Review follow-up from commit 11df793. Three fixes:
1. Visible semantics: StreamingRegion.Visible now strictly describes the
current (2r+1)×(2r+1) window, not window + hysteresis retainees.
Added a parallel Resident property exposing the actual loaded set
(window + hysteresis buffer). This matters because StreamingController
(next task) reads these to decide what to render vs what to unload;
conflating them in one set would have forced awkward post-processing
downstream.
2. Doc/code disagreement: updated the RecenterTo and RegionDiff doc
comments from "radius + 1" to "radius + 2" to match the actual
implementation (which is what the tests require). Also updated the
plan doc so future readers don't hit the same contradiction.
3. Edge-clamping test coverage: added a single-axis edge test
(cx=0, cy=50 → 15 entries) and an ID-encoding test (radius=0 at
0x12,0x34 → 0x1234FFFE) so a swapped-shift bug in EncodeLandblockId
or an asymmetric off-by-one would fail a test instead of passing
silently.
9 tests green, full suite regressions-free.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
449c2caf8b