FreightBox Zero: Three-Layer Agent Safety Stack — Hard Gate, Five Locks, and Kernel Receipts for AI-Operated NVOCCs (v3)

Version 3 of the FreightBox Zero legal gate architecture paper. Expands Layer 2 from a DAN gate description to the full AEGIS Hard Gate system: tiered capability enforcement (HG-1/2A/2B/2C validated over 104 soak batches, zero false positives across ~9,800 checks), Five Locks cryptographic primitives (@ankr/aegis-guard SDK: mintApprovalToken, verifyScopedApprovalToken, verifyAndConsumeNonce, IrrNoApprovalError, checkIdempotency, emitAegisSenseEvent), 16-bit quality bitmask (bits 0-11 at promotion, bits 12-15 post-promotion drift), Merkle ledger (RFC 6962 CT-style, Ed25519 STH, S3 Object Lock 7-year anchor), multi-tenant isolation, and the 4,369-line AEGIS dashboard frontend which serves as the Captain Command Centre (approval cards with STOP/ALLOW/EXPLAIN, countdown timer, dual-control badge, cost attribution tree, fleet quality view). The failure mode matrix is expanded to 10 rows covering replay attacks, duplicate execution, under-quality agent promotion, non-repudiation disputes, and Merkle anchor tamper evidence. Layer 1 (TRUST mask session bits for 5 legal gates) and Layer 3 (KavachOS seccomp-bpf + PRAMANA SHA-256 receipt chain) are unchanged from v2. Platform live at freightbox.org. Supersedes DOI 10.5281/zenodo.20047601 (v2) and DOI 10.5281/zenodo.20047472 (v1).