With Keel we built a small typed language (DSL) to represent strategies. It uses a well defined set of components to build a DAG of steps, it carries types and clocks. This allows agents to build these strategies with a really fast feedback loop as they can be quickly validated and many common errors avoided. In a DAG its also easy to inspect intermediate results. Valid strategies are fingerprinted and the exact same artifact runs in backtesting and live. These strategies are also much easier for humans to verify as they are self describing components, and mostly linear to read and reason about.
Still trying to improve the space of how many types of different strategies can be represented in this and still trying to improve how well LLMs go from natural language to strategy. A lot of the improvements come from just giving the agents better and faster tools and faster feedback loops.