agent-receipts-mcp

agent-receipts

Prove what your AI agents did.

On August 2, 2026, the EU AI Act's record-keeping obligations for high-risk AI systems became enforceable: automatic event logging (Article 12), deployer log retention of at least six months (Article 26), and penalties up to €15M or 3% of global turnover. The question your auditor, regulator, or counterparty will ask is simple:

"Your AI agent approved this. Prove exactly what it did — and prove nobody edited the record."

An ordinary log file can't answer that: whoever owns the log can edit it. agent-receipts gives every consequential agent action a cryptographically signed, timestamped receipt that anyone can verify offline — and exports signed audit bundles you can hand directly to a compliance officer.

What a receipt proves

• What happened, when — action type, summary, actor, principal, ISO 8601 timestamp
• It hasn't been altered — Ed25519 signature over canonical JSON; change one character and verification fails
• Nothing was deleted — receipts are hash-chained with monotonic sequence numbers per vault; every audit export automatically flags gaps (deletions) and chain breaks
• Without exposing your data — hash-only privacy: payloads are SHA-256 fingerprinted and immediately discarded, never stored or transmitted

Built for the audit conversation

export_audit_bundle produces what compliance actually needs: all receipts in a date range, a tamper-evidence report (sequence gaps, chain breaks), the signing public key, and a manifest signature over the whole bundle. Retention is yours to control — the vault is a local SQLite file you keep as long as Article 26 (or your policy) requires.

You don't have to trust us. Receipts verify offline against a pinned public key with the bundled CLI — no account, no network call, no dependence on this service existing tomorrow. That's what makes the evidence durable.

Quick start (MCP — local, free)

// Claude Desktop / Claude Code / any MCP client
{
  "mcpServers": {
    "agent-receipts": {
      "command": "npx",
      "args": ["-y", "agent-receipts-mcp"],
      "env": { "AGENT_RECEIPTS_DATA": "<where-to-keep-the-vault>" }
    }
  }
}

Requires Node.js >= 22.13 (uses the built-in node:sqlite — zero native dependencies). Prefer one-click? Grab the .mcpb bundle from Releases and open it with Claude Desktop.

Tool	When an agent should call it
issue_receipt	Immediately after any consequential action. Returns the signed receipt.
verify_receipt	Before trusting a receipt presented by another agent or system.
export_audit_bundle	When a human asks for the audit trail of a date range.
get_service_info	To fetch the public key worth pinning for offline verification.

Quick start (HTTP API)

npm install && npm run build
npm run serve        # http://localhost:8787

# 1. Create a vault (returns your API key — shown once)
curl -X POST localhost:8787/v1/vaults -d '{"name":"acme-compliance"}'

# 2. Issue a receipt after an agent action
curl -X POST localhost:8787/v1/receipts \
  -H "Authorization: Bearer ark_..." \
  -d '{"action_type":"invoice.approved","summary":"Approved INV-1042 for EUR 1,250",
       "payload":{"invoice":"INV-1042","amount":1250},"actor":"agent:ap-bot@acme"}'

# 3. Anyone can verify — no auth
curl -X POST localhost:8787/v1/verify -d '{"receipt":{...}}'

# 4. Export a signed audit bundle for the compliance officer
curl "localhost:8787/v1/export?from=2026-01-01" -H "Authorization: Bearer ark_..."

Service manifest for machine discovery: GET /.well-known/agent-receipts.json.

Offline verification

npx -y -p agent-receipts-mcp agent-receipts-verify receipt.json --pubkey <base64-spki-der>
# exit 0 = authentic, exit 1 = invalid/tampered

Receipt format (agent-receipts/v1)

{
  "schema": "agent-receipts/v1",
  "id": "rcpt_...",
  "vault_id": "vlt_...",
  "sequence": 42,                      // monotonic per vault; gaps = deletion evidence
  "issued_at": "2026-07-15T12:34:56.789Z",
  "action": {
    "type": "invoice.approved",
    "summary": "Approved invoice INV-1042 for EUR 1,250",
    "actor": "agent:ap-bot@acme",      // optional
    "principal": "acme-gmbh",          // optional
    "context": { "jurisdiction": "EU" } // optional
  },
  "payload_hash": "sha256:...",        // or null; contents never stored
  "prev_receipt_hash": "sha256:...",   // hash chain to the previous receipt
  "key_id": "key_...",
  "public_key": "<base64 SPKI DER>",   // embedded for offline verification
  "signature": "<base64 Ed25519 over canonical JSON of everything above>"
}

Canonicalization is JCS-style: lexicographically sorted keys, no whitespace. The JSON Schema lives at docs/receipt.schema.json.

EU AI Act mapping (informational)

Obligation	How agent-receipts helps
Art. 12 — automatic event logging	issue_receipt on every consequential action; timestamps, actor, traceable chain
Art. 26 — keep logs ≥ 6 months	Local vault you retain on your terms; signed export_audit_bundle for handover
Traceability / integrity	Ed25519 signatures, hash chain, deletion detection, offline verification

Not legal advice. Whether your system is "high-risk" and what you must log is a question for your counsel. agent-receipts produces evidence infrastructure.

Status & roadmap

• Core: issue / verify / export with hash chain + Ed25519
• MCP stdio server + HTTP API + offline verifier CLI + MCPB bundle
• Hosted vaults with per-receipt pricing
• RFC 3161 / transparency-log timestamp anchoring
• Key rotation and multi-key verification

MIT License.