LandblockLoader.BuildEntitiesFromInfo restarted nextId at 1 per landblock,
producing colliding entity.Id values across landblocks. EntityClassificationCache
keys by entity.Id alone, so cross-LB collisions caused cache pollution:
multiple stabs sharing id=1 -> cache entry for id=1 ended up with the
CONCATENATION of multiple entities' batches -> buildings rendered up in the
air with wrong textures (visual gate observation 2026-05-10).
Audit at docs/research/2026-05-10-tier1-mutation-audit.md did not verify
entity.Id uniqueness - that was an unchecked assumption. Cache design
trusted entity.Id was globally unique; for stabs it wasn't.
Fix: optional landblockId parameter on BuildEntitiesFromInfo. When non-zero,
stab Ids are namespaced as 0xC0XXYY00 + nextId, matching the scenery
(0x80XXYY00) and interior (0x40XXYY00) namespacing already in GameWindow.cs.
The 0xC0 top byte distinguishes stabs from those. Existing tests pass
landblockId=0 and keep their legacy starting-from-1 behavior.
Known latent: if any one landblock has >256 stabs, nextId overflows the
low byte. Same pattern + same limitation as scenery/interior. Out of scope
for the immediate Tier 1 cache bug; not affecting current Holtburg play.
Adds 2 regression tests pinning the namespacing + the legacy fallback.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
