It's sort of a double prompt scenario since the FileSystemAccessAPI requires users to actually select the file/directory for the web app to use. You can save th

It's sort of a double prompt scenario since the FileSystemAccessAPI requires users to actually select the file/directory for the web app to use. You can save the file handles into IndexedDB in which case the user will only be prompted if they refresh the page to authorize the web app to continue using that file/directory. From my use of it, the only real vulnerability I see is that Chrome still considers anything from file:// to be the same origin. This means as a developer you absolutely should not be saving file handles to IndexedDB if you are loading your app via file:// instead of https:// https://. This is a pretty niche use case, but I do think static html "apps" are an underappreciated form for distributing software and this new API makes such apps a lot more powerful. I wrote a plugin for TiddlyWiki that lets it operate really smoothly using this API https://github.com/slaymaker1907/TW5-browser-nativesaver https://github.com/slaymaker1907/TW5-browser-nativesaver that demonstrates why this API is worth the trouble.