Say two, because two is what ships

Trimming Southern California from seven focus regions to two was a measured
call — seven came to 0.73M lattice points and a 6.6 second field build against
0.13M and 0.8 — but the comment above the array went on describing seven, with
arithmetic for a configuration that no longer existed.

That comment is the only place the per-axis limitation of `buildAxis` is
written down next to real numbers, so it now records what happened rather than
what was planned. Also corrected the coarse cell size (10x, not 6x) and the
Bay Area's instance count.

The marketing pages cite these figures. A repository comment that disagrees
with them is how the two start drifting.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/cities/socal.ts

@@ -2116,8 +2116,8 @@ export const LANDMARKS: Landmark[] = [
  * same reason. One instance here is a city block, not a building, and a block
  * reads as its tallest thing.
  *
- * The whole set comes to about fifty-five thousand instances, against San
+ * The whole set comes to about fifty-five thousand instances, against the
- * Francisco's ninety. Fewer buildings over twenty times the district area is
+ * Bay Area's eighty-three. Fewer buildings over twenty times the district area is
  * the arithmetic working correctly, not a gap to be filled: a scene unit is
  * four times longer, so a lot covers sixteen times the ground.
  */
@@ -2898,24 +2898,30 @@ export const DISTRICTS: District[] = [
 // ---- Focus regions --------------------------------------------------------
 
 /**
- * The seven rectangles that get fine terrain, at about 80 m; everywhere else is
+ * The two rectangles that get fine terrain, at about 80 m; everywhere else is
- * six times coarser, at about 480 m.
+ * ten times coarser, at about 800 m.
  *
  * This is the trade ARCHITECTURE.md §5 asked for, and the arithmetic is worth
  * writing down because it is the whole argument for the feature existing.
  * Uniform 80 m cells over this frame would be 1.08° / 0.00072 by 1.66° /
  * 0.00086 — just under 2.9 million lattice points, several seconds of build,
- * and a mesh with nothing in most of it. Coarse everywhere is 80,500. The seven
+ * and a mesh with nothing in most of it. What ships is 0.13 million, and the
- * boxes below add about 120,000 back, in the places a camera actually stops,
+ * whole city builds in about 2.3 seconds.
- * for a total near 200,000: comfortably under San Francisco's 337,000, on a
- * board twenty-five times the size.
  *
- * Where a box is *not* is as considered as where it is. The San Fernando Valley
+ * It was seven boxes when this pack was written, and that did not survive
- * and the harbour both get chapters and neither gets a box, because both are
+ * contact with the engine. `buildAxis` in world.ts refines **per axis**, not
- * flat: fine cells there would buy several thousand extra triangles of
+ * per rectangle: a focus region sharpens its whole row *and* its whole column,
- * absolutely level ground. The relief that matters at those two stops is the
+ * so seven boxes scattered across a basin this wide refine most of the basin
- * range behind the Valley and the coastline around the port, and neither is
+ * between them. Measured, on this data: seven regions came to 0.73 million
- * inside the frame the camera is pointed at.
+ * points and a 6.6 second field build; two come to 0.13 million and 0.8. The
+ * boxes that stayed are the two the camera spends its time in.
+ *
+ * Where a box is *not* is as considered as where it is. The San Fernando
+ * Valley and the harbour both get chapters and neither gets a box, because
+ * both are flat: fine cells there would buy several thousand extra triangles
+ * of absolutely level ground. The relief that matters at those two stops is
+ * the range behind the Valley and the coastline around the port, and neither
+ * is inside the frame the camera is pointed at.
  */
 export const FOCUS_REGIONS: FocusRegion[] = [
   { minLat: 34.01, maxLat: 34.09, minLng: -118.3, maxLng: -118.19 },
@@ -3100,7 +3106,7 @@ export const SOCAL_CITY: City = {
    */
   verticalExaggeration: 3.4,
 
-  // ~80 m inside a focus region, ~480 m outside one. See FOCUS_REGIONS for the
+  // ~80 m inside a focus region, ~800 m outside one. See FOCUS_REGIONS for the
   // arithmetic; the short version is that this is the difference between
   // 200,000 lattice points and 2.8 million.
   cellLat: 0.00072,