I have been evaluating and testing the Filesystem API for a local first web based CAD editor and having direct r/w access to the filesystem is a great way to make such a thing, couple with the FilesystemObserver[1] API this makes building proper editors on the web a breeze.

In place of this, Firefox recommends using the origin private file system (OPFS)[2] which is basically a sandboxed filesystem that the users cannot access. Though I agree from a security perspective it kind of makes sense (not particularly for my usecase), but it removes the ability for the user to have realtime changes on local files.

An example of this is using the web based tool as an intermediary step or a processing step in a bigger pipeline; I save it using my web tool and then native applications automatically handle file updates. This just creates an extra step for Firefox/Safari to replicate changes locally by having to manually update local files.

Also neither Firefox nor Safari support showDirectoryPicker() which also creates blocks for building a web based editor.

I love Firefox and I hope they can add support for this. I have stopped caring about Safari/Webkit completely because it's hellish to try and maintain feature parity while NOT sacrificing innovation and ease of use.

[1] https://developer.mozilla.org/en-US/docs/Web/API/FileSystemO...

[2] https://developer.mozilla.org/en-US/docs/Web/API/File_System...