I liked the idea of Facebook's watchman. Cross-platform and it would only add a watcher on each dir once, regardless of how many apps needed watcher functionality.

But it's currently uninstallable for weeks on macOS without some pain (https://github.com/facebook/watchman/issues/1199).

There is `rs-notify` and `watchexec` that builds on that but seems a bit unstable.

It's 2024, and we still don't have a good way to reliably watch a large number of files :(

The bit rot is pretty crazy. Watchman's decline was a bit shocking.