fix(ssh): cancelled controlmaster stream waits

Return promptly when the ssh executor receives a user interrupt while ControlMaster-owned streams remain open.

Fixes #2180

packages/coding-agent/src/ssh/ssh-executor.ts

@@ -42,6 +42,42 @@ export interface SSHResult {
 	artifactId?: string;
 }
 
+type SSHExitEvent = { kind: "exit"; exitCode: number } | { kind: "error"; error: unknown };
+
+function sshExitEvent(exitCode: number): SSHExitEvent {
+	return { kind: "exit", exitCode };
+}
+
+function sshErrorEvent(error: unknown): SSHExitEvent {
+	return { kind: "error", error };
+}
+
+function createAbortWaiter(
+	signal: AbortSignal | undefined,
+	streamAbort: AbortController,
+): { promise: Promise<ptree.AbortError> | undefined; cleanup: () => void } {
+	if (!signal) {
+		return { promise: undefined, cleanup: () => {} };
+	}
+
+	const { promise, resolve } = Promise.withResolvers<ptree.AbortError>();
+	const onAbort = () => {
+		const error = new ptree.AbortError(signal.reason, "<cancelled>");
+		if (!streamAbort.signal.aborted) {
+			streamAbort.abort(error);
+		}
+		resolve(error);
+	};
+
+	if (signal.aborted) {
+		onAbort();
+		return { promise, cleanup: () => {} };
+	}
+
+	signal.addEventListener("abort", onAbort, { once: true });
+	return { promise, cleanup: () => signal.removeEventListener("abort", onAbort) };
+}
+
 function quoteForCompatShell(command: string): string {
 	if (command.length === 0) {
 		return "''";
@@ -94,19 +130,34 @@ export async function executeSSH(
 		maxColumns: resolveOutputMaxColumns(settings),
 	});
 
-	const streams = [child.stdout.pipeTo(sink.createInput())];
+	const streamAbort = new AbortController();
+	const abortWaiter = createAbortWaiter(options?.signal, streamAbort);
+	const streamOptions = { signal: streamAbort.signal };
+	const streams = [child.stdout.pipeTo(sink.createInput(), streamOptions)];
 	if (child.stderr) {
-		streams.push(child.stderr.pipeTo(sink.createInput()));
+		streams.push(child.stderr.pipeTo(sink.createInput(), streamOptions));
 	}
-	await Promise.allSettled(streams).catch(() => {});
+	const streamsSettled = Promise.allSettled(streams).then(() => {});
 
 	try {
+		const exitEvent = child.exited.then(sshExitEvent, sshErrorEvent);
+		const abortEvent = abortWaiter.promise?.then(sshErrorEvent);
+		const event = await (abortEvent ? Promise.race([exitEvent, abortEvent]) : exitEvent);
+		if (event.kind === "error") {
+			throw event.error;
+		}
+
+		await streamsSettled;
 		return {
-			exitCode: await child.exited,
+			exitCode: event.exitCode,
 			cancelled: false,
 			...(await sink.dump()),
 		};
 	} catch (err) {
+		if (!streamAbort.signal.aborted) {
+			streamAbort.abort(err);
+		}
+		void streamsSettled;
 		if (err instanceof ptree.Exception) {
 			if (err instanceof ptree.TimeoutError) {
 				return {
@@ -129,5 +180,7 @@ export async function executeSSH(
 			};
 		}
 		throw err;
+	} finally {
+		abortWaiter.cleanup();
 	}
 }