Giving autonomous AI agents direct signing keys creates an immediate security hazard if prompt injection occurs. CareRail is a deterministic payment firewall for AI agents on NEAR that air-gaps untrusted LLM runtimes from private keys. Agents only hold restricted FunctionCallAccessKeys allowing payment proposals with zero transfer authority. Proposals are evaluated by a fail-closed deterministic policy engine. Any transaction exceeding the autonomous threshold (0.10 NEAR) locks on-chain in PolicyVault (carerail-274071e4.testnet), strictly requiring owner Ed25519 authorization via NEP-413. Fully verified on NEAR testnet with 12 automated invariant suites (100% passing) and an interactive security dashboard.
Loops House