ResearchResearch paperSafety & Alignment · Reinforcement Learning · Agents & Tool Use1 source · Oct 17, 2026

Write Once, Check Many: Reusable Ledgers for Post-Hoc Policy Compliance Auditing of Agent Trajectories

We propose write once, check many, a framework in which a writer model converts each agent trajectory into a policy-independent ledger of the agent's actions and outcomes.

Key points

  • Auditing LLM agents against policies is critical to ensure safety but requires rereading long trajectories once per policy.
  • Can we instead record each trajectory once and reuse that record for policies not known in advance?
  • On 900 trajectories from SHADE-Arena, $τ$-bench, and $τ^2$-bench, we show that a 12B reader of narrative ledgers can either match or in fact achieve higher AUC than the same 12B model reading full trajectories.
  • Our results suggest that reusable, policy-independent records can make retrospective agent auditing more efficient and effective, and highlight important considerations in ledger design.

Sources (1)

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