.to)
})
// A cut-short block still closes its fence, so the copy pastes as valid markdown.
text = [FENCE + (b.lang === 'text' ? '' : b.lang), ...Array.from(lines, (l) => (l ?? '').trimEnd()), FENCE].join('\n')
} else if (b.type === 'hr') {
text = '---'
} else {
const inline = inlineText(b.units.slice(0, local))
if (b.type === 'h') text = `${'#'.repeat(b.level)} ${inline}`
else if (b.type === 'li') text = `- ${inline}`
else if (b.type === 'oli') text = `${b.num}. ${inline}`
else text = inline
}
const tight = prev === b.type && (b.type === 'li' || b.type === 'oli')
out += (out ? (tight ? '\n' : '\n\n') : '') + text
prev = b.type
}
return out
}
type Pace = { word: number; comma: number; sentence: number; block: number; fence: number; line: number; jitter: number }
function wobble(i: number) {
const r = Math.sin((i + 1) * 12.9898) * 43758.5453
return (r - Math.floor(r)) * 2 - 1
}
function scheduleOf(doc: Doc, p: Pace): number[] {
const at: number[] = []
let time = 0
let k = 0
const beat = (len: number) => p.word * (1 + p.jitter * wobble(k++)) * (0.82 + 0.035 * Math.min(10, len))
for (const b of doc.blocks) {
if (b.type === 'code') {
at.push(time)
time += p.fence
b.chunks.forEach((c, j) => {
at.push(time)
time += beat(c.to - c.from)
const nextChunk = b.chunks[j + 1]
if (!nextChunk || nextChunk.line !== c.line) time += p.line
})
if (b.closed) at.push(time)
time += p.block
continue
}
if (b.type === 'hr') {
at.push(time)
time += p.block
continue
}
b.units.forEach((u) => {
at.push(time)
const word = u.map((part) => part.text).join('').trimEnd()
time += beat(word.length)
if (/[.!?]$/.test(word)) time += p.sentence
else if (/[,;:]$/.test(word)) time += p.comma
})
time += p.block
}
return at
}
function chunkedSchedule(total: number, chunk: number, stepMs: number): number[] {
return Array.from({ length: total }, (_, i) => Math.floor(i / Math.max(1, chunk)) * stepMs)
}
function phraseStart(k: number, firstMs: number, stepMs: number) {
return k === 0 ? 0 : firstMs + (k - 1) * stepMs
}
function phraseIndex(ms: number, n: number, firstMs: number, stepMs: number) {
let k = 0
while (k + 1 < n && phraseStart(k + 1, firstMs, stepMs) <= ms) k += 1
return k
}
const THEME_VARS = [
'[--ts-page:#EEEEF3] dark:[--ts-page:#0E0E0F]',
'[--ts-panel:#F4F4FA] dark:[--ts-panel:#1B1B1C]',
'[--ts-well:#EEEEF3] dark:[--ts-well:#0E0E0F]',
'[--ts-raised:#DFDFE3] dark:[--ts-raised:#2D2D2E]',
'[--ts-raised-hover:#CACACD] dark:[--ts-raised-hover:#373738]',
'[--ts-border:#DFDFE3] dark:[--ts-border:#2D2D2E]',
'[--ts-border-strong:#CACACD] dark:[--ts-border-strong:#373738]',
'[--ts-hairline:#DFDFE3] dark:[--ts-hairline:#2D2D2E]',
'[--ts-rim:#CACACD] dark:[--ts-rim:#F4F4FA2E]',
'[--ts-text:#1B1B1C] dark:[--ts-text:#F4F4FA]',
'[--ts-body:#373738] dark:[--ts-body:#CACACD]',
'[--ts-muted:#575759] dark:[--ts-muted:#9B9B9E]',
'[--ts-faint:#7B7B7D]',
'[--ts-selection:#A0A0A233] dark:[--ts-selection:#5E5E6333]',
'[--ts-success:#047857] dark:[--ts-success:#34D399]',
'[--ts-ai:#0369A1] dark:[--ts-ai:#7DD3FC]',
'[--ts-attention:#B45309] dark:[--ts-attention:#FFB574]',
'[--ts-red:#C8262C] dark:[--ts-red:#E5484D]',
'[--ts-primary:#1B1B1C] dark:[--ts-primary:#F4F4FA]',
'[--ts-primary-hover:#373738] dark:[--ts-primary-hover:#FFFFFF]',
'[--ts-on-primary:#F4F4FA] dark:[--ts-on-primary:#0E0E0F]',
'[--ts-focus:#1B1B1C99] dark:[--ts-focus:#F4F4FA99]',
'[--ts-focus-gap:#F4F4FA] dark:[--ts-focus-gap:#1B1B1C]',
'[--ts-dot:#1B1B1C] dark:[--ts-dot:#F4F4FA]',
'[--ts-elev-card:0_2px_6px_rgba(0,0,0,0.06),0_28px_56px_-16px_rgba(0,0,0,0.25)] dark:[--ts-elev-card:0_2px_6px_rgba(0,0,0,0.5),0_36px_72px_-18px_rgba(0,0,0,0.9)]',
'[--ts-elev-1:0_1px_2px_rgba(0,0,0,0.08)] dark:[--ts-elev-1:0_1px_2px_rgba(0,0,0,0.5)]',
].join(' ')
// Padding lives on the measured inner box, so the card's height can follow it.
const CARD =
'relative w-full overflow-hidden rounded-[24px] border border-(color:--ts-border) bg-(--ts-panel) shadow-(--ts-elev-card)'
const CARD_PAD = 'p-4 min-[400px]:p-5'
const FOOTER_PAD = 'mx-4 mb-4 min-[400px]:mx-5 min-[400px]:mb-5'
const NO_FLOW = { lead: 0, step: 0 }
const WELL = 'rounded-2xl border border-(color:--ts-border) bg-(--ts-well)'
const TITLE = 'min-w-0 truncate text-[15px] leading-6 font-semibold text-(color:--ts-text)'
const META = 'shrink-0 text-[12px] leading-4 tabular-nums text-(color:--ts-muted)'
const FOCUS =
'outline-none focus-visible:ring-2 focus-visible:ring-(color:--ts-focus) focus-visible:ring-offset-2 focus-visible:ring-offset-(color:--ts-focus-gap)'
// A scroll box clips an offset ring, so its ring draws inward.
const FOCUS_INSET = 'outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-(color:--ts-focus)'
const HIT_BASE = "relative pointer-coarse:after:absolute pointer-coarse:after:content-['']"
const HIT_ICON = `${HIT_BASE} pointer-coarse:after:-inset-1.5`
const HIT_ROW = `${HIT_BASE} pointer-coarse:after:-inset-y-1.5 min-[360px]:pointer-coarse:after:-inset-x-1.5 max-[359px]:pointer-coarse:after:-inset-x-1`
const ROW_GAP = 'gap-1 min-[360px]:pointer-coarse:gap-3 max-[359px]:pointer-coarse:gap-2'
const BTN = `${FOCUS} inline-flex h-8 shrink-0 items-center justify-center gap-1.5 rounded-full px-4 text-[12px] leading-4 font-semibold transition-[background-color,color,border-color,box-shadow] duration-150 disabled:opacity-50`
const BTN_PRIMARY = `${BTN} bg-(--ts-primary) text-(color:--ts-on-primary) shadow-(--ts-elev-1) hover:bg-(--ts-primary-hover)`
// Opaque, so the dots behind the footer never show through the label.
const BTN_SECONDARY = `${BTN} border border-(color:--ts-border-strong) bg-(--ts-panel) text-(color:--ts-text) hover:bg-(--ts-raised)`
const BTN_GHOST = `${BTN} text-(color:--ts-muted) hover:bg-(--ts-raised) hover:text-(color:--ts-text)`
const BTN_ICON = `${FOCUS} inline-grid size-8 shrink-0 place-items-center rounded-full text-(color:--ts-muted) transition-[background-color,color] duration-150 hover:bg-(--ts-raised) hover:text-(color:--ts-text)`
type Tone = 'neutral' | 'ai' | 'attention' | 'success' | 'red'
const TONE_VAR: Record<Tone, string> = {
neutral: 'var(--ts-dot)',
ai: 'var(--ts-ai)',
attention: 'var(--ts-attention)',
success: 'var(--ts-success)',
red: 'var(--ts-red)',
}
const TONE_STRENGTH: Record<Tone, number> = { neutral: 6, ai: 14, attention: 14, success: 10, red: 12 }
const REDUCED_QUERY = '(prefers-reduced-motion: reduce)'
function subscribeReduced(onChange: () => void) {
if (typeof window === 'undefined' || !window.matchMedia) return () => {}
const mq = window.matchMedia(REDUCED_QUERY)
mq.addEventListener('change', onChange)
return () => mq.removeEventListener('change', onChange)
}
function getReduced() {
return typeof window !== 'undefined' && !!window.matchMedia && window.matchMedia(REDUCED_QUERY).matches
}
function getReducedServer() {
return false
}
function plural(n: number, word: string) {
return `${n}${NBSP}${word}${n === 1 ? '' : 's'}`
}
function fmtDuration(ms: number) {
const s = ms / 1000
if (s < 60) return `${s.toFixed(1)}s`
const whole = Math.round(s)
return `${Math.floor(whole / 60)}m${NBSP}${String(whole % 60).padStart(2, '0')}s`
}
function legacyCopy(text: string) {
// Selecting the scratch field moves focus; hand it back to whatever held it.
const prev = document.activeElement instanceof HTMLElement ? document.activeElement : null
const area = document.createElement('textarea')
area.value = text
area.setAttribute('readonly', '')
area.style.position = 'fixed'
area.style.opacity = '0'
document.body.appendChild(area)
area.select()
let ok = false
try {
ok = document.execCommand('copy')
} catch {
ok = false
}
area.remove()
prev?.focus({ preventScroll: true })
return ok
}
// An embedded frame may refuse the clipboard API; the selection copy still works there.
function copyText(text: string): Promise<boolean> {
if (typeof navigator === 'undefined' || !navigator.clipboard) return Promise.resolve(legacyCopy(text))
return navigator.clipboard.writeText(text).then(
() => true,
() => legacyCopy(text),
)
}
function useCopied(ms: number) {
const [copied, setCopied] = useState(0)
useEffect(() => {
if (!copied) return
const id = window.setTimeout(() => setCopied(0), ms)
return () => window.clearTimeout(id)
}, [copied, ms])
return [copied > 0, () => setCopied((n) => n + 1)] as const
}
type Mode = TokenStreamStatus
type Feedback = 'up' | 'down' | null
const LIVE_LINE: Record<Mode, string> = {
waiting: 'Working on an answer',
writing: 'Writing an answer',
done: 'Answer ready',
stopped: 'Stopped',
}
/**
* @typedef {object} TokenStreamProps
* @property {string} [markdown] Supplies the answer parsed and revealed as Markdown; left out, the demo uses sample text and host mode uses an empty answer, while passing it turns the demo off.
* @property {TokenStreamStatus} [status] Controls waiting, writing, done or stopped presentation; left out, host mode infers done from nonempty Markdown and waiting otherwise, while passing it turns the demo off.
* @property {string[]} [waitingPhrases] Supplies rotating work messages before the answer; left out, the demo uses sample messages and host mode shows none, while passing it turns the demo off.
* @property {number} [wordsPerSecond] Sets a positive reveal speed; left out or nonpositive, the tuned word timing is used.
* @property {string} [label] Adds metadata text to the answer header; left out, no label is shown, while passing it turns the demo off.
* @property {() => void} [onStop] Handles stopping and makes the stop control available during host writing; left out, host streams have no stop control.
* @property {() => void} [onContinue] Handles continuing and makes the Continue control available after a host stop; left out, host stopped answers have no Continue control.
* @property {() => void} [onRetry] Handles retrying and makes retry controls available in host mode; left out, host answers have no retry controls.
* @property {(value: 'up'|'down'|null) => void} [onFeedback] Reports the current rating while rating state remains local; left out, rating controls still update locally.
* @property {number} [elapsedMs] Shows how long a host answer took in milliseconds; left out, no host duration is shown, while passing it turns the demo off.
* @property {string} [className] Adds classes to the outermost root; left out, only the built-in classes are used.
* @property {Partial<Tuning>} [tuning] Overrides stream measurements, timing and motion values; left out, every value in TUNING is used.
*/
type AnswerCardProps = {
doc: Doc
phrases: string[]
label?: string
reduce: boolean
t: Tuning
ghost: boolean
mode: Mode
tone: Tone
shown: number
wordMs: number
words: number
tookMs: number | null
feedback: Feedback
phraseStartAt: number
runKey: number
segKey?: number
stopRef?: React.RefObject<HTMLButtonElement | null>
continueRef?: React.RefObject<HTMLButtonElement | null>
copyRef?: React.RefObject<HTMLButtonElement | null>
onStop?: () => void
onContinue?: () => void
onRetry?: () => void
onRate?: (up: boolean) => void
onCopyAnswer?: (done: () => void) => void
onCopyCode?: (code: string, done: () => void) => void
}
function gapBefore(prev: Block['type'] | null, cur: Block['type']) {
if (prev === null) return ''
if (cur === 'h') return 'mt-5'
if (cur === 'hr' || prev === 'hr') return 'mt-4'
if (prev === 'h') return 'mt-2'
if (cur === 'li' || cur === 'oli') return prev === cur ? '' : 'mt-2'
return 'mt-3'
}
type InkProps = { inkMs: number; risePx: number }
function useInk<T extends HTMLElement>(delay: number, inkMs: number, risePx: number) {
const ref = useRef<T>(null)
const atMount = useRef({ delay, inkMs, risePx })
useLayoutEffect(() => {
const el = ref.current
const { delay: wait, inkMs: ms, risePx: rise } = atMount.current
if (!el || wait < 0 || typeof el.animate !== 'function') return
const a = el.animate(
[
{ opacity: 0, transform: `translateY(${rise}px)` },
{ opacity: 1, transform: 'none' },
],
{ duration: ms, delay: wait, easing: INK_EASE, fill: 'backwards' },
)
return () => a.cancel()
}, [])
return ref
}
// These compare content, so settled blocks skip renders when a controlled answer grows.
function sameUnit(a: Unit, b: Unit) {
return (
a === b ||
(a.length === b.length &&
a.every((p, i) => p.text === b[i].text && p.kind === b[i].kind && p.href === b[i].href))
)
}
function sameTokens(a: Token[], b: Token[]) {
return a === b || (a.length === b.length && a.every((tok, i) => tok.text === b[i].text && tok.kind === b[i].kind))
}
function sameBlockProps<P extends { block: { sig: string } }>(a: Readonly<P>, b: Readonly<P>) {
const keys = Object.keys(a) as (keyof P)[]
if (keys.length !== Object.keys(b).length) return false
return keys.every((k) => (k === 'block' ? a.block.sig === b.block.sig : Object.is(a[k], b[k])))
}
type BlockEl = HTMLHeadingElement & HTMLLIElement & HTMLParagraphElementState
- every hook, handler, effect and disposal
- the animation loop, frame by frame
Tree
- the JSX, every className and inline style
Why · Remix · Check
- the mechanism, the tuning points, the checks
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