[v4] Tailwind CLI ignores .gitignore in watch mode

[condemil]

What version of Tailwind CSS are you using?

v4.0.0-beta.9

What build tool (or framework if it abstracts the build tool) are you using?

@tailwindcss/cli@4.0.0-beta.9

What version of Node.js are you using?

$ node --version
v23.5.0

What browser are you using?

N/A

What operating system are you using?

macOS

Reproduction URL

git clone https://gist.github.com/condemil/b9990c17d419a0d9d1f0cc0f637fdb3c tw4-watch-gitignore-repro

Describe your issue

When tailwindcss cli is running in watch mode and ignored file is modified the output will contain css from the ignored file:

To reproduce:

1. Run the tailwindcss cli in watch mode

$ DEBUG=1 npx @tailwindcss/cli@4.0.0-beta.9 -i input.css -o output.css -w
≈ tailwindcss v4.0.0-beta.9

Done in 35ms

[36.26ms] [@tailwindcss/cli] (initial build)
[ 9.24ms]   ↳ Setup compiler
[ 7.97ms]   ↳ Scan for candidates
[10.85ms]   ↳ Build CSS
[ 1.84ms]   ↳ Write output

2. Check that output.css doesn't have h-100

$ cat output.css | grep h-1
$

3. Modify test.go and observe tailwindcss cli log

Done in 11ms

[11.25ms] [@tailwindcss/cli] (watcher)
[ 1.66ms]   ↳ Scan for candidates
[ 7.72ms]   ↳ Build CSS
[ 1.64ms]   ↳ Write output

4. Check that output.css now have h-100

$ cat output.css | grep h-1
  .h-100 {

[condemil]

I assume watch mode also picks up output.css. If I specify duration-700 and after I change it to duration-800, the old value (duration-700) stays in output.css until I restart tailwindcss cli.

Edit: As mentioned below by @wongjn this is expected for the old values to stay in output.css, this comment can be ignored, but the initial issue is still valid.

[wongjn]

I believe what you've described is intended behavior to keep things fast, see #14180, #4098

[condemil]

@wongjn you're right, let's forget that the old values stays in output.css. Still, the data in .gitignore file should be respected to prevent watching for ignored files/directories.

[ur5us]

This is a big problem if you work on an app that logs periodically, s. rails/tailwindcss-rails#491 (comment).

[jamesremuscat]

Tailwind is also watching .git for changes, which doesn't seem right either...