v8_middleware does not work with Cloudflare Workers

[singingwolfboy]

Reproduction

https://github.com/singingwolfboy/test-cf-rr-middleware

System Info

System:
    OS: macOS 26.0.1
    CPU: (8) arm64 Apple M1
    Memory: 105.34 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 25.1.0 - /opt/homebrew/bin/node
    npm: 11.6.2 - /opt/homebrew/bin/npm
    pnpm: 10.20.0 - /opt/homebrew/bin/pnpm
    bun: 1.3.1 - /opt/homebrew/bin/bun
  Browsers:
    Firefox: 142.0.1
    Safari: 26.0.1
  npmPackages:
    @react-router/dev: ^7.9.5 => 7.9.5 
    @react-router/node: ^7.9.5 => 7.9.5 
    react-router: ^7.9.5 => 7.9.5 
    vite: ^7.1.12 => 7.1.12

Used Package Manager

npm

Expected Behavior

I expect that the v8_middleware feature should work as documented, both on local development and on production, using Cloudflare Workers.

Actual Behavior

Trying to launch the dev server produces an error, as documented in the reproduction repo:

[vite] Internal server error: Failed to load url node:stream (resolved id: node:stream) in /Users/singingwolfboy/clones/test-cf-rr-middleware/node_modules/@react-router/dev/dist/config/defaults/entry.server.node.tsx. Does the file exist?
      at CustomModuleRunner.cachedModule (workers/runner-worker.js:1302:20)
      at request (workers/runner-worker.js:1152:83)
      at null.<anonymous> (/Users/singingwolfboy/clones/test-cf-rr-middleware/node_modules/@react-router/dev/dist/config/defaults/entry.server.node.tsx:1:1)
      at Object.runInlinedModule (workers/runner-worker.js:1403:4)
      at CustomModuleRunner.directRequest (workers/runner-worker.js:1206:59)
      at CustomModuleRunner.cachedRequest (workers/runner-worker.js:1113:73)
      at null.<anonymous> (/server-build/virtual:react-router/server-build:2:5)
      at Object.runInlinedModule (workers/runner-worker.js:1403:4)
      at CustomModuleRunner.directRequest (workers/runner-worker.js:1206:59)
      at CustomModuleRunner.cachedRequest (workers/runner-worker.js:1113:73)
[vite] Unexpected Node.js imports for environment "ssr". Do you need to enable the "nodejs_compat" compatibility flag? Refer to https://developers.cloudflare.com/workers/runtime-apis/nodejs/ for more details.
 - "node:stream" imported from "node_modules/@react-router/dev/dist/config/defaults/entry.server.node.tsx"

[singingwolfboy]

Update: the problem was that I had deleted the app/entry.server.tsx file. Now it works, so this is not a bug report for the functionality of React Router.

However, it could maybe be considered a documentation problem. The docs for entry.server.tsx very prominently start with a callout saying "This file is optional". Since I was trying to make the simplest possible reproduction of the problem I was running into, I deleted this "optional" file without thinking much about it. I figured that it would be simpler to go with the default settings, without thinking of why that file was there, which led to the internal server error above.

Perhaps the documentation should be a bit more nuanced: this file is octional in some situations, but is clearly necessary (with some customizations) in certain situations, like with Cloudflare. As a result, I'm not going to close this GitHub issue, but I'll leave it open as a reminder to update the documentation on this point.

(Although if someone from the React Router team wants to close it, I won't be offended!)

[brophdawg11]

Thanks for catching this - I updated the docs in 3ef3a00 to reflect this change. We used to have defaults for cloudflare and others but removed them in v7 in favor of the ones that ship with the templates.