The following functions allow you to share data between files without the need to use the REST API. While it suffers from some drawbacks (like managing duplicate files), it offers an almost frictionless experience for users.
When a user opens a file with your plugin the file is added to a list in clientStorage with a unique ID. When the user visits another file all previously visited files are be accessible from the clientStorage. Used in combination with a list which is stored on each file, it's possible to keep a record of remote files your plugin is using for a given file. The data for each file can contain any keys or information you need to access or import data from remote files.