3 files changed, 80 insertions, 10 deletions
diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index 8309867..bcc4094 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -215,6 +215,8 @@ type LivingVillageGame() as this =
     let mutable avatarMoving = false
     let unlockFps = Environment.GetEnvironmentVariable("LV_UNLOCK_FPS") = "1"
     let perfSummaryMode = Environment.GetEnvironmentVariable("LV_PERF_SUMMARY") = "1"
+    // P24 证据钩子：每秒打印屏幕内可见 NPC 数，证明大世界村民确实被渲染。
+    let npcVisibleLog = Environment.GetEnvironmentVariable("LV_NPC_VISIBLE_LOG") = "1"
     let mutable fpsSamples: float list = []
     let mutable fpsFrames = 0
     let mutable fpsSeconds = 0.0
@@ -751,6 +753,18 @@ type LivingVillageGame() as this =
             if perfSummaryMode then
                 fpsSamples <- fps :: fpsSamples
             printfn $"fps={fps:F1} tick={world.Tick} pos=({world.Avatar.Pos.X:F0},{world.Avatar.Pos.Y:F0})"
+            if npcVisibleLog then
+                let viewport = this.GraphicsDevice.Viewport
+                let margin = float32 Sim.tilePixels
+                let visible =
+                    world.Npcs
+                    |> Array.filter (fun npc ->
+                        let sx = npc.Pos.X - camera.X
+                        let sy = npc.Pos.Y - camera.Y
+                        sx >= -margin && sx <= float32 viewport.Width + margin
+                        && sy >= -margin && sy <= float32 viewport.Height + margin)
+                    |> Array.length
+                printfn $"visible-npcs={visible} of {world.Npcs.Length}"
         prevKb <- kb
 
     override this.EndRun() =
diff --git a/src/LivingVillage.Desktop/MapGen.fs b/src/LivingVillage.Desktop/MapGen.fs
index ce9bccf..1e63ed2 100644
--- a/src/LivingVillage.Desktop/MapGen.fs
+++ b/src/LivingVillage.Desktop/MapGen.fs
@@ -30,7 +30,9 @@ module MapGen =
           RiverWidth: int
           CoreSide: int
           SpawnColumns: int
-          SpawnRows: 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 }
 
     /// 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 =
@@ -70,16 +72,20 @@ module MapGen =
           RiverWidth = 3
           CoreSide = 14
           SpawnColumns = 5
-          SpawnRows = 6 }
+          SpawnRows = 6
+          ExtraRiversideHouses = 0 }
 
     /// 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。
+    /// P24：仅对大于 256x192 的图追加沿河民居（泊松散布），保证既有 checksum 不变。
     let paramsForSize (width: int) (height: int) (seed: uint64) : Params =
         let base_ = defaultParams seed
+        let large = width > 256 || height > 192
         { base_ with
             Width = width
             Height = height
-            RiverCount = max base_.RiverCount (max 1 (height / 96)) }
+            RiverCount = max base_.RiverCount (max 1 (height / 96))
+            ExtraRiversideHouses = (if large then 10 else 0) }
 
     // ---- splitmix64 与 value noise（无外部依赖、无时钟） ----
 
@@ -275,6 +281,49 @@ module MapGen =
             buildings <- building :: buildings
             addPath building.DoorX building.DoorY
 
+        // 5b) P24：大图沿河民居加密。从既有路网瓦片出发，向四邻定向落位 3x2 白墙黛瓦民居，
+        //     门开向相邻路格并接入路网（BFS 可达）；仅在 ExtraRiversideHouses>0 时执行，
+        //     且只在核心区外的草地落位，故 64x48/256x192 输出逐字节不变。
+        if p.ExtraRiversideHouses > 0 then
+            let footprintFree (left: int) (top: int) =
+                left >= 1 && left + 2 <= w - 2 && top >= 1 && top + 1 <= h - 2
+                && [ for dx in 0 .. 2 do
+                       for dy in 0 .. 1 -> (left + dx, top + dy) ]
+                   |> List.forall (fun (x, y) ->
+                       tiles.[idx x y] = int GroundTile.Grass
+                       && not (inCore x y))
+            let overlaps (left: int) (top: int) =
+                buildings
+                |> List.exists (fun b ->
+                    left < b.Left + b.Width && b.Left < left + 3
+                    && top < b.Top + b.Height && b.Top < top + 2)
+            let directions = [ (0, -1); (0, 1); (-1, 0); (1, 0) ]
+            let mutable extraPlaced = 0
+            let mutable extraAttempts = 0
+            let maxAttempts = p.ExtraRiversideHouses * 400
+            while extraPlaced < p.ExtraRiversideHouses && extraAttempts < maxAttempts && paths.Length > 0 do
+                extraAttempts <- extraAttempts + 1
+                let nextState, raw = splitmix structureRng
+                structureRng <- nextState
+                if paths.Length > 0 then
+                    let pathX, pathY = List.item (int (raw % uint64 paths.Length)) paths
+                    let dirX, dirY = directions.[int ((raw >>> 32) % 4UL)]
+                    let doorX = pathX + dirX
+                    let doorY = pathY + dirY
+                    let left = doorX - 1
+                    let top = doorY - 1
+                    if footprintFree left top && not (overlaps left top) then
+                        let building =
+                            { Left = left
+                              Top = top
+                              Width = 3
+                              Height = 2
+                              DoorX = doorX
+                              DoorY = doorY }
+                        buildings <- building :: buildings
+                        addPath building.DoorX building.DoorY
+                        extraPlaced <- extraPlaced + 1
+
         // 6) 30 个 spawn：核心区内的规则网格。
         let sc = max 2 p.SpawnColumns
         let sr = max 2 p.SpawnRows
diff --git a/src/LivingVillage.Desktop/VillageArt.fs b/src/LivingVillage.Desktop/VillageArt.fs
index 3ad5b19..12c17ba 100644
--- a/src/LivingVillage.Desktop/VillageArt.fs
+++ b/src/LivingVillage.Desktop/VillageArt.fs
@@ -616,13 +616,20 @@ module VillageArt =
         for (x, y) in map.Bridges do
             spriteBatch.Draw(textures.TileAtlas, XnaRectangle(tileX x, tileY y, cell, cell), bridgeSource, XnaColor.White)
         for building in map.Buildings do
-            for row in building.Top .. building.Top + building.Height - 1 do
-                // 白墙朝向道路一行（门所在行），其余为黑瓦屋顶，两侧河岸朝向一致。
-                let color =
-                    if row = building.DoorY then XnaColor(236, 232, 220)
-                    else XnaColor(48, 52, 60)
-                fillRect spriteBatch pixel color (tileX building.Left) (tileY row) (building.Width * cell) (cell)
-            fillRect spriteBatch pixel (XnaColor(96, 60, 42)) (tileX building.DoorX) (tileY building.DoorY) cell cell
+            let left = building.Left
+            let right = building.Left + building.Width - 1
+            // P24：改用 256x192 同款民宅部件——黛瓦（脊/檐）+ 木墙/窗 + 门。
+            for row in building.Top .. building.DoorY - 1 do
+                let roofSprite = if row = building.Top then RoofRidgeSprite else RoofEaveSprite
+                let source = tileSourceRectangle roofSprite
+                for x in left .. right do
+                    spriteBatch.Draw(textures.TileAtlas, XnaRectangle(tileX x, tileY row, cell, cell), source, XnaColor.White)
+            for x in left .. right do
+                let wallSprite =
+                    if x = building.DoorX then DoorSprite
+                    elif (x - left) % 2 = 0 then WallWindowSprite
+                    else WallWoodSprite
+                spriteBatch.Draw(textures.TileAtlas, XnaRectangle(tileX x, tileY building.DoorY, cell, cell), tileSourceRectangle wallSprite, XnaColor.White)
 
     /// 桥头灯笼瓦片：每座桥每列的最上/最下一格（桥两端），用于挂灯笼与夜间暖光。
     let bridgeLanternTiles (map: MapGen.Result) : (int * int) list =