Read/seen ranking

When track_read or track_seen is enabled on a feed group, you can use is_read and is_seen as variables in ranking expressions. On flat content feeds, enable them with activity_marks; notification feeds use their notification configuration. On content feeds, the ranking expression may only reference is_read or is_seen when the matching activity_marks.track_read or activity_marks.track_seen is enabled, otherwise creating or updating the feed group fails with ranking by read/seen status requires notification config or matching activity_marks tracking. Notification feeds can always rank by is_read and is_seen.

A mark only applies to activities created at or before the time it was set. On aggregated notification feeds, a group that is updated after it was marked counts as unread or unseen again.

For example, a custom flat feed group that sorts by popularity and subtracts 100 points from activities the user has read:

var request = new CreateFeedGroupRequest
{
    ID = "ranked_timeline",
    ActivityMarks = new ActivityMarksConfig
    {
        TrackSeen = true,
        TrackRead = true,
    },
    ActivitySelectors = new List<ActivitySelectorConfig>
    {
        new() { Type = "following" },
    },
    Ranking = new RankingConfig
    {
        Type = "expression",
        Score = "popularity - (is_read ? 100 : 0)",
    },
};

await _feedsV3Client.CreateFeedGroupAsync(request);

To rank unseen activities first instead (this does not include popularity):

var request = new CreateFeedGroupRequest
{
    ID = "unseen_timeline",
    ActivityMarks = new ActivityMarksConfig
    {
        TrackSeen = true,
        TrackRead = true,
    },
    ActivitySelectors = new List<ActivitySelectorConfig>
    {
        new() { Type = "following" },
    },
    Ranking = new RankingConfig
    {
        Type = "expression",
        Score = "is_seen ? 0 : 100",
    },
};

await _feedsV3Client.CreateFeedGroupAsync(request);

The same expressions work on notification feeds, where marks may be resolved per activity or aggregated group.

Example expressions

Aggregated feeds

On aggregated notification feeds, is_read and is_seen are resolved at the group level. All activities within an aggregated group share the same read/seen status. On flat feeds (content feeds with activity_marks, and flat notification feeds), they are resolved per activity. Content feeds with aggregation can't use activity_marks, so they can't rank by read/seen status.