From ccedc506a5c82a62babee73c944bcdaa6a4337d3 Mon Sep 17 00:00:00 2001
From: Ayaan Zaidi <hi@obviy.us>
Date: Wed, 15 Apr 2026 10:21:41 +0530
Subject: [PATCH] fix: handle native pnpm execpath

---
 scripts/pnpm-runner.mjs          | 42 +++++++++++++++++++++++++--
 test/scripts/pnpm-runner.test.ts | 50 +++++++++++++++++++++++++++++++-
 2 files changed, 89 insertions(+), 3 deletions(-)

diff --git a/scripts/pnpm-runner.mjs b/scripts/pnpm-runner.mjs
index 0d713e99c5e..307030537f8 100644
--- a/scripts/pnpm-runner.mjs
+++ b/scripts/pnpm-runner.mjs
@@ -1,9 +1,43 @@
 import { spawn } from "node:child_process";
+import { closeSync, openSync, readSync } from "node:fs";
 import path from "node:path";
 import { buildCmdExeCommandLine } from "./windows-cmd-helpers.mjs";
 
 function isPnpmExecPath(value) {
-  return /^pnpm(?:-cli)?(?:\.(?:c?js|cmd|exe))?$/.test(path.basename(value).toLowerCase());
+  return /^pnpm(?:-cli)?(?:\.([cm]?js|cmd|exe))?$/.test(path.basename(value).toLowerCase());
+}
+
+function hasScriptShebang(value) {
+  let fd;
+  try {
+    fd = openSync(value, "r");
+    const header = Buffer.alloc(2);
+    return (
+      readSync(fd, header, 0, header.length, 0) === header.length &&
+      header[0] === 0x23 &&
+      header[1] === 0x21
+    );
+  } catch {
+    return false;
+  } finally {
+    if (fd !== undefined) {
+      closeSync(fd);
+    }
+  }
+}
+
+function isNodeRunnablePnpmExecPath(value) {
+  if (!isPnpmExecPath(value)) {
+    return false;
+  }
+  const extension = path.extname(value).toLowerCase();
+  if (extension === ".js" || extension === ".cjs" || extension === ".mjs") {
+    return true;
+  }
+  if (extension.length > 0) {
+    return false;
+  }
+  return hasScriptShebang(value);
 }
 
 export function resolvePnpmRunner(params = {}) {
@@ -14,7 +48,11 @@ export function resolvePnpmRunner(params = {}) {
   const platform = params.platform ?? process.platform;
   const comSpec = params.comSpec ?? process.env.ComSpec ?? "cmd.exe";
 
-  if (typeof npmExecPath === "string" && npmExecPath.length > 0 && isPnpmExecPath(npmExecPath)) {
+  if (
+    typeof npmExecPath === "string" &&
+    npmExecPath.length > 0 &&
+    isNodeRunnablePnpmExecPath(npmExecPath)
+  ) {
     return {
       command: nodeExecPath,
       args: [...nodeArgs, npmExecPath, ...pnpmArgs],
diff --git a/test/scripts/pnpm-runner.test.ts b/test/scripts/pnpm-runner.test.ts
index 232a7a791be..c27c604c3b2 100644
--- a/test/scripts/pnpm-runner.test.ts
+++ b/test/scripts/pnpm-runner.test.ts
@@ -1,8 +1,11 @@
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import os from "node:os";
+import path from "node:path";
 import { describe, expect, it } from "vitest";
 import { createPnpmRunnerSpawnSpec, resolvePnpmRunner } from "../../scripts/pnpm-runner.mjs";
 
 describe("resolvePnpmRunner", () => {
-  it("uses npm_execpath when it points to pnpm", () => {
+  it("uses npm_execpath when it points to a JS pnpm entrypoint", () => {
     expect(
       resolvePnpmRunner({
         npmExecPath: "/home/test/.cache/node/corepack/v1/pnpm/10.32.1/bin/pnpm.cjs",
@@ -22,6 +25,29 @@ describe("resolvePnpmRunner", () => {
     });
   });
 
+  it("uses npm_execpath when it points to a shebang pnpm script", () => {
+    const tempDir = mkdtempSync(path.join(os.tmpdir(), "pnpm-runner-"));
+    const npmExecPath = path.join(tempDir, "pnpm");
+    writeFileSync(npmExecPath, "#!/usr/bin/env node\nconsole.log('pnpm');\n");
+
+    try {
+      expect(
+        resolvePnpmRunner({
+          npmExecPath,
+          nodeExecPath: "/usr/local/bin/node",
+          pnpmArgs: ["exec", "vitest", "run"],
+          platform: "linux",
+        }),
+      ).toEqual({
+        command: "/usr/local/bin/node",
+        args: [npmExecPath, "exec", "vitest", "run"],
+        shell: false,
+      });
+    } finally {
+      rmSync(tempDir, { recursive: true, force: true });
+    }
+  });
+
   it("prepends node args when launching pnpm through node", () => {
     expect(
       resolvePnpmRunner({
@@ -44,6 +70,28 @@ describe("resolvePnpmRunner", () => {
     });
   });
 
+  it("falls back to bare pnpm when npm_execpath points to a native pnpm binary", () => {
+    const tempDir = mkdtempSync(path.join(os.tmpdir(), "pnpm-runner-"));
+    const npmExecPath = path.join(tempDir, "pnpm");
+    writeFileSync(npmExecPath, Buffer.from([0x7f, 0x45, 0x4c, 0x46]));
+
+    try {
+      expect(
+        resolvePnpmRunner({
+          npmExecPath,
+          pnpmArgs: ["exec", "vitest", "run"],
+          platform: "linux",
+        }),
+      ).toEqual({
+        command: "pnpm",
+        args: ["exec", "vitest", "run"],
+        shell: false,
+      });
+    } finally {
+      rmSync(tempDir, { recursive: true, force: true });
+    }
+  });
+
   it("falls back to bare pnpm on non-Windows when npm_execpath is missing", () => {
     expect(
       resolvePnpmRunner({