Bug: RSC `renderToReadableStream/createFromReadableStream` gets stuck for certain objects on development

[hi-ogawa]

React version: 19.2

(This didn't reproduce on 19.1.1. Based on old reproduction hi-ogawa/react-router-templates@e6eddd0, it reproduced since at least 19.2.0-canary-19baee81-20250725.)

Steps To Reproduce

When serializing and deserializing certain objects with the same object reference as a property and as a prop, createFromReadableStream gets stuck.

import { renderToReadableStream } from "react-server-dom-xxx/server.edge";
import { createFromReadableStream } from "react-server-dom-xxx/client.edge";

async function test1() {
 // serialize same `obj` reference as top-level object and as prop
 const obj = {};
 function Test(_props: { obj: {} }) {
 return "test";
 }
 const original = {
 obj: obj,
 node: <Test obj={obj} />,
 }
 console.log("[original]", original);
 const stream = renderToReadableStream(original);
 console.log("[stream]", stream);
 const restored = await createFromReadableStream(stream); // 👈 this gets stuck
 console.log("[restored]", restored);
}

Interestingly, it works if the order of properties are flipped, for example:

 const original = {
 node: <Test obj={obj} />,
 obj: obj,
 }

This happens only on development. I initially observed this behavior on react-router remix-run/react-router#14085 and minimized a reproduction to the above pattern.

Link to code example:

• parcel https://github.com/hi-ogawa/reproductions/tree/main/react-router-14085-rsc-dup-obj-parcel
• vite https://github.com/hi-ogawa/reproductions/tree/main/react-router-14085-rsc-dup-obj

The current behavior

createFromReadableStream gets stuck

The expected behavior

createFromReadableStream can deserialize stream