Bite-sized TDD plan for the unification spec. Phase 1 (outdoor node) + Phase 2
(outdoor-root flood) are additive + unit-tested (full code/tests in the plan).
Phase 3 is the single visual-gated cutover (wire one path, repoint exit portals,
delete the branch/BuildFromExterior/DrawPortal/OutsideView). Phase 4 cleanup.
Pure-outdoor regression guard keeps open-world rendering byte-identical.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
