About
A chat card for documents and code an assistant writes, with a side panel that shows the code, a live preview and versions.
Built with React and Tailwind. Copy the prompt and paste it into Claude Code, Cursor or Lovable: your agent adds Artifact to your project and fits it to your theme.
Code
How Artifact is used: the demo's code. The component's own source comes with a free account.
Usage.tsx
"use client"
import * as React from "react"
import { useMemo, useSyncExternalStore, useEffect } from "react"
import { cn } from "@/lib/utils"
import { Menu } from "@base-ui/react/menu"
import { Tooltip as TooltipPrimitive } from "@base-ui/react/tooltip"
import { Artifact, ArtifactKind, Icon, IconNode, Spinner, XIcon, createIcon } from "@/components/ui/artifact"
const FIT_CSS = "html,body{overflow:hidden}[data-fit-small] [data-fit-hide]{display:none!important}"
/**
* 21st shows a demo in a small frame: about 674 by 421 on a component page, 358 by 224 on a
* phone and 245 by 139 on a profile card. A demo taller than its frame gets scrollbars, which
* render white on dark pages. FitFrame fills the frame exactly instead.
*
* - "scale": the content shrinks until it fits, centered. For visuals such as orbs.
* - "crop": the content stays at full size from the top and fades out at the bottom. For text
* that streams in, where a changing scale would make the page breathe.
*
* `minWidth` lays out a wide demo (a table, a two column panel) at that width and scales it down
* to the frame, instead of letting it collapse to a narrow layout. The frame centers it, so it
* shrinks evenly on both sides.
*
* Anything marked `data-fit-hide` (state buttons, the chatcn.dev line) drops out in frames
* shorter than `hideBelow`, so a profile card shows the visual alone.
*/
function FitFrame({
children,
mode = "scale",
hideBelow = 360,
minWidth,
}: {
children: React.ReactNode
mode?: "scale" | "crop"
hideBelow?: number
minWidth?: string
}) {
const content = React.useRef<HTMLDivElement>(null)
const [cropped, setCropped] = React.useState(false)
React.useLayoutEffect(() => {
const el = content.current
if (!el) return
const measure = () => {
const vw = window.innerWidth
const vh = window.innerHeight
el.toggleAttribute("data-fit-small", vh < hideBelow)
// Layout sizes ignore the transform, so measuring never feeds back.
const w = Math.max(el.offsetWidth, el.scrollWidth)
const h = Math.max(el.offsetHeight, el.scrollHeight)
const scale = mode === "scale" ? Math.min(1, vw / w, vh / h) : 1
el.style.transform = scale < 1 ? `scale(${scale})` : ""
setCropped(mode === "crop" && h > vh + 1)
}
measure()
const observer = new ResizeObserver(measure)
observer.observe(el)
// Content that changes inside a fixed width box (a headline that cycles words) never resizes
// the box itself, so changes below it measure again on the next frame.
let frame = 0
const mutations = new MutationObserver(() => {
cancelAnimationFrame(frame)
frame = requestAnimationFrame(measure)
})
mutations.observe(el, { subtree: true, childList: true, characterData: true })
window.addEventListener("resize", measure)
return () => {
observer.disconnect()
mutations.disconnect()
cancelAnimationFrame(frame)
window.removeEventListener("resize", measure)
}
}, [mode, hideBelow])
const fade = "linear-gradient(to bottom, #000 calc(100% - 40px), transparent)"
return (
<div
className="flex w-full justify-center overflow-hidden"
style={{
height: "100dvh",
alignItems: mode === "crop" ? "flex-start" : "center",
maskImage: cropped ? fade : undefined,
WebkitMaskImage: cropped ? fade : undefined,
}}
>
<style>{FIT_CSS}</style>
<div
ref={content}
className="w-full shrink-0"
style={{ transformOrigin: mode === "crop" ? "top center" : "center", minWidth }}
>
{children}
</div>
</div>
)
}
/** Streaming state shared by text and reasoning parts. */
type ChatcnTextState = "streaming" | "done"
/** Assistant or user prose. */
type ChatcnTextPart = { type: "text"; text: string; state?: ChatcnTextState }
/** Model reasoning or thinking text. */
type ChatcnReasoningPart = {
type: "reasoning"
text: string
id?: string
state?: ChatcnTextState
}
/**
* chatcn message contract.
*
* A structural mirror of AI SDK 7 `UIMessage` parts with no runtime import, so an AI SDK message
* can be passed straight in while assistant-ui, LangGraph, AG-UI or a static mock can be adapted
* to the same shape. A type test pins this file to the installed `ai` package.
*/
/** Lifecycle of a tool call, identical to AI SDK 7 tool part states. */
type ToolState =
| "input-streaming"
| "input-available"
| "approval-requested"
| "approval-responded"
| "output-available"
| "output-error"
| "output-denied"
/** Human approval attached to a tool call. */
interface ChatcnApproval {
id: string
approved?: boolean
/** Reason the user gave when responding (usually a denial). */
reason?: string
/** Reason the agent gave when asking. */
requestReason?: string
}
/** A tool call: static (`tool-${name}`) or dynamic (`dynamic-tool` with `toolName`). */
type ChatcnToolPart = {
type: `tool-${string}` | "dynamic-tool"
toolCallId: string
/** Present on `dynamic-tool` parts. Use `getToolName` to read the name of any tool part. */
toolName?: string
state: ToolState
title?: string
/** Partial while `input-streaming`, complete afterwards. */
input?: unknown
/** Raw input text received so far: a string while `input-streaming` (AI SDK types it loosely). */
rawInput?: unknown
output?: unknown
errorText?: string
approval?: ChatcnApproval
providerExecuted?: boolean
/** True while an `output-available` result is still being refined. */
preliminary?: boolean
}
/** A web source cited by the response. */
type ChatcnSourceUrlPart = {
type: "source-url"
sourceId: string
url: string
title?: string
}
/** A document source cited by the response. */
type ChatcnSourceDocumentPart = {
type: "source-document"
sourceId: string
mediaType: string
title: string
filename?: string
}
/** An attached or generated file (hosted URL or data URL). */
type ChatcnFilePart = { type: "file"; mediaType: string; url: string; filename?: string }
/** App-defined structured data (`data-${name}`), reconciled by `id`. */
type ChatcnDataPart<D = unknown> = { type: `data-${string}`; id?: string; data: D }
/** Boundary between agent steps. */
type ChatcnStepStartPart = { type: "step-start" }
/** Every part type chatcn renders natively. */
type ChatcnKnownPart =
| ChatcnTextPart
| ChatcnReasoningPart
| ChatcnToolPart
| ChatcnSourceUrlPart
| ChatcnSourceDocumentPart
| ChatcnFilePart
| ChatcnDataPart
| ChatcnStepStartPart
/** Any other part (for example AI SDK `custom` or `reasoning-file`): render a fallback, never crash. */
type ChatcnUnknownPart = { type: string; [key: string]: unknown }
/** Any message part. Narrow with `isKnownPart` first, then switch on `part.type`. */
type ChatcnPart = ChatcnKnownPart | ChatcnUnknownPart
/** A chat message, structurally compatible with AI SDK `UIMessage`. */
interface ChatcnMessage<P extends ChatcnPart = ChatcnPart> {
id: string
role: "system" | "user" | "assistant"
parts: P[]
metadata?: unknown
}
/** Points at a part: by index for prose, by `toolCallId` for tool calls. */
type ChatcnPartRef = { messageId: string; partIndex?: number; toolCallId?: string }
type Resolved = Readonly<Record<string, unknown>>
/** One timeline operation. */
type ChatcnStreamOp =
| { op: "message"; message: ChatcnMessage }
| { op: "part"; messageId: string; part: ChatcnPart }
| ({ op: "text-delta"; delta: string } & ChatcnPartRef)
| ({ op: "tool-input-delta"; delta: string } & ChatcnPartRef)
| ({
op: "patch"
patch: Record<string, unknown> | ((resolved: Resolved) => Record<string, unknown>)
} & ChatcnPartRef)
| { op: "await"; key: string; auto?: { after: number; value: unknown } }
/** A timed, optionally guarded operation. */
type ChatcnStreamStep = ChatcnStreamOp & {
at: number
when?: (resolved: Resolved) => boolean
}
/** A built script. */
interface ChatcnScript {
steps: ChatcnStreamStep[]
duration: number
}
/** Options for `useChatcnStream`. */
interface UseChatcnStreamOptions {
/** Start playing on mount. Defaults to true. */
autoplay?: boolean
loop?: boolean
speed?: number
}
/** Playback status. */
type ChatcnStreamStatus = "idle" | "playing" | "paused" | "awaiting" | "done"
/** Return value of `useChatcnStream`. */
interface UseChatcnStreamResult {
messages: ChatcnMessage[]
/** Parts of all messages, in order. */
parts: ChatcnPart[]
state: ChatcnStreamStatus
time: number
/** Key of the `await` step blocking playback, for example an approval id. */
awaiting: string | null
play: () => void
pause: () => void
reset: () => void
seek: (ms: number) => void
resolve: (key: string, value?: unknown) => void
}
type Guard = ChatcnStreamStep["when"]
/** Options for chunked streaming builder steps. */
interface ChunkOptions {
/** Delay between chunks in ms. */
chunkMs?: number
/** Approximate characters per chunk. */
chunkSize?: number
}
/** Split text into chunks of about `size` characters, breaking after whitespace when possible. */
function chunkText(text: string, size: number, byWord = true): string[] {
const chunks: string[] = []
let i = 0
while (i < text.length) {
let end = Math.min(text.length, i + size)
if (byWord && end < text.length) {
const space = text.indexOf(" ", end)
if (space !== -1 && space - end < size) end = space + 1
}
chunks.push(text.slice(i, end))
i = end
}
return chunks
}
/**
* Tolerant JSON parser for streaming tool input.
*
* Parses as much of a truncated JSON document as possible: unterminated strings keep their text,
* open objects and arrays are closed, partial literals (`tr`, `nul`) are completed, partial numbers
* (`12.`, `3e`) are trimmed and trailing commas are ignored. Keys without a value are dropped.
* Single pass, no eval, no dependencies.
*/
/** Result of `parsePartialJson`. */
interface PartialJsonResult {
/** Best-effort value, `undefined` when nothing could be parsed yet. */
value: unknown
/** True when the text held one finished JSON value (trailing commas tolerated). */
complete: boolean
}
const NONE = Symbol("none")
type Parsed = unknown | typeof NONE
const LITERALS: Record<string, [string, unknown]> = {
t: ["true", true],
f: ["false", false],
n: ["null", null],
}
const ESCAPES: Record<string, string> = {
'"': '"',
"\\": "\\",
"/": "/",
b: "\b",
f: "\f",
n: "\n",
r: "\r",
t: "\t",
}
const NUMBER_CHAR = /[-+.eE0-9]/
class Parser {
i = 0
/** Set when input ran out or a syntax error was hit; unwinds every open container. */
stopped = false
readonly s: string
constructor(s: string) {
this.s = s
}
ws(): void {
const s = this.s
while (this.i < s.length) {
const c = s.charCodeAt(this.i)
if (c !== 32 && c !== 10 && c !== 13 && c !== 9) return
this.i++
}
}
value(): Parsed {
this.ws()
const c = this.s[this.i]
if (c === undefined) return this.stop()
if (c === "{") return this.object()
if (c === "[") return this.array()
if (c === '"') return this.string()
if (c === "-" || (c >= "0" && c <= "9")) return this.number()
if (c in LITERALS) return this.literal(c)
return this.stop()
}
stop(): typeof NONE {
this.stopped = true
return NONE
}
object(): Record<string, unknown> {
const obj: Record<string, unknown> = {}
this.i++
while (true) {
this.ws()
const c = this.s[this.i]
if (c === "}") {
this.i++
return obj
}
if (c === ",") {
this.i++
continue
}
if (c !== '"') {
this.stop()
return obj
}
const key = this.string()
if (this.stopped) return obj
this.ws()
if (this.s[this.i] !== ":") {
this.stop()
return obj
}
this.i++
const v = this.value()
if (v !== NONE) {
// defineProperty keeps a "__proto__" key from replacing the prototype.
Object.defineProperty(obj, key, {
value: v,
enumerable: true,
writable: true,
configurable: true,
})
}
if (this.stopped) return obj
this.ws()
const next = this.s[this.i]
if (next === ",") this.i++
else if (next !== "}") {
this.stop()
return obj
}
}
}
array(): unknown[] {
const arr: unknown[] = []
this.i++
while (true) {
this.ws()
const c = this.s[this.i]
if (c === "]") {
this.i++
return arr
}
if (c === ",") {
this.i++
continue
}
const v = this.value()
if (v !== NONE) arr.push(v)
if (this.stopped) return arr
this.ws()
const next = this.s[this.i]
if (next === ",") this.i++
else if (next !== "]") {
this.stop()
return arr
}
}
}
string(): string {
const s = this.s
let out = ""
let start = ++this.i
while (this.i < s.length) {
const c = s[this.i]
if (c === '"') {
out += s.slice(start, this.i++)
return out
}
if (c !== "\\") {
this.i++
continue
}
out += s.slice(start, this.i)
start = this.i
const e = s[this.i + 1]
if (e === undefined) break
if (e === "u") {
const hex = s.slice(this.i + 2, this.i + 6)
if (hex.length < 4) break
const code = Number.parseInt(hex, 16)
out += Number.isNaN(code) ? hex : String.fromCharCode(code)
this.i += 6
} else {
out += ESCAPES[e] ?? e
this.i += 2
}
start = this.i
}
// Ran out of input inside the string. A partial escape (start sits on it) is dropped.
if (s[start] !== "\\") out += s.slice(start)
this.stopped = true
const last = out.charCodeAt(out.length - 1)
return last >= 0xd800 && last <= 0xdbff ? out.slice(0, -1) : out
}
number(): Parsed {
const s = this.s
const start = this.i
while (this.i < s.length && NUMBER_CHAR.test(s[this.i] as string)) this.i++
const token = s.slice(start, this.i)
// Trim a dangling sign, dot or exponent left by truncation (`12.`, `3e`, `-`).
const trimmed = token.replace(/[-+.eE]+$/, "")
if (trimmed !== token) this.stopped = true
const n = Number(trimmed)
return trimmed === "" || Number.isNaN(n) ? this.stop() : n
}
literal(first: string): Parsed {
const [word, value] = LITERALS[first] as [string, unknown]
const rest = this.s.slice(this.i, this.i + word.length)
if (rest === word) {
this.i += word.length
return value
}
if (this.i + rest.length === this.s.length && word.startsWith(rest)) {
this.i += rest.length
this.stopped = true
return value
}
return this.stop()
}
}
/** Parse possibly truncated JSON, returning the best-effort value and whether it was complete. */
function parsePartialJson(text: string): PartialJsonResult {
const p = new Parser(text)
const v = p.value()
if (!p.stopped) p.ws()
return { value: v === NONE ? undefined : v, complete: !p.stopped && p.i === text.length }
}
/** True when an approval resolution value means yes (`true` or `{ approved: true }`). */
function isApproved(value: unknown): boolean {
return (
value === true ||
(typeof value === "object" && value !== null && "approved" in value && value.approved === true)
)
}
/** Fluent script builder. Every method appends steps at the builder's current time. */
class ChatcnScriptBuilder {
private steps: ChatcnStreamStep[] = []
private t = 0
private messageId: string | null = null
private partCount = new Map<string, number>()
private tool: { id: string; guard: Guard } | null = null
private ids = { message: 0, call: 0, approval: 0 }
private push(op: ChatcnStreamOp, when?: Guard): this {
this.steps.push(when ? { ...op, at: this.t, when } : { ...op, at: this.t })
return this
}
private addMessage(role: ChatcnMessage["role"], id?: string): string {
const messageId = id ?? `msg_${++this.ids.message}`
this.partCount.set(messageId, 0)
this.push({ op: "message", message: { id: messageId, role, parts: [] } })
return messageId
}
private addPart(part: ChatcnPart): number {
if (!this.messageId) this.messageId = this.addMessage("assistant")
const messageId = this.messageId
const index = this.partCount.get(messageId) ?? 0
this.partCount.set(messageId, index + 1)
this.push({ op: "part", messageId, part })
return index
}
private toolRef(): { messageId: string; toolCallId: string } {
if (!this.tool || !this.messageId) throw new Error("Call toolCall() before tool steps.")
return { messageId: this.messageId, toolCallId: this.tool.id }
}
/** Advance the builder clock. */
wait(ms: number): this {
this.t += ms
return this
}
/** Add a finished user message. */
user(text: string, options: { id?: string } = {}): this {
const id = this.addMessage("user", options.id)
this.messageId = id
this.addPart({ type: "text", text, state: "done" })
this.messageId = null
return this
}
/** Start an assistant message; later parts go into it. */
assistant(options: { id?: string } = {}): this {
this.messageId = this.addMessage("assistant", options.id)
return this
}
/** Stream a text or reasoning part chunk by chunk, then mark it done. */
text(text: string, options: ChunkOptions & { type?: "text" | "reasoning" } = {}): this {
const { chunkMs = 30, chunkSize = 12, type = "text" } = options
const partIndex = this.addPart({ type, text: "", state: "streaming" })
const messageId = this.messageId as string
for (const delta of chunkText(text, chunkSize)) {
this.wait(chunkMs).push({ op: "text-delta", messageId, partIndex, delta })
}
return this.push({ op: "patch", messageId, partIndex, patch: { state: "done" } })
}
/** Stream a reasoning part. */
reasoning(text: string, options: ChunkOptions = {}): this {
return this.text(text, { ...options, type: "reasoning" })
}
/** Append any part as is. */
part(part: ChatcnPart): this {
this.addPart(part)
return this
}
/** Start a tool call. Without `input` it begins in `input-streaming`. */
toolCall(call: {
name: string
toolCallId?: string
input?: unknown
title?: string
dynamic?: boolean
}): this {
const id = call.toolCallId ?? `call_${++this.ids.call}`
const part: ChatcnToolPart = {
type: call.dynamic ? "dynamic-tool" : `tool-${call.name}`,
toolCallId: id,
state: call.input === undefined ? "input-streaming" : "input-available",
}
if (call.dynamic) part.toolName = call.name
if (call.title) part.title = call.title
if (call.input !== undefined) part.input = call.input
this.addPart(part)
this.tool = { id, guard: undefined }
return this
}
/** Stream the tool input as JSON in character chunks, then mark it `input-available`. */
streamInput(input: unknown, options: ChunkOptions = {}): this {
const { chunkMs = 40, chunkSize = 6 } = options
const ref = this.toolRef()
const raw = typeof input === "string" ? input : JSON.stringify(input)
for (const delta of chunkText(raw, chunkSize, false)) {
this.wait(chunkMs).push({ op: "tool-input-delta", ...ref, delta })
}
const value = typeof input === "string" ? parsePartialJson(input).value : input
return this.push({
op: "patch",
...ref,
patch: { state: "input-available", input: value, rawInput: undefined },
})
}
/**
* Ask for approval and wait for `resolve(approvalId, value)`. Later tool steps only run when the
* value is approving; a denial moves the call to `output-denied`. `auto` resolves on its own.
*/
awaitApproval(
options: {
approvalId?: string
requestReason?: string
auto?: { after: number; value: unknown }
} = {},
): this {
const ref = this.toolRef()
const id = options.approvalId ?? `approval_${++this.ids.approval}`
const approval = options.requestReason ? { id, requestReason: options.requestReason } : { id }
const approved: Guard = (r) => isApproved(r[id])
this.push({ op: "patch", ...ref, patch: { state: "approval-requested", approval } })
this.push(
options.auto ? { op: "await", key: id, auto: options.auto } : { op: "await", key: id },
)
this.push(
{
op: "patch",
...ref,
patch: { state: "approval-responded", approval: { ...approval, approved: true } },
},
approved,
)
this.push(
{
op: "patch",
...ref,
patch: (r) => {
const v = r[id]
const reason = typeof v === "object" && v !== null && "reason" in v ? v.reason : undefined
return { state: "output-denied", approval: { ...approval, approved: false, reason } }
},
},
(r) => !isApproved(r[id]),
)
;(this.tool as { guard: Guard }).guard = approved
return this
}
/** Finish the tool call with output after `delayMs`. */
output(output: unknown, options: { delayMs?: number } = {}): this {
const ref = this.toolRef()
return this.wait(options.delayMs ?? 400).push(
{ op: "patch", ...ref, patch: { state: "output-available", output } },
this.tool?.guard,
)
}
/** Fail the tool call after `delayMs`. */
error(errorText: string, options: { delayMs?: number } = {}): this {
const ref = this.toolRef()
return this.wait(options.delayMs ?? 400).push(
{ op: "patch", ...ref, patch: { state: "output-error", errorText } },
this.tool?.guard,
)
}
/** Append a raw step at the current time. */
step(op: ChatcnStreamOp, when?: Guard): this {
return this.push(op, when)
}
/** Finish the script. */
build(): ChatcnScript {
return { steps: [...this.steps], duration: this.t }
}
}
/** Start a script builder. */
function script(): ChatcnScriptBuilder {
return new ChatcnScriptBuilder()
}
/** Time source. The default uses `performance.now()` and `setTimeout`. */
interface ChatcnClock {
now(): number
setTimeout(fn: () => void, ms: number): unknown
clearTimeout(handle: unknown): void
}
/** Options for `createChatcnStream`. */
interface ChatcnStreamOptions {
speed?: number
loop?: boolean
/** Hold on the last frame before looping, in script ms. Defaults to 1200. */
loopDelay?: number
clock?: ChatcnClock
}
/** Immutable engine state; a new object is created on every change. */
interface ChatcnStreamSnapshot {
messages: ChatcnMessage[]
/** Parts of all messages, in order. */
parts: ChatcnPart[]
time: number
status: ChatcnStreamStatus
/** Key of the unresolved `await` step blocking the timeline. */
awaiting: string | null
}
/** Controller returned by `createChatcnStream`. */
interface ChatcnStream {
play(): void
pause(): void
reset(): void
seek(ms: number): void
resolve(key: string, value?: unknown): void
getSnapshot(): ChatcnStreamSnapshot
subscribe(listener: () => void): () => void
readonly duration: number
}
const realClock: ChatcnClock = {
now: () => globalThis.performance?.now() ?? Date.now(),
setTimeout: (fn, ms) => globalThis.setTimeout(fn, ms),
clearTimeout: (h) => globalThis.clearTimeout(h as ReturnType<typeof setTimeout>),
}
type AwaitStep = Extract<ChatcnStreamStep, { op: "await" }>
const EPSILON = 1e-6
function replaceAt<T>(list: T[], index: number, item: T): T[] {
const copy = list.slice()
copy[index] = item
return copy
}
function applyOp(
messages: ChatcnMessage[],
step: ChatcnStreamOp,
resolved: Resolved,
): ChatcnMessage[] {
if (step.op === "await") return messages
if (step.op === "message") {
const i = messages.findIndex((m) => m.id === step.message.id)
return i < 0 ? [...messages, step.message] : replaceAt(messages, i, step.message)
}
const mi = messages.findIndex((m) => m.id === step.messageId)
const msg = messages[mi]
if (!msg) return messages
let parts: ChatcnPart[]
if (step.op === "part") parts = [...msg.parts, step.part]
else {
const pi =
step.toolCallId === undefined
? (step.partIndex ?? msg.parts.length - 1)
: msg.parts.findIndex((p) => (p as ChatcnToolPart).toolCallId === step.toolCallId)
const part = msg.parts[pi] as Record<string, unknown> | undefined
if (!part) return messages
let next: Record<string, unknown>
if (step.op === "text-delta") next = { ...part, text: `${part.text ?? ""}${step.delta}` }
else if (step.op === "tool-input-delta") {
const rawInput = `${part.rawInput ?? ""}${step.delta}`
next = { ...part, rawInput, input: parsePartialJson(rawInput).value }
} else {
next = { ...part, ...(typeof step.patch === "function" ? step.patch(resolved) : step.patch) }
for (const key in next) if (next[key] === undefined) delete next[key]
}
parts = replaceAt(msg.parts, pi, next as ChatcnPart)
}
return replaceAt(messages, mi, { ...msg, parts })
}
/** Create a player for a script. Nothing runs until `play()` or `seek()`. */
function createChatcnStream(
script: ChatcnScript | ChatcnStreamStep[],
options: ChatcnStreamOptions = {},
): ChatcnStream {
const list = Array.isArray(script) ? script : script.steps
const steps = [...list].sort((a, b) => a.at - b.at)
const last = steps.at(-1)?.at ?? 0
const duration = Array.isArray(script) ? last : Math.max(script.duration, last)
const { speed = 1, loop = false, loopDelay = 1200, clock = realClock } = options
const end = loop ? duration + loopDelay : duration
const listeners = new Set<() => void>()
let messages: ChatcnMessage[] = []
let time = 0
let cursor = 0
let playing = false
let awaiting: AwaitStep | null = null
let resolved: Record<string, unknown> = {}
let timer: unknown = null
let anchorWall = 0
let anchorTime = 0
let snapshot = makeSnapshot()
function status(): ChatcnStreamStatus {
if (awaiting) return "awaiting"
if (playing) return "playing"
if (cursor >= steps.length && time >= duration) return "done"
return cursor === 0 && time === 0 ? "idle" : "paused"
}
function makeSnapshot(): ChatcnStreamSnapshot {
const parts = messages.flatMap((m) => m.parts)
return { messages, parts, time, status: status(), awaiting: awaiting?.key ?? null }
}
function emit() {
snapshot = makeSnapshot()
for (const fn of listeners) fn()
}
const scriptNow = () => anchorTime + (clock.now() - anchorWall) * speed
function anchor() {
anchorWall = clock.now()
anchorTime = time
}
function clear(keepResolved: boolean) {
messages = []
time = 0
cursor = 0
awaiting = null
if (!keepResolved) resolved = {}
}
/** Apply steps due by `target`, stopping at an unresolved await. Seeking passes `auto` awaits. */
function advance(target: number, seeking = false) {
awaiting = null
while (cursor < steps.length) {
const step = steps[cursor] as ChatcnStreamStep
if (step.at > target + EPSILON) break
if (step.op === "await" && !(step.key in resolved)) {
if (!seeking || !step.auto) {
awaiting = step
time = step.at
return
}
resolved = { ...resolved, [step.key]: step.auto.value }
}
if (!step.when || step.when(resolved)) messages = applyOp(messages, step, resolved)
cursor++
}
time = Math.min(target, duration)
}
/** Arm the timer for the next step, an `auto` await or the loop restart. */
function schedule() {
if (timer !== null) clock.clearTimeout(timer)
timer = null
if (!playing) return
const blocker = awaiting
if (blocker) {
const auto = blocker.auto
if (auto)
timer = clock.setTimeout(() => api.resolve(blocker.key, auto.value), auto.after / speed)
return
}
const next = steps[cursor]
if (!next && !loop && time >= duration - EPSILON) {
playing = false
return
}
const target = next ? next.at : end
timer = clock.setTimeout(tick, Math.max(0, (target - scriptNow()) / speed))
}
function tick() {
timer = null
const now = scriptNow()
advance(now)
if (loop && !awaiting && cursor >= steps.length && now >= end - EPSILON) {
clear(false)
advance(0)
}
anchor()
schedule()
emit()
}
const api: ChatcnStream = {
duration,
play() {
if (playing) return
if (status() === "done") clear(false)
playing = true
advance(time)
anchor()
schedule()
emit()
},
pause() {
if (!playing) return
if (!awaiting) advance(scriptNow())
playing = false
schedule()
emit()
},
reset() {
playing = false
clear(false)
schedule()
emit()
},
seek(ms) {
clear(true)
advance(Math.max(0, Math.min(ms, duration)), true)
anchor()
schedule()
emit()
},
resolve(key, value = true) {
resolved = { ...resolved, [key]: value }
if (awaiting?.key !== key) return
advance(time)
anchor()
schedule()
emit()
},
getSnapshot: () => snapshot,
subscribe(listener) {
listeners.add(listener)
return () => listeners.delete(listener)
},
}
return api
}
/**
* Play a scripted chatcn stream in React. Pass a stable script (a module constant or memoized);
* a new script, `loop` or `speed` value starts a fresh stream.
*/
function useChatcnStream(
script: ChatcnScript | ChatcnStreamStep[],
{ autoplay = true, loop = false, speed = 1 }: UseChatcnStreamOptions = {},
): UseChatcnStreamResult {
const stream = useMemo(() => createChatcnStream(script, { loop, speed }), [script, loop, speed])
const snapshot = useSyncExternalStore(stream.subscribe, stream.getSnapshot, stream.getSnapshot)
useEffect(() => {
if (autoplay) stream.play()
return () => stream.pause()
}, [stream, autoplay])
return {
messages: snapshot.messages,
parts: snapshot.parts,
state: snapshot.status,
time: snapshot.time,
awaiting: snapshot.awaiting,
play: stream.play,
pause: stream.pause,
reset: stream.reset,
seek: stream.seek,
resolve: stream.resolve,
}
}
/* A coding agent writes a React component as an artifact, then revises it on request. Loops. */
const V1 = `type UsageMeterProps = {
used: number
limit: number
resetsOn: string
}
export function UsageMeter({ used, limit, resetsOn }: UsageMeterProps) {
const percent = Math.min(100, Math.round((used / limit) * 100))
const barWidth = \`\${percent}%\`
const nearLimit = percent >= 80
const usedLabel = used.toLocaleString("en-US")
const limitLabel = limit.toLocaleString("en-US")
return (
<section className="w-80 rounded-(--chatcn-radius-lg) bg-(color:--chatcn-card) p-4 shadow-(--chatcn-shadow-sm)">
<header className="flex items-baseline justify-between">
<h3 className="text-[0.875rem]/[1.25rem] tracking-[-0.003em] font-medium text-(color:--chatcn-fg)">Agent runs</h3>
<span className="text-[0.8125rem]/[1.25rem] tabular-nums text-(color:--chatcn-fg-subtle)">{percent}%</span>
</header>
<p className="mt-2 text-[1.5rem]/[2rem] tracking-[-0.022em] font-semibold tabular-nums tracking-tight text-(color:--chatcn-fg)">
{usedLabel}
<span className="text-[0.875rem]/[1.25rem] tracking-[-0.003em] font-normal text-(color:--chatcn-fg-subtle)"> / {limitLabel}</span>
</p>
<div className="mt-3 h-1.5 overflow-hidden rounded-full bg-(color:--chatcn-fill)">
<div className="h-full rounded-full bg-(color:--chatcn-fg)" style={{ width: barWidth }} />
</div>
{nearLimit && (
<p className="mt-3 rounded-(--chatcn-radius-md) bg-(color:--chatcn-red)/10 px-3 py-2 text-[0.8125rem]/[1.25rem] font-medium text-(color:--chatcn-red)">
Warning: you have used {percent}% of your monthly runs.
</p>
)}
</section>
)
}
`
const V2 = `type UsageMeterProps = {
used: number
limit: number
resetsOn: string
}
export function UsageMeter({ used, limit, resetsOn }: UsageMeterProps) {
const percent = Math.min(100, Math.round((used / limit) * 100))
const barWidth = \`\${percent}%\`
const nearLimit = percent >= 80
const usedLabel = used.toLocaleString("en-US")
const limitLabel = limit.toLocaleString("en-US")
return (
<section className="w-80 rounded-(--chatcn-radius-lg) bg-(color:--chatcn-card) p-4 shadow-(--chatcn-shadow-sm)">
<header className="flex items-baseline justify-between">
<h3 className="text-[0.875rem]/[1.25rem] tracking-[-0.003em] font-medium text-(color:--chatcn-fg)">Agent runs</h3>
<span className="text-[0.75rem]/[1rem] tabular-nums text-(color:--chatcn-fg-subtle)">Resets {resetsOn}</span>
</header>
<p className="mt-2 text-[1.5rem]/[2rem] tracking-[-0.022em] font-semibold tabular-nums tracking-tight text-(color:--chatcn-fg)">
{usedLabel}
<span className="text-[0.875rem]/[1.25rem] tracking-[-0.003em] font-normal text-(color:--chatcn-fg-subtle)"> / {limitLabel}</span>
</p>
<div className="mt-3 h-1.5 overflow-hidden rounded-full bg-(color:--chatcn-fill)">
<div className="h-full rounded-full bg-(color:--chatcn-fg)" style={{ width: barWidth }} />
</div>
{nearLimit && (
<p className="mt-2.5 text-[0.75rem]/[1rem] text-(color:--chatcn-fg-muted)">
{percent}% used. New runs pause at the limit until {resetsOn}.
</p>
)}
</section>
)
}
`
const run = script()
.user(
"Build a usage meter card for the billing page: plan limit, current usage, and a warning once they pass 80%.",
{ id: "u1" },
)
.wait(700)
.assistant({ id: "a1" })
.text("I'll write it as a small React component with a progress bar and a warning state.", {
chunkMs: 28,
})
.wait(250)
.toolCall({ name: "create_artifact", toolCallId: "art_1" })
.streamInput({ title: "Usage meter", content: V1 }, { chunkMs: 30, chunkSize: 14 })
.output({ version: 1 }, { delayMs: 200 })
.wait(200)
.text("The card takes `used`, `limit` and `resetsOn`. The warning shows from 80% onward.", {
chunkMs: 26,
})
.wait(2600)
.user("Make the warning quieter, it reads like an error. And show when the limit resets.", {
id: "u2",
})
.wait(700)
.assistant({ id: "a2" })
.text("Toned it down to a muted note under the bar and moved the reset date into the header.", {
chunkMs: 26,
})
.wait(250)
.toolCall({ name: "update_artifact", toolCallId: "art_2" })
.streamInput({ title: "Usage meter", content: V2 }, { chunkMs: 30, chunkSize: 14 })
.output({ version: 2 }, { delayMs: 200 })
.wait(1200)
.build()
/* -------------------------------------------------------------------------------------------------
* Reading artifacts out of the message stream
* -----------------------------------------------------------------------------------------------*/
interface ArtifactRun {
toolCallId: string
messageId: string
version: number
content: string
streaming: boolean
createdAt: number
}
/** True for tool parts, static or dynamic. */
function isToolPart(part: { type: string }): part is ChatcnToolPart {
return part.type === "dynamic-tool" || part.type.startsWith("tool-")
}
function artifactRuns(messages: ChatcnMessage[], times: Map<string, number>): ArtifactRun[] {
const runs: ArtifactRun[] = []
for (const message of messages) {
for (const part of message.parts) {
if (!isToolPart(part)) continue
const tool = part as ChatcnToolPart
if (tool.type !== "tool-create_artifact" && tool.type !== "tool-update_artifact") continue
const input = (tool.input ?? {}) as { content?: string }
if (!times.has(tool.toolCallId)) times.set(tool.toolCallId, Date.now())
runs.push({
toolCallId: tool.toolCallId,
messageId: message.id,
version: runs.length + 1,
content: input.content ?? "",
streaming: tool.state === "input-streaming" || tool.state === "input-available",
createdAt: times.get(tool.toolCallId) ?? Date.now(),
})
}
}
return runs
}
/* -------------------------------------------------------------------------------------------------
* Types
* -----------------------------------------------------------------------------------------------*/
interface ArtifactVersion {
id: string
/** Shown in the list. Defaults to `Version 3`. */
label?: string
/** When this version was written. Drives "Edited 2 min ago". */
createdAt?: Date | number | string
/** Lines added since the previous version. Computed from `content` when omitted. */
additions?: number
/** Lines removed since the previous version. Computed from `content` when omitted. */
deletions?: number
/** One line on what changed, for example the user request that produced it. */
summary?: string
/** Full content of this version. Only used to compute the diff summary. */
content?: string
}
const iconNode: IconNode = [
["path", {"d":"m18.5 11.5-4.73-4.73a2.5 2.5 0 0 0-3.54 0L5.5 11.5"}],
["path", {"d":"M12 19v-9"}],
]
const ArrowUpIcon: Icon = /* @__PURE__ */ createIcon("arrow-up", iconNode)
/* -------------------------------------------------------------------------------------------------
* Types
* -----------------------------------------------------------------------------------------------*/
type ArtifactView = "code" | "preview"
interface ArtifactRenderContext {
content: string
language?: string
streaming: boolean
}
interface ArtifactPanelProps extends Omit<React.ComponentProps<"section">, "title" | "content"> {
title: React.ReactNode
kind?: ArtifactKind
/** Short type label next to the title, for example `React component`. */
label?: React.ReactNode
/** The artifact source: code, markdown or HTML. */
content: string
/** Language of `content`, for `renderCode` and the download extension. */
language?: string
/** Download file name. Defaults to the title plus an extension from `language`. */
filename?: string
/** True while the model is writing. Code shows a caret and follows the end. */
streaming?: boolean
versions?: ArtifactVersion[]
version?: string
onVersionChange?: (id: string) => void
view?: ArtifactView
defaultView?: ArtifactView
onViewChange?: (view: ArtifactView) => void
/** A rendered preview, or a function of the content. Use `JsxPreview` for React artifacts. */
preview?: React.ReactNode | ((context: ArtifactRenderContext) => React.ReactNode)
/** HTML to preview in a sandboxed iframe. HTML artifacts use `content` by default. */
previewHtml?: string
/** URL to preview in a sandboxed iframe. */
previewSrc?: string
/** iframe sandbox tokens. Never add `allow-same-origin` next to `allow-scripts`. */
sandbox?: string
/** A runtime error from the preview. Shows a bar with `onFixError`. */
previewError?: React.ReactNode
onFixError?: () => void
/** Replace the code view, for example with a highlighted code block. */
renderCode?: (context: ArtifactRenderContext) => React.ReactNode
/** Extra header actions, placed before copy. Use `ArtifactPanelAction`. */
actions?: React.ReactNode
onClose?: () => void
fullscreen?: boolean
defaultFullscreen?: boolean
onFullscreenChange?: (fullscreen: boolean) => void
}
/* -------------------------------------------------------------------------------------------------
* Layout context: lets the panel adapt to the side panel or the mobile sheet.
* -----------------------------------------------------------------------------------------------*/
type Presentation = "side" | "sheet" | "inline"
const LayoutContext = React.createContext<{ presentation: Presentation; titleId?: string }>({
presentation: "inline",
})
function useControllable<T>(prop: T | undefined, initial: T, onChange?: (value: T) => void) {
const [state, setState] = React.useState(initial)
const value = prop ?? state
const set = React.useCallback(
(next: T) => {
if (prop === undefined) setState(next)
onChange?.(next)
},
[prop, onChange],
)
return [value, set] as const
}
/* -------------------------------------------------------------------------------------------------
* Helpers
* -----------------------------------------------------------------------------------------------*/
const EXTENSIONS: Record<string, string> = {
tsx: "tsx",
jsx: "jsx",
typescript: "ts",
ts: "ts",
javascript: "js",
js: "js",
html: "html",
css: "css",
markdown: "md",
md: "md",
python: "py",
py: "py",
json: "json",
svg: "svg",
mermaid: "mmd",
}
function slugify(text: string) {
return (
text
.toLowerCase()
.replace(/[^a-z0-9]+/g, "-")
.replace(/^-|-$/g, "") || "artifact"
)
}
/** The model is writing here: the same square caret the rest of chatcn uses. */
function Caret() {
return (
<span
aria-hidden="true"
data-slot="streaming-caret"
className="bg-(color:--chatcn-accent) ms-0.5 inline-block size-[0.55em] translate-y-[0.04em] rounded-[2px] align-baseline"
/>
)
}
/**
* Plain monochrome code with line numbers. While streaming it follows the end, unless the reader
* has scrolled up, and the caret marks where the model is writing.
*/
function ArtifactCode({
content,
streaming = false,
className,
}: {
content: string
streaming?: boolean
className?: string
}) {
const scrollRef = React.useRef<HTMLDivElement>(null)
const pinned = React.useRef(true)
const lines = React.useMemo(() => {
const all = content.split("\n")
if (!streaming && all.length > 1 && all.at(-1) === "") all.pop()
return all
}, [content, streaming])
const digits = String(lines.length).length
React.useLayoutEffect(() => {
const el = scrollRef.current
if (el && streaming && pinned.current) el.scrollTop = el.scrollHeight
}, [content, streaming])
return (
<div
ref={scrollRef}
data-slot="artifact-code"
onScroll={(event) => {
const el = event.currentTarget
pinned.current = el.scrollHeight - el.scrollTop - el.clientHeight < 64
}}
className={cn(
"chatcn-scroll size-full overflow-auto [overflow-anchor:none]",
"text-[0.8125rem]/[1.25rem] font-mono leading-5",
className,
)}
>
{/* biome-ignore lint/a11y/noNoninteractiveTabindex: scrollable code must be reachable by keyboard */}
<pre tabIndex={0} className="chatcn-focus w-max min-w-full py-3 outline-offset-[-2px]">
<code className="block">
{lines.map((line, i) => (
<span key={i} className="flex">
<span
aria-hidden="true"
className="bg-(color:--chatcn-bg) text-(color:--chatcn-fg-subtle) sticky start-0 shrink-0 ps-4 pe-4 text-end tabular-nums select-none"
style={{ width: `calc(${digits}ch + 2rem)` }}
>
{i + 1}
</span>
<span className="text-(color:--chatcn-fg) pe-6 whitespace-pre">
{line}
{streaming && i === lines.length - 1 ? <Caret /> : null}
</span>
</span>
))}
</code>
</pre>
</div>
)
}
interface TooltipProps {
content: React.ReactNode
children: React.ReactElement
side?: "top" | "bottom" | "left" | "right"
align?: "start" | "center" | "end"
/** A shortcut hint shown after the label, for example `⌘C`. */
shortcut?: React.ReactNode
}
function Tooltip({ content, children, side = "top", align = "center", shortcut }: TooltipProps) {
return (
<TooltipPrimitive.Root>
<TooltipPrimitive.Trigger render={children} />
<TooltipPrimitive.Portal>
<TooltipPrimitive.Positioner side={side} align={align} sideOffset={6} className="z-50">
<TooltipPrimitive.Popup
data-slot="tooltip"
className={cn(
"rounded-(--chatcn-radius-sm) bg-(color:--chatcn-fg) text-[0.75rem]/[1rem] text-(color:--chatcn-bg) shadow-(--chatcn-shadow-md) flex max-w-xs origin-(--transform-origin) items-center gap-2 px-2 py-1 font-medium text-pretty",
"ease-(--chatcn-ease-out) transition-[opacity,scale] duration-125",
"data-[ending-style]:scale-97 data-[ending-style]:opacity-0 data-[ending-style]:duration-100 data-[starting-style]:scale-97 data-[starting-style]:opacity-0",
// Once one tooltip is open, the next appears without animation. Reduced motion keeps
// only the fade.
"data-[instant]:transition-none motion-reduce:transition-opacity motion-reduce:data-[ending-style]:scale-100 motion-reduce:data-[starting-style]:scale-100",
)}
>
{content}
{shortcut ? <span className="font-normal opacity-60">{shortcut}</span> : null}
</TooltipPrimitive.Popup>
</TooltipPrimitive.Positioner>
</TooltipPrimitive.Portal>
</TooltipPrimitive.Root>
)
}
type ButtonVariant = "solid" | "outline" | "ghost" | "subtle"
type ButtonSize = "xs" | "sm" | "md" | "lg" | "icon-xs" | "icon-sm" | "icon-md" | "icon-lg"
interface ButtonProps extends React.ComponentProps<"button"> {
variant?: ButtonVariant
size?: ButtonSize
}
interface CopyButtonProps extends Omit<ButtonProps, "value" | "onCopy"> {
value: string | (() => string)
label?: string
onCopy?: (value: string) => void
}
const base = cn(
"chatcn-focus inline-flex shrink-0 items-center justify-center gap-1.5 font-medium whitespace-nowrap select-none",
"ease-(--chatcn-ease-standard) transition-[background-color,color,box-shadow,scale] duration-150",
"active:scale-(--chatcn-press-scale) active:duration-100 disabled:pointer-events-none disabled:opacity-50",
"[&_svg]:pointer-events-none [&_svg]:shrink-0",
)
const variants: Record<ButtonVariant, string> = {
solid: "bg-(color:--chatcn-primary) text-(color:--chatcn-primary-fg) hover:bg-(color:--chatcn-primary-hover)",
outline: "bg-(color:--chatcn-card) text-(color:--chatcn-fg) shadow-(--chatcn-shadow-xs) hover:bg-(color:--chatcn-fill-hover)",
ghost: "text-(color:--chatcn-fg-muted) hover:bg-(color:--chatcn-fill-hover) hover:text-(color:--chatcn-fg)",
subtle: "bg-(color:--chatcn-fill) text-(color:--chatcn-fg) hover:bg-(color:--chatcn-fill-hover)",
}
// Heights follow the control scale: 24, 28, 32, 36. Radii stay concentric inside 12 px surfaces.
const sizes: Record<ButtonSize, string> = {
xs: "h-6 rounded-(--chatcn-radius-sm) px-2 text-[0.75rem]/[1rem] [&_svg]:size-3.5",
sm: "h-7 rounded-(--chatcn-radius-sm) px-2.5 text-[0.8125rem]/[1.25rem] [&_svg]:size-3.5",
md: "h-8 rounded-(--chatcn-radius-md) px-3 text-[0.875rem]/[1.25rem] tracking-[-0.003em] [&_svg]:size-4",
lg: "h-9 rounded-(--chatcn-radius-md) px-3.5 text-[0.875rem]/[1.25rem] tracking-[-0.003em] [&_svg]:size-4",
"icon-xs": "size-6 rounded-(--chatcn-radius-sm) active:scale-(--chatcn-press-scale-icon) [&_svg]:size-3.5",
"icon-sm": "size-7 rounded-(--chatcn-radius-sm) active:scale-(--chatcn-press-scale-icon) [&_svg]:size-3.5",
"icon-md": "size-8 rounded-(--chatcn-radius-md) active:scale-(--chatcn-press-scale-icon) [&_svg]:size-4",
"icon-lg": "size-9 rounded-(--chatcn-radius-md) active:scale-(--chatcn-press-scale-icon) [&_svg]:size-4",
}
/** Class names for anything that should look like a button, such as a link. */
function buttonVariants({
variant = "ghost",
size = "md",
}: {
variant?: ButtonVariant
size?: ButtonSize
} = {}) {
return cn(base, variants[variant], sizes[size])
}
function Button({
variant = "ghost",
size = "md",
type = "button",
className,
...props
}: ButtonProps) {
return (
<button
type={type}
data-slot="button"
data-variant={variant}
className={cn(buttonVariants({ variant, size }), className)}
{...props}
/>
)
}
const iconNode2: IconNode = [
["path", {"d":"M11.5 9h7a2.5 2.5 0 0 1 2.5 2.5v7a2.5 2.5 0 0 1-2.5 2.5h-7A2.5 2.5 0 0 1 9 18.5v-7A2.5 2.5 0 0 1 11.5 9"}],
["path", {"d":"M6 15h-.5A2.5 2.5 0 0 1 3 12.5v-7A2.5 2.5 0 0 1 5.5 3h7A2.5 2.5 0 0 1 15 5.5V6"}],
]
const CopyIcon: Icon = /* @__PURE__ */ createIcon("copy", iconNode2)
const iconNode3: IconNode = [
["path", {"d":"m4.5 12.75 3.23 3.23a2.5 2.5 0 0 0 3.54 0l8.48-8.48"}],
]
const CheckIcon: Icon = /* @__PURE__ */ createIcon("check", iconNode3)
/** Copy swaps to a check with a 150 ms blur crossfade, holds for 1.5 s and announces itself. */
function CopyButton({
value,
label = "Copy",
onCopy,
onClick,
children,
size = "icon-sm",
className,
...props
}: CopyButtonProps) {
// A counter, not a flag: copying again while the check shows restarts the 1.5 s hold.
const [copies, setCopies] = React.useState(0)
const [copied, setCopied] = React.useState(false)
React.useEffect(() => {
if (!copies) return
setCopied(true)
const id = window.setTimeout(() => setCopied(false), 1500)
return () => window.clearTimeout(id)
}, [copies])
// Reduced motion keeps the crossfade and drops the scale and blur.
const layer = cn(
"ease-(--chatcn-ease-out) absolute transition-[opacity,scale,filter] duration-150",
"motion-reduce:scale-100 motion-reduce:blur-none motion-reduce:transition-opacity",
)
return (
<Button
{...props}
size={size}
aria-label={children ? undefined : copied ? "Copied" : label}
onClick={(event) => {
// Compose with handlers injected by wrappers such as Tooltip instead of replacing them.
onClick?.(event)
if (event.defaultPrevented) return
const text = typeof value === "function" ? value() : value
navigator.clipboard
?.writeText(text)
.then(() => {
setCopies((n) => n + 1)
onCopy?.(text)
})
// Clipboard access can be denied (insecure context, permissions). Stay quiet and unchanged.
.catch(() => {})
}}
className={cn("relative", className)}
>
{children ? (
<>
<span className="relative grid size-3.5 place-items-center">
<CopyIcon
className={cn(
layer,
copied ? "scale-75 opacity-0 blur-[2px]" : "scale-100 opacity-100",
)}
/>
<CheckIcon
className={cn(
layer,
copied ? "scale-100 opacity-100" : "scale-75 opacity-0 blur-[2px]",
)}
/>
</span>
{children}
</>
) : null}
{children ? null : (
<>
<CopyIcon
className={cn(
layer,
copied ? "scale-75 opacity-0 blur-[2px]" : "scale-100 opacity-100",
)}
/>
<CheckIcon
className={cn(
layer,
copied ? "scale-100 opacity-100" : "scale-75 opacity-0 blur-[2px]",
)}
/>
</>
)}
<span aria-live="polite" className="sr-only">
{copied ? "Copied" : ""}
</span>
</Button>
)
}
/* -------------------------------------------------------------------------------------------------
* Small parts
* -----------------------------------------------------------------------------------------------*/
interface ArtifactPanelActionProps extends React.ComponentProps<typeof Button> {
/** Tooltip and accessible name. */
label: string
}
/** An icon action for the panel header, with a tooltip. */
function ArtifactPanelAction({ label, children, ...props }: ArtifactPanelActionProps) {
return (
<Tooltip content={label} side="bottom">
<Button size="icon-sm" aria-label={label} {...props}>
{children}
</Button>
</Tooltip>
)
}
function downloadText(text: string, name: string, type = "text/plain") {
const url = URL.createObjectURL(new Blob([text], { type }))
const a = document.createElement("a")
a.href = url
a.download = name
document.body.appendChild(a)
a.click()
a.remove()
window.setTimeout(() => URL.revokeObjectURL(url), 1000)
}
const iconNode4: IconNode = [
["path", {"d":"M3.5 15v2.5a3 3 0 0 0 3 3h11a3 3 0 0 0 3-3V15"}],
["path", {"d":"m7.5 10.5 3.09 3.09a2 2 0 0 0 2.82 0l3.09-3.09"}],
["path", {"d":"M12 3.5v7"}],
]
const DownloadIcon: Icon = /* @__PURE__ */ createIcon("download", iconNode4)
const iconNode5: IconNode = [
["path", {"d":"M14 4v3.5a2.5 2.5 0 0 0 2.5 2.5H20"}],
["path", {"d":"m20.25 3.75-2.71 2.71"}],
["path", {"d":"M10 20v-3.5A2.5 2.5 0 0 0 7.5 14H4"}],
["path", {"d":"m3.75 20.25 2.71-2.71"}],
]
const Minimize2Icon: Icon = /* @__PURE__ */ createIcon("minimize-2", iconNode5)
const iconNode6: IconNode = [
["path", {"d":"M14.5 3.5H18A2.5 2.5 0 0 1 20.5 6v3.5"}],
["path", {"d":"m13.75 10.25 3.21-3.21"}],
["path", {"d":"M9.5 20.5H6A2.5 2.5 0 0 1 3.5 18v-3.5"}],
["path", {"d":"m10.25 13.75-3.21 3.21"}],
]
const Maximize2Icon: Icon = /* @__PURE__ */ createIcon("maximize-2", iconNode6)
/** Code and Preview. A segmented control with a sliding pill; keyboard switches never animate. */
function ViewToggle({
value,
onChange,
panelId,
disabledPreview,
}: {
value: ArtifactView
onChange: (view: ArtifactView) => void
panelId: string
disabledPreview?: boolean
}) {
const [instant, setInstant] = React.useState(false)
const views: ArtifactView[] = ["code", "preview"]
return (
<div
role="tablist"
aria-label="Artifact view"
data-slot="artifact-view-toggle"
data-view={value}
data-instant={instant ? "" : undefined}
onKeyDown={(event) => {
if (!["ArrowLeft", "ArrowRight", "Home", "End"].includes(event.key)) return
event.preventDefault()
setInstant(true)
const next = value === "code" ? "preview" : "code"
if (next === "preview" && disabledPreview) return
onChange(event.key === "Home" ? "code" : event.key === "End" ? "preview" : next)
const target = event.currentTarget.querySelector<HTMLButtonElement>(
`[data-view-option="${event.key === "Home" ? "code" : event.key === "End" ? "preview" : next}"]`,
)
target?.focus()
}}
onPointerDown={() => setInstant(false)}
className="group/toggle bg-(color:--chatcn-fill) rounded-(--chatcn-radius-md) relative grid h-7 grid-cols-2 p-0.5"
>
<span
aria-hidden="true"
className={cn(
"bg-(color:--chatcn-card) shadow-(--chatcn-shadow-xs) rounded-(--chatcn-radius-sm) absolute inset-y-0.5 start-0.5 w-[calc(50%-2px)]",
"ease-(--chatcn-ease-in-out) transition-[translate] duration-200",
"group-data-[view=preview]/toggle:translate-x-full rtl:group-data-[view=preview]/toggle:-translate-x-full",
"group-data-[instant]/toggle:transition-none motion-reduce:transition-none",
)}
/>
{views.map((view) => {
const selected = value === view
return (
<button
key={view}
type="button"
role="tab"
data-view-option={view}
aria-selected={selected}
aria-controls={panelId}
tabIndex={selected ? 0 : -1}
disabled={view === "preview" && disabledPreview}
onClick={() => onChange(view)}
className={cn(
"chatcn-focus rounded-(--chatcn-radius-sm) text-[0.75rem]/[1rem] relative z-[1] min-w-16 px-2.5 font-medium",
"ease-(--chatcn-ease-standard) transition-colors duration-150 disabled:opacity-50",
selected ? "text-(color:--chatcn-fg)" : "text-(color:--chatcn-fg-subtle) hover:text-(color:--chatcn-fg)",
)}
>
{view === "code" ? "Code" : "Preview"}
</button>
)
})}
</div>
)
}
interface ArtifactVersionsProps extends Omit<React.ComponentProps<"div">, "onChange"> {
/** Oldest first. */
versions: ArtifactVersion[]
value?: string
defaultValue?: string
onValueChange?: (id: string) => void
/** Show "Edited 2 min ago" and the diff summary next to the switcher. */
showMeta?: boolean
disabled?: boolean
}
function toTime(value: ArtifactVersion["createdAt"]) {
if (value === undefined) return undefined
const t = value instanceof Date ? value.getTime() : new Date(value).getTime()
return Number.isNaN(t) ? undefined : t
}
/** Re-renders every 30 seconds so relative times stay true without ticking visibly. */
function useNow(active: boolean, fallback: number) {
// Starts empty and reads the clock after mount: a render must not read it (Next.js prerender).
// Until then times read relative to the newest one, so the first render is stable.
const [now, setNow] = React.useState<number | null>(null)
React.useEffect(() => {
if (!active) return
setNow(Date.now())
const id = window.setInterval(() => setNow(Date.now()), 30_000)
return () => window.clearInterval(id)
}, [active])
return now ?? fallback
}
/**
* Line diff counts between two texts. Exact LCS for normal artifact sizes; above about four
* million cell comparisons it falls back to a multiset count, which is close and never slow.
*/
function diffLines(previous: string, next: string): { additions: number; deletions: number } {
const a = previous.split("\n")
const b = next.split("\n")
// Trim the shared head and tail first: most edits touch a small region.
let start = 0
while (start < a.length && start < b.length && a[start] === b[start]) start++
let endA = a.length - 1
let endB = b.length - 1
while (endA >= start && endB >= start && a[endA] === b[endB]) {
endA--
endB--
}
const x = a.slice(start, endA + 1)
const y = b.slice(start, endB + 1)
if (x.length === 0 || y.length === 0) return { additions: y.length, deletions: x.length }
let common = 0
if (x.length * y.length <= 4_000_000) {
let prev = new Uint32Array(y.length + 1)
let row = new Uint32Array(y.length + 1)
for (let i = 1; i <= x.length; i++) {
for (let j = 1; j <= y.length; j++) {
row[j] =
x[i - 1] === y[j - 1]
? (prev[j - 1] as number) + 1
: Math.max(prev[j] as number, row[j - 1] as number)
}
;[prev, row] = [row, prev]
}
common = prev[y.length] as number
} else {
const counts = new Map<string, number>()
for (const line of x) counts.set(line, (counts.get(line) ?? 0) + 1)
for (const line of y) {
const n = counts.get(line) ?? 0
if (n > 0) {
common++
counts.set(line, n - 1)
}
}
}
return { additions: y.length - common, deletions: x.length - common }
}
function statsFor(versions: ArtifactVersion[], index: number) {
const version = versions[index]
if (!version) return undefined
if (version.additions !== undefined || version.deletions !== undefined) {
return { additions: version.additions ?? 0, deletions: version.deletions ?? 0 }
}
const previous = versions[index - 1]
if (index === 0) {
return version.content !== undefined
? { additions: version.content.split("\n").length, deletions: 0 }
: undefined
}
if (version.content === undefined || previous?.content === undefined) return undefined
return diffLines(previous.content, version.content)
}
const iconNode7: IconNode = [
["path", {"d":"m14.75 6-4.23 4.23a2.5 2.5 0 0 0 0 3.54L14.75 18"}],
]
const ChevronLeftIcon: Icon = /* @__PURE__ */ createIcon("chevron-left", iconNode7)
const iconNode8: IconNode = [
["path", {"d":"m7.5 9 3.09-3.09a2 2 0 0 1 2.82 0L16.5 9"}],
["path", {"d":"m7.5 15 3.09 3.09a2 2 0 0 0 2.82 0L16.5 15"}],
]
const ChevronsUpDownIcon: Icon = /* @__PURE__ */ createIcon("chevrons-up-down", iconNode8)
/* -------------------------------------------------------------------------------------------------
* Helpers
* -----------------------------------------------------------------------------------------------*/
const NBSP = "\u00a0"
/** "just now", "2 min ago", "3 h ago", "yesterday", then a short date. */
function formatRelative(time: number, now: number) {
const s = Math.max(0, Math.round((now - time) / 1000))
if (s < 45) return "just now"
const m = Math.round(s / 60)
if (m < 60) return `${m}${NBSP}min ago`
const h = Math.round(m / 60)
if (h < 24) return `${h}${NBSP}h ago`
if (h < 48) return "yesterday"
return new Date(time).toLocaleDateString(undefined, { month: "short", day: "numeric" })
}
const MINUS = "\u2212"
function DiffStat({
additions,
deletions,
className,
}: {
additions: number
deletions: number
className?: string
}) {
return (
<span
data-slot="artifact-diff-stat"
className={cn("text-[0.75rem]/[1rem] inline-flex gap-1.5 font-mono tabular-nums", className)}
>
<span className="text-(color:--chatcn-fg-muted)">
<span className="sr-only">{additions} lines added</span>
<span aria-hidden="true">+{additions}</span>
</span>
<span className="text-(color:--chatcn-fg-subtle)">
<span className="sr-only">{deletions} lines removed</span>
<span aria-hidden="true">
{MINUS}
{deletions}
</span>
</span>
</span>
)
}
const iconNode9: IconNode = [
["path", {"d":"m9.25 18 4.23-4.23a2.5 2.5 0 0 0 0-3.54L9.25 6"}],
]
const ChevronRightIcon: Icon = /* @__PURE__ */ createIcon("chevron-right", iconNode9)
/* -------------------------------------------------------------------------------------------------
* ArtifactVersions
* -----------------------------------------------------------------------------------------------*/
function ArtifactVersions({
versions,
value: valueProp,
defaultValue,
onValueChange,
showMeta = false,
disabled = false,
className,
...props
}: ArtifactVersionsProps) {
const [valueState, setValueState] = React.useState(
() => defaultValue ?? versions.at(-1)?.id ?? "",
)
const value = valueProp ?? valueState
const index = Math.max(
0,
versions.findIndex((v) => v.id === value),
)
const current = versions[index]
const latestIndex = versions.length - 1
const hasTimes = versions.some((v) => v.createdAt !== undefined)
const newest = Math.max(0, ...versions.map((v) => toTime(v.createdAt) ?? 0))
const now = useNow(hasTimes, newest)
// A new version arriving moves an uncontrolled switcher to it, the way a fresh edit should.
const lastLatest = React.useRef(versions.at(-1)?.id)
React.useEffect(() => {
const latest = versions.at(-1)?.id
if (latest === lastLatest.current) return
const wasOnLatest = valueState === lastLatest.current
lastLatest.current = latest
if (valueProp === undefined && latest && wasOnLatest) setValueState(latest)
}, [versions, valueProp, valueState])
const select = (id: string) => {
if (valueProp === undefined) setValueState(id)
onValueChange?.(id)
}
if (!current) return null
const time = toTime(current.createdAt)
const stats = statsFor(versions, index)
const single = versions.length < 2
return (
<div
data-slot="artifact-versions"
className={cn("flex min-w-0 items-center gap-2", className)}
{...props}
>
<div className="flex shrink-0 items-center">
<Button
size="icon-xs"
aria-label="Previous version"
disabled={disabled || index === 0}
onClick={() => select(versions[index - 1]?.id ?? current.id)}
>
<ChevronLeftIcon className="rtl:-scale-x-100" />
</Button>
<Menu.Root>
<Menu.Trigger
disabled={disabled || single}
aria-label={`v${index + 1} of ${versions.length}, choose a version`}
className={cn(
"chatcn-focus rounded-(--chatcn-radius-sm) text-[0.75rem]/[1rem] text-(color:--chatcn-fg) inline-flex h-6 items-center gap-1 px-1.5 font-medium whitespace-nowrap tabular-nums select-none",
"ease-(--chatcn-ease-standard) transition-colors duration-150",
"hover:bg-(color:--chatcn-fill-hover) data-[popup-open]:bg-(color:--chatcn-fill-hover) disabled:pointer-events-none",
)}
>
{/* The trailing space keeps the computed text "v4 of 4", matching the accessible name. */}
{`v${index + 1} `}
{single ? null : (
<>
<span className="text-(color:--chatcn-fg-subtle) font-normal @max-[26rem]:hidden">
of {versions.length}
</span>
<ChevronsUpDownIcon aria-hidden="true" className="text-(color:--chatcn-fg-subtle) size-3" />
</>
)}
</Menu.Trigger>
<Menu.Portal>
<Menu.Positioner side="bottom" align="end" sideOffset={6} className="z-50 outline-none">
<Menu.Popup
data-slot="artifact-versions-menu"
className={cn(
"rounded-(--chatcn-radius-lg) bg-(color:--chatcn-surface) shadow-(--chatcn-shadow-lg) chatcn-scroll max-h-(--available-height) w-72 overflow-y-auto p-1 outline-none",
"ease-(--chatcn-ease-out) origin-(--transform-origin) transition-[opacity,scale] duration-180",
"data-[starting-style]:scale-96 data-[starting-style]:opacity-0",
"data-[ending-style]:scale-98 data-[ending-style]:opacity-0 data-[ending-style]:duration-140",
"data-[instant]:transition-none motion-reduce:transition-opacity",
)}
>
<Menu.RadioGroup value={current.id} onValueChange={(id: string) => select(id)}>
{versions
.map((version, i) => ({ version, i }))
.reverse()
.map(({ version, i }) => {
const t = toTime(version.createdAt)
const s = statsFor(versions, i)
return (
<Menu.RadioItem
key={version.id}
value={version.id}
closeOnClick
className={cn(
"rounded-(--chatcn-radius-md) grid cursor-default grid-cols-[1rem_minmax(0,1fr)_auto] items-start gap-x-2 px-2 py-1.5 outline-none select-none",
"data-[highlighted]:bg-(color:--chatcn-fill-hover)",
)}
>
<span className="grid h-5 place-items-center">
<Menu.RadioItemIndicator keepMounted={false}>
<CheckIcon className="text-(color:--chatcn-fg) size-3.5" />
</Menu.RadioItemIndicator>
</span>
<span className="flex min-w-0 flex-col">
<span className="text-[0.8125rem]/[1.25rem] text-(color:--chatcn-fg) flex items-baseline gap-1.5 leading-5 font-medium">
{version.label ?? `Version ${i + 1}`}
{i === latestIndex ? (
<span className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle) font-normal">
Latest
</span>
) : null}
</span>
{version.summary ? (
<span className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-muted) truncate">
{version.summary}
</span>
) : null}
{t !== undefined ? (
<span className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle)">
Edited {formatRelative(t, now)}
</span>
) : null}
</span>
{s ? <DiffStat {...s} className="leading-5" /> : <span />}
</Menu.RadioItem>
)
})}
</Menu.RadioGroup>
</Menu.Popup>
</Menu.Positioner>
</Menu.Portal>
</Menu.Root>
<Button
size="icon-xs"
aria-label="Next version"
disabled={disabled || index >= latestIndex}
onClick={() => select(versions[index + 1]?.id ?? current.id)}
>
<ChevronRightIcon className="rtl:-scale-x-100" />
</Button>
</div>
{showMeta && (time !== undefined || stats) ? (
<span
data-slot="artifact-versions-meta"
// Inside a narrow @container (the artifact panel), the switcher keeps the room.
className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle) flex min-w-0 items-center gap-2 truncate @max-[28rem]:hidden"
>
{time !== undefined ? (
<span className="truncate">Edited {formatRelative(time, now)}</span>
) : null}
{stats && index > 0 ? <DiffStat {...stats} /> : null}
</span>
) : null}
</div>
)
}
const iconNode10: IconNode = [
["path", {"d":"M3 12a9 9 0 1 0 18 0 9 9 0 1 0-18 0"}],
["path", {"d":"M12 7.75v5"}],
["path", {"d":"M12 16.25h.01"}],
]
const CircleAlertIcon: Icon = /* @__PURE__ */ createIcon("circle-alert", iconNode10)
/* -------------------------------------------------------------------------------------------------
* ArtifactPanel
* -----------------------------------------------------------------------------------------------*/
function ArtifactPanel({
title,
kind = "code",
label,
content,
language,
filename,
streaming = false,
versions,
version,
onVersionChange,
view: viewProp,
defaultView,
onViewChange,
preview,
previewHtml,
previewSrc,
sandbox = "allow-scripts allow-forms allow-popups allow-modals",
previewError,
onFixError,
renderCode,
actions,
onClose,
fullscreen: fullscreenProp,
defaultFullscreen = false,
onFullscreenChange,
className,
onKeyDown,
...props
}: ArtifactPanelProps) {
const { presentation, titleId: contextTitleId } = React.useContext(LayoutContext)
const fallbackTitleId = React.useId()
const titleId = contextTitleId ?? fallbackTitleId
const bodyId = React.useId()
const html = previewHtml ?? (kind === "html" ? content : undefined)
const hasPreview =
preview !== undefined || html !== undefined || previewSrc !== undefined || kind === "image"
const hasToolbar = hasPreview || streaming || Boolean(versions?.length)
// Code while the model writes, then the preview once it is done, unless the reader chose.
const chose = React.useRef(false)
const initialView: ArtifactView = defaultView ?? (hasPreview && !streaming ? "preview" : "code")
const [viewState, setViewState] = React.useState<ArtifactView>(initialView)
const view = hasPreview ? (viewProp ?? viewState) : "code"
const setView = (next: ArtifactView) => {
chose.current = true
if (viewProp === undefined) setViewState(next)
onViewChange?.(next)
}
const wasStreaming = React.useRef(streaming)
React.useEffect(() => {
if (wasStreaming.current === streaming) return
wasStreaming.current = streaming
if (chose.current || viewProp !== undefined || !hasPreview) return
const next = streaming ? "code" : "preview"
setViewState(next)
onViewChange?.(next)
}, [streaming, hasPreview, viewProp, onViewChange])
const [fullscreen, setFullscreen] = useControllable(
fullscreenProp,
defaultFullscreen,
onFullscreenChange,
)
const isFullscreen = fullscreen && presentation !== "sheet"
// An iframe reloads on every srcDoc change, so it only takes content once writing settles.
const [settledHtml, setSettledHtml] = React.useState(streaming ? undefined : html)
React.useEffect(() => {
if (!streaming) setSettledHtml(html)
}, [html, streaming])
const renderContext: ArtifactRenderContext = { content, language, streaming }
const titleText = typeof title === "string" ? title : "artifact"
const extension =
EXTENSIONS[language ?? ""] ?? (kind === "html" ? "html" : kind === "document" ? "md" : "txt")
const downloadName = filename ?? `${slugify(titleText)}.${extension}`
const lineCount = content ? content.split("\n").length : 0
let body: React.ReactNode
if (view === "code") {
body = renderCode ? (
renderCode(renderContext)
) : (
<ArtifactCode content={content} streaming={streaming} />
)
} else if (preview !== undefined) {
body = (
<div data-slot="artifact-preview" className="chatcn-scroll size-full overflow-auto">
{typeof preview === "function" ? preview(renderContext) : preview}
</div>
)
} else if (kind === "image" && !html && !previewSrc) {
body = (
<div
data-slot="artifact-preview"
className="chatcn-scroll grid size-full place-items-center overflow-auto p-6"
>
<img
src={content}
alt={titleText}
className="rounded-(--chatcn-radius-md) shadow-(--chatcn-shadow-border) max-h-full max-w-full object-contain"
/>
</div>
)
} else if (previewSrc || settledHtml !== undefined) {
body = (
<iframe
data-slot="artifact-preview"
title={`${titleText} preview`}
src={previewSrc}
srcDoc={previewSrc ? undefined : settledHtml}
sandbox={sandbox}
className="bg-(color:--chatcn-bg) size-full border-0"
/>
)
} else {
body = (
<div className="text-[0.8125rem]/[1.25rem] text-(color:--chatcn-fg-subtle) flex size-full items-center justify-center gap-2">
<Spinner />
Building preview…
</div>
)
}
return (
<section
aria-labelledby={titleId}
data-slot="artifact-panel"
data-artifact-view={view}
data-streaming={streaming ? "" : undefined}
data-fullscreen={isFullscreen ? "" : undefined}
data-presentation={presentation}
onKeyDown={(event) => {
onKeyDown?.(event)
if (event.defaultPrevented || event.key !== "Escape") return
if (isFullscreen) {
event.preventDefault()
setFullscreen(false)
} else if (onClose && presentation !== "sheet") {
event.preventDefault()
onClose()
}
}}
className={cn(
"bg-(color:--chatcn-bg) text-(color:--chatcn-fg) @container flex size-full min-h-0 min-w-0 flex-col",
isFullscreen && "fixed inset-0 z-50",
className,
)}
{...props}
>
<header
data-slot="artifact-panel-header"
className={cn(
"flex h-12 shrink-0 items-center gap-2 ps-4 pe-2",
!hasToolbar && "border-(color:--chatcn-border) border-b",
)}
>
<div className="flex min-w-0 flex-1 items-baseline gap-2">
<h2 id={titleId} className="text-[0.875rem]/[1.25rem] tracking-[-0.003em] text-(color:--chatcn-fg) truncate font-medium">
{title}
</h2>
{label ? (
<span className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle) shrink-0 truncate max-sm:hidden">
{label}
</span>
) : null}
</div>
<div className="flex shrink-0 items-center gap-0.5">
{actions}
<Tooltip content={kind === "code" ? "Copy code" : "Copy"} side="bottom">
<CopyButton
value={() => content}
label={kind === "code" ? "Copy code" : "Copy"}
disabled={content.length === 0}
/>
</Tooltip>
<ArtifactPanelAction
label="Download"
disabled={content.length === 0 || streaming}
onClick={() =>
downloadText(content, downloadName, kind === "html" ? "text/html" : "text/plain")
}
>
<DownloadIcon />
</ArtifactPanelAction>
{presentation === "sheet" ? null : (
<ArtifactPanelAction
label={isFullscreen ? "Exit full screen" : "Full screen"}
onClick={() => setFullscreen(!isFullscreen)}
>
{isFullscreen ? <Minimize2Icon /> : <Maximize2Icon />}
</ArtifactPanelAction>
)}
{onClose ? (
<>
<span aria-hidden="true" className="bg-(color:--chatcn-border) mx-1 h-4 w-px" />
<ArtifactPanelAction label="Close artifact" onClick={onClose}>
<XIcon />
</ArtifactPanelAction>
</>
) : null}
</div>
</header>
{/* An empty toolbar is only a gap: it shows when it holds a toggle, progress or versions. */}
{hasToolbar ? (
<div
data-slot="artifact-panel-toolbar"
className="border-(color:--chatcn-border) flex h-10 shrink-0 items-center gap-3 border-b ps-3 pe-2"
>
{hasPreview ? <ViewToggle value={view} onChange={setView} panelId={bodyId} /> : null}
<div
aria-live="polite"
className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle) flex min-w-0 items-center gap-1.5"
>
{streaming ? (
<>
<Spinner className="text-(color:--chatcn-fg)" />
<span className="text-(color:--chatcn-fg-muted)">Writing…</span>
<span aria-hidden="true" className="@max-[28rem]:hidden">
·
</span>
<span className="tabular-nums @max-[28rem]:hidden">
{lineCount}
{" "}lines
</span>
</>
) : null}
</div>
{versions && versions.length > 0 ? (
<ArtifactVersions
versions={versions}
value={version}
onValueChange={onVersionChange}
showMeta={!streaming}
disabled={streaming}
className="ms-auto min-w-0 flex-row-reverse"
/>
) : null}
</div>
) : null}
<div
id={bodyId}
{...(hasPreview
? { role: "tabpanel", "aria-label": view === "code" ? "Code" : "Preview" }
: {})}
data-slot="artifact-panel-body"
className="relative min-h-0 flex-1"
>
{body}
{previewError && view === "preview" ? (
<div
role="alert"
className="bg-(color:--chatcn-surface) shadow-(--chatcn-shadow-md) rounded-(--chatcn-radius-lg) absolute inset-x-3 bottom-3 flex items-start gap-2.5 p-3"
>
<CircleAlertIcon className="text-(color:--chatcn-red) mt-0.5 size-4 shrink-0" />
<div className="text-[0.8125rem]/[1.25rem] text-(color:--chatcn-fg) min-w-0 flex-1">
<p className="font-medium">The preview hit an error</p>
<p className="text-(color:--chatcn-fg-muted) text-[0.75rem]/[1rem] mt-0.5 font-mono break-words">
{previewError}
</p>
</div>
{onFixError ? (
<Button size="sm" variant="solid" onClick={onFixError}>
Fix error
</Button>
) : null}
</div>
) : null}
</div>
</section>
)
}
/* -------------------------------------------------------------------------------------------------
* JsxPreview
* -----------------------------------------------------------------------------------------------*/
interface JsxPreviewProps extends Omit<React.ComponentProps<"div">, "children" | "onError"> {
/** JSX source. A whole component works too: the returned JSX is extracted. */
jsx: string
/** True while the model is still writing. Renders the complete part and holds the last good tree on errors. */
streaming?: boolean
/** Components the JSX may use, by tag name: `{ Button, Card }`. Nothing else capitalized renders. */
components?: Record<string, React.ElementType>
/** Values for `{name}` and `{user.name}` expressions. */
bindings?: Record<string, unknown>
/** Load images from remote hosts and data URLs. Defaults to true. */
allowImages?: boolean
/** What to do with a capitalized tag that is not in `components`. */
unknownComponent?: "unwrap" | "omit"
/** Called on a parse error (complete input only) or a render error. */
onError?: (error: Error) => void
/** Replace the calm fallback. */
renderError?: (error: Error, source: string) => React.ReactNode
}
/* -------------------------------------------------------------------------------------------------
* Tree
* -----------------------------------------------------------------------------------------------*/
type JsxValue =
| string
| number
| boolean
| null
| undefined
| JsxValue[]
| { [key: string]: JsxValue }
type JsxNode =
| { kind: "text"; value: string }
| { kind: "expr"; value: JsxValue; unsupported?: boolean }
| { kind: "element"; name: string; props: Record<string, JsxValue>; children: JsxNode[] }
interface ParseResult {
nodes: JsxNode[]
/** True when the input ended early and open elements were closed for it. */
partial: boolean
}
/* -------------------------------------------------------------------------------------------------
* Source extraction: model output is often a whole component, not bare JSX.
* -----------------------------------------------------------------------------------------------*/
/** Finds the JSX in a component source: the first `return (<...` or the first tag. */
function extractJsx(source: string): string {
const fence = /```[\w-]*\n([\s\S]*?)(```|$)/.exec(source)
const text = fence ? (fence[1] ?? "") : source
const ret = /return\s*\(?\s*(?=<[A-Za-z>])/.exec(text)
if (ret) return text.slice(ret.index + ret[0].length)
// A component whose return has not arrived yet: its generics are not JSX.
if (/\b(function|export|const|import)\b|=>/.test(text.slice(0, text.search(/<|$/)))) return ""
const tag = /<[A-Za-z>]/.exec(text)
return tag ? text.slice(tag.index) : ""
}
/** Thrown internally when the input ends mid-construct. Streaming callers render what came before. */
class EndOfInput extends Error {}
class JsxParseError extends Error {
/** Offset in the extracted JSX where parsing stopped. */
readonly position: number
constructor(message: string, position: number) {
super(message)
this.name = "JsxParseError"
this.position = position
}
}
/** Marks an expression the parser will not evaluate. */
const UNSUPPORTED = Symbol("unsupported")
/** Evaluates literal-only expressions. Returns UNSUPPORTED for anything that would need code. */
function evaluate(expr: string, bindings: Record<string, unknown>): JsxValue | typeof UNSUPPORTED {
const src = expr.replace(/\/\*[\s\S]*?\*\//g, "").trim()
if (src === "") return undefined
let i = 0
const ws = () => {
while (i < src.length && /\s/.test(src[i] as string)) i++
}
const fail = () => {
throw UNSUPPORTED
}
const value = (): JsxValue => {
ws()
const ch = src[i]
if (ch === '"' || ch === "'" || ch === "`") {
const quote = ch
let out = ""
i++
while (i < src.length && src[i] !== quote) {
if (quote === "`" && src[i] === "$" && src[i + 1] === "{") fail()
if (src[i] === "\\") {
const next = src[i + 1] ?? ""
out += next === "n" ? "\n" : next === "t" ? "\t" : next
i += 2
} else out += src[i++]
}
if (src[i] !== quote) fail()
i++
return out
}
if (ch === "{") {
i++
const obj: Record<string, JsxValue> = {}
ws()
while (src[i] !== "}") {
ws()
let key: string
if (src[i] === '"' || src[i] === "'") key = String(value())
else {
const m = /^[A-Za-z_$][\w$-]*/.exec(src.slice(i))
if (!m) fail()
key = (m as RegExpExecArray)[0]
i += key.length
}
ws()
if (src[i] !== ":") fail()
i++
obj[key] = value()
ws()
if (src[i] === ",") i++
ws()
if (i >= src.length) fail()
}
i++
return obj
}
if (ch === "[") {
i++
const arr: JsxValue[] = []
ws()
while (src[i] !== "]") {
arr.push(value())
ws()
if (src[i] === ",") i++
ws()
if (i >= src.length) fail()
}
i++
return arr
}
const num = /^-?(?:\d+\.?\d*|\.\d+)(?:e[+-]?\d+)?/i.exec(src.slice(i))
if (num) {
i += num[0].length
return Number(num[0])
}
const path = /^[A-Za-z_$][\w$]*(?:\??\.[A-Za-z_$][\w$]*|\[(?:\d+|"[^"]*"|'[^']*')\])*/.exec(
src.slice(i),
)
if (path) {
const word = path[0]
i += word.length
if (word === "true") return true
if (word === "false") return false
if (word === "null") return null
if (word === "undefined") return undefined
const keys = word.match(/[A-Za-z_$][\w$]*|\d+|"[^"]*"|'[^']*'/g) ?? []
let current: unknown = bindings
for (const raw of keys) {
const key = raw.replace(/^["']|["']$/g, "")
if (current === null || typeof current !== "object" || !Object.hasOwn(current, key)) fail()
current = (current as Record<string, unknown>)[key]
}
if (typeof current === "function" || typeof current === "symbol") fail()
return current as JsxValue
}
return fail()
}
try {
const result = value()
ws()
return i === src.length ? result : UNSUPPORTED
} catch (error) {
if (error === UNSUPPORTED) return UNSUPPORTED
throw error
}
}
/** Reads a balanced `{...}` body, aware of strings, template literals and comments. */
function readBraced(src: string, start: number): { body: string; end: number } {
let depth = 0
let i = start
while (i < src.length) {
const ch = src[i]
// A quote right after a letter is prose inside nested JSX ("Don't"), not a string.
const prose = (ch === "'" || ch === '"') && /[\w.!?]/.test(src[i - 1] ?? "")
if ((ch === '"' || ch === "'" || ch === "`") && !prose) {
const quote = ch
i++
while (i < src.length && src[i] !== quote) i += src[i] === "\\" ? 2 : 1
if (i >= src.length) throw new EndOfInput()
} else if (ch === "/" && src[i + 1] === "*") {
const close = src.indexOf("*/", i + 2)
if (close < 0) throw new EndOfInput()
i = close + 1
} else if (ch === "{") depth++
else if (ch === "}") {
depth--
if (depth === 0) return { body: src.slice(start + 1, i), end: i + 1 }
}
i++
}
throw new EndOfInput()
}
/* -------------------------------------------------------------------------------------------------
* Parser
* -----------------------------------------------------------------------------------------------*/
const ENTITIES: Record<string, string> = {
amp: "&",
lt: "<",
gt: ">",
quot: '"',
apos: "'",
nbsp: " ",
middot: "·",
hellip: "…",
times: "×",
rarr: "→",
larr: "←",
copy: "©",
}
function decodeEntities(text: string) {
return text.replace(/&(#x[0-9a-f]+|#\d+|[a-z]+);/gi, (match, code: string) => {
if (code[0] === "#") {
const n =
code[1]?.toLowerCase() === "x" ? Number.parseInt(code.slice(2), 16) : Number(code.slice(1))
return Number.isFinite(n) && n > 0 && n < 0x110000 ? String.fromCodePoint(n) : match
}
return ENTITIES[code.toLowerCase()] ?? match
})
}
/** JSX whitespace: lines are trimmed, blank lines dropped, line breaks become one space. */
function jsxText(raw: string) {
if (!raw.includes("\n")) return decodeEntities(raw)
const lines = raw.split(/\r?\n/)
const kept: string[] = []
lines.forEach((line, i) => {
let value = line
if (i > 0) value = value.trimStart()
if (i < lines.length - 1) value = value.trimEnd()
if (value) kept.push(value)
})
return decodeEntities(kept.join(" "))
}
/**
* Parses JSX into a plain tree. With `tolerant`, input that ends mid-way still yields the
* complete part: open elements are closed and a half-written tag is left out.
*/
function parseJsx(
input: string,
options: { bindings?: Record<string, unknown>; tolerant?: boolean } = {},
): ParseResult {
const src = extractJsx(input)
const bindings = options.bindings ?? {}
let i = 0
let partial = false
const ws = () => {
while (i < src.length && /\s/.test(src[i] as string)) i++
}
const need = () => {
if (i >= src.length) throw new EndOfInput()
}
const parseName = () => {
const m = /^[A-Za-z][\w.:-]*/.exec(src.slice(i))
if (!m) {
need()
throw new JsxParseError(`Expected a tag name at ${i}`, i)
}
i += m[0].length
return m[0]
}
/**
* Two patterns that model-written UI leans on, still without running code:
* `{flag && <Jsx />}` renders when the binding is truthy, and
* `{items.map((item, i) => <Jsx />)}` renders the template once per item in a bound array.
*/
const expand = (body: string): JsxNode[] | null => {
const sub = (template: string, scope: Record<string, unknown>) =>
parseJsx(template, { bindings: scope, tolerant: options.tolerant }).nodes
const cond = /^\s*(!?)\s*([A-Za-z_$][\w$.]*)\s*&&\s*\(?\s*(?=<)/.exec(body)
if (cond) {
const value = evaluate(cond[2] as string, bindings)
if (value === UNSUPPORTED) return [{ kind: "expr", value: null, unsupported: true }]
const truthy = cond[1] ? !value : Boolean(value)
return truthy ? sub(body.slice(cond[0].length), bindings) : []
}
const map =
/^\s*([A-Za-z_$][\w$.]*)\.map\(\s*\(?\s*([A-Za-z_$][\w$]*)\s*(?:,\s*([A-Za-z_$][\w$]*)\s*)?\)?\s*=>\s*\(?\s*(?=<)/.exec(
body,
)
if (map) {
const list = evaluate(map[1] as string, bindings)
if (!Array.isArray(list)) return [{ kind: "expr", value: null, unsupported: true }]
const template = body.slice(map[0].length)
return list.flatMap((item, index) =>
sub(template, {
...bindings,
[map[2] as string]: item,
...(map[3] ? { [map[3]]: index } : {}),
}),
)
}
return null
}
/** Stops at the end of input in tolerant mode, keeping every child that finished. */
const stop = () => {
if (!options.tolerant) throw new EndOfInput()
i = src.length
partial = true
}
const parseChildren = (until: string): JsxNode[] => {
const children: JsxNode[] = []
while (i < src.length) {
if (src.startsWith("</", i)) {
const at = i
i += 2
ws()
if (i >= src.length || !/[\w>]/.test(src[i] as string)) {
stop()
break
}
const name = src[i] === ">" ? "" : parseName()
ws()
if (i >= src.length) {
// The closing tag is still arriving: treat the element as closed.
stop()
break
}
if (src[i] !== ">") throw new JsxParseError(`Expected > at ${i}`, i)
i++
if (name !== until) {
throw new JsxParseError(`Expected </${until}> but found </${name}>`, at)
}
return children
}
if (src[i] === "<") {
try {
children.push(parseElement())
} catch (error) {
// Only an unfinished opening tag gets here: leave the half-written element out.
if (!(error instanceof EndOfInput)) throw error
stop()
break
}
continue
}
if (src[i] === "{") {
try {
const { body, end } = readBraced(src, i)
i = end
const expanded = expand(body)
if (expanded) children.push(...expanded)
else {
const value = evaluate(body, bindings)
children.push(
value === UNSUPPORTED
? { kind: "expr", value: null, unsupported: true }
: { kind: "expr", value },
)
}
} catch (error) {
if (!(error instanceof EndOfInput)) throw error
stop()
break
}
continue
}
const next = src.slice(i).search(/[<{]/)
const end = next < 0 ? src.length : i + next
const text = jsxText(src.slice(i, end))
if (text) children.push({ kind: "text", value: text })
i = end
}
if (!options.tolerant) throw new JsxParseError(`<${until}> is never closed`, i)
partial = true
return children
}
const parseElement = (): JsxNode => {
i++ // <
ws()
need()
let name = ""
if (src[i] !== ">") name = parseName()
const props: Record<string, JsxValue> = {}
while (true) {
ws()
need()
if (src.startsWith("/>", i)) {
i += 2
return { kind: "element", name, props, children: [] }
}
if (src[i] === "/" && i + 1 >= src.length) throw new EndOfInput()
if (src[i] === ">") {
i++
break
}
if (src[i] === "{") {
// Spread props would need evaluation: skipped.
i = readBraced(src, i).end
continue
}
const attr = /^[A-Za-z_][\w:.-]*/.exec(src.slice(i))
if (!attr) throw new JsxParseError(`Unexpected ${src[i]} in <${name}> at ${i}`, i)
i += attr[0].length
ws()
need()
if (src[i] !== "=") {
props[attr[0]] = true
continue
}
i++
ws()
need()
const quote = src[i]
if (quote === '"' || quote === "'") {
const close = src.indexOf(quote, i + 1)
if (close < 0) throw new EndOfInput()
props[attr[0]] = decodeEntities(src.slice(i + 1, close))
i = close + 1
} else if (quote === "{") {
const { body, end } = readBraced(src, i)
i = end
const value = evaluate(body, bindings)
if (value !== UNSUPPORTED) props[attr[0]] = value
} else throw new JsxParseError(`Unexpected ${quote} in <${name}> at ${i}`, i)
}
return { kind: "element", name, props, children: parseChildren(name) }
}
ws()
if (i >= src.length) return { nodes: [], partial: options.tolerant === true }
if (src[i] !== "<") throw new JsxParseError("Expected JSX to start with a tag", i)
try {
const root = parseElement()
return { nodes: [root], partial }
} catch (error) {
if (error instanceof EndOfInput) {
if (!options.tolerant) throw new JsxParseError("The JSX ends before it is complete", i)
return { nodes: [], partial: true }
}
throw error
}
}
/** Where a parse error stopped, as a line and column in the source the caller passed. */
function errorLocation(error: Error, source: string) {
if (!(error instanceof JsxParseError)) return null
const extracted = extractJsx(source)
const base = extracted ? source.indexOf(extracted) : -1
if (base < 0) return null
const offset = Math.min(source.length, base + error.position)
const before = source.slice(0, offset)
return { line: before.split("\n").length, column: offset - before.lastIndexOf("\n") }
}
function JsxPreviewFallback({ error, source }: { error: Error; source: string }) {
const [showSource, setShowSource] = React.useState(false)
const location = React.useMemo(() => errorLocation(error, source), [error, source])
// The offset is noise once the line is named.
const message = location ? error.message.replace(/ at \d+$/, "") : error.message
const lines = React.useMemo(() => source.split("\n"), [source])
const sourceRef = React.useRef<HTMLPreElement>(null)
// Opening the source brings the failing line into view inside the box, never scrolling the page.
React.useLayoutEffect(() => {
const box = sourceRef.current
const row = box?.querySelector<HTMLElement>("[data-error-line]")
if (!box || !row) return
box.scrollTop = Math.max(0, row.offsetTop - box.clientHeight / 2 + row.offsetHeight / 2)
}, [showSource])
return (
<div role="alert" data-slot="jsx-preview-error" className="flex flex-col gap-3 p-4">
<div className="flex items-start gap-2.5">
<CircleAlertIcon className="text-(color:--chatcn-fg-subtle) mt-0.5 size-4 shrink-0" />
<div className="flex min-w-0 flex-1 flex-col gap-0.5">
<p className="text-[0.8125rem]/[1.25rem] text-(color:--chatcn-fg) font-medium">This preview could not render</p>
<p className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-muted) font-mono break-words">
{location ? (
<span className="text-(color:--chatcn-fg) tabular-nums">Line {location.line}: </span>
) : null}
{message}
</p>
</div>
<Button
size="xs"
variant="ghost"
aria-expanded={showSource}
onClick={() => setShowSource((v) => !v)}
>
{showSource ? "Hide source" : "Show source"}
</Button>
</div>
{showSource ? (
<pre
ref={sourceRef}
data-slot="jsx-preview-source"
className="rounded-(--chatcn-radius-md) bg-(color:--chatcn-inset) text-[0.75rem]/[1rem] text-(color:--chatcn-fg-muted) chatcn-scroll relative max-h-72 overflow-auto py-2.5 font-mono leading-5"
>
{lines.map((text, i) => {
const failing = location?.line === i + 1
return (
<span
key={i}
data-error-line={failing ? "" : undefined}
className={cn(
"grid grid-cols-[2.5rem_minmax(0,1fr)] pe-3",
failing && "bg-(color:--chatcn-red-bg) text-(color:--chatcn-fg)",
)}
>
<span
aria-hidden="true"
className={cn(
"pe-3 text-end tabular-nums select-none",
failing ? "text-(color:--chatcn-red)" : "text-(color:--chatcn-fg-subtle)",
)}
>
{i + 1}
</span>
<span className="break-words whitespace-pre-wrap">{text || " "}</span>
</span>
)
})}
</pre>
) : null}
</div>
)
}
interface RenderOptions {
components: Record<string, React.ElementType>
allowImages: boolean
unknownComponent: "unwrap" | "omit"
}
/* -------------------------------------------------------------------------------------------------
* Error boundary
* -----------------------------------------------------------------------------------------------*/
class PreviewBoundary extends React.Component<
{
resetKey: string
fallback: (error: Error) => React.ReactNode
children: React.ReactNode
onError?: (error: Error) => void
},
{ error: Error | null; key: string }
> {
state = { error: null as Error | null, key: this.props.resetKey }
static getDerivedStateFromError(error: Error) {
return { error }
}
static getDerivedStateFromProps(
props: { resetKey: string },
state: { error: Error | null; key: string },
) {
return props.resetKey === state.key ? null : { error: null, key: props.resetKey }
}
componentDidCatch(error: Error) {
this.props.onError?.(error)
}
render() {
return this.state.error ? this.props.fallback(this.state.error) : this.props.children
}
}
function toChild(value: JsxValue, key: number): React.ReactNode {
if (value === null || value === undefined || typeof value === "boolean") return null
if (typeof value === "string" || typeof value === "number") return value
if (Array.isArray(value)) return value.map((v, i) => toChild(v, i))
// Objects are not valid children in React; show nothing rather than crash.
void key
return null
}
const DROPPED_TAGS = new Set(
"script style iframe frame frameset object embed link meta base template noscript portal applet".split(
" ",
),
)
/* -------------------------------------------------------------------------------------------------
* Renderer
* -----------------------------------------------------------------------------------------------*/
const ALLOWED_TAGS = new Set(
(
"a abbr article aside b blockquote br button caption code col colgroup dd del details dfn div dl dt em figcaption figure footer form h1 h2 h3 h4 h5 h6 header hr i img input ins kbd label legend li main mark meter nav ol optgroup option output p pre progress q s samp section select small span strong sub summary sup table tbody td textarea tfoot th thead time tr u ul var fieldset hgroup " +
"svg g path circle ellipse line polyline polygon rect text tspan defs lineargradient radialgradient stop clippath mask use title desc"
).split(" "),
)
const ATTR_RENAME: Record<string, string> = {
class: "className",
for: "htmlFor",
tabindex: "tabIndex",
readonly: "readOnly",
maxlength: "maxLength",
colspan: "colSpan",
rowspan: "rowSpan",
viewbox: "viewBox",
"stroke-width": "strokeWidth",
"stroke-linecap": "strokeLinecap",
"stroke-linejoin": "strokeLinejoin",
"stroke-dasharray": "strokeDasharray",
"fill-rule": "fillRule",
"clip-rule": "clipRule",
"stop-color": "stopColor",
"stop-opacity": "stopOpacity",
"text-anchor": "textAnchor",
}
const ALLOWED_ATTRS = new Set(
(
"className id title role style alt src href target rel type name placeholder value defaultValue checked defaultChecked disabled readOnly required min max step maxLength rows cols colSpan rowSpan htmlFor tabIndex width height loading open dateTime lang dir hidden " +
"viewBox fill stroke strokeWidth strokeLinecap strokeLinejoin strokeDasharray strokeOpacity fillOpacity fillRule clipRule d cx cy r rx ry x y x1 y1 x2 y2 points transform opacity offset stopColor stopOpacity gradientUnits gradientTransform textAnchor preserveAspectRatio xmlns"
).split(" "),
)
function safeStyle(value: JsxValue): React.CSSProperties | undefined {
let entries: [string, JsxValue][] = []
if (typeof value === "string") {
entries = value
.split(";")
.map((decl) => decl.split(":"))
.filter((pair) => pair.length >= 2)
.map(([k, ...v]) => [
(k as string).trim().replace(/-([a-z])/g, (_, c: string) => c.toUpperCase()),
v.join(":").trim(),
])
} else if (value && typeof value === "object" && !Array.isArray(value)) {
entries = Object.entries(value)
}
const style: Record<string, string | number> = {}
for (const [key, v] of entries) {
if (typeof v !== "string" && typeof v !== "number") continue
const text = String(v)
if (/url\s*\(|expression\s*\(|javascript:|@import/i.test(text)) continue
if (/^(behavior|MozBinding)$/i.test(key)) continue
// Fixed boxes could cover the host app; they render in flow instead.
if (key === "position" && /fixed|sticky/i.test(text)) continue
style[key] = v
}
return Object.keys(style).length ? (style as React.CSSProperties) : undefined
}
const URL_ATTRS = new Set(["href", "src"])
function safeUrl(value: string, tag: string, allowImages: boolean) {
const url = value.trim()
if (tag === "img") {
if (!allowImages) return undefined
if (/^data:image\/(png|jpe?g|gif|webp|avif|svg\+xml)[;,]/i.test(url)) return url
}
if (/^(https?:|mailto:|tel:)/i.test(url)) return url
return undefined
}
function renderNodes(nodes: JsxNode[], options: RenderOptions, path = "0"): React.ReactNode[] {
return nodes.map((node, index) => {
const key = `${path}.${index}`
if (node.kind === "text") return node.value
if (node.kind === "expr") return node.unsupported ? null : toChild(node.value, index)
const children = renderNodes(node.children, options, key)
if (node.name === "") return <React.Fragment key={key}>{children}</React.Fragment>
const isComponent = /^[A-Z]/.test(node.name)
if (isComponent) {
const Component =
options.components[node.name] ??
node.name
.split(".")
.reduce<unknown>(
(acc, part) =>
acc && (typeof acc === "object" || typeof acc === "function")
? (acc as Record<string, unknown>)[part]
: undefined,
options.components,
)
if (!Component) {
return options.unknownComponent === "omit" ? null : (
<React.Fragment key={key}>{children}</React.Fragment>
)
}
const props: Record<string, unknown> = { key }
for (const [name, value] of Object.entries(node.props)) {
if (/^on[A-Z]/.test(name) || name === "ref" || name === "dangerouslySetInnerHTML") continue
props[name] = value
}
return React.createElement(
Component as React.ElementType,
props,
...(children.length ? children : []),
)
}
const tag = node.name.toLowerCase()
if (DROPPED_TAGS.has(tag)) return null
if (!ALLOWED_TAGS.has(tag)) return <React.Fragment key={key}>{children}</React.Fragment>
// SVG gradient and clip tags are case sensitive.
const element =
tag === "lineargradient"
? "linearGradient"
: tag === "radialgradient"
? "radialGradient"
: tag === "clippath"
? "clipPath"
: tag
const props: Record<string, unknown> = { key }
for (const [raw, value] of Object.entries(node.props)) {
const name = ATTR_RENAME[raw.toLowerCase()] ?? raw
const isData = /^(data|aria)-[\w-]+$/.test(name)
if (!isData && !ALLOWED_ATTRS.has(name)) continue
if (name === "style") {
const style = safeStyle(value)
if (style) props.style = style
continue
}
if (URL_ATTRS.has(name)) {
const url = typeof value === "string" ? safeUrl(value, tag, options.allowImages) : undefined
if (url) props[name] = url
continue
}
if (value !== null && typeof value === "object") continue
props[name] = value
}
if (tag === "a") {
props.target = "_blank"
props.rel = "noopener noreferrer"
}
if (tag === "img") {
if (!props.src) return null
props.referrerPolicy = "no-referrer"
props.loading = "lazy"
}
if (tag === "form") props.onSubmit = (event: React.FormEvent) => event.preventDefault()
if (tag === "input" || tag === "textarea" || tag === "select") {
// Uncontrolled, so React never warns about a value without onChange.
if ("value" in props) {
props.defaultValue = props.value
delete props.value
}
if ("checked" in props) {
props.defaultChecked = props.checked
delete props.checked
}
}
if (tag === "input" || tag === "img" || tag === "br" || tag === "hr" || tag === "col") {
return React.createElement(element, props)
}
return React.createElement(element, props, ...children)
})
}
function JsxPreview({
jsx,
streaming = false,
components,
bindings,
allowImages = true,
unknownComponent = "unwrap",
onError,
renderError,
className,
style,
...props
}: JsxPreviewProps) {
// Parsing can trail the stream by a frame without anyone noticing; typing stays smooth.
const deferred = React.useDeferredValue(jsx)
const source = streaming ? deferred : jsx
const lastGood = React.useRef<JsxNode[]>([])
const parsed = React.useMemo(() => {
try {
const result = parseJsx(source, { bindings, tolerant: streaming })
lastGood.current = result.nodes
return { nodes: result.nodes, error: null as Error | null }
} catch (error) {
// Mid-stream errors are usually a token away from fixing themselves: hold the last tree.
if (streaming) return { nodes: lastGood.current, error: null }
return { nodes: [], error: error as Error }
}
}, [source, bindings, streaming])
React.useEffect(() => {
if (parsed.error) onError?.(parsed.error)
}, [parsed.error, onError])
const fallback = (error: Error) =>
renderError ? renderError(error, jsx) : <JsxPreviewFallback error={error} source={jsx} />
let content: React.ReactNode
if (parsed.error) content = fallback(parsed.error)
else {
const options: RenderOptions = { components: components ?? {}, allowImages, unknownComponent }
content = (
<PreviewBoundary resetKey={source} fallback={fallback} onError={onError}>
{renderNodes(parsed.nodes, options)}
</PreviewBoundary>
)
}
return (
<div
data-slot="jsx-preview"
data-streaming={streaming ? "" : undefined}
className={cn("chatcn-scroll relative isolate min-w-0 overflow-auto", className)}
// Contain paint and layout: fixed children stay inside, nothing paints over the app.
style={{ contain: "layout paint", ...style }}
{...props}
>
{content}
</div>
)
}
/** Sample props for the preview. JsxPreview never runs the component, it reads these. */
const bindings = {
used: 8420,
limit: 10000,
usedLabel: "8,420",
limitLabel: "10,000",
percent: 84,
barWidth: "84%",
nearLimit: true,
resetsOn: "Nov 1",
}
/* -------------------------------------------------------------------------------------------------
* Demo
* -----------------------------------------------------------------------------------------------*/
function ArtifactScene() {
const { messages } = useChatcnStream(run, { loop: true })
const times = React.useRef(new Map<string, number>()).current
if (messages.length === 0) times.clear()
const runs = artifactRuns(messages, times)
const latest = runs.at(-1)
const [open, setOpen] = React.useState(false)
const [selected, setSelected] = React.useState<string | null>(null)
// The panel opens by itself when the first artifact starts, and follows each new version,
// unless the reader has picked an older one. Focus stays in the conversation.
const seen = React.useRef<string | null>(null)
React.useEffect(() => {
if (!latest || seen.current === latest.toolCallId) return
const following = selected === null || selected === seen.current
seen.current = latest.toolCallId
if (following) setSelected(latest.toolCallId)
// On phones the panel is a modal sheet, so it waits for a tap instead of covering the reply.
if (runs.length === 1) setOpen(true)
}, [latest, selected, runs.length])
const current = runs.find((r) => r.toolCallId === selected) ?? latest
const versions: ArtifactVersion[] = runs.map((r, i) => ({
id: r.toolCallId,
content: r.content,
createdAt: r.createdAt,
summary: i === 0 ? "Usage meter with a warning state" : "Quieter warning, reset date in header",
}))
// Stick the thread to the bottom while it grows, unless the reader scrolled up.
const threadRef = React.useRef<HTMLDivElement>(null)
const pinned = React.useRef(true)
React.useLayoutEffect(() => {
const el = threadRef.current
if (el && pinned.current) el.scrollTop = el.scrollHeight
}, [messages])
const conversation = (
<div className="bg-(color:--chatcn-bg) flex size-full min-h-0 flex-col">
<div
ref={threadRef}
onScroll={(event) => {
const el = event.currentTarget
pinned.current = el.scrollHeight - el.scrollTop - el.clientHeight < 64
}}
className="chatcn-scroll min-h-0 flex-1 overflow-y-auto"
>
<div className="mx-auto flex max-w-xl flex-col gap-6 px-5 py-6">
{messages.map((message) =>
message.role === "user" ? (
<div key={message.id} className="flex justify-end">
<p className="rounded-(--chatcn-radius-xl) bg-(color:--chatcn-fill) text-[0.9375rem]/[1.5rem] tracking-[-0.006em] text-(color:--chatcn-fg) max-w-[85%] px-3.5 py-2 text-pretty">
{message.parts.map((p) =>
p.type === "text" ? (p as { text: string }).text : null,
)}
</p>
</div>
) : (
<div key={message.id} className="flex flex-col gap-3">
{message.parts.map((part, i) => {
if (part.type === "text") {
const text = (part as { text: string }).text
return (
<p key={i} className="text-[0.9375rem]/[1.5rem] tracking-[-0.006em] text-(color:--chatcn-fg) leading-6 text-pretty">
{text.split("`").map((chunk, j) =>
j % 2 === 1 ? (
<code
key={j}
className="bg-(color:--chatcn-fill) rounded-(--chatcn-radius-xs) text-[0.8125rem]/[1.25rem] px-1 py-0.5 font-mono"
>
{chunk}
</code>
) : (
chunk
),
)}
</p>
)
}
if (!isToolPart(part)) return null
const r = runs.find((x) => x.toolCallId === (part as ChatcnToolPart).toolCallId)
if (!r) return null
const isOpen = open && current?.toolCallId === r.toolCallId
return (
<Artifact
key={r.toolCallId}
title="Usage meter"
label="React component"
kind="code"
version={r.version}
status={r.streaming ? "streaming" : "done"}
content={r.content}
open={isOpen}
onOpenChange={(next) => {
if (next) setSelected(r.toolCallId)
setOpen(next)
}}
/>
)
})}
</div>
),
)}
</div>
</div>
<div className="px-4 pb-4">
<div className="rounded-(--chatcn-radius-xl) bg-(color:--chatcn-card) shadow-(--chatcn-shadow-sm) mx-auto flex max-w-xl items-end gap-2 p-2 ps-3.5">
<span className="text-[0.9375rem]/[1.5rem] tracking-[-0.006em] text-(color:--chatcn-fg-subtle) flex-1 py-1.5">Reply…</span>
<span
aria-hidden="true"
className="bg-(color:--chatcn-fill) text-(color:--chatcn-fg-subtle) rounded-(--chatcn-radius-md) grid size-8 place-items-center [&_svg]:size-4"
>
<ArrowUpIcon />
</span>
</div>
</div>
</div>
)
// A plain split instead of ArtifactLayout: FitFrame scales this scene, and the resizable group
// measures its scaled width, which would leave the panel narrow.
const shown = open && current !== undefined
return (
<div className="rounded-(--chatcn-radius-xl) shadow-(--chatcn-shadow-border) bg-(color:--chatcn-bg) flex h-[30rem] w-full overflow-hidden">
<div className="min-w-0 flex-1">{conversation}</div>
<div
className="border-(color:--chatcn-border) flex shrink-0 justify-end overflow-hidden border-s transition-[width,opacity] duration-500 ease-out motion-reduce:transition-none"
style={{ width: shown ? "27rem" : 0, opacity: shown ? 1 : 0 }}
>
<div className="h-full w-[27rem] shrink-0">
{current ? (
<ArtifactPanel
title="Usage meter"
label="React component"
language="tsx"
filename="usage-meter.tsx"
content={current.content}
streaming={current.streaming}
versions={versions}
version={current.toolCallId}
onVersionChange={setSelected}
onClose={() => setOpen(false)}
preview={({ content, streaming }) => (
<div className="bg-(color:--chatcn-bg-subtle) grid min-h-full place-items-center p-8">
<JsxPreview jsx={content} streaming={streaming} bindings={bindings} />
</div>
)}
/>
) : null}
</div>
</div>
</div>
)
}
/** The line under each 21st demo that points back to the kit. */
function MoreOn({ slug, children }: { slug: string; children: React.ReactNode }) {
return (
<p data-fit-hide className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-faint) text-center text-balance">
{children}{" "}
<a
href={`https://chatcn.dev/docs/components/${slug}`}
target="_blank"
rel="noopener"
className="text-(color:--chatcn-fg-subtle) hover:text-(color:--chatcn-fg) underline underline-offset-2"
>
chatcn.dev
</a>
</p>
)
}
/**
* The kit's artifact walkthrough, laid out wide with the panel beside the chat: the agent writes
* a usage meter, the panel opens on it, then a second version lands on request. Loops.
*/
export default function ArtifactPreview() {
return (
<FitFrame minWidth="54rem">
<div className="flex w-full flex-col items-center justify-center gap-4 p-6">
<ArtifactScene />
<MoreOn slug="artifact">Documents and code an assistant makes, beside the chat. On</MoreOn>
</div>
</FitFrame>
)
}
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