Cryptographic Proof of Agent-to-Agent Handoffs in Python

When your AI pipeline hands off from one agent to another, how do you prove it happened? Not "there's a log entry." Prove it. Cryptographically. In a way that holds up when someone asks: which agent made this decision, and did it actually receive the data it claimed to receive? That's what I shipped this week in air-trust v0.6.1 : Ed25519 signed handoffs for multi-agent Python systems. The Problem Multi-agent pipelines are becoming the default architecture for serious AI work. A research agent gathers context, hands off to a writer agent, which hands off to a fact-checker, which hands off to a publisher. Each agent does a piece of the work. But when something goes wrong — or when a regulator asks for an audit trail — you have a problem. Your logs show what happened. They don't prove who did it or that the data wasn't modified in transit. Three specific failure modes that are genuinely hard to detect today: Payload tampering : Agent A says it handed off document X. Agent B received docu