Function contract_free_twin 

pub fn contract_free_twin(src: &str) -> String

The contract-free twin of a source: the Assume range-check lines stripped. The checks belong to the CONTROL PLANE (the digital side validates each word before the DAC fires, and runs them as ordinary bytecode in the digital fallback), so the region DATAFLOW both lanes lower is this twin — exposed for the mixed-signal composition to build its fallback configs from the same text the analog lane extracts.