Si one-pass sweep of T-750's 38 open children (2026-06-07) found 3 more done-but-open:
- T-958 block irregularity (block_irregularity.rs, tested, wired)
- T-983 CityGenerationContext extension (all 4 fields, PR #145)
- T-975 ocean/lake water mask (features.rs, D-209/D-223)
Rest of T-750 is genuinely open or blocked — drift was concentrated in the #957
walkable-quarter merge.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>