SkillEvolBench: Benchmarking the Evolution from Episodic Experience to Procedural Skills

AuthorsYingtie Lei, Zhongwei Wan, Jiankun Zhang et al.

arXiv 20262026

TL;DR

SkillEvolBench uses frozen skill libraries plus Raw-Trajectory controls to show a lossy abstraction bottleneck where distilled skills often trail raw episodic reuse on ESR 37.6% vs 44.7% ARSR.

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THE PROBLEM

Agents reuse episodes but fail to form reusable skills

SkillEvolBench shows that Raw-Trajectory achieves mean ESR 37.6% and ARSR 44.7%, while distilled skills frequently underperform on these deployment metrics.

This means episodic agent work in realistic environments becomes brittle task-local memory instead of durable procedural skills, breaking robustness under context shift and composition.

HOW IT WORKS

SkillEvolBench — episodic trajectories to frozen procedural skills

SkillEvolBench connects Episodic Task Attempts, Structured Verifier Feedback, Skill Author, and an Environment-specific Shared Skill Library to evolve skills before frozen deployment.

You can think of SkillEvolBench like a software team’s playbook: noisy incident logs are periodically distilled into reusable runbooks instead of replaying old chat transcripts.

This design lets SkillEvolBench test selective procedural abstraction that a plain context window or naive trajectory replay cannot, especially under adversarial shortcuts and multi-skill composition.

DIAGRAM

SkillEvolBench role progression within a task family

This diagram shows how SkillEvolBench moves a family through canonical, enriched, variant, context-shift, adversarial, and composition roles.

DIAGRAM

SkillEvolBench evaluation protocol across environments

This diagram shows how SkillEvolBench initializes libraries, runs acquisition, freezes skills, evaluates deployment, replays, and then resets per environment.

PROCESS

How SkillEvolBench Handles a Skill Evolution Episode

  1. 01

    Initialization and Skill Conditions

    SkillEvolBench sets Sc(e, f) for each environment and family, choosing between experience-based self-generated, zero-shot, or gap-exposed curated skills.

  2. 02

    Acquisition From Episodic Evidence to Skill Updates

    SkillEvolBench runs canonical, enriched, and variant roles, compacts trajectories into ˜τ and pairs them with Structured Verifier Feedback vr for the Skill Author.

  3. 03

    Frozen Deployment and Replay

    SkillEvolBench freezes the Environment-specific Shared Skill Library, then measures ESR, CSSR, ARSR, and CompSR plus replay LSR and RSR without further updates.

  4. 04

    Capacity Diagnostic With Tier-3 Forcing

    SkillEvolBench activates Always+Tier3, forcing new scripts, references, or assets per revision to test whether larger libraries improve frozen deployment.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    SkillEvolBench benchmark design

    SkillEvolBench introduces 180 tasks across six environments and five task families each, with role-conditioned arcs and an Environment-specific Shared Skill Library plus Skill Author loop.

  • 02

    Procedural vs episodic reuse analysis

    SkillEvolBench contrasts curated and self-generated skills against No-Skill and Raw-Trajectory, showing Raw-Trajectory mean ESR 37.6% and ARSR 44.7% as strong baselines.

  • 03

    Capacity and cost diagnostics

    SkillEvolBench uses Always and Always+Tier3 policies to show that larger skill libraries often add cost without improving ESR, revealing procedural clutter and episode-specific drift.

RESULTS

By the Numbers

RSR

48.2%

+? vs No-Skill (Raw-Trajectory strongest replay baseline)

ESR

37.6%

Raw-Trajectory deployment success across models and harnesses

ARSR

44.7%

Raw-Trajectory adversarial robustness under frozen deployment

CompSR

25.7%

Raw-Trajectory composition success vs skill-based conditions

SkillEvolBench evaluates across 180 tasks and six environments, decomposing deployment into ESR, CSSR, ARSR, and CompSR. The MAIN_RESULT shows Raw-Trajectory dominates many skill variants on ESR 37.6%, ARSR 44.7%, and CompSR 25.7%, revealing a lossy abstraction bottleneck.

BENCHMARK

By the Numbers

SkillEvolBench evaluates across 180 tasks and six environments, decomposing deployment into ESR, CSSR, ARSR, and CompSR. The MAIN_RESULT shows Raw-Trajectory dominates many skill variants on ESR 37.6%, ARSR 44.7%, and CompSR 25.7%, revealing a lossy abstraction bottleneck.

BENCHMARK

Mean deployment success by memory baseline

ESR across SkillEvolBench for Raw-Trajectory and representative skill variants.

KEY INSIGHT

The Counterintuitive Finding

SkillEvolBench finds Raw-Trajectory achieves mean ESR 37.6% and ARSR 44.7%, while many distilled skill variants score lower on these deployment metrics.

This is surprising because curated and self-generated skills were expected to compress and improve episodic evidence, yet SkillEvolBench shows abstraction often discards useful contextual and procedural cues.

WHY IT MATTERS

What this unlocks for the field

SkillEvolBench gives researchers a controlled way to measure when episodic experience becomes durable procedural knowledge instead of task-local patches.

With SkillEvolBench, builders can systematically stress-test new skill authoring, retrieval, and capacity strategies under context shift, adversarial shortcuts, and multi-skill composition before deploying agentic systems.

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