*** Bug 213775 has been marked as a duplicate of this bug. ***
Now that we have the Origin Private File System, any word about the picker methods?
I think this can be considered done. This work essentially morphed into supporting the File System standard. As per https://github.com/WebKit/standards-positions/issues/28 we don't think the methods mentioned in comment 3 are a good idea.
Current spec link: https://fs.spec.whatwg.org/
Reopen this as
Reopened as we have one interface `FileSystemWritableFileStream` unimplemented as in current spec:
I'm a WordPress core committer working at Automattic and WordPress could really use this feature in the WordPress Playground  project which runs an entire WordPress in the browser via WebAssembly.
The in-browser storage  already works great in Safari, but loading and saving changes to the local directory only works in Google Chrome . Implementing it in WebKit would unlock using Safari as a WordPress development environment or even as a runtime for the Blocknotes app  where all notes are stored on the disk and synchronized across all the devices through iCloud. Ditto for other WordPress-based portable WASM apps.
FileSystemWritableFileStream will be helpful for my note-taking app as well. It's working in Chrome but not Safari, and currently only working solution with using Web Worker is not very practical for me, so I need this to be implemented in Safari.