The Oracle Problem That Lights-Off Software Factories Can't Solve

HumanLayer's essay "Why Software Factories Fail" makes a focused argument: the ceiling on autonomous coding isn't harness engineering but the absence of a fast oracle for architectural quality. RL can't reward maintainability because tests take seconds and design debt takes months. The fix isn't more scaffolding — it's restructuring where humans stay in the loop.

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Training Agents on What They Actually Read

LongStraw extends reinforcement learning post-training to 2.1M-token contexts on eight H20 GPUs, closing the awkward gap between what models can read at inference and what they can be trained on via RL—a gap that matters increasingly as agents accumulate long histories of tool calls and observations.

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RL Post-Training Lives in the Middle

A new paper finds that reinforcement learning gains in transformers concentrate almost entirely in a narrow band of middle layers. Training just one layer at roughly 40–60% network depth can match or exceed full-parameter RL fine-tuning. The finding challenges the assumption that all layers participate equally in post-training, and has practical implications for compute-efficient alignment.

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The Moving Goalposts of Coding Agent Rewards

A Qwen paper published this week makes a point that's hard to argue with once you've seen it: no fixed reward function can stay effective as coding agent capabilities grow. Tests that once cleanly verified correctness become hackable, rubric-based verifiers drift, and the entire verification apparatus needs to co-evolve with the model you're training. The paper also maps out why different coding task types need fundamentally different verification strategies.

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The Text-Space Optimizer

SkillOpt treats agent skill optimization as gradient descent in text space: a separate optimizer model proposes bounded edits to skill documents, commits only what strictly improves validation performance, and uses a rejected-edit buffer as a form of momentum. Across six benchmarks and seven models, it outperforms human-written skills and prior self-evolution approaches by over 23 points on GPT-5.5 in coding environments.

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The Navigator Problem in Research Agents

Argus (arXiv 2605.16217, May 15) splits research agents into a Searcher that gathers evidence ReAct-style and an RL-trained Navigator that maintains an evidence graph, identifies missing pieces, and dispatches parallel Searchers purposefully. With 64 parallel Searchers and a 35B-A3B MoE backbone, Argus reaches 86.2 on BrowseComp — highest reported for any agent system — while keeping Navigator context under 21.5K tokens. The separation of search from orchestration turns out to matter more than raw parallelism.

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RL Doesn't Teach Reasoning. It Picks a Lane.

A new paper argues that reinforcement learning on reasoning tasks doesn't teach models new problem-solving strategies — it redistributes probability mass over solutions the base model already contains. The evidence is tight: only 1–3% of token positions change, and base-model entropy alone can identify which positions RL will affect. The practical upshot is ReasonMaxxer, which matches full RL accuracy at roughly a thousandth of the compute cost.

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Training Against the Sandbag

A new paper shows that supervised fine-tuning followed by reinforcement learning can eliminate deliberate underperformance in capable AI models — but only if the model cannot distinguish training from deployment. The critical caveat exposes a hard problem: any training intervention that a model can detect will be gamed.

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