The trick to putting LLM agents in high-stakes systems isn’t a smarter model — it’s containing the model to one node so the rest of the system is ordinary, testable code. Here are the structural moves, with the contracts and types to implement them.

Demos love autonomous agents that loop, call tools, and “figure it out.” Production hates them. The moment an agent’s behavior depends on which path the model wandered down today, you can’t test it, can’t audit it, and can’t let it touch anything that matters. In a regulated or high-consequence system — money movement, healthcare, infrastructure — “it usually works” is a non-starter.

This is Level 1 of a six-level maturity model for running LLM systems in production: the determinism layer . Before you can do evals, confidence routing, or anything else higher up the stack, you need the part underneath to hold still.…