An AI agent audit trail you can actually prove.
Application logs tell you what an agent supposedly did — and anyone with write access can change them. a2a cloud gives every agent run an Ed25519-signed, hash-chained receipt: inputs, outputs, tool calls, cost, caller identity, and the scoped grant that authorized it. Not a log you can argue with. Evidence you can verify.
tamper-evident · hash-chained · replayable
Your audit trail is not evidence until it's verifiable.
Most 'agent audit trails' are application logs: a stream of text the agent's own process writes, stored somewhere it — or an attacker — can edit or delete. When a regulator, a customer, or an incident review asks what the agent did and under whose authority, mutable logs don't answer it. You're asking them to trust the record kept by the party being audited.
Every run, signed and chained into an evidence trail.
A receipt is a first-class primitive on a2a cloud, not a logging add-on. It ties who called, what authority they held, what the agent did, and what it produced into one signed artifact.
Signed, not logged
Every run returns an Ed25519-signed receipt. The signature covers inputs, outputs, tool calls, cost, caller identity, and grants — tamper-evident by construction, not by policy.
Hash-chained
Receipts chain by hash, so a deleted or edited entry breaks the chain. You can prove the record is complete, not just present.
Caller + authority bound
Each receipt records who called, under which scoped grant, with what audience and TTL. It answers 'was it the user, the agent, or the agent acting for the user?'
Replayable
Deterministic re-execution from the receipt: same inputs, same grants, same outputs. Evidence you can re-run, not just read.
Per-tool-call cost
Cost and elapsed time are captured per tool call and attributed to the caller — spend you can audit down to the individual action.
Verifiable outside the process
A receipt is verified by a party outside the agent runtime. Your auditor checks the signature — they don't have to trust the process that produced it.
Mutable logs vs. signed receipts.
Frequently asked.
What is an AI agent audit trail?
A record of what an autonomous agent did — its inputs, tool calls, outputs, cost, and the identity and authority behind each action. On a2a cloud, that trail is a chain of cryptographically signed receipts rather than mutable application logs, so it stands up as evidence.
How is a signed receipt different from a log?
A log is a line of text an application writes and can later edit or delete. A receipt is an Ed25519-signed, hash-chained record of a run. The signature and chain make tampering detectable, and the receipt binds the caller, the scoped grant, and the result together.
Can I prove what an AI agent actually did?
Yes. Each run produces a signed receipt covering inputs, outputs, tool calls, cost, caller identity, and the grant that authorized it. Because receipts are signed and hash-chained, a third party can verify the record independently and detect any alteration or deletion.
Does this help with SOC 2 and the EU AI Act?
Signed receipts give auditors append-only, retained, per-decision evidence — the kind SOC 2 controls and EU AI Act Article 12 record-keeping ask for. a2a cloud also exposes decision records and enforces a retention floor. See the compliance page for details.
What does non-repudiation mean for agents?
Non-repudiation means an actor cannot credibly deny having performed an action. Because each agent action is signed with a per-agent key and chained, the receipt is proof the run happened as recorded — the agent (or its operator) cannot later disown it.
Trust the receipt.
a2a cloud deploys any agent — LangGraph, OpenAI Agents SDK, CrewAI, or custom — and ships it with a managed Postgres database, an MCP server, an API, a frontend, and an Ed25519-signed receipt for every run. Scoped grants, no ambient production access. One deploy, the whole agent app, with proof.