Hey, thanks for creating such a useful package! When following your README with a dummy project, tsdown didn't run correctly:

ℹ tsdown v0.15.9 powered by rolldown v1.0.0-beta.44

 ERROR  SyntaxError: Unexpected identifier 'I'

 ELIFECYCLE  Command failed with exit code 1.

Turns out this is caused by this using line. Not a big issue, updating to Node 24 made it run without further errors.

It would probably be good to add a notice to the README, and maybe to declare the requirement in package.json under engines: https://docs.npmjs.com/cli/v11/configuring-npm/package-json#engines

Let me know if you'd like a PR!