feat(prompts): add accessible mode to spinner

.changeset/moody-lions-follow.md

@@ -0,0 +1,5 @@
+---
+"@clack/prompts": minor
+---
+
+Add accessible mode to `spinner`: when enabled via the `accessible` option, the global setting, or the `ACCESSIBLE` env var, the spinner emits static, append-only, screen-reader friendly output, a plain start line, a "still working" heartbeat every 30 seconds, and a plain final line. Instead of animated in-place repaints.

packages/prompts/src/common.ts

@@ -72,6 +72,7 @@ export interface CommonOptions {
 	output?: Writable;
 	signal?: AbortSignal;
 	withGuide?: boolean;
+	accessible?: boolean;
 }
 
 export function formatInstructionFooter(instructions: string[], hasGuide: boolean): string[] {

packages/prompts/src/spinner.ts

@@ -1,5 +1,5 @@
 import { styleText } from 'node:util';
-import { block, getColumns, settings } from '@clack/core';
+import { block, getColumns, isAccessible, settings } from '@clack/core';
 import { wrapAnsi } from 'fast-wrap-ansi';
 import { cursor, erase } from 'sisteransi';
 import {
@@ -32,6 +32,8 @@ export interface SpinnerResult {
 	readonly isCancelled: boolean;
 }
 
+const ACCESSIBLE_HEARTBEAT_MS = 30_000;
+
 const defaultStyleFn: SpinnerOptions['styleFrame'] = (frame) => styleText('magenta', frame);
 
 export const spinner = ({
@@ -46,8 +48,9 @@ export const spinner = ({
 	...opts
 }: SpinnerOptions = {}): SpinnerResult => {
 	const isCI = isCIFn();
+	const accessible = isAccessible(opts.accessible);
 
-	let unblock: () => void;
+	let unblock: (() => void) | undefined;
 	let loop: NodeJS.Timeout;
 	let isSpinnerActive = false;
 	let isCancelled = false;
@@ -131,15 +134,24 @@ export const spinner = ({
 
 	const start = (msg = ''): void => {
 		isSpinnerActive = true;
-		unblock = block({ output });
 		_message = removeTrailingDots(msg);
 		_origin = performance.now();
+		registerHooks();
+		if (accessible) {
+			if (_message !== '') {
+				output.write(`${_message}\n`);
+			}
+			loop = setInterval(() => {
+				output.write(_message === '' ? 'still working\n' : `still working: ${_message}\n`);
+			}, ACCESSIBLE_HEARTBEAT_MS);
+			return;
+		}
+		unblock = block({ output });
 		if (hasGuide) {
 			output.write(`${styleText('gray', S_BAR)}\n`);
 		}
 		let frameIndex = 0;
 		let indicatorTimer = 0;
-		registerHooks();
 		loop = setInterval(() => {
 			if (isCI && _message === _prevMessage) {
 				return;
@@ -175,23 +187,40 @@ export const spinner = ({
 		if (!isSpinnerActive) return;
 		isSpinnerActive = false;
 		clearInterval(loop);
-		clearPrevMessage();
-		const step =
-			code === 0
-				? styleText('green', S_STEP_SUBMIT)
-				: code === 1
-					? styleText('red', S_STEP_CANCEL)
-					: styleText('red', S_STEP_ERROR);
+		if (!accessible) {
+			clearPrevMessage();
+		}
 		_message = msg ?? _message;
 		if (!silent) {
-			if (indicator === 'timer') {
-				output.write(`${step}  ${_message} ${formatTimer(_origin)}\n`);
+			if (accessible) {
+				const fallback =
+					code === 1
+						? (cancelMessage ?? settings.messages.cancel)
+						: code === 2
+							? (errorMessage ?? settings.messages.error)
+							: 'Done';
+				const finalMessage = _message || fallback;
+				if (indicator === 'timer') {
+					output.write(`${finalMessage} ${formatTimer(_origin)}\n`);
+				} else {
+					output.write(`${finalMessage}\n`);
+				}
 			} else {
-				output.write(`${step}  ${_message}\n`);
+				const step =
+					code === 0
+						? styleText('green', S_STEP_SUBMIT)
+						: code === 1
+							? styleText('red', S_STEP_CANCEL)
+							: styleText('red', S_STEP_ERROR);
+				if (indicator === 'timer') {
+					output.write(`${step}  ${_message} ${formatTimer(_origin)}\n`);
+				} else {
+					output.write(`${step}  ${_message}\n`);
+				}
 			}
 		}
 		clearHooks();
-		unblock();
+		unblock?.();
 	};
 
 	const stop = (msg = ''): void => _stop(msg, 0);

packages/prompts/test/spinner-accessible.test.ts

@@ -0,0 +1,106 @@
+import { settings, updateSettings } from '@clack/core';
+import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest';
+import * as prompts from '../src/index.js';
+import { MockWritable } from './test-utils.js';
+
+// biome-ignore lint/suspicious/noControlCharactersInRegex: matching ANSI escape codes is the point
+const ANSI_REGEX = /\x1b\[/;
+
+describe('spinner (accessible)', () => {
+	let originalAccessibleEnv: string | undefined;
+	let originalCIEnv: string | undefined;
+	let output: MockWritable;
+
+	beforeEach(() => {
+		originalAccessibleEnv = process.env.ACCESSIBLE;
+		originalCIEnv = process.env.CI;
+		delete process.env.ACCESSIBLE;
+		output = new MockWritable();
+		vi.useFakeTimers();
+	});
+
+	afterEach(() => {
+		vi.useRealTimers();
+		vi.restoreAllMocks();
+		process.env.ACCESSIBLE = originalAccessibleEnv;
+		process.env.CI = originalCIEnv;
+		settings.accessible = undefined;
+	});
+
+	test('renders static append-only output with no decorations', () => {
+		const result = prompts.spinner({ output, accessible: true, withGuide: true });
+
+		result.start('Loading');
+		result.message('Installing');
+		result.message('Linking');
+		vi.advanceTimersByTime(30_000);
+		result.stop('Installed');
+		vi.advanceTimersByTime(60_000);
+
+		expect(output.buffer).toEqual(['Loading\n', 'still working: Linking\n', 'Installed\n']);
+		expect(output.buffer.join('')).not.toMatch(ANSI_REGEX);
+	});
+
+	test('falls back to plain status words when stopped without a message', () => {
+		for (const [end, line] of [
+			['stop', 'Done\n'],
+			['cancel', 'Canceled\n'],
+			['error', 'Something went wrong\n'],
+		] as const) {
+			output = new MockWritable();
+			const result = prompts.spinner({ output, accessible: true });
+			result.start('Working');
+			result[end]();
+			expect(output.buffer).toEqual(['Working\n', line]);
+		}
+	});
+
+	test('abort signal cancels with a plain line', () => {
+		const controller = new AbortController();
+		const onCancel = vi.fn();
+		const result = prompts.spinner({
+			output,
+			accessible: true,
+			signal: controller.signal,
+			onCancel,
+		});
+
+		result.start('Working');
+		controller.abort();
+
+		expect(output.buffer).toEqual(['Working\n', 'Canceled\n']);
+		expect(result.isCancelled).toBe(true);
+		expect(onCancel).toHaveBeenCalledOnce();
+	});
+
+	test('accessible takes precedence over CI mode', () => {
+		process.env.CI = 'true';
+		const result = prompts.spinner({ output, accessible: true });
+
+		result.start('Loading');
+		vi.advanceTimersByTime(1000);
+		result.stop('Done');
+
+		expect(output.buffer).toEqual(['Loading\n', 'Done\n']);
+	});
+
+	test('enabled via ACCESSIBLE env var', () => {
+		process.env.ACCESSIBLE = '1';
+		const result = prompts.spinner({ output });
+
+		result.start('Loading');
+		result.stop('Done');
+
+		expect(output.buffer).toEqual(['Loading\n', 'Done\n']);
+	});
+
+	test('accessible: false option overrides the global setting', () => {
+		updateSettings({ accessible: true });
+		const result = prompts.spinner({ output, accessible: false });
+
+		result.start('Loading');
+		result.stop('Done');
+
+		expect(output.buffer.join('')).toMatch(ANSI_REGEX);
+	});
+});