From a4d040d30f2cb30fffbd841b3f0a7052158e2e21 Mon Sep 17 00:00:00 2001
From: Mario Zechner <badlogicgames@gmail.com>
Date: Tue, 13 Oct 2026 10:05:19 +0000
Subject: [PATCH] fix(chord): a forked child host no longer inherits its
 parent's CHORD2_LOCK

forkDriver spread process.env into the child, so a child host that forks its own children (or a test run inside a p2 worker) passed its lock on, and children without a lock of their own failed with "locked".
---
 packages/chord/src/manager.ts       | 11 ++++++-----
 packages/chord/test/manager.test.ts | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/packages/chord/src/manager.ts b/packages/chord/src/manager.ts
index d8146e683..ae185bf75 100644
--- a/packages/chord/src/manager.ts
+++ b/packages/chord/src/manager.ts
@@ -161,13 +161,14 @@ const LOCK_ENV = "CHORD2_LOCK";
 export function forkDriver(options: ForkDriverOptions): Driver {
 	return {
 		spawn() {
+			// A lock this process inherited (e.g. as a child host itself) is not the child's: it gets only its own.
+			const env: NodeJS.ProcessEnv = { ...process.env };
+			delete env[LOCK_ENV];
+			Object.assign(env, options.env);
+			if (options.lock !== undefined) env[LOCK_ENV] = options.lock;
 			// Detached: the child leads a process group, so the whole tree can be killed.
 			const child: ChildProcess = fork(options.entry, [...(options.args ?? [])], {
-				env: {
-					...process.env,
-					...options.env,
-					...(options.lock === undefined ? {} : { [LOCK_ENV]: options.lock }),
-				},
+				env,
 				execArgv: [...(options.execArgv ?? [])],
 				detached: true,
 				stdio: ["ignore", options.onOutput ? "pipe" : "inherit", options.onOutput ? "pipe" : "inherit", "ipc"],
diff --git a/packages/chord/test/manager.test.ts b/packages/chord/test/manager.test.ts
index 4c2fb6aaf..7281ff720 100644
--- a/packages/chord/test/manager.test.ts
+++ b/packages/chord/test/manager.test.ts
@@ -45,6 +45,24 @@ describe("processLock", () => {
 });
 
 describe("host manager (real child processes)", () => {
+	// A child host that forks its own children used to pass its CHORD2_LOCK on, so they failed with "locked".
+	it("a child without a lock does not inherit the parent's lock", async () => {
+		const name = `chord2-test-${process.pid}-inherited`;
+		const release = await processLock(name);
+		const previous = process.env.CHORD2_LOCK;
+		process.env.CHORD2_LOCK = name;
+		const manager = createHostManager({ driver: driver() });
+		try {
+			await manager.start();
+			assert.equal(manager.status, "running");
+		} finally {
+			if (previous === undefined) delete process.env.CHORD2_LOCK;
+			else process.env.CHORD2_LOCK = previous;
+			await manager.stop();
+			await release();
+		}
+	});
+
 	it("starts a child host, links it, stops it gracefully", async () => {
 		const manager = createHostManager({ driver: driver() });
 		const instance = await manager.start();