Why Petri nets? Visual (humans can reason about them), mathematical (ODEs, invariants), executable, and compositional. LLMs can manipulate the structure without losing semantic meaning.
You define a Petri net, simulate it with ODEs, and the structure becomes a scaffold for LLM-generated code. The net is the spec that both humans and LLMs can reason about.
I use Claude Code with a skill file that enforces: sketch topology → validate with simulation → extend monotonically → never delete, only grow. The discipline works with how LLMs operate.