Persistent Causal State for Operating-System Enforcement Engineering a Stateful, Auditable, and Fail-Closed Linux Policy Runtime

Most operating-system enforcement mechanisms decide from the current request: an executable, a credential, a path, a socket address, or a static label. This local view is efficient and dependable, but it cannot directly express risk that emerges from a sequence of individually ordinary actions. Unix-AGB (Aletheion Guard Bridge) investigates a complementary architecture in which normalized kernel observations update persistent, namespace-isolated causal state; a deterministic policy layer then compiles only restrictive decisions into shortlived enforcement records. Exact events remain the historical truth, learned state remainsreplaceable, and Linux retains final enforcement authority. The key design constraint is monotonic authority: learned or stateful inference may only reduce existing privilege; it cannot manufacture permission. This article explains the engineering of that pipeline: contracts, identity, ordering, persistence, policy revisions, authenticated caches, seccomp user-notification handoff, recovery, packaging, and experimental validation. It also states the boundary of the result. The current system is a controlled prototype with packaged, opt-in, exact-launch egress enforcement; it is not a production security service and does not yet establish security efficacy on natural unknown attacks.