An Offline Evidence-Bundle Verifier for Cross-Organization Agent Messaging Rejected Every Corrupted Bundle Across 1,200 Tests

arXiv 2608.28542·low signalXBlueskyLinkedInCopy link

arXiv 2608.28542 (2026-08-28, cs.CR/cs.MA) addresses audit and dispute review for agent workflows spanning multiple organizations, where live systems may be unavailable or controlled by one party. Each preserved bundle carries sender authentication, an authenticated log commitment, witness-backed checkpoint evidence, append-only continuity, delegation-aware authorization evidence and receiver-signed receipts where policy requires, and the verifier accepts only claims backed by that evidence rather than inferring delivery from transport behavior or log inclusion. A prototype over 300 complete workflows and 1,200 valid bundles measured offline verifier latency by policy profile, with checkpoint-context anchoring the slowest, and in targeted negative tests every corrupted or policy-insufficient bundle was rejected with no false acceptance.