diff --git a/packages/server/src/terminal/terminal.test.ts b/packages/server/src/terminal/terminal.test.ts
index 707017acb..d68ae9b59 100644
--- a/packages/server/src/terminal/terminal.test.ts
+++ b/packages/server/src/terminal/terminal.test.ts
@@ -1,5 +1,12 @@
 import { describe, it, expect, afterEach } from "vitest";
-import { createTerminal, type TerminalSession } from "./terminal.js";
+import {
+  createTerminal,
+  ensureNodePtySpawnHelperExecutableForCurrentPlatform,
+  type TerminalSession,
+} from "./terminal.js";
+import { chmodSync, mkdtempSync, mkdirSync, rmSync, statSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
 
 // Extract text from a single row
 function getRowText(state: ReturnType<TerminalSession["getState"]>, rowIndex: number): string {
@@ -40,12 +47,19 @@ async function waitForLines(
 
 describe("Terminal", () => {
   const sessions: TerminalSession[] = [];
+  const temporaryDirs: string[] = [];
 
   afterEach(async () => {
     for (const session of sessions) {
       session.kill();
     }
     sessions.length = 0;
+    while (temporaryDirs.length > 0) {
+      const dir = temporaryDirs.pop();
+      if (dir) {
+        rmSync(dir, { recursive: true, force: true });
+      }
+    }
   });
 
   function trackSession(session: TerminalSession): TerminalSession {
@@ -54,6 +68,24 @@ describe("Terminal", () => {
   }
 
   describe("createTerminal", () => {
+    it("ensures darwin prebuild spawn-helper is executable", () => {
+      const packageRoot = mkdtempSync(join(tmpdir(), "terminal-node-pty-helper-"));
+      temporaryDirs.push(packageRoot);
+      const prebuildDir = join(packageRoot, "prebuilds", `darwin-${process.arch}`);
+      mkdirSync(prebuildDir, { recursive: true });
+      const helperPath = join(prebuildDir, "spawn-helper");
+      writeFileSync(helperPath, "#!/bin/sh\necho helper\n");
+      chmodSync(helperPath, 0o644);
+
+      ensureNodePtySpawnHelperExecutableForCurrentPlatform({
+        packageRoot,
+        platform: "darwin",
+        force: true,
+      });
+
+      expect(statSync(helperPath).mode & 0o111).toBe(0o111);
+    });
+
     it("creates a terminal session with an id, name, and cwd", async () => {
       const session = trackSession(
         await createTerminal({
diff --git a/packages/server/src/terminal/terminal.ts b/packages/server/src/terminal/terminal.ts
index a88ace471..293976ae5 100644
--- a/packages/server/src/terminal/terminal.ts
+++ b/packages/server/src/terminal/terminal.ts
@@ -1,8 +1,13 @@
 import * as pty from "node-pty";
 import xterm, { type Terminal as TerminalType } from "@xterm/headless";
 import { randomUUID } from "crypto";
+import { chmodSync, existsSync, statSync } from "node:fs";
+import { dirname, join } from "node:path";
+import { createRequire } from "node:module";
 
 const { Terminal } = xterm;
+const require = createRequire(import.meta.url);
+let nodePtySpawnHelperChecked = false;
 
 export interface Cell {
   char: string;
@@ -83,6 +88,73 @@ export interface CreateTerminalOptions {
   name?: string;
 }
 
+type EnsureNodePtySpawnHelperExecutableOptions = {
+  packageRoot?: string;
+  platform?: NodeJS.Platform;
+  arch?: string;
+  force?: boolean;
+};
+
+function resolveNodePtyPackageRoot(): string | null {
+  try {
+    const packageJsonPath = require.resolve("node-pty/package.json");
+    return dirname(packageJsonPath);
+  } catch {
+    return null;
+  }
+}
+
+function ensureExecutableBit(path: string): void {
+  if (!existsSync(path)) {
+    return;
+  }
+  const stat = statSync(path);
+  if (!stat.isFile()) {
+    return;
+  }
+  // node-pty 1.1.0 shipped darwin prebuild spawn-helper without execute bit.
+  if ((stat.mode & 0o111) === 0o111) {
+    return;
+  }
+  chmodSync(path, stat.mode | 0o111);
+}
+
+export function ensureNodePtySpawnHelperExecutableForCurrentPlatform(
+  options: EnsureNodePtySpawnHelperExecutableOptions = {}
+): void {
+  const platform = options.platform ?? process.platform;
+  if (platform !== "darwin") {
+    return;
+  }
+  if (nodePtySpawnHelperChecked && !options.force) {
+    return;
+  }
+
+  const packageRoot = options.packageRoot ?? resolveNodePtyPackageRoot();
+  if (!packageRoot) {
+    return;
+  }
+  const arch = options.arch ?? process.arch;
+
+  const candidates = [
+    join(packageRoot, "build", "Release", "spawn-helper"),
+    join(packageRoot, "build", "Debug", "spawn-helper"),
+    join(packageRoot, "prebuilds", `darwin-${arch}`, "spawn-helper"),
+  ];
+
+  for (const candidate of candidates) {
+    try {
+      ensureExecutableBit(candidate);
+    } catch {
+      // best-effort hardening only
+    }
+  }
+
+  if (!options.force) {
+    nodePtySpawnHelperChecked = true;
+  }
+}
+
 function extractCell(terminal: TerminalType, row: number, col: number): Cell {
   const buffer = terminal.buffer.active;
   const line = buffer.getLine(row);
@@ -212,6 +284,8 @@ export async function createTerminal(options: CreateTerminalOptions): Promise<Te
     allowProposedApi: true,
   });
 
+  ensureNodePtySpawnHelperExecutableForCurrentPlatform();
+
   // Create PTY
   const ptyProcess = pty.spawn(shell, [], {
     name: "xterm-256color",