hope everyone is having a good day

New #1 on PostTrainBench: Opus 4.8 (max reasoning) hits 37.23% — up from 28.56% for 4.7, the largest single improvement we've seen. Fable 5 runs underway now that AI research behavior is no longer silently degraded. PostTrainBench asks how well frontier AI can train weaker language models. That makes it one of the first benchmarks for recursive self-improvement: AI improving AI, with progress measured in the loop itself.

Model shaping is still a craft of a few. That's what AI agents are for: learning it and doing it for everyone else. As a part of FrontierSWE benchmark we built a 20-hour post-training task on @tinkerapi and found the real bottleneck is research intuition.

claude fable 5 is live. spawn 5.0 was built with it: 1,687 prompts, 102 sessions, my job shifted from architecture to judging taste. what we built, each of which would've been at least a month with a whole team on opus: — a from-scratch physics engine (mantle) that rivals rapier, testable in a day as a side thread — clustered froxel lighting: 8 lights to 1,000 fully dynamic ("it's stupid fast" — creator of threejs) — realtime diffuse GI on webgpu, on your phone (landing in the next update) — million-particle gpu vfx with a shader architecture beyond what unreal and unity ship — mmo-scale netcode plus, for good measure: an (alpha) native ios app. all of it in about a week. all of it running on mobile. and the list doesn't include half of what we shipped — full changelog in the thread below. and the part the benchmarks won't show you: this model has a wonderful personality. it's genuinely funny. i laughed so hard i cried multiple times, mid-physics-rewrite. the genius and the character aren't separate features.

Gotta love that "6.3.6 Decision theory evaluation" is right before "6.3.7 Overeager behavior in GUI computer use" in the Fable/Mythos system card. Dizzying sci-fi rationalist vibes next to prosaic bad-for-market-share failures. (they're both quite sci-fi to be fair)

this is absolutely incredible.

DELTARUNE Chapter 5!!! Comes out in a little less than 15 days!!!

In medieval times, within the arms race of ever more demonic torture devices, some sadistic genius came up with the idea of the Little Ease. This was a prison cell built so small in every dimension that a grown man could not stand upright in it nor lie down at full length nor properly sit. The pain is relentless and without relief and inflicted by one's own body. Prisoners were known to go insane within a few days. A stay at the Little Ease was considered even more cruel than the rack, the thumbscrew, and the other ghoulish machinery of the Tower of London. A breeding pig will spend her whole life in a version of that box. These are social, roaming creatures (more intelligent than dogs) who will never leave this corset of steel. They have been selectively bred to be bigger than their frames can support. Yet we put them in cells so confined that they cannot comfortably sit, and their attempts to do so (for example, by sneaking their limbs into adjacent stalls) reliably lead to fractures and sprains. They cannot sweat, yet have nothing to roll around in to cool themselves off. Except their own manure, which (contrary to the common misconception) they are so averse to (thanks to their strong sense of smell) that new sows will often suffer from constipation to avoid soiling the space from which they eat and sleep. Here is how the writer Matthew Scully described what saw at one of Smithfield’s “gestation barn”: > “Sores, tumors, ulcers, pus pockets, lesions, cysts, bruises, torn ears, swollen legs everywhere. Roaring, groaning, tail biting, fighting, and other “Vices,” as they’re called in the industry. Frenzied chewing on bars and chains, stereotypical “vacuum” chewing on nothing at all, stereotypical rooting and nest building with imaginary straw. And “social defeat,” lots of it, in every third or fourth stall some completely broken being you know is alive only because she blinks and stares up at you … creatures beyond the power of pity to help or indifference to make more miserable, dead to the world except as heaps of flesh into which the [insemination] rod may be stuck once more and more flesh reproduced.” — The Save Our Bacon Act is trying to unroll the few state protections we have against this barbaric cruelty - for example California’s Prop 12 - which banned the sale of pork from pigs kept in gestation crates. It’s incredibly important we don’t end up with this sort of federal preemption. SOB will not only kill the most important animal welfare related laws in the US of the past decade, but more importantly, it will also restrict ALL future legislative progress (aka how the animal welfare movement has gotten its biggest wins). The Senate is currently deciding whether to add the SOB Act to the Farm Bill. With relatively little money now, we can discourage the most pivotal senators in the Ag committee from backing this amendment. Defeating this bill is even more important given the amount of philanthropic funding I expect to come online in the next year or two. It will plausibly be over 10x more expensive to repeal SOB than to prevent it from passing in the first place. All that money that could be spent transforming our society's relationship to mass animal suffering will instead have to be spent just getting us back to where we are right now. That's why money spent now fighting this bill (and I mean right NOW) is so effective. If you’re in a position to donate six figures, please DM me.

Anthropic Urges Global Pause in AI Development, Flags ‘Self-Improvement’ Risk on.wsj.com/4o5IBpe