The subscriptions of the feeds, are kept in keys named "feed:<id>", but these are difficult to reference at the moment. There should be a set of "feed:<id>" items and a hash of urls to "feed:<id>". That way I can deduplicate feeds and make it easier to resubscribe.

In the original version I had a filter that added all items matching a regex to a channel. In the settings page there should be a place to add keywords to a channel (even if it has no feeds) and gather all items matching those keywords (or perhaps) regex.