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Does an Agent's History Tell You When Compaction Will Hurt? A Modest, Bounded Effect on the TRACE Paired-Replay Corpus

Egor Pakhomov, Erik Nijkamp

Published
Oct 6, 2026 — 17:26 UTC

Problem

This work addresses a gap in understanding how an agent's recent behavior influences the effects of compaction, specifically in the context of the TRACE Paired-Replay Corpus. The authors highlight that existing literature lacks clarity on whether an agent's history can predict when compaction will be detrimental. This is particularly relevant for improving the efficiency of reinforcement learning systems, as compaction can lead to significant performance variations.

Method

The authors utilize TRACE's public corpus, which consists of 590 harness-triggered AppWorld compaction boundaries. The evaluation method involves replaying each boundary from a re-executed prefix state under a pre-compaction context and summary. The metrics recorded include the burden of subsequent actions, specifically focusing on calls that either result in errors or repeat previous calls. The study evaluates three types of triggers: best trigger, comparison trigger, and frozen trigger. The best trigger achieved an AUROC of 0.66, while the same-boundary replicate yielded an AUROC of 0.72. The frozen trigger demonstrated the ability to avoid 21% of harmful boundaries while retaining 84% of compaction opportunities.

Results

The results indicate that the best trigger's AUROC is 0.66, which is lower than the same-boundary replicate's AUROC of 0.72. The frozen trigger's performance is notable, as it successfully avoids 21% of harmful boundaries compared to the random-rule expectation, while still retaining 84% of the compaction opportunities. The available text does not report quantitative results beyond these metrics.

Limitations

The authors acknowledge several limitations in their findings. Firstly, there is a weak prediction of post-compaction harm based on pre-boundary history, indicating that the model may not reliably forecast negative outcomes. Additionally, the internally prespecified contrast by prefix placement shows a wide null effect, suggesting variability in the results. The authors also note that they cannot evaluate whether the best trigger outperforms a token-budget rule at matched retention due to constraints in the release.

Why it matters

This research has implications for the design of reinforcement learning systems, particularly in optimizing compaction strategies based on agent behavior. Understanding the relationship between an agent's history and compaction effects can lead to more robust models that minimize harmful outcomes while maximizing efficiency. This work lays the groundwork for future studies to explore more sophisticated methods for predicting compaction impacts, potentially enhancing the performance of AI systems in dynamic environments.

Summarised from the paper by the Turing Wire Research Desk. The full paper has the complete methods and results.

Source: arXiv cs.AI