From 9d14a051560c31ed04e839a9693e1becfe3d9462 Mon Sep 17 00:00:00 2001
From: Santusht kotai <115890693+santusht06@users.noreply.github.com>
Date: Tue, 25 Aug 2026 18:17:06 +0530
Subject: [PATCH] module: forward execArgv to ESM loader hook worker

When spawning the internal worker thread for asynchronous loader hooks
in AsyncLoaderHookWorker, process.execArgv was not passed to the
InternalWorker constructor options.

As a result, custom CLI flags such as `--conditions <tag>` set when
creating a Worker thread were omitted from the loader hook worker
thread's environment.

This commit forwards `process.execArgv` to the `InternalWorker` instance
so that loader hooks registered within worker threads receive custom
conditions and options.

Fixes: https://github.com/nodejs/node/issues/50885
Signed-off-by: Santusht kotai <115890693+santusht06@users.noreply.github.com>
---
 lib/internal/modules/esm/hooks.js             |  1 +
 .../test-esm-loader-worker-conditions.mjs     | 53 +++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 test/es-module/test-esm-loader-worker-conditions.mjs

diff --git a/lib/internal/modules/esm/hooks.js b/lib/internal/modules/esm/hooks.js
index 4ced5521aca2..c7300fcbb721 100644
--- a/lib/internal/modules/esm/hooks.js
+++ b/lib/internal/modules/esm/hooks.js
@@ -529,6 +529,7 @@ class AsyncLoaderHookWorker {
       stdin: false,
       stdout: false,
       trackUnmanagedFds: false,
+      execArgv: process.execArgv,
       workerData: {
         lock,
       },
diff --git a/test/es-module/test-esm-loader-worker-conditions.mjs b/test/es-module/test-esm-loader-worker-conditions.mjs
new file mode 100644
index 000000000000..825f317fb8cf
--- /dev/null
+++ b/test/es-module/test-esm-loader-worker-conditions.mjs
@@ -0,0 +1,53 @@
+import { mustCall, mustNotCall } from '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import assert from 'node:assert';
+import { Worker } from 'node:worker_threads';
+
+const loaderURL = fixtures.fileURL('es-module-loaders', 'loader-resolve-passthru.mjs');
+const targetURL = fixtures.fileURL('es-modules', 'conditional-exports.mjs');
+
+// Test that custom conditions passed to Worker via execArgv
+// are forwarded to the internal ESM loader hook worker thread when using register().
+{
+  const worker = new Worker(
+    `
+    import assert from 'node:assert';
+    import { register } from 'node:module';
+    register(${JSON.stringify(loaderURL.href)});
+    const ns = await import(${JSON.stringify(targetURL.href)});
+    assert.strictEqual(ns.default, 'from custom condition');
+    `,
+    {
+      eval: true,
+      execArgv: ['--conditions', 'custom-condition', '--no-warnings'],
+    }
+  );
+
+  worker.on('error', mustNotCall());
+  worker.on('exit', mustCall((code) => {
+    assert.strictEqual(code, 0);
+  }));
+}
+
+// Test that custom conditions passed to Worker via execArgv
+// are forwarded to the internal ESM loader hook worker thread when using registerHooks().
+{
+  const worker = new Worker(
+    `
+    import assert from 'node:assert';
+    import { registerHooks } from 'node:module';
+    registerHooks(${JSON.stringify(loaderURL.href)});
+    const ns = await import(${JSON.stringify(targetURL.href)});
+    assert.strictEqual(ns.default, 'from custom condition');
+    `,
+    {
+      eval: true,
+      execArgv: ['--conditions', 'custom-condition', '--no-warnings'],
+    }
+  );
+
+  worker.on('error', mustNotCall());
+  worker.on('exit', mustCall((code) => {
+    assert.strictEqual(code, 0);
+  }));
+}