From 729b8b8a52e4b8fb712da8b55230cd550906227f Mon Sep 17 00:00:00 2001
From: "Yuichiro Tachibana (Tsuchiya)" <t.yic.yt@gmail.com>
Date: Sat, 22 Nov 2025 22:26:56 +0900
Subject: [PATCH 1/2] fix(web-worker): transfer MessagePort objects to worker
 as event.ports

MessagePort objects can be transferred to another process such as a worker and can be accessed via events.ports
as written in https://developer.mozilla.org/en-US/docs/Web/API/MessageEvent/ports
> The ports read-only property of the MessageEvent interface is an array of MessagePort objects containing all MessagePort objects sent with the message, in order.
Refs: https://developer.mozilla.org/en-US/docs/Web/API/MessageChannel, https://github.com/mdn/dom-examples/tree/9a8acd0da2417372655b22d5a0ced768e76deb1c/channel-messaging-basic
---
 packages/web-worker/src/utils.ts       |  4 ++++
 test/core/src/web-worker/worker.ts     |  5 +++++
 test/core/test/web-worker-node.test.ts | 12 ++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/packages/web-worker/src/utils.ts b/packages/web-worker/src/utils.ts
index e3c1d976a970..0c1a3012a299 100644
--- a/packages/web-worker/src/utils.ts
+++ b/packages/web-worker/src/utils.ts
@@ -29,12 +29,14 @@ function createClonedMessageEvent(
 
   debug('clone worker message %o', data)
   const origin = typeof location === 'undefined' ? undefined : location.origin
+  const ports = transfer?.filter((t): t is MessagePort => t instanceof MessagePort)
 
   if (typeof structuredClone === 'function' && clone === 'native') {
     debug('create message event, using native structured clone')
     return new MessageEvent('message', {
       data: structuredClone(data, { transfer }),
       origin,
+      ports,
     })
   }
   if (clone !== 'none') {
@@ -50,12 +52,14 @@ function createClonedMessageEvent(
     return new MessageEvent('message', {
       data: ponyfillStructuredClone(data, { lossy: true } as any),
       origin,
+      ports,
     })
   }
   debug('create message event without cloning an object')
   return new MessageEvent('message', {
     data,
     origin,
+    ports,
   })
 }
 
diff --git a/test/core/src/web-worker/worker.ts b/test/core/src/web-worker/worker.ts
index 90d90793c3fc..de29dcddd1e2 100644
--- a/test/core/src/web-worker/worker.ts
+++ b/test/core/src/web-worker/worker.ts
@@ -1,3 +1,8 @@
 self.onmessage = (e) => {
   self.postMessage(`${e.data} world`)
+
+  const port = e.ports[0]
+  if (port) {
+    port.postMessage(`${e.data} world via port`)
+  }
 }
diff --git a/test/core/test/web-worker-node.test.ts b/test/core/test/web-worker-node.test.ts
index dd4cf1865b34..ff0b5d03318e 100644
--- a/test/core/test/web-worker-node.test.ts
+++ b/test/core/test/web-worker-node.test.ts
@@ -211,6 +211,18 @@ it('self injected into worker and its deps should be equal', async () => {
   expect(await testSelfWorker(new Worker(new URL('../src/web-worker/selfWorker.ts', import.meta.url)))).toBeTruthy()
 })
 
+it('transfer MessagePort objects to worker as event.ports', async () => {
+  expect.assertions(1)
+
+  const worker = new MyWorker()
+  const channel = new MessageChannel()
+  expect(new Promise<string>((resolve, reject) => {
+    channel.port1.onmessage = e => resolve(e.data as string)
+    channel.port1.onmessageerror = reject
+  })).resolves.toBe('hello world via port')
+  worker.postMessage('hello', [channel.port2])
+})
+
 it('throws syntax error if no arguments are provided', () => {
   const worker = new MyWorker()
 

From 81bc9ee933f649413fbc4e6431cddb158ebef2f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ari=20Perkki=C3=B6?= <ari.perkkio@gmail.com>
Date: Mon, 24 Nov 2025 09:28:11 +0200
Subject: [PATCH 2/2] test: await expectation

---
 test/core/test/web-worker-node.test.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/test/core/test/web-worker-node.test.ts b/test/core/test/web-worker-node.test.ts
index ff0b5d03318e..1977446feca3 100644
--- a/test/core/test/web-worker-node.test.ts
+++ b/test/core/test/web-worker-node.test.ts
@@ -216,11 +216,12 @@ it('transfer MessagePort objects to worker as event.ports', async () => {
 
   const worker = new MyWorker()
   const channel = new MessageChannel()
-  expect(new Promise<string>((resolve, reject) => {
+  const promise = new Promise<string>((resolve, reject) => {
     channel.port1.onmessage = e => resolve(e.data as string)
     channel.port1.onmessageerror = reject
-  })).resolves.toBe('hello world via port')
+  })
   worker.postMessage('hello', [channel.port2])
+  await expect(promise).resolves.toBe('hello world via port')
 })
 
 it('throws syntax error if no arguments are provided', () => {