Zambo is the Trust Layer for AI work. Every AI job returns a verifiable receipt: a SHA-256-committed record of exactly what was executed, checkable by anyone at https://zambo.dev/verify. Zambo implements AER-1 (IETF draft-zambo-aer1, rev -19), the open draft standard for AI agent execution receipts, and operates as an ERC-8004 validator: its validation responses are backed by AER-1 receipt verification (canonical-bytes digest, evidence hash, and workflow Merkle root recomputation against the draft). A receipt proves the record was not changed afterward; it does not prove the answer was right.