Looks like these safeguards are in place:
* System and root directories cannot be selected. * Can only being activated after user action. * Requires https. * Double-confirmation for write access.
No API like this could ever be bulletproof, but it's a start I guess.
Very cool API though, and it really does open up a whole new world of possibilities.
> System and root directories cannot be selected.
That desperately needs something like the Public Suffix List [1] - a community-managed list where authors of software can blacklist directories containing sensitive files or such files directly for all browsers implementing this feature.
If I were to design such a list, it would include ~/.ssh, ~/.aws, ~/.config, ~/Library, ~/.{ba,z}sh{rc,_profile,_history}, ~/.m2, ~/.npm, ~/.npmrc, ~/.profile at the very least. Because users will get phished.
Those are some pretty flimsy safeguards. I don't keep my secrets in system directories and using HTTPS doesn't mean the site isn't malicious.