That's a great idea, and it never crossed my mind because of the way I was using the app. The app itself saves decks as flat text files, but these are slightly different from the exported text files (that's why I had the exported decks folder vs. the decks folder). So I'd been saving and tweaking my decks with the app through the decks folder, and then just exporting my changes as a new Octgn export.
But I like your idea....yeah, I can make it so that you could load in an Octgn file and then tweak it that way. Give me a day or so and I'll see what I can come up with.
Right now, updating new cards to the 'database' is manual only. It's a labor of love. I scan the new cards once I've bought them and then I add them in one-at-a-time by dragging the scanned image where it belongs and then filling in all the information for the card. Press the Save Card button and then on to the next one.
After I have them manually entered this way, I then have to take the Octgn set for the new pack/deluxe and put it through another tool I wrote that strips out the card names and their unique Octgn ID numbers and save it as text that gets added to the Octgn.txt file. This is done so the Octgn exports continue to work properly. The add new cards tab was how I initially built the Cards.txt file that the program uses.
My intentions are to keep the files up-to-date as each new chapter pack / deluxe box comes out and then release a self-extracting file to my Google Drive so anyone that wants to keep using the app just needs to download the latest 'patch' to remain up-to-date.