[PR #700] [MERGED] fix: don't await createFromReadableStream before hydrateRoot (#695) #783

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opened 2026-05-06 13:10:05 +02:00 by BreizhHardware · 0 comments

BreizhHardware commented

2026-05-06 13:10:05 +02:00

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📋 Pull Request Information

Original PR: https://github.com/cloudflare/vinext/pull/700
Author: @southpolesteve
Created: 3/28/2026
Status: ✅ Merged
Merged: 3/28/2026
Merged by: @southpolesteve

Base: main ← Head: fix/695-useeffect-not-firing-after-rsc-hydration

📝 Commits (2)

7c56295 fix: don't await createFromReadableStream before hydrateRoot (#695)
96e238e fix: move effect-test page to app-router-cloudflare example

📊 Changes

3 files changed (+40 additions, -1 deletions)

View changed files

➕ examples/app-router-cloudflare/app/effect-test/page.tsx (+26 -0)
📝 packages/vinext/src/server/app-browser-entry.ts (+1 -1)
📝 tests/e2e/cloudflare-workers/hydration.spec.ts (+13 -0)

📄 Description

Summary

Fixes #695 -- useEffect callbacks never firing after RSC hydration on Cloudflare Workers.

createFromReadableStream returns a React thenable, not a resolved component tree. Awaiting it before passing to hydrateRoot blocked hydration until the entire RSC stream was consumed, which prevented passive effects from ever being scheduled.
In production on Workers, RSC chunks arrive progressively via injected <script> tags, so the stream takes longer to close -- making the bug reliably reproducible there but not locally (where RSC data is available synchronously in window.__VINEXT_RSC__).
The fix is one line: remove the await so the thenable is passed directly to hydrateRoot, matching the React RSC contract and the pattern already used in app-ssr-entry.ts.

Changes

packages/vinext/src/server/app-browser-entry.ts -- remove await on createFromReadableStream (line 182)
tests/fixtures/cf-app-basic/app/effect-test/page.tsx -- new "use client" fixture page that uses useEffect to flip a status flag
tests/e2e/cloudflare-workers/hydration.spec.ts -- regression test that verifies useEffect fires after RSC hydration on the Workers e2e project

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/cloudflare/vinext/pull/700 **Author:** [@southpolesteve](https://github.com/southpolesteve) **Created:** 3/28/2026 **Status:** ✅ Merged **Merged:** 3/28/2026 **Merged by:** [@southpolesteve](https://github.com/southpolesteve) **Base:** `main` ← **Head:** `fix/695-useeffect-not-firing-after-rsc-hydration` --- ### 📝 Commits (2) - [`7c56295`](https://github.com/cloudflare/vinext/commit/7c56295d5a0e3e89d0ddefdef9859638ea1fd0b2) fix: don't await createFromReadableStream before hydrateRoot (#695) - [`96e238e`](https://github.com/cloudflare/vinext/commit/96e238eb6073c0608f11bfffd2112ecf7748dfed) fix: move effect-test page to app-router-cloudflare example ### 📊 Changes **3 files changed** (+40 additions, -1 deletions) <details> <summary>View changed files</summary> ➕ `examples/app-router-cloudflare/app/effect-test/page.tsx` (+26 -0) 📝 `packages/vinext/src/server/app-browser-entry.ts` (+1 -1) 📝 `tests/e2e/cloudflare-workers/hydration.spec.ts` (+13 -0) </details> ### 📄 Description ## Summary Fixes #695 -- `useEffect` callbacks never firing after RSC hydration on Cloudflare Workers. - `createFromReadableStream` returns a React **thenable**, not a resolved component tree. Awaiting it before passing to `hydrateRoot` blocked hydration until the entire RSC stream was consumed, which prevented passive effects from ever being scheduled. - In production on Workers, RSC chunks arrive progressively via injected `<script>` tags, so the stream takes longer to close -- making the bug reliably reproducible there but not locally (where RSC data is available synchronously in `window.__VINEXT_RSC__`). - The fix is one line: remove the `await` so the thenable is passed directly to `hydrateRoot`, matching the React RSC contract and the pattern already used in `app-ssr-entry.ts`. ## Changes - `packages/vinext/src/server/app-browser-entry.ts` -- remove `await` on `createFromReadableStream` (line 182) - `tests/fixtures/cf-app-basic/app/effect-test/page.tsx` -- new `"use client"` fixture page that uses `useEffect` to flip a status flag - `tests/e2e/cloudflare-workers/hydration.spec.ts` -- regression test that verifies `useEffect` fires after RSC hydration on the Workers e2e project --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>