Keep Cave Age spawns below the roof

docs/PORTING.md

@@ -276,6 +276,11 @@ dimension skylight while retaining local block light. The latter is the closest
 server-safe modern equivalent to Legacy's removed per-dimension light-table
 scaling hook.
 
+Version 0.2.18.1 prevents Cave Ages from choosing a spawn on their upper roof.
+Their grounded arrival search now begins with the floor below player Y=64 and
+works downward. If it finds no suitable footing, the existing floor-Y=63
+platform fallback places the player at Y=64.
+
 Version 0.2.14.0 restores the legacy Linking and Descriptive Book artwork for
 inventory items and gives each book its matching open-book texture when placed
 on a Book Stand. Return Linking Books created inside another Age also retain and