Brummel
7d52eff41f
Bite-sized, placeholder-free plan for the walk-forward axis, in three tasks: (1) extract MetricStats::from_values from McAggregate::from_draws + serde derive (behaviour-preserving, the 7 mc tests guard); (2) the walkforward module — WindowRoller (bounds-only iterator), walk_forward over the shared run_indexed core, continuous OOS stitch (empty segment -> +0.0), on-demand param_stability, + crate exports + module-header doc-lag fix; (3) the aura walkforward CLI demo bridging engine+registry via optimize, with serde_json for the summary line. RED-first tests 1-11 (incl. 7b empty-segment stitch) per the spec. refs #69