Channel metadata (banner, avatar, description, counts) was fetched only the first time a channel was seen: the subscription import asked only for channels with no details, and the channel page only for ones missing a join date. 394 of 397 subscribed channels had July metadata. Both now also refresh details older than DETAILS_MAX_AGE (7 days), through one shared staleness rule; channels.list costs 1 unit per 50 channels.