diff --git a/scripts/profile-extension-memory.mjs b/scripts/profile-extension-memory.mjs
index 77e5a68c13a0..349c53722593 100644
--- a/scripts/profile-extension-memory.mjs
+++ b/scripts/profile-extension-memory.mjs
@@ -4,6 +4,7 @@ import { spawn } from "node:child_process";
 import { existsSync, mkdtempSync, readdirSync, rmSync, writeFileSync } from "node:fs";
 import os from "node:os";
 import path from "node:path";
+import { pathToFileURL } from "node:url";
 import { ensureExtensionMemoryBuild } from "./ensure-extension-memory-build.mjs";
 import { formatErrorMessage } from "./lib/error-format.mjs";
 
@@ -168,9 +169,17 @@ function summarizeStderr(stderr, lines = 8, maxChars = STDERR_PREVIEW_MAX_CHARS)
   )}`;
 }
 
-async function runCase({ repoRoot, env, hookPath, name, body, timeoutMs }) {
+export async function runCase({
+  repoRoot,
+  env,
+  hookPath,
+  name,
+  body,
+  timeoutMs,
+  spawnImpl = spawn,
+}) {
   return await new Promise((resolve) => {
-    const child = spawn(
+    const child = spawnImpl(
       process.execPath,
       ["--import", hookPath, "--input-type=module", "--eval", body],
       {
@@ -185,10 +194,21 @@ async function runCase({ repoRoot, env, hookPath, name, body, timeoutMs }) {
     let stderrRssTail = "";
     let maxRssMb = null;
     let timedOut = false;
+    let settled = false;
     const timer = setTimeout(() => {
       timedOut = true;
       child.kill("SIGKILL");
     }, timeoutMs);
+    timer.unref?.();
+
+    function settle(result) {
+      if (settled) {
+        return;
+      }
+      settled = true;
+      clearTimeout(timer);
+      resolve(result);
+    }
 
     child.stdout.on("data", (chunk) => {
       stdout = appendBoundedOutput(stdout, chunk);
@@ -199,14 +219,27 @@ async function runCase({ repoRoot, env, hookPath, name, body, timeoutMs }) {
       maxRssMb = rssScan.maxRssMb;
       stderr = appendBoundedOutput(stderr, chunk);
     });
-    child.on("close", (code, signal) => {
-      clearTimeout(timer);
+    child.on("error", (error) => {
       const stderrText = formatCapturedOutput(stderr);
-      resolve({
+      settle({
+        name,
+        code: null,
+        signal: null,
+        timedOut,
+        error: formatErrorMessage(error),
+        stdout: formatCapturedOutput(stdout),
+        stderr: stderrText,
+        maxRssMb: maxRssMb ?? parseMaxRssMb(stderrText),
+      });
+    });
+    child.on("close", (code, signal) => {
+      const stderrText = formatCapturedOutput(stderr);
+      settle({
         name,
         code,
         signal,
         timedOut,
+        error: null,
         stdout: formatCapturedOutput(stdout),
         stderr: stderrText,
         maxRssMb: maxRssMb ?? parseMaxRssMb(stderrText),
@@ -411,9 +444,11 @@ async function main() {
   }
 }
 
-try {
-  await main();
-} catch (error) {
-  console.error(`[extension-memory] ${formatErrorMessage(error)}`);
-  process.exit(1);
+if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
+  try {
+    await main();
+  } catch (error) {
+    console.error(`[extension-memory] ${formatErrorMessage(error)}`);
+    process.exit(1);
+  }
 }
diff --git a/test/scripts/profile-extension-memory.test.ts b/test/scripts/profile-extension-memory.test.ts
index b69694c6d476..d50c8e18afce 100644
--- a/test/scripts/profile-extension-memory.test.ts
+++ b/test/scripts/profile-extension-memory.test.ts
@@ -1,8 +1,10 @@
 import { spawnSync } from "node:child_process";
+import { EventEmitter } from "node:events";
 import { mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import path from "node:path";
 import { describe, expect, it } from "vitest";
+import { runCase } from "../../scripts/profile-extension-memory.mjs";
 
 const SCRIPT_PATH = path.resolve("scripts/profile-extension-memory.mjs");
 
@@ -59,15 +61,7 @@ describe("scripts/profile-extension-memory", () => {
       );
 
       const result = runProfileExtensionMemory(
-        [
-          "--extension",
-          "noisy",
-          "--skip-combined",
-          "--concurrency",
-          "1",
-          "--json",
-          reportPath,
-        ],
+        ["--extension", "noisy", "--skip-combined", "--concurrency", "1", "--json", reportPath],
         root,
       );
 
@@ -85,4 +79,37 @@ describe("scripts/profile-extension-memory", () => {
       rmSync(root, { recursive: true, force: true });
     }
   });
+
+  it("resolves spawn errors without waiting for the timeout", async () => {
+    const startedAt = Date.now();
+    const result = await runCase({
+      repoRoot: process.cwd(),
+      env: process.env,
+      hookPath: "missing-hook.mjs",
+      name: "spawn-error",
+      body: "",
+      timeoutMs: 30_000,
+      spawnImpl: () => {
+        const child = new EventEmitter() as EventEmitter & {
+          kill: () => boolean;
+          stderr: EventEmitter;
+          stdout: EventEmitter;
+        };
+        child.stderr = new EventEmitter();
+        child.stdout = new EventEmitter();
+        child.kill = () => true;
+        queueMicrotask(() => child.emit("error", new Error("spawn denied")));
+        return child;
+      },
+    });
+
+    expect(Date.now() - startedAt).toBeLessThan(1000);
+    expect(result).toMatchObject({
+      code: null,
+      error: "spawn denied",
+      name: "spawn-error",
+      signal: null,
+      timedOut: false,
+    });
+  });
 });