From b4654bc1acaf462c77210fdefde2eb7ee551998a Mon Sep 17 00:00:00 2001
From: Marco Ippolito <marcoippolito54@gmail.com>
Date: Tue, 30 Sep 2025 05:45:51 +0200
Subject: [PATCH] module: use sync cjs when importing cts

---
 lib/internal/modules/esm/loader.js             |  4 +++-
 test/es-module/test-typescript-commonjs.mjs    | 10 ++++++++++
 test/es-module/test-typescript-module.mjs      | 11 +++++++++++
 test/fixtures/typescript/cts/issue-59963/a.cts |  3 +++
 test/fixtures/typescript/cts/issue-59963/b.mts |  2 ++
 test/fixtures/typescript/cts/issue-59963/c.cts |  2 ++
 test/fixtures/typescript/mts/issue-59963/a.mts |  3 +++
 test/fixtures/typescript/mts/issue-59963/b.cts |  3 +++
 test/fixtures/typescript/mts/issue-59963/c.mts |  1 +
 9 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 test/fixtures/typescript/cts/issue-59963/a.cts
 create mode 100644 test/fixtures/typescript/cts/issue-59963/b.mts
 create mode 100644 test/fixtures/typescript/cts/issue-59963/c.cts
 create mode 100644 test/fixtures/typescript/mts/issue-59963/a.mts
 create mode 100644 test/fixtures/typescript/mts/issue-59963/b.cts
 create mode 100644 test/fixtures/typescript/mts/issue-59963/c.mts

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index 02ec3183bc596b..300da51afe6185 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -504,7 +504,9 @@ class ModuleLoader {
     const loadResult = this.#loadSync(url, { format, importAttributes });
 
     // Use the synchronous commonjs translator which can deal with cycles.
-    const finalFormat = loadResult.format === 'commonjs' ? 'commonjs-sync' : loadResult.format;
+    const finalFormat =
+      loadResult.format === 'commonjs' ||
+      loadResult.format === 'commonjs-typescript' ? 'commonjs-sync' : loadResult.format;
 
     if (finalFormat === 'wasm') {
       assert.fail('WASM is currently unsupported by require(esm)');
diff --git a/test/es-module/test-typescript-commonjs.mjs b/test/es-module/test-typescript-commonjs.mjs
index e757cfd231fbfb..548f440e59b5aa 100644
--- a/test/es-module/test-typescript-commonjs.mjs
+++ b/test/es-module/test-typescript-commonjs.mjs
@@ -174,3 +174,13 @@ test('expect failure of a .cts file requiring esm in node_modules', async () =>
   match(result.stderr, /ERR_UNSUPPORTED_NODE_MODULES_TYPE_STRIPPING/);
   strictEqual(result.code, 1);
 });
+
+test('cts -> require mts -> import cts', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    fixtures.path('typescript/cts/issue-59963/a.cts'),
+  ]);
+
+  strictEqual(result.stderr, '');
+  strictEqual(result.stdout, 'Hello from c.cts\n');
+  strictEqual(result.code, 0);
+});
diff --git a/test/es-module/test-typescript-module.mjs b/test/es-module/test-typescript-module.mjs
index 6a43808b82ef9c..eab2fc620fd18e 100644
--- a/test/es-module/test-typescript-module.mjs
+++ b/test/es-module/test-typescript-module.mjs
@@ -98,3 +98,14 @@ test('execute .ts file importing a module', async () => {
   strictEqual(result.stdout, 'Hello, TypeScript!\n');
   strictEqual(result.code, 0);
 });
+
+test('mts -> import cts -> require mts', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    '--no-warnings',
+    fixtures.path('typescript/mts/issue-59963/a.mts'),
+  ]);
+
+  strictEqual(result.stderr, '');
+  strictEqual(result.stdout, 'Hello from c.mts\n');
+  strictEqual(result.code, 0);
+});
diff --git a/test/fixtures/typescript/cts/issue-59963/a.cts b/test/fixtures/typescript/cts/issue-59963/a.cts
new file mode 100644
index 00000000000000..8826591bd39f02
--- /dev/null
+++ b/test/fixtures/typescript/cts/issue-59963/a.cts
@@ -0,0 +1,3 @@
+const { message } = require("./b.mts");
+interface Foo {};
+console.log(message);
diff --git a/test/fixtures/typescript/cts/issue-59963/b.mts b/test/fixtures/typescript/cts/issue-59963/b.mts
new file mode 100644
index 00000000000000..bd3cf1998f9b65
--- /dev/null
+++ b/test/fixtures/typescript/cts/issue-59963/b.mts
@@ -0,0 +1,2 @@
+interface Foo {};
+export { message } from "./c.cts";
diff --git a/test/fixtures/typescript/cts/issue-59963/c.cts b/test/fixtures/typescript/cts/issue-59963/c.cts
new file mode 100644
index 00000000000000..20dc004237b945
--- /dev/null
+++ b/test/fixtures/typescript/cts/issue-59963/c.cts
@@ -0,0 +1,2 @@
+const message: string = "Hello from c.cts";
+module.exports = { message };
diff --git a/test/fixtures/typescript/mts/issue-59963/a.mts b/test/fixtures/typescript/mts/issue-59963/a.mts
new file mode 100644
index 00000000000000..99c938acf5e9b8
--- /dev/null
+++ b/test/fixtures/typescript/mts/issue-59963/a.mts
@@ -0,0 +1,3 @@
+import { message } from "./b.cts";
+interface Foo {};
+console.log(message);
diff --git a/test/fixtures/typescript/mts/issue-59963/b.cts b/test/fixtures/typescript/mts/issue-59963/b.cts
new file mode 100644
index 00000000000000..75b724f21c4b3e
--- /dev/null
+++ b/test/fixtures/typescript/mts/issue-59963/b.cts
@@ -0,0 +1,3 @@
+const { message } = require("./c.mts");
+interface Foo {};
+module.exports = { message };
diff --git a/test/fixtures/typescript/mts/issue-59963/c.mts b/test/fixtures/typescript/mts/issue-59963/c.mts
new file mode 100644
index 00000000000000..4e7f88ba124584
--- /dev/null
+++ b/test/fixtures/typescript/mts/issue-59963/c.mts
@@ -0,0 +1 @@
+export const message: string = "Hello from c.mts";