That was my first thought too. The downside is that you’d have to pack the thread’s items into separate files in a suitable format (JSON would be the obvious choice), which would then also have to maintain the parent-child relationship so that the threads are structured correctly when displayed. SQLite would therefore be a good option, as it is simply a text file (albeit monolithic), and you could easily adopt the item’s database structure from the Hub without having to implement a major conversion to your own format within the add-on. Alternatively, it would also be possible to incorporate an export function into the local app to a specific single-file format (which would still need to be specified), should the need arise.