Rails 8: 404 request to /assets/tailwindcss in fresh project with esbuild

[JangoCG]

In a fresh Rails 8 project using tailwind and esbuild, the browser always tries to request a non-existent asset:

Failed to load resource: the server responded with a status of 404 (Not Found)
http://localhost:3000/assets/tailwindcss

Tailwind itself is working correctly (classes apply, CSS compiles).
But this extra GET request to /assets/tailwindcss fails with 404 on every page load.

Steps to reproduce

rails new railstailwindbug \
  --javascript=esbuild \
  --css=tailwind

cd railstailwindbug
bin/dev

Then open http://localhost:3000/
Check the browser console → you’ll see the 404 for /assets/tailwindcss.

Expected behavior
No request to /assets/tailwindcss should be made, since the file does not exist.
Only the compiled Tailwind CSS should be loaded.

Actual behavior
Every page load triggers a GET request to /assets/tailwindcss, which fails with:

GET http://localhost:3000/assets/tailwindcss 404 (Not Found)

This issue persists even when deploying the app using the official Dockerfile and Kamal.

Environment

• Rails: 8.0.2.1
• M4 Mac Max
• Happens when running locally with bin/dev
• Also happens when deployed with kamal on an AMD VPS