tsdown watch mode stops reacting after first rebuild in some projects

[zougari47]

I didn't raise an issue because when I have started an empty project and install tsdown + typescript it works fine.

The Problem

When I run tsdown --watch and I edit the src/index.ts first time it rebuild but second time and so on it's not! And the most wired thing is if I change a file in the outisde src like tsdown.config.ts or package.json it rebuild.

Now you might think somthing I miss in tsconfig or tsdown config but. I have tried so many things and it's same result.

Environment:
tsdown: 0.21.10
TypeScript: 6.0.3
Node: v24.14.1
Package manager: pnpm 10.27.0
OS:

PRETTY_NAME="Ubuntu 24.04.4 LTS"
NAME="Ubuntu"
VERSION_ID="24.04"
VERSION="24.04.4 LTS (Noble Numbat)"
VERSION_CODENAME=noble
ID=ubuntu
ID_LIKE=debian

And this is the repository .