- GravityFlipConfig wraps List<GravityFlipRegion> via ArrayCodec under the
KeyedCodec("Regions", ...) entry. Decoded list is a mutable ArrayList
(NOT List.of(arr)) so Phase 4 commands can mutate at runtime.
- GravityFlipPlugin.configHolder uses the named overload
withConfig("regions", GravityFlipConfig.CODEC) — produces
<dataDirectory>/regions.json. The 1-arg overload would hardcode config.json.
- configHolder() javadoc documents the save contract (no auto-save on
shutdown; mutators must call configHolder.save() explicitly) and the shared
mutable reference caveat that 02-02's RegionRegistry will resolve.
- 4 round-trip tests cover: empty default, two-region order preservation,
empty list, and list mutability (regression guard against List.of).
kayjaydee
216f544d9b