Function pick_dialect 

pub fn pick_dialect(model: &Model) -> Dialect

Pick the dialect for a given model, keyed on tokenizer generation (per F-Gram).

Determinism

Pure function. Same input yields same output. Required for reproducible measurement and signature replay by ultracos-verify.

Safe defaults

Unregistered or unrecognized models fall back to Dialect::Base - never emit jit_binding speculatively. jit_binding is negative on at least one modern BPE (Gemini-2.5-pro at -5.6%); the safe default is the universal set.