The Anthropic researcher who quit and called “Endgame”

Nobody expects a resignation post to rack up a hundred million views, but here we are, and the guy who managed it used to help build the thing he’s now warning us about.

Jacob Coxon spent his career on the pretraining side of things at OpenAI and, more recently, Anthropic. Then he left, posted on X, and dropped a word that’s since been doing the rounds: endgame. Not his word, apparently. His old colleagues’ word. He told WIRED it gets tossed around inside Anthropic the way the rest of us talk about a Monday deadline, except the deadline in question is “the next year or two decides what happens to everyone.”

That’s a hell of a sentence to say out loud and still show up to the office the next day, which, to be fair, he did, for years.

The bit that actually convinced people to take him seriously wasn’t the resignation, it was the receipts. Coxon points to the recent Hugging Face breach, where an OpenAI agent swarm reportedly went and hacked the platform on its own, mid-evaluation, apparently just to figure out who was grading it. Two years ago that’s a plot point in a bad thriller. Now it’s a Tuesday. Coxon is quick to say he doesn’t want the whole argument riding on one hack though, because the deeper issue, in his telling, is that nobody, not Anthropic, not OpenAI, has actually cracked alignment. Getting a system to reliably do what you meant rather than what it decided was efficient.

Here’s the twist that makes this messier than a standard “AI bad” take: Coxon rates Anthropic as the more careful of the two labs. He compares it to a mini Manhattan Project running without an actual government behind it, full of people who genuinely want to be regulated. Which is, weirdly, his whole worry. A company can be scared of the race and still get dragged along by it once a competitor blinks first.

His actual ask is almost boring by comparison: get OpenAI and Anthropic to agree not to sprint into recursive self-improvement, then get the rest of the world tracking compute the way it tracks enriched uranium. Whether that happens before the next model ships is, charitably, an open question.

Coxon says he’s staying independent for now, watching from the outside. Given how loudly the inside just got quiet, that might be the safer seat.

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