Task 9 (commit 2f489a8) called _cache.Populate inside the per-tuple
foreach loop, but _walkScratch contains one tuple per (entity, MeshRefIndex)
and the cache is keyed by entity.Id. For multi-MeshRef entities (multi-part
Setup buildings, statues, multi-MeshRef NPCs), each iteration's Populate
OVERWROTE the previous one — only the last MeshRef's batches survived.
The bug was invisible at commit time because Task 10 had not landed
(cache populates but isn't read). It would have manifested the moment
Task 10 wired the cache-hit fast path: every multi-part static building
in Holtburg would render as N stacked copies of its last part.
Fix: restructure the per-entity loop with a flush-on-entity-change pattern.
Track the previous entity's Id; when the iteration moves to a different
entity, flush the previous entity's accumulated _populateScratch via one
Populate call. After the loop, flush the final entity. _populateScratch
is now cleared at flush time, not per-iteration.
Caught by code review (subagent-driven-development) before Task 10 dispatched.
Verified: 1699/8 baseline preserved, sentinel 105/105 unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
00fa8ae839