1 files changed, 23 insertions, 17 deletions
diff --git a/src/LivingVillage.Desktop/MapGen.fs b/src/LivingVillage.Desktop/MapGen.fs
index 1e63ed2..63b14bc 100644
--- a/src/LivingVillage.Desktop/MapGen.fs
+++ b/src/LivingVillage.Desktop/MapGen.fs
@@ -32,7 +32,9 @@ module MapGen =
           SpawnColumns: int
           SpawnRows: int
           /// P24：大图额外沿河民居数量（沿现有路网泊松散布）。默认 0，64x48/256x192 不受影响。
-          ExtraRiversideHouses: int }
+          ExtraRiversideHouses: int
+          /// P25：是否放置孤立装饰石块。默认 true；大图关闭，避免草地上出现游离石板 tile。
+          DecorativeStones: bool }
 
     /// P20 第二步：一条贯穿全图的东西向河道（每列恰好一段，宽度下限 RiverWidth）。
     type River =
@@ -73,7 +75,8 @@ module MapGen =
           CoreSide = 14
           SpawnColumns = 5
           SpawnRows = 6
-          ExtraRiversideHouses = 0 }
+          ExtraRiversideHouses = 0
+          DecorativeStones = true }
 
     /// P23 尺寸自适应参数：河道数量随高度增长（约每 96 行一条），其余沿用默认。
     /// 64x48 / 256x192 仍得到 2 条河道，与既有输出逐字节一致；512x384 得到 4 条。
@@ -85,7 +88,8 @@ module MapGen =
             Width = width
             Height = height
             RiverCount = max base_.RiverCount (max 1 (height / 96))
-            ExtraRiversideHouses = (if large then 10 else 0) }
+            ExtraRiversideHouses = (if large then 10 else 0)
+            DecorativeStones = not large }
 
     // ---- splitmix64 与 value noise（无外部依赖、无时钟） ----
 
@@ -203,20 +207,22 @@ module MapGen =
         let attempts = max 100 ((w * h) / 16)
         let mutable placed: (int * int) list = []
         let mutable scatterRng = p.Seed ^^^ 0xC0FFEEUL
-        for _ in 1 .. attempts do
-            let nextState, raw = splitmix scatterRng
-            scatterRng <- nextState
-            let x = int (raw % uint64 w)
-            let y = int ((raw >>> 20) % uint64 h)
-            let far =
-                placed
-                |> List.forall (fun (px, py) ->
-                    let dx = px - x
-                    let dy = py - y
-                    dx * dx + dy * dy > minSq)
-            if far && not (inCore x y) && tiles.[idx x y] = int GroundTile.Grass then
-                tiles.[idx x y] <- int GroundTile.Stone
-                placed <- (x, y) :: placed
+        // P25：大图禁用孤立装饰石块，避免草地上出现游离石板 tile（64x48/256x192 保持开启）。
+        if p.DecorativeStones then
+            for _ in 1 .. attempts do
+                let nextState, raw = splitmix scatterRng
+                scatterRng <- nextState
+                let x = int (raw % uint64 w)
+                let y = int ((raw >>> 20) % uint64 h)
+                let far =
+                    placed
+                    |> List.forall (fun (px, py) ->
+                        let dx = px - x
+                        let dy = py - y
+                        dx * dx + dy * dy > minSq)
+                if far && not (inCore x y) && tiles.[idx x y] = int GroundTile.Grass then
+                    tiles.[idx x y] <- int GroundTile.Stone
+                    placed <- (x, y) :: placed
 
         // 5) 交通：桥 + 石板路网 + 沿河民居（白墙黑瓦矩形色块，门朝远岸路）。
         let mutable structureRng = p.Seed ^^^ 0x51AB1EUL