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Main Authors: Yu, Ye, Yuan, Xiaopeng, Jin, Haibo, Liu, Heming, Yu, Yaoning, Wang, Haohan
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.09315
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author Yu, Ye
Yuan, Xiaopeng
Jin, Haibo
Liu, Heming
Yu, Yaoning
Wang, Haohan
author_facet Yu, Ye
Yuan, Xiaopeng
Jin, Haibo
Liu, Heming
Yu, Yaoning
Wang, Haohan
contents Recent advances in LLM agents enable systems that autonomously refine workflows, accumulate reusable skills, self-train their underlying models, and maintain persistent memory. However, we show that such self-evolution is often non-monotonic: adapting to new task distributions can progressively degrade previously acquired capabilities across all major evolution channels. We identify this phenomenon as \emph{capability erosion under self-evolution} and show that it consistently emerges across workflow, skill, model, and memory evolution. To mitigate this issue, we propose \emph{Capability-Preserving Evolution} (CPE), a general stabilization principle that constrains destructive capability drift during continual adaptation. Across all four evolution dimensions, CPE consistently improves retained capability stability while preserving adaptation performance. For example, in workflow evolution, CPE improves retained simple-task performance from 41.8\% to 52.8\% under GPT-5.1 optimization while simultaneously achieving stronger complex-task adaptation. Our findings suggest that stable long-horizon self-evolving agents require not only acquiring new capabilities, but also explicitly preserving previously learned ones during continual adaptation.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09315
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Do Self-Evolving Agents Forget? Capability Degradation and Preservation in Lifelong LLM Agent Adaptation
Yu, Ye
Yuan, Xiaopeng
Jin, Haibo
Liu, Heming
Yu, Yaoning
Wang, Haohan
Artificial Intelligence
Computation and Language
Recent advances in LLM agents enable systems that autonomously refine workflows, accumulate reusable skills, self-train their underlying models, and maintain persistent memory. However, we show that such self-evolution is often non-monotonic: adapting to new task distributions can progressively degrade previously acquired capabilities across all major evolution channels. We identify this phenomenon as \emph{capability erosion under self-evolution} and show that it consistently emerges across workflow, skill, model, and memory evolution. To mitigate this issue, we propose \emph{Capability-Preserving Evolution} (CPE), a general stabilization principle that constrains destructive capability drift during continual adaptation. Across all four evolution dimensions, CPE consistently improves retained capability stability while preserving adaptation performance. For example, in workflow evolution, CPE improves retained simple-task performance from 41.8\% to 52.8\% under GPT-5.1 optimization while simultaneously achieving stronger complex-task adaptation. Our findings suggest that stable long-horizon self-evolving agents require not only acquiring new capabilities, but also explicitly preserving previously learned ones during continual adaptation.
title Do Self-Evolving Agents Forget? Capability Degradation and Preservation in Lifelong LLM Agent Adaptation
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2605.09315