I tested the 'deterministic agent loop' claims with four experiments. They all failed — including my own fix.

A certain genre of "production-grade AI agent" article has been making the rounds. You know the shape: it argues that ReAct loops break in production, so you have to stack deterministic constraints on top of the LLM's uncertainty — a pre-AL gate, an LLM-as-Judge at temperature 0, a phase gate, a decision state machine. The one I have in mind claims 7000+ lines of production Rust. The direction is right . Agent loops do need engineering guardrails; you can't let the LLM declare victory on its…