For CLI usage I found that the best option was instead of watching my source directory just to watch a magic file. Then I configured my editor to touch that file when saving. This has a few benefits:

1. No need to worry about which files to watch or ignoring build outputs.

2. Works with every project with no setup.

3. Easy to trigger a re-run without actually changing a file.

4. Always runs after all files are saved instead of starting after the first file is saved and racing the rest.

5. Infinitely scalable.