rejoin the Pokemon Tower across the LAVENDER_TOWN / ROUTE_10 seam

The tower's drawing straddles the map boundary -- roof band and top
window courses in Route 10's last rows, the rest in Lavender -- so each
map folded its half upright alone: two half-buildings, Lavender's under
a fabricated yellow cap.

Buildings templates gain `topRows`: drawing rows composited ABOVE the
matched grid, for a drawing no single map holds. The model is built
from the complete 16-row artwork (96px facade under the real 32px
purple band) while placement still matches only the on-map rows; depth
now derives from the matched footprint rather than sprite height,
identical for every whole-drawing template. A `claimOnly` twin template
claims Route 10's roof rows and stamps nothing, so the top half no
longer also stands as its own building. Both templates verified to
place exactly once, world-wide, at the intended coordinates.

lib/Buildings.lua

@@ -98,9 +98,24 @@ local models = {}          -- "<tileset>:<index>" -> prebuilt local quads
 
 -- Composite the template out of the atlas and flood the silhouette in from
 -- the border. Returns flat arrays indexed y * W + x.
+--
+-- `topRows`, when a template carries it, is extra drawing rows composited
+-- ABOVE the matched grid: rows of the same drawing that are not on the
+-- map this template places on. The Pokemon Tower is the case that needs
+-- it -- the drawing straddles the LAVENDER_TOWN / ROUTE_10 boundary, its
+-- roof band and top window courses standing in the route's last rows, so
+-- no single map's grid holds the whole building. The matcher never sees
+-- topRows (placement is still by `tiles` alone); they exist so the MODEL
+-- is built from the complete drawing and the tower rises to its real
+-- height instead of folding as two half-buildings.
 local function read(t, data, perRow)
   local tiles = t.tiles
-  local bh, bw = #tiles, #tiles[1]
+  if t.topRows then
+    tiles = {}
+    for _, row in ipairs(t.topRows) do tiles[#tiles + 1] = row end
+    for _, row in ipairs(t.tiles) do tiles[#tiles + 1] = row end
+  end
+  local bh, bw = #tiles, #t.tiles[1]
   local W, H = bw * 8, bh * 8
   local col, ax, ay = {}, {}, {}
   for sy = 0, H - 1 do
@@ -258,7 +273,13 @@ local function measure(sp, t)
     shadeTexel[s] = shadeTexel[s] or shadeTexel[BLACK] or 0
   end
 
-  return { top = top, ytop = ytop, D = H,
+  -- Depth is the MATCHED footprint, not the sprite height. The two are
+  -- the same number for every whole-drawing template (the sprite is
+  -- built from `tiles` alone), but a template with `topRows` has a
+  -- sprite taller than its footprint -- the tower's 16-row drawing
+  -- stands on the 8 rows of it that are actually on the map, and D = H
+  -- would have pushed its body 64px south into the town plaza.
+  return { top = top, ytop = ytop, D = #t.tiles * 8,
            recess = recess, interior = interior, shadeTexel = shadeTexel }
 end
 
@@ -610,9 +631,18 @@ function Buildings.build(S, map, data, perRow)
             if not built then
               local key = tileset.id .. ":" .. index
               if not models[key] then
-                local sp = read(t, data, perRow)
-                local pr = measure(sp, t)
-                models[key] = emit(model(sp, pr, t), sp, atlasW, atlasH)
+                if t.claimOnly then
+                  -- claim the cells, stamp nothing: the drawing here is
+                  -- the off-map half of a building another map models in
+                  -- full (the tower's roof rows on ROUTE_10 -- Lavender's
+                  -- placement composites them via topRows). Left to the
+                  -- detector they stood as a second half-building.
+                  models[key] = {}
+                else
+                  local sp = read(t, data, perRow)
+                  local pr = measure(sp, t)
+                  models[key] = emit(model(sp, pr, t), sp, atlasW, atlasH)
+                end
               end
               built = models[key]
             end