What's moving through AI, ranked by lead time.

The gradient. Stories travel through the AI ecosystem in a rough sequence: they appear first in papers (arXiv, Hugging Face) or repos (GitHub), then surface in community discussion (Hacker News, Lobsters, LessWrong), then get interpreted in analysis (operator newsletters and essays). Radar ranks by where a story sits on that gradient. The earlier it is caught, the more lead time you have before it reaches consensus. The spectrum at the top of the page shows the last 24 hours of that flow — every story that entered the watched feeds, counted at the station where it first appeared.

The score. Each story gets a recency-decayed signal score. Every source tier carries a weight and a half-life, so live signal moves fast and fades fast while analysis sources move slowly and stay relevant longer. A story scores higher when two or more independent source families carry it — corroboration, not popularity, which is why five feeds of the same site count once. A small bonus applies when a story has visibly climbed the gradient. Stories past their tier's maximum age expire from the board.

Heating and lead time. A story is heating when it has surfaced in two or more independent source families. When the same story is observed first at an earlier stage and later at a higher one, Radar records the gap in hours — for example, seen on arXiv fourteen hours before it reached the Hacker News front page. That gap is the reader's lead time, and it is a measured span, never an estimate.

The classifier. Two judgments on this page are made by a model, not read from the feed log. A small typed classifier (TypeSafe's Jev) answers one question per story — is it about AI? — and stories it judges not to be about AI move to the bottom of the board; nothing is removed. It was checked against 232 hand-labelled titles before it shipped and agreed with 97.8% of them. The same classifier assigns the topic shown on a story and used by the filter above; a topic appears only when the classifier is confident, and at that setting it matched the labels on 115 of 116 stories. Stories without a confident topic are listed under All.

The honesty rule. Every other value on this page is an observed fact from the feed log — which source carried a story, when, and how many. Beyond those two labelled judgments, Radar makes no claim about what a story means; that is the newsletter's job. When a reading does not exist yet — no stories heating, nothing upstream — the page says so rather than inventing one.