PrimeIntellect-ai · sirouk · Aug 24, 2026
diff --git a/packages/coding-agent/.changes/fix-status-forkserver-probe.md b/packages/coding-agent/.changes/fix-status-forkserver-probe.md
@@ -0,0 +1 @@
+- Fixed `prime-agent status` terminating active IPython forkservers by excluding internal control sockets from daemon discovery and preserving the established forkserver connection.
diff --git a/packages/coding-agent/src/cli/daemon-ps.ts b/packages/coding-agent/src/cli/daemon-ps.ts
@@ -1,5 +1,6 @@
 import { spawnSync } from "node:child_process";
 import { existsSync, lstatSync, readdirSync, readFileSync, rmSync, unlinkSync } from "node:fs";
+import { tmpdir } from "node:os";
 import { basename, dirname, join, resolve } from "node:path";
 import chalk from "chalk";
 import { APP_NAME, getAgentDir, VERSION } from "../config.js";
@@ -99,7 +100,11 @@ export function parseSsListeners(stdout: string, appName: string): DiscoveredDae
 		if (!owner || !processNameMatches(owner[1]!, appName)) {
 			continue;
 		}
-		daemons.push({ pid: Number.parseInt(owner[2]!, 10), socketPath: normalizeSocketPath(socketPath) });
+		const normalized = normalizeSocketPath(socketPath);
+		if (isKernelForkServerSocketPath(normalized)) {
+			continue;
+		}
+		daemons.push({ pid: Number.parseInt(owner[2]!, 10), socketPath: normalized });
 	}
 	return daemons;
 }
@@ -116,6 +121,9 @@ export function parseLsofListeners(stdout: string): DiscoveredDaemonProcess[] {
 			pid = Number.parseInt(value, 10);
 		} else if (field === "n" && pid !== undefined && value.startsWith("/")) {
 			const socketPath = normalizeSocketPath(value);
+			if (isKernelForkServerSocketPath(socketPath)) {
+				continue;
+			}
 			const key = `${pid}:${socketPath}`;
 			if (!seen.has(key)) {
 				seen.add(key);
@@ -881,6 +889,18 @@ export function isWorkerSocketPath(socketPath: string): boolean {
 	);
 }
 
+/** Internal kernel forkserver listeners are not daemon control sockets. */
+export function isKernelForkServerSocketPath(socketPath: string): boolean {
+	if (process.platform === "win32") return false;
+	const normalized = normalizeSocketPath(socketPath);
+	const socketDirectory = dirname(normalized);
+	return (
+		basename(normalized) === "control.sock" &&
+		basename(socketDirectory).startsWith("prime-agent-forkserver-") &&
+		resolve(dirname(socketDirectory)) === resolve(tmpdir())
+	);
+}
+
 async function stopBackgroundService(
 	socketPath: string,
 	pid: number | undefined,

diff --git a/packages/coding-agent/src/core/kernel/fork-server.ts b/packages/coding-agent/src/core/kernel/fork-server.ts
@@ -178,6 +178,12 @@ export class ForkServer {
 			};
 
 			server.on("connection", (socket) => {
+				// The Python forkserver owns the first connection for its lifetime. A
+				// discovery probe must not replace that control channel when it connects.
+				if (this.conn) {
+					socket.destroy();
+					return;
+				}
 				this.conn = socket;
 				socket.setEncoding("utf8");
 				socket.on("data", (chunk: string) => this.onData(chunk));

diff --git a/packages/coding-agent/test/daemon-ps.test.ts b/packages/coding-agent/test/daemon-ps.test.ts
@@ -1,8 +1,10 @@
+import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { describe, expect, it } from "vitest";
 import {
 	type DaemonInfo,
 	evaluateShutdownQuietPeriod,
+	isKernelForkServerSocketPath,
 	isWorkerSocketPath,
 	mergeDiscoveredDaemonProcesses,
 	parseLsofListeners,
@@ -26,11 +28,20 @@ describe("worker socket classification", () => {
 	});
 });
 
+describe("forkserver socket classification", () => {
+	it.runIf(process.platform !== "win32")("recognizes only internal forkserver control sockets", () => {
+		expect(isKernelForkServerSocketPath(join(tmpdir(), "prime-agent-forkserver-abc123", "control.sock"))).toBe(true);
+		expect(isKernelForkServerSocketPath(join(tmpdir(), "prime-agent-forkserver-abc123", "daemon.sock"))).toBe(false);
+		expect(isKernelForkServerSocketPath(join(tmpdir(), "custom", "control.sock"))).toBe(false);
+	});
+});
+
 describe("parseSsListeners", () => {
 	const stdout = [
 		"Netid State  Recv-Q Send-Q Local Address:Port  Peer Address:Port",
 		'u_str LISTEN 0      511    /tmp/custom.sock 10147608 * 0 users:(("prime-agent",pid=1234,fd=22))',
 		'u_str LISTEN 0      511    /tmp/prime-agent-1000/daemon.sock 79453846 * 0 users:(("prime-agent",pid=5678,fd=24))',
+		'u_str LISTEN 0      511    /tmp/prime-agent-forkserver-probe/control.sock 79453847 * 0 users:(("prime-agent",pid=2468,fd=25))',
 		'u_str LISTEN 0      4096   /run/dbus/system_bus_socket 123 * 0 users:(("dbus-daemon",pid=900,fd=3))',
 		'u_str ESTAB  0      0      /tmp/other.sock 456 * 0 users:(("prime-agent",pid=4321,fd=9))',
 		"",
@@ -48,6 +59,7 @@ describe("parseSsListeners", () => {
 		const daemons = parseSsListeners(stdout, "prime-agent");
 		expect(daemons.some((daemon) => daemon.socketPath.includes("dbus"))).toBe(false);
 		expect(daemons.some((daemon) => daemon.pid === 4321)).toBe(false);
+		expect(daemons.some((daemon) => daemon.pid === 2468)).toBe(false);
 	});
 
 	it("honors a different app name", () => {
@@ -57,7 +69,17 @@ describe("parseSsListeners", () => {
 
 describe("parseLsofListeners", () => {
 	it("pairs each pid with its listening unix socket paths", () => {
-		const stdout = ["p1234", "fu", "n/tmp/a.sock", "p5678", "n/tmp/b.sock", "n0x0 (not a path)", ""].join("\n");
+		const stdout = [
+			"p1234",
+			"fu",
+			"n/tmp/a.sock",
+			"p2468",
+			"n/tmp/prime-agent-forkserver-probe/control.sock",
+			"p5678",
+			"n/tmp/b.sock",
+			"n0x0 (not a path)",
+			"",
+		].join("\n");
 		expect(parseLsofListeners(stdout)).toEqual([
 			{ pid: 1234, socketPath: "/tmp/a.sock" },
 			{ pid: 5678, socketPath: "/tmp/b.sock" },

diff --git a/packages/coding-agent/test/kernel-fork-server-protocol.test.ts b/packages/coding-agent/test/kernel-fork-server-protocol.test.ts
@@ -1,5 +1,6 @@
 import { spawnSync } from "node:child_process";
 import { existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { createConnection, type Server } from "node:net";
 import { homedir, tmpdir } from "node:os";
 import { join } from "node:path";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
@@ -231,6 +232,23 @@ describeIf("forkserver kill/liveness protocol (stub python)", () => {
 		await expect(handle.isAlive()).rejects.toBeInstanceOf(ForkServerUnavailable);
 	}, 15_000);
 
+	it("keeps the established control channel when another client probes the socket", async () => {
+		const handle = await spawnStubKernel();
+		const listener = (server as unknown as { server?: Server }).server;
+		const address = listener?.address();
+		expect(typeof address).toBe("string");
+
+		await new Promise<void>((resolve, reject) => {
+			const probe = createConnection(address as string);
+			probe.once("connect", () => probe.end());
+			probe.once("close", () => resolve());
+			probe.once("error", reject);
+		});
+
+		expect(server!.isDead).toBe(false);
+		expect(await handle.isAlive()).toBe(true);
+	}, 15_000);
+
 	describe("forkserver orphan journal", () => {
 		let journalPath = "";
 		const savedJournal = process.env[ORPHAN_PROCESS_JOURNAL_ENV];
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		- Fixed `prime-agent status` terminating active IPython forkservers by excluding internal control sockets from daemon discovery and preserving the established forkserver connection.