I shipped back-end support for algorithmic feeds in the last release. In this release I shipped front-end support. The feature needs testing and polish, so it's still not possible to navigate to the feeds editor, but if you know where to look, you can try it 😉.

"Algorithmic feeds" currently means support for custom hashtag, mention, and keyword feeds (e.g everything that mentions "#fediverse" and "#activitypub" but not "x" or "facebook").

Here's the full changelog:

Added

• Front-end support for user-defined algorithmic feeds.
• Allow editing optional properties on published posts.
• Support undoing a dislike.

Fixed

• Handle concurrent duplicate inbox delivery.
• Don't apply custom themes on the drafts and posts pages.
• Adapt duration units in thread analysis.
• Restore the spinning loader.

Changed

• Restrict theme overrides to color and reduce reliance on !important.
• Render the homepage description in a basic segment.

Removed

• The deliver_to state and the recipients fallback.

In the next release, algorithmic feeds get wired into the navigation!

#ktistec #crystallang #activitypub #fediverse

There are two significant new additions in release v3.8.0 of ktistec.

First, the actor cards on the followed/following pages show relevant actor status. On the followed page, it tells you how long it has been since that actor published an activity (create, announce, like, etc.) that was sent to your server. It's a proxy for how active they are (or are not). On the following page, it tells you how long it has been since you have been able to send to that server. It's a proxy for whether that server is reachable or that actor is still alive.

Second, the backend for user-defined algorithmic feeds is in place, along with a keyword/hashtag/mention feeds implementation. You can't set up a feed via the user-interface, but the feeds work if you set one up directly in the database—which is how I've been previewing them. I plan to release the frontend next week.

Here's the full changelog:

Added

• Display activity status on actor cards.
• Back-end support for user-defined algorithmic feeds.
• Apply community-relayed moderator deletes received as a Group's wrapped Announce.
• Follow a web page's rel="alternate" link when searching.

Fixed

• Avoid loading entire has_many collections when constructing child records.
• Evaluate the same-origin fetch gate against an embedded node's own identifier.
• Accept a delete of an uncached object or actor without verification.
• Catch MIME::Multipart::Error in local file-upload handling.
• Map malformed request-body parse failures to Bad Request.

#ktistec #crystallang #activitypub #fediverse

i'm sure inline json-ld contexts with server extensions seem like the wrong thing, but they're preferable to identical copies of the same context hosted externally and served by a dozen or more instances of a server or family of servers.

i could be persuaded to change my mind if a server allowed meaningful customization. but if a server is publishing a canonical vocabulary of extensions for that server, it should be hosted in a single, well-know location.

#fediverse #activitypub

I started to work on algorithmic feeds but was side-tracked by interoperability work. No complaints. It turned out to be a productive detour.

Here's the full changelog for release v3.7.0 of Ktistec:

Added

• Support FEP-2c59: Discovery of a Webfinger address from an ActivityPub actor.
• Support ActivityPub Update activities for actor profile changes.

Fixed

• Disambiguate reblog IDs from status IDs. (fixes #151)
• Correct the quote_policy mapping to public/nobody values.
• Ignore malformed pagination parameters instead of raising.
• Treat "cannot be reconnected" errors as connection failures.
• Infer a media attachment's type when mediaType is missing.
• Faster, case-insensitive, actor username lookups.
• Faster statuses_count using an approximate count.

Changed

• Resolve JSON-LD contexts by matching their digest against a bundled copy.

The first version of algorithmic feeds won't be very algorithmic—it will let you create a feed that filters by keywords, hashtags, and mentions. That covers a lot of ground for me personally, and lays the groundwork for future enhancements.

#ktistec #crystallang #activitypub #fediverse

It is said that there are only two hard things in computer science: cache invalidation and naming things. The story goes: you have something that is expensive to compute, so you compute it once and then you cache it and use the cached value in the future. But the inputs to that computation change, and so the cached value grows stale. You have to decide when and how to recompute that value.

In Ktistec, presenting accurate tag counts is expensive because not every tagged post counts. Posts are deleted, actors are blocked. My own drafts don't count, but when they're published they do. A post tagged with the same hashtag more than once, must count as one. And tag cardinality is not uniform: #3dprinting has hundreds of thousands of posts, others have one or two. Even with indexes, there is no single query that counts all cases in an acceptable amount of time.

So I reached for a cache, counted once and then cached the count. Because I didn't want to maintain adjustments from every place in the code that changed something that touched the count, I settled for eventual consistency and recomputed counts after every server restart.

As it turns out, that's not good enough. On a server with reasonable traffic, an event that affects some tag's count happens every few hours. Days or weeks later there is significant drift. Worse, the implementation didn't recompute on first read, it recomputed on first write (a new tagged object arrives).

This release fixes all that. Counts are still eventually consistent, but all counts are recomputed in a regular background task, so they really are eventually consistent, and care was taken in constructing the query to minimize database (read) locking to ~100-200msec.

Is it better? Yes! Is it perfect? Probably not. Cache invalidation is hard.

Here's the full changelog for this release:

Added

• Background task to reconcile tag statistics.

Fixed

• Prevent model hook callbacks from interleaving.
• Add spacing between content and the sticky footer.

Changed

• Replace Semantic UI with Fomantic UI.
• Cache the PURL and GoToSocial JSON-LD contexts.
• Reduce database lock time when reconciling tags.
• Block npm dependency install scripts.

Removed

• The unused idx_relationships_type database index.

In the next release, I'm going to fix a few bugs in the Mastodon-compatible API. These require an internal redesign, so I've held off until a few other things were out of the way. And I'm turning my attention to reading and better tools for surfacing and finding interesting content.

#ktistec #crystallang #activitypub #fediverse