This document defines JAC v0.5, a minimal declared-dependency chain infrastructure for agent and AI-agent receipt systems. JAC is a profile over the Judgment Event Protocol (JEP) and, when AI-agent behavior receipts are used, over HJS. JAC does not define an independent event format, signature syntax, hash format, replay mechanism, identity framework, or governance framework. JAC uses JEP extension fields to bind a signed event or receipt element to a declared parent dependency. The core is intentionally small: a single chain extension records a declared dependency link. Optional extensions can record state declarations, assignment references, handoff references, result references, capability claims, input/output references, and declared chain breaks. JAC provides infrastructure only. It records signed dependency declarations; it does not determine factual causality, responsibility, fault, authorization validity, assignment validity, handoff validity, task correctness, fairness, entitlement, legal effect, or regulatory compliance.