It should be possible to write protocol specifications in Lean, e.g., this is a recent case study on specifying two-phase commit in Lean [1] and proving its safety [2].

However, there are no model checkers for Lean. Currently, you either have to write a full proof by hand, with some assistance from LLMs, or rely on random simulation, similar to property-based testing.

[1] https://protocols-made-fun.com/lean/2025/04/25/lean-two-phas... [2] https://protocols-made-fun.com/lean/2025/05/10/lean-two-phas...