def dec_run
import mylsm-lsm-store@0.3.2.0/src/Wal.bend as Walimport Base
195# Fuel-exact runner: consumes exactly len-bounded input, returns the state
196# (no extraction — callers extract). Proof-only workhorse.
197def dec_run(fuel: Nat, rest: String, st: DecState) -> DecState:
198 match fuel rest:
199 case 0n _:
200 st
201 case 1n+f SNil{}:
202 st
203 case 1n+f SCon{h, +t}:
204 dec_run(f, t, dec_step(st, h))