OptionalFullOnly reclaim once a FULL sync has been observed (every row seen), so "all-NULL" is trustworthy and not an artifact of a partial / incremental pass. MJC signals this; default false = never reclaim.
OptionalReclaimU7 — the master opt-in. Default OFF: nothing is EVER reclaimed unless a deployment explicitly turns it on. A promoted column is non-destructive by default (it simply lingers all-NULL); this only lets an opted-in deployment reclaim the space.
Options for planColumnReclamations. Reclaim is DESTRUCTIVE, so every gate defaults to OFF/safe.