feat(mapgen): P28 512 沿河民居加密至 16 并宽度 2/3/4 分层

- ExtraRiversideHouses 10 -> 16（沿河 +6 座），宽度加权 2/3/4 形成聚落层次
- 仅 large 分支执行、默认图不消耗 RNG：64x48=6042052、256x192=1284656962 锁定不变
- 新增 LargeMapHouseDensityHierarchyOnlyGrowsLargeMaps 回归

1 files changed, 15 insertions, 0 deletions

diff --git a/src/LivingVillage.Desktop.Tests/MapGenTests.fs b/src/LivingVillage.Desktop.Tests/MapGenTests.fs
index 6486dd7..b737707 100644
--- a/src/LivingVillage.Desktop.Tests/MapGenTests.fs
+++ b/src/LivingVillage.Desktop.Tests/MapGenTests.fs
@@ -256,6 +256,21 @@ type MapGenTests () =
         Assert.IsTrue(a.Buildings = b.Buildings)
         Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
 
+    /// P28：512 沿河民居由 10 -> 16 增密（+6），并出现 2/3/4 三档宽度（附属小筑/民居/大宅），
+    /// 形成聚落层次；默认图仍为 0，不消耗 RNG，故 64/256 checksum 锁定不变。
+    [<TestMethod>]
+    member _.LargeMapHouseDensityHierarchyOnlyGrowsLargeMaps () =
+        Assert.AreEqual<int>(16, (MapGen.paramsForSize 512 384 (uint64 1)).ExtraRiversideHouses)
+        Assert.AreEqual<int>(0, (MapGen.paramsForSize 64 48 (uint64 1)).ExtraRiversideHouses)
+        Assert.AreEqual<int>(0, (MapGen.paramsForSize 256 192 (uint64 1)).ExtraRiversideHouses)
+        let map = MapGen.generateWithSize 512 384 (uint64 4242)
+        Assert.IsTrue(map.Buildings.Length >= 22, sprintf "P28 512 must place >=22 houses, saw %d" map.Buildings.Length)
+        let widths = map.Buildings |> List.map (fun b -> b.Width) |> Set.ofList
+        Assert.IsTrue(widths.Contains 2, "outbuilding width 2 must appear")
+        Assert.IsTrue(widths.Contains 3, "house width 3 must appear")
+        Assert.IsTrue(widths.Contains 4, "hall width 4 must appear")
+        Assert.AreEqual<int>(24, map.Buildings.Length)
+
     [<TestMethod>]
     member _.DefaultSizeHouseCountUnchanged () =
         Assert.AreEqual<int>(4, (MapGen.generateWithSize 64 48 (uint64 4242)).Buildings.Length)