ApplyLoadedTerrainLocked registered every static Setup light per apply, and RegisterOwnedLight appends unconditionally. A landblock can RE-apply without an unload in between (#168 ForceReloadWindow, Far->Near promotion) and static entity ids are deterministic, so each re-apply stacked another copy of the same lights under the same owner - the [seam-ent] x2->x4 growth, invisible to the identity-keyed [seam-blk] probe (stacked copies share one owner identity while intensity multiplies). The wash intensifies over the session and the stacked exact-tie copies destabilize the 128-cap pool selection sort. Fix: UnregisterOwner(entity.Id) before the per-entity register loop - re-apply idempotent, first apply a no-op. The live-spawn path keeps its existing guid-dedup teardown (GameWindow:3134 -> :4679). Suites green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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