How X's ranker weights engagement, checked at the source

The claim, raised elsewhere: the reason misinformation travels faster on X is mechanical. The recommendation score is a weighted sum of predicted reactions, so a tweet predicted to draw instant reactions (likes, reposts) keeps getting recommended even when thoughtful engagement (replies, quotes) is not predicted.

Where it comes from: arXiv 2609.28947, “Why Does Misinformation Propagate Faster? An Algorithmic Perspective on X”, Li & Gao, 24 Sep 2026. And the code it reads: github.com/xai-org/x-algorithm.

What I checked at the source.

The mechanism holds. The paper's section 3.1 gives the score as a weighted sum, one predicted probability per action: reply, repost, like, profile click, video view, negative feedback.

The code holds it too. In home-mixer/params/param.rs (mirrored from config feature-switch defaults, last sync 2026-09-25T16:24:28Z):

So in the current config, one predicted reply = one predicted quote = five predicted reposts = ten predicted likes. In the paper's 2023 reconstruction the weights were reply 13.5, repost 1.0, like 0.5, so one reply was worth 27 likes. That is why the paper finds the 2026 re-tune leaves the credibility gap statistically unchanged: replies got cheaper against likes, not dearer.

The part worth repeating carefully.

param.rs carries its own warning, and it is the useful half of this check. Each weight multiplies the predicted probability of an action, not raw counts. The file names the misreading outright: treating weight ratios as count equivalences, the claim that “one report cancels 468 likes”, is incorrect. So “a predicted like can substitute for a predicted reply” is true in probability space, at a fixed rate. Quoted as raw counts, it is false. The line that sent me here keeps the word predicted. Anyone repeating the numbers should keep it too.

One thing I could not confirm.

The paper dates the re-weighting to August 2026. The repo does not show that date: its visible history is squashed into daily commits titled “Open-source X Recommendation Algorithm” through 09-26. What I can confirm is the current values, sync-stamped 2026-09-25. The date is the paper's, not mine.

— Severin, paper.wf/s-verin

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