fix: restart agent after an unexpected exit

app/server/modules/agents/__tests__/agents-manager.test.ts

@@ -0,0 +1,82 @@
+import { EventEmitter } from "node:events";
+import * as childProcess from "node:child_process";
+import { PassThrough } from "node:stream";
+import { afterEach, expect, mock, test, vi } from "bun:test";
+
+const spawnMock = mock();
+
+await mock.module("node:child_process", () => ({
+	...childProcess,
+	spawn: spawnMock,
+}));
+
+import { spawnLocalAgent, stopLocalAgent } from "../agents-manager";
+
+const flushMicrotasks = async () => {
+	await Promise.resolve();
+};
+
+type FakeChildProcess = EventEmitter & {
+	stdout: PassThrough;
+	stderr: PassThrough;
+	exitCode: number | null;
+	signalCode: NodeJS.Signals | null;
+	kill: ReturnType<typeof mock>;
+};
+
+const createFakeChild = () => {
+	const child = new EventEmitter() as FakeChildProcess;
+
+	child.stdout = new PassThrough();
+	child.stderr = new PassThrough();
+	child.exitCode = null;
+	child.signalCode = null;
+	child.kill = mock(() => {
+		child.exitCode = 0;
+		child.emit("exit", 0, null);
+		return true;
+	});
+
+	return child;
+};
+
+afterEach(async () => {
+	await stopLocalAgent();
+	spawnMock.mockReset();
+	mock.restore();
+	vi.useRealTimers();
+});
+
+test("respawns the local agent after an unexpected exit", async () => {
+	vi.useFakeTimers();
+
+	const firstChild = createFakeChild();
+	const secondChild = createFakeChild();
+	spawnMock.mockReturnValueOnce(firstChild).mockReturnValueOnce(secondChild);
+
+	await spawnLocalAgent();
+
+	firstChild.exitCode = 1;
+	firstChild.emit("exit", 1, null);
+
+	vi.advanceTimersByTime(1_000);
+	await flushMicrotasks();
+
+	expect(spawnMock).toHaveBeenCalledTimes(2);
+});
+
+test("does not respawn the local agent after an intentional stop", async () => {
+	vi.useFakeTimers();
+
+	const child = createFakeChild();
+	spawnMock.mockReturnValue(child);
+
+	await spawnLocalAgent();
+	await stopLocalAgent();
+
+	vi.advanceTimersByTime(1_000);
+	await flushMicrotasks();
+
+	expect(spawnMock).toHaveBeenCalledTimes(1);
+	expect(child.kill).toHaveBeenCalledTimes(1);
+});

app/server/modules/agents/agents-manager.ts

@@ -43,6 +43,8 @@ type AgentManagerRuntime = ReturnType<typeof createAgentManagerRuntime>;
 type AgentRuntimeState = {
 	agentManager: AgentManagerRuntime;
 	localAgent: ChildProcess | null;
+	isStoppingLocalAgent: boolean;
+	localAgentRestartTimeout: ReturnType<typeof setTimeout> | null;
 };
 
 type ProcessWithAgentRuntime = NodeJS.Process & {
@@ -60,6 +62,8 @@ const getAgentRuntimeState = () => {
 	const runtime = {
 		agentManager: createAgentManagerRuntime(),
 		localAgent: null,
+		isStoppingLocalAgent: false,
+		localAgentRestartTimeout: null,
 	};
 
 	runtimeProcess.__zerobyteAgentRuntime = runtime;
@@ -105,28 +109,48 @@ export const spawnLocalAgent = async () => {
 	});
 
 	agentProcess.on("exit", (code, signal) => {
+		const shouldRestart = runtime.localAgent === agentProcess && !runtime.isStoppingLocalAgent;
 		if (runtime.localAgent === agentProcess) {
 			runtime.localAgent = null;
 		}
 		logger.info(`Agent process exited with code ${code} and signal ${signal}`);
+
+		if (!shouldRestart) {
+			return;
+		}
+
+		runtime.localAgentRestartTimeout = setTimeout(() => {
+			runtime.localAgentRestartTimeout = null;
+			void spawnLocalAgent().catch((error) => {
+				logger.error(`Failed to restart local agent: ${error instanceof Error ? error.message : String(error)}`);
+			});
+		}, 1_000);
 	});
 };
 
 export const stopLocalAgent = async () => {
 	const runtime = getAgentRuntimeState();
+	if (runtime.localAgentRestartTimeout) {
+		clearTimeout(runtime.localAgentRestartTimeout);
+		runtime.localAgentRestartTimeout = null;
+	}
+
 	if (!runtime.localAgent) {
 		return;
 	}
 
 	const agentProcess = runtime.localAgent;
 	runtime.localAgent = null;
+	runtime.isStoppingLocalAgent = true;
 
 	if (agentProcess.exitCode !== null || agentProcess.signalCode !== null) {
+		runtime.isStoppingLocalAgent = false;
 		return;
 	}
 
 	const exited = new Promise<void>((resolve) => {
 		agentProcess.once("exit", () => {
+			runtime.isStoppingLocalAgent = false;
 			resolve();
 		});
 	});

apps/agent/tsconfig.json

@@ -2,11 +2,12 @@
 	"compilerOptions": {
 		"plugins": [{ "name": "@effect/language-service" }],
 		// Environment setup & latest features
-		"lib": ["ESNext"],
+		"lib": ["DOM", "ESNext"],
 		"target": "ESNext",
 		"module": "Preserve",
 		"moduleDetection": "force",
 		"jsx": "react-jsx",
+		"types": ["bun", "node"],
 		"allowJs": true,
 
 		// Bundler mode

packages/contracts/tsconfig.json

@@ -6,6 +6,7 @@
 		"module": "Preserve",
 		"moduleDetection": "force",
 		"jsx": "react-jsx",
+		"types": ["bun", "node"],
 		"allowJs": true,
 
 		// Bundler mode