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 {