SKILL.state: Scalable Long-Horizon Agent Skills

Sanket Badhe, Priyanka Tiwari, Jonghyun Chung


Abstract
Large Language Models (LLMs) increasingly act as autonomous agents executing complex, long-running procedural skills. Existing agent runtimes maintain execution by continually appending observations, actions, and intermediate reasoning traces to an ever-growing conversation history, causing latency degradation and context-poisoning failures over long horizons. We present SKILL.state, a runtime architecture that replaces append-only conversational history with an explicit, mutable execution state. At each execution step, the model receives only the immutable skill specification, the current structured execution state, and the latest observation. Intermediate reasoning is discarded immediately after producing a validated state update, preventing prompt growth with execution history. Across diverse datasets, models, and execution environments, SKILL.state improves task accuracy while substantially reducing cumulative token consumption. Our results demonstrate that explicit execution state is an effective and architecture-agnostic abstraction for scalable long-horizon agent skills.
Anthology ID:
2026.emnlp-industry.264
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
4434–4449
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.264/
DOI:
Bibkey:
Cite (ACL):
Sanket Badhe, Priyanka Tiwari, and Jonghyun Chung. 2026. SKILL.state: Scalable Long-Horizon Agent Skills. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 4434–4449, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SKILL.state: Scalable Long-Horizon Agent Skills (Badhe et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-industry.264.pdf