Firefox File System Access Extension

This extension brings the File System Access API to Firefox that helps web apps such as vscode.dev read and write local files and folders.

Main features

Implemented showOpenFilePicker(), showDirectoryPicker(), showSaveFilePicker() and related interfaces.
Set to enable specific File System Access features on matching web pages.
Provides File System Access API for other compatible WebExtensions.

The local file operations required by this extension cannot be performed in the browser, and a helper app needs to be installed to assist in the related work.
The optional Code Editor feature is provided by the Code Editor extension.

By default, FileSystemHandle will lose its instance methods after cloning (e.g. using IndexedDB or postMessage), and requires additional configuration of the FS_CONFIG.CLONE_ENABLED. Web developers can use __FILE_SYSTEM_TOOLS__.parseHandle(handle) to restore the instance methods.
Limited Worker context support and requires additional configuration of the FS_CONFIG.WORKER_ENABLED.
Read file size is limited by the FS_CONFIG.FILE_SIZE_LIMIT. Web developers can read large file streams and slices with handle.getFile({ _allowNonNative: true }), and write large file in-place with handle.createWritable({ _inPlace: true, keepExistingData: true }).
DataTransferItem.prototype.getAsFileSystemHandle is not implemented.