TODO: File System Access API

[H-Plus-Time]

Parts of this are relatively easy to work with if you're using one of the Wasm*Store instances, for instance:

const stream = await instance.get(fooUrl);
const fsHandle = await window.showSaveFilePicker();
const writableStream = await fsHandle.createWritable();
await stream.pipeTo(writableStream);

The parts that aren't are:

• [ ] fs.get, of any kind (full file streams, ranges, etc)
• [ ] byte ranged fs.write
• [ ] fs.list
• [ ] fs.delete
• [ ] fs.copy

It's likely easier to start with the OPFS first, then account for the required user interaction bits.