From cc07d5c4f84ccd05d1ce94d3ef7b91122f2c8079 Mon Sep 17 00:00:00 2001
From: Michael Yong <wrong92@gmail.com>
Date: Thu, 20 Aug 2026 11:19:57 -0700
Subject: [PATCH] Register start-bb signal handlers before spawning

---
 scripts/start-bb.mjs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/scripts/start-bb.mjs b/scripts/start-bb.mjs
index 4c6e0f2be0..3d354e50bc 100644
--- a/scripts/start-bb.mjs
+++ b/scripts/start-bb.mjs
@@ -26,12 +26,7 @@ function waitForProcess(child) {
 }
 
 export async function runBuildProcess(request) {
-  const child = spawn(request.command, request.args, {
-    cwd: request.cwd,
-    detached: supportsProcessGroups(),
-    env: request.env,
-    stdio: "inherit",
-  });
+  let child;
   let stopPromise;
   const stopChild = () => {
     stopPromise ??= stopProcessGroupLeaderFirst({
@@ -42,10 +37,18 @@ export async function runBuildProcess(request) {
   };
   const handleSigint = () => stopChild();
   const handleSigterm = () => stopChild();
+  // Register before spawn so a child that becomes ready immediately cannot
+  // prompt another process to signal us before the handlers exist.
   process.on("SIGINT", handleSigint);
   process.on("SIGTERM", handleSigterm);
 
   try {
+    child = spawn(request.command, request.args, {
+      cwd: request.cwd,
+      detached: supportsProcessGroups(),
+      env: request.env,
+      stdio: "inherit",
+    });
     const result = await waitForProcess(child);
     await stopPromise;
     return result;