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Opera: A Verbal Critic Framework for Long-horizon Coding Agents

Long-horizon coding agents need timely corrections, yet feedback can be ineffective or even harmful when it misjudges ongoing work or fails to address the underlying problem.

By Mei, Hu, Dai +7arXiv

Score████░░░░░░4.2

Caveats

  • Preprint; not yet peer reviewed.

VerdictWorth a reader's time today.

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Abstract

Long-horizon coding agents need timely corrections, yet feedback can be ineffective or even harmful when it misjudges ongoing work or fails to address the underlying problem. Existing critics focus on evaluating trajectories and generating feedback, but rarely track what happens after feedback is delivered. We present Opera, a verbal critic framework that treats each correction as a persistent note, followed until the diagnosed problem is resolved. Opera decides when to review through periodic and event-driven triggers, diagnoses issues with typed operators, audits feedback against visible evidence before delivery, and tracks the agent's subsequent actions to distinguish mere compliance from actual resolution. As a test-time critic, Opera improves the resolve rate of non-critic agents by up to 12.4, 15.0, and 8.9 percentage points on Terminal-Bench 2.1, a SWE-Bench Pro subset, and DeepSWE v1.1, respectively, across four policy models, and achieves the highest mean resolve rate among competitive critic baselines on all three benchmarks, and also improves policy models when the policy critiques itself. Beyond inference, Opera-guided rollouts provide approximately on-policy training data: fine-tuning Qwen3.5-9B on them improves its resolve rate on held-out SWE-Bench Pro repositories by 10.2 percentage points without a critic at inference time, matching fine-tuning on rollouts from a stronger model, while preserving its performance when switching harness, i.e., from Openhands to Terminus-2, which the latter substantially degrades. Our code is available at: https://github.com/dongyuanjushi/Opera.

Kai Mei, Zhiyuan Hu, Yutong Dai, Juntao Tan, Yifan Zhang, Dingjie Song, Dimitris N. Metaxas, Silvio Savarese, Ran Xu, Zeyuan Chen

The editor's rubric

Heuristic review

DimensionLevelWeightWhat that level means
Leverage████░ 424%A general-purpose tool used across several fields (Adam, ResNet, LoRA, next-generation sequencing).
Magnitude██░░░ 218%Solid incremental gain on a meaningful problem.
Evidence███░░ 314%Solid: multiple benchmarks or cohorts, ablations, fair baselines, released code or data.
Novelty██░░░ 216%A new combination of known ideas.
Trajectory██░░░ 218%Some room to improve with obvious engineering.
Stakes██░░░ 210%Benefits a professional community (practitioners, clinicians, engineers).

Editor’s rationale

Heuristic triage from title and abstract text only, not a reading of the paper. Cues found: method (we propose); breadth (many tasks); verification (multiple benchmarks, held-out test, code released); stakes (general AI).

How the score was computed

rank-2026-10-07

Score████░░░░░░4.2

Score = 10 × (65% × adjusted merit / 10 + 25% × attention + 10% × freshness)

Merit
5.2 / 10
Weighted rubric, evidence-gated.
Adjusted merit
4.5 / 10
Shrunk toward the desk prior by editor confidence (40%).
Attention
40%
Citations, upvotes, points, mentions.
Freshness
32%
Half-life decay since publication.
  • Citations0 (reference 15, via semantic-scholar, Oct 10, 2026, 02:05 UTC)
  • Influential citations0 (reference 3, via semantic-scholar, Oct 10, 2026, 02:05 UTC)
  • Hugging Face upvotes14 (reference 25, via hf-daily, Oct 11, 2026, 13:49 UTC)
  • GitHub stars7 (reference 250, via hf-daily, Oct 11, 2026, 13:49 UTC)

The record

  • Reviewed by heuristic-v6 on Oct 11, 2026, 02:05 UTC. Paper type: method.
  • BRIEF, No.10 in the Artificial Intelligence edition of October 12, 2026.