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Your Policy Is Secretly a Harness: The Decision Geometry of Agent Interfaces

Language model agents are post-trained and deployed through a harness, the prompts, tools, and control logic that present a task to the model and execute its outputs. Harnesses are often revised and j

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#24Peak rank
3Days on list
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Oct 28, 2026First seen

About this paper

Under KL-regularized control, a policy encodes its harness preferences, so deployed performance equals harness potential minus policy mismatch, and harness comparisons must separate these terms to predict training gains.

Language model agents are post-trained and deployed through a harness, the prompts, tools, and control logic that present a task to the model and execute its outputs. Harnesses are often revised and judged by how an already trained model performs under them, which assumes that what the model learned under one harness carries over to the next. We ask what a policy learns from its harness and what survives when the harness changes. Under KL-regularized control, we show that the log odds of an optimal policy recover how strongly its harness favors each action over the others, so a trained policy carries the preferences of its harness. Deployed return then equals the ceiling of the harness,…

KL-regularized controllog oddsoptimal policyharnessmismatchceilingMiniWoB++Terminal-Bench Lite
Upvotes
7
Authors
3
Published
Oct 27, 2026

Summary and abstract excerpt via Hugging Face Papers ↗ · arXiv.

Trending history

Your Policy Is Secretly a Harness: The Decision Geometry of Agent Interfaces was first seen on Hugging Face · Daily papers on Oct 28, 2026. Since then it has appeared in 18 checks on 3 different days. Its best position was #24 of 30, reached on Oct 30, 01:28 UTC. It dropped off the list after Oct 30, 03:28 UTC.

Rank history

Position on Hugging Face · Daily papers at every check (lower is better).

#1#11#20#30 07:2818:2805:2816:2803:28 Oct 28, 07:28 UTC · #30Oct 28, 11:28 UTC · #30Oct 28, 19:28 UTC · #30Oct 28, 21:28 UTC · #30Oct 28, 23:28 UTC · #30Oct 29, 01:28 UTC · #29Oct 29, 03:28 UTC · #29Oct 29, 05:28 UTC · #27Oct 29, 07:28 UTC · #28Oct 29, 09:28 UTC · #28Oct 29, 11:28 UTC · #29Oct 29, 15:28 UTC · #29Oct 29, 17:28 UTC · #29Oct 29, 19:28 UTC · #29Oct 29, 21:28 UTC · #28Oct 29, 23:28 UTC · #27Oct 30, 01:28 UTC · #24Oct 30, 03:28 UTC · #24

Last 14 days

Best rank per day (UTC).

Oct 26today

Metric history

Platform metric as reported by Hugging Face.

0257 07:2818:2805:2816:2803:28 Oct 28, 07:28 UTC · 5Oct 28, 11:28 UTC · 6Oct 28, 19:28 UTC · 6Oct 28, 21:28 UTC · 6Oct 28, 23:28 UTC · 6Oct 29, 01:28 UTC · 7Oct 29, 03:28 UTC · 7Oct 29, 05:28 UTC · 7Oct 29, 07:28 UTC · 7Oct 29, 09:28 UTC · 7Oct 29, 11:28 UTC · 7Oct 29, 15:28 UTC · 7Oct 29, 17:28 UTC · 7Oct 29, 19:28 UTC · 7Oct 29, 21:28 UTC · 7Oct 29, 23:28 UTC · 7Oct 30, 01:28 UTC · 7Oct 30, 03:28 UTC · 7

Questions

Is Your Policy Is Secretly a Harness: The Decision Geometry of Agent Interfaces trending on HF Daily Papers right now?

Not at the moment. It was last on the list on Oct 30, 03:28 UTC, after 3 days of trending.

What is the highest rank Your Policy Is Secretly a Harness: The Decision Geometry of Agent Interfaces reached?

#24 on Hugging Face · Daily papers, on Oct 30, 01:28 UTC. Trendoday checks this list every 120 minutes.

How long has Your Policy Is Secretly a Harness: The Decision Geometry of Agent Interfaces been trending?

It was first seen on Oct 28, 2026 and has been on the list on 3 days (18 checks) since.