Setting the file. One moment.
Skill 163 · Signed Audit Trails Recipe
Subchapter 163.4
references/receipt-format.mdMarkdown1 KBView on GitHub
The recipe’s sign.sh hook runs protect-mcp@0.7.4 sign, which appends one
receipt per line to ./receipts/receipts.jsonl. Each line is a v2 envelope
like this one:
{
"v": 2,
"type": "decision_receipt",
"algorithm": "ed25519",
"kid": "generated",
"issuer": "protect-mcp",
"issued_at": "2026-09-26T12:59:48.265Z",
"payload": {
"tool": "Read",
"decision": "allow",
"reason_code": "post_execution_receipt",
"policy_digest": "none",
"scope": "tu-1790427588265-c8x5",
"mode": "enforce",
"request_id": "tu-1790427588265-c8x5",
"spec": "draft-farley-acta-signed-receipts-01",
"issuer_certification": "self-signed"
},
"signature": "0b5d28f45db30666c6addbc6e417e4825104b04b..."
}The receipt records the tool name, and it does not record the tool input or
output. Changing any signed field after signing, such as issued_at,
issuer, or payload.decision, makes verification fail.
The receipt holds no public key. The verifier needs the publicKey value from
./protect-mcp.key, which you pass with --key.
The receipts also carry no hash of the previous receipt. The verifier checks each signature, so it cannot detect a deleted or reordered line.