Agent Audit Trail: A Standard Logging Format for Autonomous AI Systems

This document specifies a standard logging format for autonomous AI agent systems. The Agent Audit Trail (AAT) defines a JSON-based record structure with mandatory fields for agent identity, action classification, outcome tracking, and trust level reporting. Records are linked via tamper-evident hash chaining using SHA-256 per RFC 8785, with optional ECDSA signatures for non-repudiation. The format addresses requirements from the EU AI Act (Regulation 2024/1689), which mandates automatic recording of events for high-risk AI systems effective August 2026. It also maps to SOC 2 Trust Services Criteria, ISO/IEC 42001, and PCI DSS v4.0.1 logging requirements. The design is transport-agnostic and supports export to JSONL, Syslog (RFC 5424), and CSV while preserving chain integrity. Privacy is addressed through input/output hashing and tombstone- based deletion compatible with GDPR Article 17.