fix(cli): exit cleanly when stdin is an open pipe that never closes

src/lib/commands/read-stdin.ts

@@ -23,15 +23,17 @@ export async function readStdin() {
 		}, waitDelay).unref();
 	}
 
-	stream.on('data', (chunk) => {
+	const onData = (chunk: Buffer) => {
 		bufferChunks.push(chunk);
 
 		// If we got some data already, we can clear the timeout, as we will get more
 		if (timeout) {
 			clearTimeout(timeout);
 			timeout = null;
 		}
-	});
+	};
+
+	stream.on('data', onData);
 
 	try {
 		await once(stream, 'end', { signal: controller.signal });
@@ -41,6 +43,14 @@ export async function readStdin() {
 		if (casted.name === 'AbortError') {
 			return;
 		}
+	} finally {
+		// Stop reading from stdin so its open handle can't keep the event loop (and
+		// the CLI) alive after the command finishes (#1206). This only helps when the
+		// await above settles ('end' or the no-data abort). A writer that sends data
+		// but never closes stdin still hangs up there; that needs the lazy stdin
+		// reading discussed in #1206.
+		stream.off('data', onData);
+		stream.pause();
 	}
 
 	if (timeout) {

test/e2e/commands/stdin-held-open.test.ts

@@ -0,0 +1,58 @@
+import { mkdir, rm } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { execa } from 'execa';
+
+import { TestTmpRoot } from '../__helpers__/tmp.js';
+
+const DistApify = fileURLToPath(new URL('../../../dist/apify.js', import.meta.url));
+
+// How long the CLI gets to exit on its own. The command itself finishes in well
+// under a second; the broken behavior never exits at all, so any finite deadline
+// separates the two. Generous to absorb slow CI runners.
+const EXIT_DEADLINE_MS = 15_000;
+
+describe('[e2e] stdin held open (#1206)', () => {
+	const emptyDir = path.join(TestTmpRoot, 'stdin-held-open');
+
+	beforeAll(async () => {
+		await rm(emptyDir, { recursive: true, force: true });
+		await mkdir(emptyDir, { recursive: true });
+	});
+
+	afterAll(async () => {
+		await rm(emptyDir, { recursive: true, force: true });
+	});
+
+	it('exits on its own when stdin is a pipe that never closes', async () => {
+		// The runCli helper cannot express this scenario: it either ignores stdin or
+		// writes input and closes it. execa with stdin: 'pipe' and no `input` keeps
+		// the child's stdin open for the child's whole lifetime (verified on execa 9),
+		// which is what spawned subprocesses (CI runners, agent shells) see. Before
+		// the fix, the startup stdin read left process.stdin flowing with a data
+		// listener attached, so the CLI printed all its output but never exited.
+		const result = await execa('node', [DistApify, 'run'], {
+			cwd: emptyDir,
+			reject: false,
+			timeout: EXIT_DEADLINE_MS,
+			stdin: 'pipe',
+			env: {
+				APIFY_CLI_DISABLE_TELEMETRY: '1',
+				APIFY_CLI_SKIP_UPDATE_CHECK: '1',
+				APIFY_DISABLE_KEYRING: '1',
+			},
+		});
+
+		// `timedOut` is the regression signal: the broken build completes the command
+		// (same stderr) but never exits, so execa kills it at the deadline.
+		expect(result.timedOut, `stderr: ${result.stderr}`).toBe(false);
+
+		// Sanity: the command really ran and failed naturally (an empty dir is not an
+		// actor project). Keep this on `apify run`: --version, --help, and unknown
+		// commands all call process.exit(), which exits even with a leaked stdin
+		// handle and would mask the regression.
+		expect(result.exitCode).toBe(1);
+		expect(result.stderr).toContain('Actor is of an unknown format');
+	});
+});