I’m using PubSubHubbub (which has been renamed to WebSub lately) to get rid of polling for some feeds.
Unfortunately, TT-RSS (latest git) stopped getting update notification after a week for the feed at http://cweiske.de/tagebuch/feed/
The reason is that my hub only hands out subscriptions valid for a week. The subscription needs to be renewed before it expires, and TT-RSS does not do this yet.
This behavior is specified in the WebSub spec section 5.3.1:
Hubs may make the hub.lease_seconds equal to the value the subscriber passed in their subscription request but may change the value depending on the hub’s policies. To sustain a subscription, the subscriber must re-request the subscription on the hub before hub.lease_seconds seconds has elapsed.
I think tt-rss should store the subscription end date in the feeds table, and have the cronjob renew the subscription a day or 12 hours before it expires.