Resolve the SP2b multi-pick semantics:
- range count drawn in [min,max] (a fixed {N$$} keeps min==max and does NOT
draw, so its seed sequence is byte-for-byte unchanged);
- independent (~) = N draws WITH replacement, each branch resolved
independently (a lone ref re-rolls every time);
- unique lone-ref (count>=2, wildcard surface) = N DISTINCT options from the
ref filtered pool — a per-site SP2a multi-select. count==1 stays on the
legacy single-pick branch path (seed safe).
Extracts ref_option_pool (catalog lookup + :expr/!null filter + chain
constraints, incl. the strict-unknown raise + warnings) from _resolve_ref so
both the single pick and the lone-ref multi-pick share it. Also closes the
coverage gap: a $var branch inside a multi-block on the combine surface.
DumiFlex
63b824e4a1