namespace LivingVillage.Desktop.Tests

open System
open LivingVillage.Headless
open System.IO
open Microsoft.Xna.Framework
open Microsoft.VisualStudio.TestTools.UnitTesting
open LivingVillage.Kernel
open LivingVillage.Kernel.Sim
open LivingVillage.Desktop
open LivingVillage.Desktop.ChineseText
open LivingVillage.Desktop.CjkGlyphAtlas
open LivingVillage.Desktop.VillageArt
open LivingVillage.Desktop.VillagePresentation

[<TestClass>]
type PrototypeTests () =

    [<TestMethod>]
    member _.SceneContainsTheJiangnanPrototypeAndReachableHomeDoor () =
        let first = createScene ()
        let second = createScene ()
        let requiredProps =
            [ WhiteWallDarkTileHome
              HomeDoor
              RiverChannel
              RiverBank
              StoneBridge
              StonePaving
              Bamboo
              VegetableGarden ]

        Assert.AreEqual<PrototypeScene>(first, second)
        Assert.AreEqual<PrototypeScene>(scene, first)
        Assert.IsTrue(first.Homes.Length > 0, "The prototype needs at least one home.")
        Assert.IsTrue(
            requiredProps
            |> List.forall (fun prop -> first.Elements |> List.exists (fun element -> element.Prop = prop)),
            "The scene is missing one or more required Jiangnan elements.")

        let home = first.Homes |> List.head
        Assert.IsTrue(isNearHomeDoor first.InitialPlayerPosition home)

    [<TestMethod>]
    member _.HomeEntryAndExitExposeExplicitSuccessAndFailureBranches () =
        let scene = createScene ()
        let home = scene.Homes |> List.head
        let entered = enterHome scene.InitialPlayerPosition Outside

        match entered with
        | Ok (Inside enteredHome) ->
            Assert.AreEqual<HomeId>(home.Id, enteredHome)
        | Ok Outside -> Assert.Fail("Entering a home must produce Inside state.")
        | Error failure -> Assert.Fail(sprintf "Expected entry to succeed, got %A." failure)

        match entered with
        | Ok inside ->
            match enterHome scene.InitialPlayerPosition inside with
            | Error (AlreadyInsideHome homeId) -> Assert.AreEqual<HomeId>(home.Id, homeId)
            | other -> Assert.Fail(sprintf "Expected AlreadyInsideHome, got %A." other)
        | Error _ -> Assert.Fail("The first entry must succeed before checking the duplicate entry.")

        match exitHome (Inside home.Id) with
        | Ok Outside -> ()
        | other -> Assert.Fail(sprintf "Expected exit to succeed, got %A." other)

        match exitHome Outside with
        | Error NotInsideHome -> ()
        | other -> Assert.Fail(sprintf "Expected NotInsideHome, got %A." other)

        match exitHome (Inside(HomeId 999)) with
        | Error(HomeNotFound(HomeId 999)) -> ()
        | other -> Assert.Fail(sprintf "Expected HomeNotFound, got %A." other)

        let farAway : TilePosition =
            { X = scene.InitialPlayerPosition.X + 20
              Y = scene.InitialPlayerPosition.Y + 20 }
        match enterHome farAway Outside with
        | Error NotNearHomeDoor -> ()
        | other -> Assert.Fail(sprintf "Expected NotNearHomeDoor, got %A." other)

    [<TestMethod>]
    member _.FourWayInputMapsToFourDirections () =
        Assert.AreEqual<Direction option>(Some North, directionForInput UpInput)
        Assert.AreEqual<Direction option>(Some South, directionForInput DownInput)
        Assert.AreEqual<Direction option>(Some West, directionForInput LeftInput)
        Assert.AreEqual<Direction option>(Some East, directionForInput RightInput)
        Assert.AreEqual<Direction option>(None, directionForInput NoInput)

    [<TestMethod>]
    member _.AnimationFrameChangesWithSimulationTick () =
        let first = animationFrame (SimulationTick 0L)
        let second = animationFrame (SimulationTick 4L)
        let nextCycle = animationFrame (SimulationTick 8L)

        Assert.AreNotEqual<CharacterAnimationFrame>(first, second)
        Assert.AreEqual<CharacterAnimationFrame>(first, nextCycle)

    [<TestMethod>]
    member _.NpcIdProducesStableAndDistinctCharacterStyles () =
        let first = characterStyle (NpcId 0)
        let sameNpc = characterStyle (NpcId 0)
        let second = characterStyle (NpcId 1)

        Assert.AreEqual<CharacterStyle>(first, sameNpc)
        Assert.AreNotEqual<CharacterStyle>(first, second)

    [<TestMethod>]
    member _.StageOneCopyProvidesChineseInteractionLabels () =
        Assert.AreEqual<string>("互动", stageOneCopy.Interact)
        Assert.AreEqual<string>("需求", stageOneCopy.Needs)
        Assert.AreEqual<string>("交易", stageOneCopy.Trade)
        Assert.AreEqual<string>("进入民居", stageOneCopy.EnterHome)

    [<TestMethod>]
    member _.MenuControlsAndSettingsUseChineseDisplayCopy () =
        let state = MenuState.create SimulationControl.initial false
        let itemLabels = MenuState.items state |> List.map MenuState.itemLabel
        let controlLabels = MenuState.controlRows |> List.map (fun row -> row.Action)
        let settingsLabels = MenuState.settings |> List.map MenuState.settingsLabel

        Assert.IsTrue(itemLabels |> List.contains "开始")
        Assert.IsTrue(itemLabels |> List.contains "读档")
        Assert.IsTrue(itemLabels |> List.contains "退出")
        Assert.AreEqual<string>("设置", MenuState.itemLabel SettingsItem)
        Assert.AreEqual<string>("操作说明", MenuState.itemLabel ControlsItem)
        Assert.AreEqual<string list>(
            [ "移动"
              "互动"
              "对话"
              "观察"
              "需求"
              "年鉴"
              "关系"
              "暂停"
              "速度"
              "保存"
              "读取"
              "菜单或关闭"
              "选择"
              "确认" ],
            controlLabels)
        Assert.AreEqual<string list>([ "1倍速"; "2倍速"; "5倍速"; "暂停" ], settingsLabels)

    [<TestMethod>]
    member _.InteractionPanelsUseChineseLabelsAndExplicitTradeResults () =
        let world = Sim.initialWorldN 42UL 4
        let nearby =
            { world with
                Avatar = { world.Avatar with Pos = world.Npcs.[0].Pos } }
        let openedWorld, opened = M5Interaction.apply Interact nearby M5Interaction.initial
        let title = M5Interaction.titleText opened
        let needsWorld, needsView = M5Interaction.apply ToggleNeeds openedWorld M5Interaction.initial
        let needsText = String.concat "|" (M5Interaction.panelLines needsWorld needsView)
        let _, chronicleView = M5Interaction.apply ShowChronicle nearby M5Interaction.initial
        let chronicleText = String.concat "|" (M5Interaction.panelLines nearby chronicleView)
        let request =
            { Buyer = NpcId 0
              Seller = NpcId 1
              Item = Food
              Quantity = 1 }
        let quote = Sim.quotePrice request nearby
        let successText = M5Interaction.tradeResultText request quote (Sim.trade request nearby)
        let failureRequest = { request with Quantity = 0 }
        let failureText =
            M5Interaction.tradeResultText failureRequest (Sim.quotePrice failureRequest nearby) (Sim.trade failureRequest nearby)

        Assert.IsTrue(title.Contains("互动"))
        Assert.IsTrue(title.Contains("闲聊"))
        Assert.IsFalse(title.Contains("SMALLTALK"))
        Assert.IsTrue(needsText.Contains("需求"))
        Assert.IsTrue(needsText.Contains("饥饿"))
        Assert.IsTrue(chronicleText.Contains("年鉴"))
        Assert.IsTrue(chronicleText.Contains("暂无记录"))
        Assert.IsTrue(successText.Contains("交易成功"))
        Assert.IsTrue(successText.Contains("报价"))
        Assert.IsTrue(failureText.Contains("交易失败"))
        Assert.IsTrue(failureText.Contains("数量"))

    [<TestMethod>]
    member _.DayNightAndSpeedUseChineseDisplayCopy () =
        Assert.AreEqual<string>("白天", M6Presentation.dayNightLabel Day)
        Assert.AreEqual<string>("夜晚", M6Presentation.dayNightLabel Night)
        Assert.AreEqual<string>("暂停", M6Presentation.clockLabel { Paused = true; Speed = OneX })
        Assert.AreEqual<string>("1倍速", M6Presentation.clockLabel { Paused = false; Speed = OneX })
        Assert.AreEqual<string>("2倍速", M6Presentation.clockLabel { Paused = false; Speed = TwoX })
        Assert.AreEqual<string>("5倍速", M6Presentation.clockLabel { Paused = false; Speed = FiveX })

    [<TestMethod>]
    member _.JiangnanArtPlanIsDeterministicAndContainsRequiredElements () =
        let first = samplePlan ()
        let second = samplePlan ()
        let requiredProps =
            [ VillageArt.WhiteWallDarkTileHouse
              VillageArt.StoneBridge
              VillageArt.Bamboo
              VillageArt.VegetableGarden ]

        Assert.AreEqual<JiangnanArtPlan>(first, second)
        Assert.IsTrue(
            requiredProps
            |> List.forall (fun prop -> first.Props |> List.exists (fun sprite -> sprite.Kind = prop)),
            "The Jiangnan plan is missing one or more required props.")
        Assert.IsTrue(first.Tiles |> List.exists (fun tile -> tile.Kind = (VillageArt.RiverWater)))
        Assert.IsTrue(first.Tiles |> List.exists (fun tile -> tile.Kind = (VillageArt.StonePaving)))

    [<TestMethod>]
    member _.PauseHelpOpensFromPlayingAndRestoresSimulationControl () =
        let original = { Paused = false; Speed = TwoX }
        let state = { MenuState.create original true with Page = Playing }

        let helpState, pausedControl = MenuState.enterPauseHelp original state
        Assert.AreEqual<MenuPage>(Controls, helpState.Page)
        Assert.AreEqual<MenuPage>(Playing, helpState.ReturnPage)
        Assert.IsTrue(pausedControl.Paused)
        Assert.AreEqual<SimulationSpeed>(TwoX, pausedControl.Speed)

        let backState, restoredControl = MenuState.exitPauseHelp original helpState
        Assert.AreEqual<MenuPage>(Playing, backState.Page)
        Assert.IsFalse(restoredControl.Paused)
        Assert.AreEqual<SimulationControl>(original, restoredControl)

    [<TestMethod>]
    member _.ControlsPageKeyColumnIsUniformAndNeverOverprintsActions () =
        let layout = TitleScreen.layout 1280 720
        let rows = MenuState.controlRows

        // Every row: key-name rectangle and action rectangle must be disjoint.
        for rowIndex in 0 .. rows.Length - 1 do
            let keyRect, actionRect = TitleScreen.controlRowRects layout rowIndex
            Assert.IsTrue(TitleScreen.rectsDisjoint keyRect actionRect, sprintf "row %d key overlaps action" rowIndex)

        // The key column is uniform: every row shares the same x and width.
        let keyRects = [ 0 .. rows.Length - 1 ] |> List.map (fun index -> TitleScreen.controlRowRects layout index |> fst)
        Assert.AreEqual<int>(1, keyRects |> List.map (fun rect -> rect.X) |> List.distinct |> List.length)
        Assert.AreEqual<int>(1, keyRects |> List.map (fun rect -> rect.Width) |> List.distinct |> List.length)

        // The key column fits the longest key name (latin glyph: 6px * scale 2 per char).
        let longestKey = rows |> List.maxBy (fun row -> row.Keys.Length)
        Assert.IsTrue(layout.ControlsKeyWidth >= longestKey.Keys.Length * 12, sprintf "key width %d too small for %s" layout.ControlsKeyWidth longestKey.Keys)

        // The controls panel holds every row plus the footer inside the viewport.
        let panelBottom = layout.ControlsPanelY + 60 + rows.Length * layout.ControlsRowHeight + 48
        Assert.IsTrue(panelBottom <= 720, sprintf "controls panel bottom %d overflows" panelBottom)

    [<TestMethod>]
    member _.CornerStatusShowsDayMoneyAndEnergyFromRealData () =
        let world = Sim.initialWorldN 42UL 0
        let lines = M5Interaction.cornerStatusLines world
        Assert.AreEqual<int>(2, lines.Length)
        Assert.IsTrue(lines.[0].StartsWith("天数 "), sprintf "day line: %s" lines.[0])
        Assert.IsTrue(lines.[1].StartsWith("金钱 "), sprintf "money line: %s" lines.[1])
        Assert.IsTrue(lines.[1].Contains("精力"))

        let nextDay = { world with Tick = world.Tick + Sim.ticksPerDay }
        Assert.AreNotEqual<string>(lines.[0], M5Interaction.cornerStatusLines nextDay |> List.item 0)

        let richWorld =
            { world with
                Avatar =
                    { world.Avatar with
                        Mind =
                            { world.Avatar.Mind with
                                Needs = { world.Avatar.Mind.Needs with Money = 88.0f; Energy = 76.0f } } } }
        let richLines = M5Interaction.cornerStatusLines richWorld
        Assert.IsTrue(richLines.[1].Contains("88"), sprintf "money value missing: %s" richLines.[1])
        Assert.IsTrue(richLines.[1].Contains("76"), sprintf "energy value missing: %s" richLines.[1])

        Assert.IsTrue(ChineseText.requiredUiLabels |> List.contains "天数")
        Assert.IsTrue(ChineseText.requiredUiLabels |> List.contains "金钱")
        Assert.IsTrue(ChineseText.requiredUiLabels |> List.contains "精力")

    [<TestMethod>]
    member _.TitleScreenSelectionCursorAndLabelNeverOverprint () =
        let layout = TitleScreen.layout 1280 720

        // Heading must sit fully above the first menu row (no same-line overprint).
        Assert.IsTrue(layout.FirstItemY - layout.HeadingY >= 32, sprintf "heading clearance %d" (layout.FirstItemY - layout.HeadingY))

        // Every menu row: cursor rectangle and label rectangle must be disjoint.
        for rowIndex in 0 .. 5 do
            let cursor, label = TitleScreen.selectionRects layout rowIndex
            Assert.IsTrue(TitleScreen.rectsDisjoint cursor label, sprintf "row %d cursor overlaps label" rowIndex)
            Assert.AreEqual<int>(cursor.Y, label.Y)

        // Cursor column leaves real clearance: label starts beyond cursor + margin.
        Assert.IsTrue(layout.TextX >= layout.CursorX + layout.CursorWidth)

    [<TestMethod>]
    member _.TitleScreenLayoutIsDeterministicAndLayered () =
        let first = TitleScreen.layout 1280 720
        let second = TitleScreen.layout 1280 720
        Assert.AreEqual<TitleScreen.TitleLayout>(first, second)

        // Title: existing CJK atlas text, large scale, centered headline.
        Assert.AreEqual<string>("江南水乡", first.TitleText)
        Assert.AreEqual<int>(4, first.TitleScale)

        // Background must be a layered gradient, never a flat fullscreen block.
        Assert.IsTrue(first.SkyBands.Length >= 4)
        Assert.AreEqual<int>(first.SkyBands.Length, first.SkyBands |> List.distinct |> List.length)

        // Skyline reuses the Jiangnan roof tiles (ridge=8, eave=9) across the full width.
        let roofSlots = TitleScreen.roofSlots
        Assert.AreEqual<int>(8, fst roofSlots)
        Assert.AreEqual<int>(9, snd roofSlots)
        Assert.AreEqual<int>(1280 / 32, first.RoofTileSlots.Length)
        Assert.IsTrue(first.RoofTileSlots |> List.forall (fun slot -> slot = 8 || slot = 9))
        Assert.IsTrue(first.RoofTileSlots |> List.contains 8)
        Assert.IsTrue(first.RoofTileSlots |> List.contains 9)

        // Water band reuses the water tile slot and anchors the lantern row.
        Assert.AreEqual<int>(1, TitleScreen.waterSlot)
        Assert.AreEqual<int>(2, first.WaterRows.Length)
        Assert.IsTrue(first.Lanterns.Length >= 3)
        let lanternColor, lanternHalo = TitleScreen.lanternColors
        Assert.AreEqual<int>(212, lanternColor.R)
        Assert.AreEqual<int>(92, lanternColor.G)
        Assert.AreEqual<int>(74, lanternColor.B)
        Assert.IsTrue(lanternHalo.R > lanternColor.R && lanternHalo.G > lanternColor.G)

        // Menu items form one vertical column below the title.
        Assert.IsTrue(first.MenuTopY > first.TitleY)
        Assert.IsTrue(first.MenuLineHeight > 0)
        Assert.IsTrue(first.PanelX + first.PanelWidth <= 1280)
        Assert.IsTrue(first.PanelY + first.PanelHeight <= 720)

    [<TestMethod>]
    member _.NpcVariantsAreStableAndAnimationCoversFourDirectionsAndSixFrames () =
        let sameNpc = npcVisualVariant (NpcId 7)
        let repeatedNpc = npcVisualVariant (NpcId 7)
        let otherNpc = npcVisualVariant (NpcId 8)
        let directions =
            [ NorthFacing
              SouthFacing
              WestFacing
              EastFacing ]
        let sprites = directions |> List.map (fun direction -> npcSpriteSpec (NpcId 0) direction true 4L)

        Assert.AreEqual<NpcVisualVariant>(sameNpc, repeatedNpc)
        Assert.AreNotEqual<NpcVisualVariant>(sameNpc, otherNpc)
        Assert.AreEqual<int>(4, sprites |> List.map (fun sprite -> sprite.Direction) |> List.distinct |> List.length)
        Assert.IsTrue(sprites |> List.forall (fun sprite -> sprite.Frame = WalkFrame FrameTwo))
        Assert.AreEqual<AnimationFrame>(FrameOne, (VillageArt.animationFrame 0L))
        Assert.AreEqual<AnimationFrame>(FrameTwo, (VillageArt.animationFrame 4L))
        Assert.AreEqual<AnimationFrame>(FrameThree, (VillageArt.animationFrame 8L))
        Assert.AreEqual<AnimationFrame>(FrameFour, (VillageArt.animationFrame 12L))
        Assert.AreEqual<AnimationFrame>(FrameFive, (VillageArt.animationFrame 16L))
        Assert.AreEqual<AnimationFrame>(FrameSix, (VillageArt.animationFrame 20L))
        Assert.AreEqual<AnimationFrame>(FrameOne, (VillageArt.animationFrame 24L))

    [<TestMethod>]
    member _.VillagersUseFourDistinctVariantsDistinctFromTheAvatar () =
        let npcVariants = [ 0 .. 63 ] |> List.map (fun id -> npcVisualVariant (NpcId id)) |> Set.ofList

        Assert.AreEqual<int>(4, npcVariants.Count)
        Assert.IsFalse(npcVariants.Contains StrawHat)
        Assert.AreEqual<NpcVisualVariant>(StrawHat, (avatarSpriteSpec SouthFacing true 0L).Variant)

        let variantXes =
            npcVariants
            |> Set.toList
            |> List.map (fun variant ->
                let rect = characterSourceRectangle { Variant = variant; Direction = SouthFacing; Frame = WalkFrame FrameOne }
                rect.X)
            |> Set.ofList
        Assert.AreEqual<int>(4, variantXes.Count)
        Assert.AreEqual<int>(5120, VillageArt.characterAtlasWidth)

    [<TestMethod>]
    member _.WalkAnimationCoversSixFramesDeterministically () =
        // 24-tick cycle, new frame every 4 sim ticks, no wall-clock dependency.
        let frames = [ 0L; 4L; 8L; 12L; 16L; 20L ] |> List.map VillageArt.animationFrame
        Assert.AreEqual<AnimationFrame list>([ FrameOne; FrameTwo; FrameThree; FrameFour; FrameFive; FrameSix ], frames)

        let cycleFrames =
            [ 0L; 4L; 8L; 12L; 16L; 20L ]
            |> List.map VillageArt.animationFrame
            |> List.distinct
        Assert.AreEqual<AnimationFrame list>([ FrameOne; FrameTwo; FrameThree; FrameFour; FrameFive; FrameSix ], cycleFrames)

        // Every frame maps to a distinct atlas cell column across the five variants.
        let perFrameX =
            [ FrameOne; FrameTwo; FrameThree; FrameFour; FrameFive; FrameSix ]
            |> List.map (fun frame ->
                let rect = characterSourceRectangle { Variant = IndigoRobe; Direction = NorthFacing; Frame = WalkFrame frame }
                rect.X / 32)
        Assert.AreEqual<int list>([ 0; 1; 2; 3; 4; 5 ], perFrameX)

        // Idle breath poses occupy the two cells after the walk cycle for each (variant, direction).
        let idleXes =
            [ IdleOne; IdleTwo ]
            |> List.map (fun frame ->
                let rect = characterSourceRectangle { Variant = IndigoRobe; Direction = NorthFacing; Frame = IdleFrame frame }
                rect.X / 32)
        Assert.AreEqual<int list>([ 6; 7 ], idleXes)

    [<TestMethod>]
    member _.ChineseCopyProvidesFormalSceneTimeMenuAndStatusLabels () =
        let labels =
            [ sceneLabel VillageScene
              sceneLabel Waterway
              sceneLabel WhiteWallHome
              sceneLabel StoneBridgeScene
              sceneLabel ChineseText.BambooGrove
              sceneLabel VegetableGardenScene
              dayNightLabel DayTime
              dayNightLabel NightTime
              menuHeading MainMenuHeading
              menuHeading SettingsHeading
              menuHeading ControlsHeading
              statusHeading StatusHeading
              statusHeading ReadyStatus
              statusHeading PausedStatus ]

        Assert.IsTrue(labels |> List.forall (fun label -> not (String.IsNullOrWhiteSpace label)))
        Assert.IsTrue(labels |> List.forall (fun label -> not (label.Contains("?"))))
        Assert.AreEqual<string>("江南水乡", copy.SceneTitle)
        Assert.AreEqual<string>("准备就绪", copy.Ready)

    [<TestMethod>]
    member _.ChineseTextWrapsAndUsesAnExplicitMissingGlyphPolicy () =
        let supported = Set.ofList [ '江'; '南'; '水'; '乡' ]
        let layout = layoutText 4 supported "江南水乡村"

        Assert.AreEqual<string list>([ "江南水乡"; "□" ], layout.Lines)
        Assert.AreEqual<char list>([ '村' ], layout.MissingGlyphs)
        Assert.IsFalse(String.concat "" layout.Lines |> fun text -> text.Contains("?"))

    [<TestMethod>]
    member _.DesktopPixelPositionUsesExplicitSceneTileMapping () =
        let doorPixel : PixelPosition =
            { X = float32 (31 * Sim.tilePixels + Sim.tilePixels / 2)
              Y = float32 (23 * Sim.tilePixels + Sim.tilePixels / 2) }

        let expectedSceneTile : TilePosition = { X = 6; Y = 5 }
        let expectedWorldTile : TilePosition = { X = 31; Y = 23 }
        Assert.AreEqual<TilePosition>(expectedSceneTile, sceneTileFromPixel doorPixel)
        Assert.AreEqual<TilePosition>(expectedWorldTile, worldTileForSceneTile expectedSceneTile)

    [<TestMethod>]
    member _.HomeInteractionPrioritizesEntryExitBeforeNpcDialogue () =
        let doorPixel : PixelPosition =
            { X = float32 (31 * Sim.tilePixels + Sim.tilePixels / 2)
              Y = float32 (23 * Sim.tilePixels + Sim.tilePixels / 2) }
        let farPixel = { X = 0.0f; Y = 0.0f }

        Assert.AreEqual<HomeInputAction>(EnterHomeAction(HomeId 1), homeInputAction doorPixel Outside)
        Assert.AreEqual<HomeInputAction>(ExitHomeAction(HomeId 1), homeInputAction doorPixel (Inside(HomeId 1)))
        Assert.AreEqual<HomeInputAction>(DialogueAction, homeInputAction farPixel Outside)
        Assert.AreEqual<HomeMode>(Outside, resetHomeMode ())

    [<TestMethod>]
    member _.JiangnanDesktopRenderPlanIsDeterministicAndHasInteriorElements () =
        let first = VillageArt.sampleRenderPlan ()
        let second = VillageArt.sampleRenderPlan ()

        Assert.AreEqual<VillageArt.JiangnanRenderPlan>(first, second)
        let expectedOrigin : TilePosition = { X = 25; Y = 18 }
        Assert.AreEqual<TilePosition>(expectedOrigin, first.Origin)
        Assert.IsTrue(first.Grounds |> List.exists (fun (_, kind) -> kind = VillageArt.Water))
        Assert.IsTrue(first.Grounds |> List.exists (fun (_, kind) -> kind = VillageArt.StonePath))
        Assert.IsTrue(first.Props |> List.exists (fun prop -> prop.Kind = VillageArt.Bridge))
        // P64 补入椅/凳/床尾凳/壶 4 件家具 → 内景元素 4 → 8。
        Assert.AreEqual<int>(8, first.Interior.Elements.Length)

    [<TestMethod>]
    member _.HouseFacadeCoversRoofEaveAndWalledDoorRow () =
        let plan = VillageArt.sampleRenderPlan ()
        let footprint = VillageArt.planFootprint plan |> Set.ofList
        let door = scene.Homes |> List.head |> fun home -> VillageArt.worldTile plan home.Door

        // The enterable home must present a full facade: ridge, eave, and a walled row with the door.
        for dx in -2 .. 1 do
            Assert.IsTrue(footprint.Contains({ X = door.X + dx; Y = door.Y - 2 } : TilePosition), sprintf "missing ridge tile dx=%d" dx)
            Assert.IsTrue(footprint.Contains({ X = door.X + dx; Y = door.Y - 1 } : TilePosition), sprintf "missing eave tile dx=%d" dx)
            Assert.IsTrue(footprint.Contains({ X = door.X + dx; Y = door.Y } : TilePosition), sprintf "missing wall tile dx=%d" dx)
        // 12 house + 3 bridge + 3 bamboo + 2 garden + 2x2 willow + 2 shrub + 2 flowers + 2 reeds
        // + 1 bench + 2 lanterns + 2 stone lanterns + 1 water vat + 1 market stall (P17)
        // + P64 上半部补种 4 菜畦(2格)+2 竹丛(3格)+2 灌木+2 花丛 = 37 + 18 = 55。
        Assert.AreEqual<int>(55, footprint.Count)

    [<TestMethod>]
    member _.VegetationAndRiversidePropsDecorateTheScene () =
        let plan = VillageArt.sampleRenderPlan ()
        let kinds = plan.Props |> List.map (fun prop -> prop.Kind)
        let count kind = kinds |> List.filter (fun candidate -> candidate = kind) |> List.length
        let grounds = plan.Grounds |> List.map fst |> Set.ofList

        Assert.AreEqual<int>(2, count VillageArt.WillowTree)
        Assert.IsTrue(count VillageArt.ShrubPatch >= 2)
        Assert.IsTrue(count VillageArt.FlowerBush >= 2)
        Assert.AreEqual<int>(2, count VillageArt.ReedCluster)
        Assert.AreEqual<int>(1, count VillageArt.StoneBench)
        Assert.AreEqual<int>(2, count VillageArt.RiverLantern)
        Assert.AreEqual<int>(2, count VillageArt.StoneLantern)
        Assert.AreEqual<int>(1, count VillageArt.WaterVat)
        Assert.AreEqual<int>(1, count VillageArt.MarketStall)

        // Reeds must root in water; lanterns and P17 street details stand on the paved bank path.
        for prop in plan.Props do
            let tile = VillageArt.worldTile plan prop.Position
            match prop.Kind with
            | VillageArt.ReedCluster -> Assert.IsTrue(grounds.Contains(prop.Position), "reeds must sit on water tiles")
            | VillageArt.RiverLantern
            | VillageArt.StoneLantern
            | VillageArt.WaterVat
            | VillageArt.MarketStall ->
                Assert.IsTrue(plan.Grounds |> List.contains (prop.Position, VillageArt.StonePath), "street details must stand on the bank path")
            | _ -> ()

    [<TestMethod>]
    member _.WaterRippleFramesAreDeterministicAndThreePhase () =
        Assert.AreEqual<int>(0, VillageArt.waterFrameTick 0L)
        Assert.AreEqual<int>(0, VillageArt.waterFrameTick 31L)
        Assert.AreEqual<int>(1, VillageArt.waterFrameTick 32L)
        Assert.AreEqual<int>(1, VillageArt.waterFrameTick 63L)
        Assert.AreEqual<int>(2, VillageArt.waterFrameTick 64L)
        Assert.AreEqual<int>(2, VillageArt.waterFrameTick 95L)
        Assert.AreEqual<int>(0, VillageArt.waterFrameTick 96L)
        Assert.AreEqual<int>(VillageArt.waterFrameTick 100L, VillageArt.waterFrameTick 100L)

    [<TestMethod>]
    member _.IdleBreathCycleIsDeterministicAndDistinctFromWalking () =
        // Two-pose breath cycle over a 48-tick window (one pose per 24 sim ticks).
        Assert.AreEqual<IdleFrame>(IdleOne, VillageArt.idleFrame 0L)
        Assert.AreEqual<IdleFrame>(IdleOne, VillageArt.idleFrame 23L)
        Assert.AreEqual<IdleFrame>(IdleTwo, VillageArt.idleFrame 24L)
        Assert.AreEqual<IdleFrame>(IdleOne, VillageArt.idleFrame 48L)
        Assert.AreEqual<IdleFrame>(VillageArt.idleFrame 77L, VillageArt.idleFrame 77L)

        // Standing still breathes; moving walks. Both stay pure functions of tick.
        Assert.AreEqual<CharacterFrame>(IdleFrame IdleOne, VillageArt.characterFrame false 0L)
        Assert.AreEqual<CharacterFrame>(IdleFrame IdleTwo, VillageArt.characterFrame false 24L)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameOne, VillageArt.characterFrame true 0L)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameTwo, VillageArt.characterFrame true 4L)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameFive, VillageArt.characterFrame true 16L)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameSix, VillageArt.characterFrame true 20L)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameOne, VillageArt.characterFrame true 24L)
        Assert.AreEqual<CharacterFrame>(VillageArt.characterFrame true 12L, VillageArt.characterFrame true 12L)

    [<TestMethod>]
    member _.NpcTradesAndWalkRhythmsAreDistinctAndDeterministic () =
        // Three trades repeat by id and stay stable, with no randomness.
        Assert.AreEqual<VillageArt.NpcTrade>(VillageArt.Farmer, VillageArt.npcTrade (NpcId 0))
        Assert.AreEqual<VillageArt.NpcTrade>(VillageArt.Peddler, VillageArt.npcTrade (NpcId 1))
        Assert.AreEqual<VillageArt.NpcTrade>(VillageArt.Scholar, VillageArt.npcTrade (NpcId 2))
        Assert.AreEqual<VillageArt.NpcTrade>(VillageArt.npcTrade (NpcId 9), VillageArt.npcTrade (NpcId 0))

        // Distinct cadences: peddler shuffles fastest, scholar strolls slowest.
        let farmer = VillageArt.rhythmFor VillageArt.Farmer
        let peddler = VillageArt.rhythmFor VillageArt.Peddler
        let scholar = VillageArt.rhythmFor VillageArt.Scholar
        Assert.IsTrue(peddler.WalkWindow < farmer.WalkWindow && farmer.WalkWindow < scholar.WalkWindow)
        Assert.IsTrue(peddler.IdleWindow < farmer.IdleWindow && farmer.IdleWindow < scholar.IdleWindow)

        // Same tick, three trade-specific frames (at 12 ticks: Farmer IV, Peddler VI, Scholar V).
        let frameAt trade tick = VillageArt.animationFrameFor (VillageArt.rhythmFor trade) tick
        let frames =
            [ VillageArt.Farmer; VillageArt.Peddler; VillageArt.Scholar ]
            |> List.map (fun trade -> frameAt trade 12L)
        Assert.AreEqual<AnimationFrame list>([ FrameFour; FrameSix; FrameFive ], frames)
        Assert.AreEqual<VillageArt.WalkRhythm>(VillageArt.rhythmFor VillageArt.Scholar, VillageArt.rhythmFor VillageArt.Scholar)

        // npcSpriteSpec now follows the NPC's own trade cadence.
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameFour, (VillageArt.npcSpriteSpec (NpcId 0) VillageArt.SouthFacing true 12L).Frame)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameSix, (VillageArt.npcSpriteSpec (NpcId 1) VillageArt.SouthFacing true 12L).Frame)
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameFive, (VillageArt.npcSpriteSpec (NpcId 2) VillageArt.SouthFacing true 12L).Frame)

    [<TestMethod>]
    member _.ChimneySmokeFramesAreDeterministicAndThreePhase () =
        Assert.AreEqual<int>(0, VillageArt.smokeFrameTick 0L)
        Assert.AreEqual<int>(0, VillageArt.smokeFrameTick 39L)
        Assert.AreEqual<int>(1, VillageArt.smokeFrameTick 40L)
        Assert.AreEqual<int>(2, VillageArt.smokeFrameTick 80L)
        Assert.AreEqual<int>(0, VillageArt.smokeFrameTick 120L)
        Assert.AreEqual<int>(VillageArt.smokeFrameTick 99L, VillageArt.smokeFrameTick 99L)

    [<TestMethod>]
    member _.PremultiplyScalesEachChannelByItsOwnAlpha () =
        // The warm lantern core: rgb(255,226,168) at alpha 34 must become 34/30/22 so the
        // premultiplied SpriteBatch blend adds a dim warm value instead of full rgb.
        let core = VillageArt.premultiply 255 226 168 34
        Assert.AreEqual<byte>(34uy, core.R)
        Assert.AreEqual<byte>(30uy, core.G)
        Assert.AreEqual<byte>(22uy, core.B)
        Assert.AreEqual<byte>(34uy, core.A)

        // General fixed-point behaviour (round half away from zero).
        let warm = VillageArt.premultiply 252 196 128 34
        Assert.AreEqual<byte>(34uy, warm.R)
        Assert.AreEqual<byte>(26uy, warm.G)
        Assert.AreEqual<byte>(17uy, warm.B)
        Assert.AreEqual<byte>(34uy, warm.A)

        // Alpha 255 is the identity; alpha 0 zeroes the colour.
        Assert.AreEqual<Color>(Color(252, 196, 128, 255), VillageArt.premultiply 252 196 128 255)
        Assert.AreEqual<Color>(Color(0, 0, 0, 0), VillageArt.premultiply 252 196 128 0)

        // A premultiplied channel can never exceed its own alpha, which is what makes an
        // opaque white core impossible for any alpha < 250.
        for alpha in [ 0; 1; 34; 70; 128; 200; 249 ] do
            let c = VillageArt.premultiply 255 255 255 alpha
            Assert.IsTrue(int c.R <= int c.A && int c.G <= int c.A && int c.B <= int c.A)
            Assert.IsTrue(int (max c.R (max c.G c.B)) < 250)

    [<TestMethod>]
    member _.WaterRipplePhaseIsDistributedPerTile () =
        // Neighbouring tiles must not share a phase in the same frame.
        let a = VillageArt.waterFrameTickAt 128L 10 20
        let b = VillageArt.waterFrameTickAt 128L 11 20
        let c = VillageArt.waterFrameTickAt 128L 10 21
        Assert.AreNotEqual<int>(a, b)
        Assert.AreNotEqual<int>(a, c)

        // Pure and in range 0..2 across the map and across ticks.
        for tick in [ 0L; 31L; 32L; 40L; 64L; 127L; 200L ] do
            for x in 0 .. 7 do
                for y in 0 .. 7 do
                    let phase = VillageArt.waterFrameTickAt tick x y
                    Assert.IsTrue(phase >= 0 && phase <= 2)
                    Assert.AreEqual<int>(phase, VillageArt.waterFrameTickAt tick x y)

        // A horizontal strip of river tiles shows at least two distinct phases at once.
        let strip = [ 0 .. 11 ] |> List.map (fun x -> VillageArt.waterFrameTickAt 128L x 12)
        Assert.IsTrue(Set.ofList strip |> Set.count >= 2)

    [<TestMethod>]
    member _.LanternGlowLayersArePremultipliedAndRadial () =
        let centerX, centerY, radius, rings, peakAlpha = 100, 100, 44, 6, 140
        let layers = VillageArt.lanternGlowLayers centerX centerY radius rings 255 214 150 peakAlpha
        Assert.IsTrue(layers.Length > 0, "the glow must emit at least one layer")
        Assert.AreEqual<(Rectangle * Color) list>(layers, VillageArt.lanternGlowLayers centerX centerY radius rings 255 214 150 peakAlpha)

        for (rect, color) in layers do
            Assert.AreEqual<int>(1, rect.Height)
            Assert.IsTrue(rect.Width >= 1)
            Assert.IsTrue(int color.R <= int color.A && int color.G <= int color.A && int color.B <= int color.A)
            Assert.IsTrue(int (max color.R (max color.G color.B)) < 250, "no ring may be near-white")
            Assert.IsTrue(rect.X >= centerX - radius && rect.X + rect.Width <= centerX + radius + 1)
            Assert.IsTrue(rect.Y >= centerY - radius && rect.Y <= centerY + radius)

        let covers px py =
            layers |> List.exists (fun (rect, _) -> rect.X <= px && px < rect.X + rect.Width && rect.Y <= py && py < rect.Y + rect.Height)
        Assert.IsTrue(covers centerX centerY, "the core must be covered")
        Assert.IsFalse(covers (centerX + radius) (centerY + radius), "a square corner must stay dark: the glow is circular")
        Assert.IsFalse(covers (centerX - radius - 5) centerY)

    [<TestMethod>]
    member _.LanternGlowIsRadialWithoutSquareCorners () =
        // P26 复核：光晕为同心圆叠加，逐像素累积 alpha；边缘/四角不得出现方斑。
        let centerX, centerY, radius, rings, peakAlpha = 80, 80, 40, 6, 140
        let layers = VillageArt.lanternGlowLayers centerX centerY radius rings 255 214 150 peakAlpha
        let size = radius * 2 + 3
        let origin = centerX - radius - 1
        let alpha = Array2D.zeroCreate<int> size size
        for (rect, color) in layers do
            for y in rect.Y .. rect.Y + rect.Height - 1 do
                for x in rect.X .. rect.X + rect.Width - 1 do
                    alpha.[y - origin, x - origin] <- alpha.[y - origin, x - origin] + int color.A
        let center = alpha.[radius + 1, radius + 1]
        Assert.IsTrue(center > 0, "the core must be lit")
        let corner = [ (0, 0); (size - 1, 0); (0, size - 1); (size - 1, size - 1) ]
        for (cx, cy) in corner do
            Assert.IsTrue(alpha.[cy, cx] = 0, "glow corner must stay empty: no square patch")
        // Radial falloff along the centre row: alpha never rises as distance from the core grows.
        let row = [ for dx in 0 .. radius -> alpha.[radius + 1, radius + 1 + dx] ]
        Assert.IsTrue(row |> List.pairwise |> List.forall (fun (a, b) -> a >= b), "glow must fade radially, not form a flat block")
        Assert.IsTrue(row.[0] = center && row.[radius] < center, "core is brightest, rim is dimmer")

    [<TestMethod>]
    member _.LanternFalloffIsMaxAtCoreAndMonotonicWithoutPlateau () =
        // P29：夜景灯光衰减函数——半径 0 处最大(=1)，向半径边缘严格单调递减至 0，无平台。
        let radius = 96.0f
        Assert.AreEqual<float32>(1.0f, VillageArt.lanternFalloff 0.0f radius)
        Assert.AreEqual<float32>(0.0f, VillageArt.lanternFalloff radius radius)
        Assert.AreEqual<float32>(0.0f, VillageArt.lanternFalloff (radius + 7.0f) radius)
        Assert.IsTrue(abs (VillageArt.lanternFalloff 0.0f 0.0f) < 1e-6f, "zero radius must contribute no light")
        let samples = [ for i in 0 .. int radius -> VillageArt.lanternFalloff (float32 i) radius ]
        for value in samples do
            Assert.IsTrue(value >= 0.0f && value <= 1.0f, "falloff must stay within [0,1]")
        samples
        |> List.pairwise
        |> List.iter (fun (a, b) -> Assert.IsTrue(b < a, sprintf "falloff must strictly decrease (no plateau): %f then %f" a b))
        // 二次衰减：一半半径处约为 0.75，且严格高于线性 0.5。
        Assert.IsTrue(abs (VillageArt.lanternFalloff (radius / 2.0f) radius - 0.75f) < 1e-4f)

    [<TestMethod>]
    member _.NightLightTilesCombineBridgeLanternsAndHouseWindows () =
        // P29：夜景光源 = 桥头灯笼 + 民居门窗暖光，确定性纯函数。
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let lights = VillageArt.nightLightTiles map
        Assert.IsTrue(lights.Length > 0, "large map must emit night lights")
        Assert.IsTrue(lights.Length > map.Buildings.Length, "windows add light sources beyond the houses themselves")
        Assert.AreEqual<(int * int) list>(lights, VillageArt.nightLightTiles map)
        for lantern in VillageArt.bridgeLanternTiles map do
            Assert.IsTrue(lights |> List.contains lantern, sprintf "bridge lantern (%d,%d) must be a light source" (fst lantern) (snd lantern))
        for building in map.Buildings do
            Assert.IsTrue(lights |> List.contains (building.DoorX, building.DoorY), "every house door must carry warm light")

    [<TestMethod>]
    member _.CharacterFeetSitOnTheTileGroundLine () =
        Assert.AreEqual<int>(16, VillageArt.characterFeetOffset)
        let destination = VillageArt.characterDestination { X = 100.0f; Y = 200.0f } (Vector2(0.0f, 0.0f))
        // Feet (sprite bottom) land half a tile below the tile centre; the sprite stays x-centred.
        Assert.AreEqual<int>(216, destination.Y + destination.Height)
        Assert.AreEqual<int>(100, destination.X + destination.Width / 2)
        Assert.AreEqual<int>(32, destination.Width)
        Assert.AreEqual<int>(48, destination.Height)

    [<TestMethod>]
    member _.RiverBandSpansTheSceneWithBankPathsAndCrossing () =
        let plan = VillageArt.sampleRenderPlan ()
        let footprintOf (value: VillageArt.JiangnanRenderPlan) = VillageArt.planFootprint value
        let waters = plan.Grounds |> List.filter (fun (_, kind) -> kind = VillageArt.Water) |> List.map fst |> Set.ofList
        let paths = plan.Grounds |> List.filter (fun (_, kind) -> kind = VillageArt.StonePath) |> List.map fst |> Set.ofList
        let door = scene.Homes |> List.head |> fun home -> home.Door

        // The river must run the full width of the decorated scene as a readable water band.
        Assert.AreEqual<int>(20, [ 0 .. 19 ] |> List.filter (fun x -> waters.Contains({ X = x; Y = 12 } : TilePosition)) |> List.length)
        Assert.IsTrue(waters.Contains({ X = 6; Y = 13 } : TilePosition))
        // Banks stay walkable stone, and the door row connects to the north bank.
        for x in 0 .. 19 do
            if x <> 6 && x <> 7 && x <> 8 then
                Assert.IsTrue(paths.Contains({ X = x; Y = 11 } : TilePosition), sprintf "missing north bank x=%d" x)
        for y in 6 .. 10 do
            Assert.IsTrue(paths.Contains({ X = 6; Y = y } : TilePosition), sprintf "missing door connector y=%d" y)
        // Bridge footprint crosses the full river between the banks.
        let bridge = plan.Props |> List.find (fun prop -> prop.Kind = VillageArt.Bridge)
        let expectedBridge : TilePosition = { X = 6; Y = 11 }
        Assert.AreEqual<TilePosition>(expectedBridge, bridge.Position)
        for y in 11 .. 13 do
            let bridgeTile = VillageArt.worldTile plan { X = 6; Y = y }
            Assert.IsTrue(footprintOf plan |> List.contains bridgeTile, sprintf "bridge tile y=%d" y)

    [<TestMethod>]
    member _.FacingUsesTheActualMovementOrTargetVector () =
        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.EastFacing, VillageArt.directionFromVector { X = 1.0f; Y = 0.1f })
        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.WestFacing, VillageArt.directionFromVector { X = -1.0f; Y = 0.1f })
        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.SouthFacing, VillageArt.directionFromVector { X = 0.1f; Y = 1.0f })
        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.NorthFacing, VillageArt.directionFromVector { X = 0.1f; Y = -1.0f })

    [<TestMethod>]
    member _.RuntimeMovementAndNpcTargetsProduceStableSpriteDirections () =
        let idle = VillageArt.facingAfterMovement { X = 4.0f; Y = 4.0f } { X = 4.0f; Y = 4.0f } VillageArt.EastFacing
        let moved = VillageArt.facingAfterMovement { X = 4.0f; Y = 4.0f } { X = 2.0f; Y = 4.0f } VillageArt.EastFacing
        let targetSpec = VillageArt.npcSpriteSpecAtTarget (NpcId 0) { X = 10.0f; Y = 10.0f } { X = 10.0f; Y = 8.0f } 4L
        let arrivedSpec = VillageArt.npcSpriteSpecAtTarget (NpcId 0) { X = 10.0f; Y = 10.0f } { X = 10.0f; Y = 10.0f } 4L

        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.EastFacing, idle)
        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.WestFacing, moved)
        Assert.AreEqual<VillageArt.FacingDirection>(VillageArt.NorthFacing, targetSpec.Direction)
        // Walking toward a target uses the walk cycle; reaching it settles into the breath cycle.
        Assert.AreEqual<CharacterFrame>(WalkFrame FrameTwo, targetSpec.Frame)
        Assert.AreEqual<CharacterFrame>(IdleFrame IdleOne, arrivedSpec.Frame)

    [<TestMethod>]
    member _.RenderPlanCoordinatesAndCharacterAtlasCellsAreDeterministic () =
        let plan = VillageArt.sampleRenderPlan ()
        let localTile : TilePosition = { X = 6; Y = 4 }
        let worldTile = VillageArt.worldTile plan localTile
        let expectedWorldTile : TilePosition = { X = 31; Y = 22 }
        Assert.AreEqual<TilePosition>(expectedWorldTile, worldTile)

        let first = VillageArt.characterSourceRectangle { Variant = IndigoRobe; Direction = NorthFacing; Frame = WalkFrame FrameOne }
        let second = VillageArt.characterSourceRectangle { Variant = JadeSash; Direction = EastFacing; Frame = WalkFrame FrameTwo }
        Assert.AreNotEqual<Rectangle>(first, second)
        Assert.AreEqual<int>(32, first.Width)
        Assert.AreEqual<int>(48, first.Height)
        Assert.AreEqual<int>(32, second.Width)
        Assert.AreEqual<int>(48, second.Height)

    [<TestMethod>]
    member _.FormalChineseUiLabelsUseTheRealGlyphAtlasBoundary () =
        Assert.IsTrue(ChineseText.requiredUiLabels |> List.forall PixelText.isRenderable)
        Assert.IsTrue(ChineseText.requiredUiLabels |> List.forall (fun label -> not (label.Contains("?"))))
        Assert.IsFalse(PixelText.isRenderable "龘")

    [<TestMethod>]
    member _.ContextualPromptSelectsOneStableReachableNpcAndClearsWhenLeaving () =
        let avatar : Vec2 =
            { X = float32 (32 * Sim.tilePixels + Sim.tilePixels / 2)
              Y = float32 (24 * Sim.tilePixels + Sim.tilePixels / 2) }
        let world =
            Sim.initialWorldN 42UL 4
            |> fun value -> { value with Avatar = { value.Avatar with Pos = avatar } }
        let npcPosition : Vec2 = { X = world.Avatar.Pos.X + 48.0f; Y = world.Avatar.Pos.Y }
        let npc = { world.Npcs.[0] with Pos = npcPosition }
        let npcs = Array.copy world.Npcs
        npcs.[0] <- npc
        for index in 1 .. npcs.Length - 1 do
            npcs.[index] <- { npcs.[index] with Pos = ({ X = 2000.0f; Y = 1400.0f } : Vec2) }
        let nearby = { world with Npcs = npcs }

        let prompt = InteractionResolver.resolve nearby Outside
        Assert.IsTrue(prompt.IsSome)
        Assert.AreEqual<InteractionAction>(TalkTo(NpcId 0), prompt.Value.Action)
        Assert.AreEqual<string>("E 交谈", prompt.Value.Text)

        let view = M5Interaction.refreshPrompt nearby M5Interaction.initial
        Assert.AreEqual<string option>(Some "E 交谈", view.Prompt)
        let farAway = { nearby with Avatar = { nearby.Avatar with Pos = ({ X = 0.0f; Y = 0.0f } : Vec2) } }
        let cleared = M5Interaction.refreshPrompt farAway view
        Assert.AreEqual<string option>(None, cleared.Prompt)

    [<TestMethod>]
    member _.HomeEntryWinsDeterministicallyAndUsesTheSameActionAsThePrompt () =
        let doorPixel : PixelPosition =
            { X = float32 (31 * Sim.tilePixels + Sim.tilePixels / 2)
              Y = float32 (23 * Sim.tilePixels + Sim.tilePixels / 2) }
        let world = Sim.initialWorldN 42UL 0 |> fun value -> { value with Avatar = { value.Avatar with Pos = ({ X = doorPixel.X; Y = doorPixel.Y } : Vec2) } }
        let prompt = InteractionResolver.resolve world Outside

        Assert.IsTrue(prompt.IsSome)
        Assert.AreEqual<InteractionAction>(EnterHome(HomeId 1), prompt.Value.Action)
        Assert.AreEqual<string>("E 进屋", prompt.Value.Text)

        let _, view = M5Interaction.apply Interact world M5Interaction.initial
        Assert.AreEqual<HomeMode>(Inside(HomeId 1), view.HomeMode)
        Assert.AreEqual<string option>(None, view.Prompt)

    [<TestMethod>]
    member _.WallBlocksNpcPromptAndOpenPanelsDoNotAcceptWorldInput () =
        let avatar : Vec2 = { X = float32 (32 * Sim.tilePixels + Sim.tilePixels / 2); Y = float32 (24 * Sim.tilePixels + Sim.tilePixels / 2) }
        let npcPosition : Vec2 = { X = avatar.X - 40.0f; Y = avatar.Y - 80.0f }
        let world = Sim.initialWorldN 42UL 1
        let npc = { world.Npcs.[0] with Pos = npcPosition }
        let blockedWorld = { world with Avatar = { world.Avatar with Pos = avatar }; Npcs = [| npc |] }

        Assert.IsFalse(InteractionResolver.hasClearPath avatar npcPosition)
        Assert.IsFalse(M5Interaction.worldInputAllowed { M5Interaction.initial with Panel = DialoguePanel })
        Assert.IsTrue(M5Interaction.worldInputAllowed M5Interaction.initial)
        Assert.IsTrue(M5Interaction.resolveAction blockedWorld Outside |> Option.isNone)

    [<TestMethod>]
    member _.TargetSelectionUsesPureDistancePriorityWithIdTiebreak () =
        let doorPixel : PixelPosition =
            { X = float32 (31 * Sim.tilePixels + Sim.tilePixels / 2)
              Y = float32 (23 * Sim.tilePixels + Sim.tilePixels / 2) }
        let avatar : Vec2 = { X = doorPixel.X - 32.0f; Y = doorPixel.Y }
        let world = Sim.initialWorldN 42UL 2

        // Door nearer than the villager: door wins by pure distance (no kind privilege).
        let doorNearer =
            { world with
                Avatar = { world.Avatar with Pos = avatar }
                Npcs = [| { world.Npcs.[0] with Pos = { X = avatar.X + 40.0f; Y = avatar.Y } } |] }
        Assert.AreEqual<InteractionAction option>(Some(EnterHome(HomeId 1)), InteractionResolver.resolve doorNearer Outside |> Option.map (fun candidate -> candidate.Action))

        // NPC nearer than the door: villager wins.
        let npcNearerWorld = { doorNearer with Npcs = [| { world.Npcs.[0] with Pos = { X = avatar.X + 4.0f; Y = avatar.Y } } |] }
        Assert.AreEqual<InteractionAction option>(Some(TalkTo(NpcId 0)), InteractionResolver.resolve npcNearerWorld Outside |> Option.map (fun candidate -> candidate.Action))

        // Exact distance tie between two villagers: lower entity id wins deterministically.
        let tieAvatar : Vec2 = { X = 1600.0f; Y = 800.0f }
        let tieWorld =
            { world with
                Avatar = { world.Avatar with Pos = tieAvatar }
                Npcs = [| { world.Npcs.[0] with Pos = { X = tieAvatar.X + 64.0f; Y = tieAvatar.Y } }
                          { world.Npcs.[1] with Pos = { X = tieAvatar.X - 64.0f; Y = tieAvatar.Y } } |] }
        Assert.AreEqual<InteractionAction option>(Some(TalkTo(NpcId 0)), InteractionResolver.resolve tieWorld Outside |> Option.map (fun candidate -> candidate.Action))

        // Array snapshot immutability: neither resolve nor refreshPrompt may mutate Npcs.
        let snapshot = Array.copy tieWorld.Npcs
        let resolvedIgnore = InteractionResolver.resolve tieWorld Outside
        CollectionAssert.AreEqual(snapshot, tieWorld.Npcs)
        let view = M5Interaction.refreshPrompt tieWorld M5Interaction.initial
        CollectionAssert.AreEqual(snapshot, tieWorld.Npcs)

    [<TestMethod>]
    member _.FloatingPromptStaysInViewportAndClearOfHudBands () =
        for (width, height) in [ (1280, 720); (1920, 1080) ] do
            let anchors : (float32 * float32) list =
                [ (100.0f, 100.0f)      // near top-left
                  (float32 width / 2.0f, float32 height / 2.0f)
                  (float32 width - 60.0f, 120.0f)   // near top-right strip
                  (200.0f, float32 height - 200.0f) // above bottom-left HUD band
                  (float32 width - 100.0f, float32 height - 120.0f) ]
            for (anchorX, anchorY) in anchors do
                for text in [ "E 交谈"; "E 进屋"; "E 出屋" ] do
                    let rect = FloatingPrompt.layout width height anchorX anchorY 0.0f 0.0f 2 text
                    let textWidth = FloatingPrompt.measureWidth text 2
                    Assert.AreEqual<int>(textWidth, rect.Width)
                    Assert.IsTrue(rect.Width > 0, "prompt must not be truncated to zero width")
                    Assert.IsTrue(rect.X >= 0 && rect.X + rect.Width <= width, sprintf "x overflow %A %A" (anchorX, anchorY) rect)
                    Assert.IsTrue(rect.Y >= 0 && rect.Y + rect.Height <= height, sprintf "y overflow %A %A" (anchorX, anchorY) rect)
                    // Never cover the bottom-left HUD band (camera 0: band starts at height - 160).
                    Assert.IsTrue(rect.Y + rect.Height <= height - FloatingPrompt.hudBottomBandHeight + 8, sprintf "bottom HUD overlap %A %A" (anchorX, anchorY) rect)
                    // Never cover the full-width top status bar.
                    Assert.IsTrue(rect.Y >= FloatingPrompt.hudTopBarHeight, sprintf "top HUD overlap %A %A" (anchorX, anchorY) rect)

    [<TestMethod>]
    member _.FloatingPromptMeasureMatchesPixelTextAdvances () =
        // E(12) space(8) 交(16) 谈(16) at scale 2.
        Assert.AreEqual<int>(52, FloatingPrompt.measureWidth "E 交谈" 2)
        Assert.AreEqual<int>(20, FloatingPrompt.measureWidth "E " 2)

    [<TestMethod>]
    member _.FloatingPromptHiddenWhilePanelsOrMenusAreOpen () =
        let world = Sim.initialWorldN 42UL 2
        let dialogueView = { M5Interaction.initial with Panel = DialoguePanel }
        let cleared = M5Interaction.refreshPrompt world dialogueView
        Assert.AreEqual<string option>(None, cleared.Prompt)
        Assert.IsFalse(M5Interaction.worldInputAllowed dialogueView)

        let needsView = { M5Interaction.initial with Panel = NeedsPanel }
        Assert.AreEqual<string option>(None, M5Interaction.refreshPrompt world needsView |> fun value -> value.Prompt)

    [<TestMethod>]
    member _.DayPhaseLightingIsPureDeterministicAndTransitionsSmoothly () =
        let ticksPerHour = Sim.ticksPerDay / 24L
        let atHour hour = M6Presentation.lightingAtTick (int64 hour * ticksPerHour)

        // Anchors: full day at noon, full night at midnight, no drift.
        Assert.AreEqual<float32>(0.0f, (atHour 12).Blend)
        Assert.AreEqual<float32>(1.0f, (atHour 0).Blend)
        Assert.AreEqual<float32>(1.0f, (atHour 2).Blend)

        // P17 window: dawn 4:00 -> 6:30 goes night -> day, monotonic (fractional hours).
        let dawnMidTick = int64 5 * ticksPerHour + ticksPerHour / 4L // 5:15
        let dawnEndTick = int64 6 * ticksPerHour + ticksPerHour / 2L // 6:30
        Assert.AreEqual<float32>(1.0f, (atHour 4).Blend)
        Assert.AreEqual<float32>(0.5f, (M6Presentation.lightingAtTick dawnMidTick).Blend)
        Assert.AreEqual<float32>(0.0f, (M6Presentation.lightingAtTick dawnEndTick).Blend)

        // P18: dusk darkening ramp is 20:00 -> 22:00 (day -> night, monotonic).
        let duskStartTick = int64 20 * ticksPerHour // 20:00
        let duskMidTick = int64 21 * ticksPerHour // 21:00
        Assert.AreEqual<float32>(0.0f, (M6Presentation.lightingAtTick duskStartTick).Blend)
        Assert.AreEqual<float32>(0.5f, (M6Presentation.lightingAtTick duskMidTick).Blend)
        Assert.AreEqual<float32>(1.0f, (atHour 22).Blend)

        // Blue hour: the dawn lingers past 6:00; dusk stays light while it warms.
        Assert.IsTrue((atHour 6).Blend > 0.0f && (atHour 6).Blend < 0.5f)
        let duskGlowTick = int64 20 * ticksPerHour + ticksPerHour / 2L // 20:30
        Assert.IsTrue((M6Presentation.lightingAtTick duskGlowTick).Blend > 0.0f)
        Assert.IsTrue((M6Presentation.lightingAtTick duskGlowTick).Blend < 0.5f, "20:30 must still be Day mode for a visible golden dusk")
        Assert.AreEqual<M6DayNight>(Day, (M6Presentation.lightingAtTick duskGlowTick).Mode)

        // Golden-hour warmth peaks mid-dawn (5:15) / mid-dusk (20:30) and vanishes at noon/midnight.
        let duskWarmthMidTick = int64 20 * ticksPerHour + ticksPerHour / 2L // 20:30
        Assert.AreEqual<float32>(0.0f, (atHour 12).SkyWarmth)
        Assert.AreEqual<float32>(0.0f, (atHour 0).SkyWarmth)
        Assert.AreEqual<float32>(1.0f, (M6Presentation.lightingAtTick dawnMidTick).SkyWarmth)
        Assert.AreEqual<float32>(1.0f, (M6Presentation.lightingAtTick duskWarmthMidTick).SkyWarmth)
        Assert.IsTrue((atHour 5).SkyWarmth > 0.5f)
        Assert.IsTrue((atHour 21).SkyWarmth > 0.5f)
        // The warm shift pushes sky and world tint redder and less blue than the plain blend;
        // this is what made the old dusk frame still read blue-grey.
        let warmDawn = atHour 5
        let warmDusk = M6Presentation.lightingAtTick duskGlowTick
        Assert.IsTrue(warmDawn.Background.R > (M6Presentation.backgroundAtBlend warmDawn.Blend).R)
        Assert.IsTrue(warmDawn.Background.B < (M6Presentation.backgroundAtBlend warmDawn.Blend).B)
        Assert.IsTrue(warmDusk.Background.R > (M6Presentation.backgroundAtBlend warmDusk.Blend).R)
        Assert.IsTrue(warmDusk.Background.B < (M6Presentation.backgroundAtBlend warmDusk.Blend).B)
        Assert.IsTrue(warmDusk.WorldTint.R > (M6Presentation.worldTintAtBlend warmDusk.Blend).R)
        Assert.IsTrue(warmDusk.WorldTint.B < (M6Presentation.worldTintAtBlend warmDusk.Blend).B)

        // P19: no daylight warm cast. Noon (and the whole 10:00-15:00 plateau) must be warmth-free
        // and channel-neutral, so the world renders at a true white balance instead of yellow.
        for hour in 10 .. 15 do
            let daylight = atHour hour
            Assert.IsTrue(abs (daylight.SkyWarmth) < 1e-6f, sprintf "hour %d must carry no warmth" hour)
            Assert.IsTrue((int daylight.WorldTint.R) = (int daylight.WorldTint.G), sprintf "hour %d world tint must be neutral" hour)
            Assert.IsTrue((int daylight.WorldTint.G) = (int daylight.WorldTint.B), sprintf "hour %d world tint must be neutral" hour)
            Assert.IsTrue((M6Presentation.goldenVeilAlpha (int64 hour * ticksPerHour)) = 0, sprintf "hour %d must have no golden veil" hour)
            Assert.IsTrue(abs (daylight.LanternGlow) < 1e-6f, sprintf "hour %d must have no lantern glow" hour)
        let noon = atHour 12
        Assert.IsTrue((int noon.WorldTint.R) = 255, "neutral day tint should be full white (no attenuation)")
        // Additive veil: positive and strongest at the golden peaks, zero at noon/midnight.
        Assert.AreEqual<int>(0, M6Presentation.goldenVeilAlpha (int64 12 * ticksPerHour))
        Assert.AreEqual<int>(0, M6Presentation.goldenVeilAlpha 0L)
        Assert.AreEqual<int>(150, M6Presentation.goldenVeilAlpha duskWarmthMidTick)
        Assert.IsTrue(M6Presentation.goldenVeilAlpha duskGlowTick > 100)
        Assert.IsTrue(M6Presentation.goldenVeilAlpha (int64 19 * ticksPerHour) = 0, "veil must start after 19:15, not bleed into afternoon")

        // Determinism without randomness.
        let once = atHour 13
        let twice = atHour 13
        Assert.AreEqual<M6RenderProfile>(once, twice)

        // Lantern glow now also lifts through the golden hour, not only at deep night.
        Assert.AreEqual<float32>(0.0f, (atHour 13).LanternGlow)
        Assert.AreEqual<float32>(1.0f, (atHour 0).LanternGlow)
        Assert.IsTrue(warmDusk.LanternGlow > 0.5f)

        // Evidence hook: fractional start hours map exactly onto sim ticks.
        Assert.AreEqual<int64>(int64 20 * ticksPerHour + ticksPerHour * 3L / 4L, M6Presentation.startTickForHour 20.75)
        Assert.AreEqual<int64>(6L * ticksPerHour, M6Presentation.startTickForHour 6.0)

    [<TestMethod>]
    member _.StartTickResolutionHonoursEvidenceHourThenDaylightThenMidnight () =
        let ticksPerHour = Sim.ticksPerDay / 24L

        // P17-FIX: the evidence hour must win on the sample/autoplay path too, otherwise
        // StartNewGame re-created the world at 00:00 and dusk/day shots were actually night.
        Assert.AreEqual<int64>(M6Presentation.startTickForHour 20.75, M6Presentation.resolveStartTick (Some 20.75) false)
        Assert.AreEqual<int64>(int64 20 * ticksPerHour + ticksPerHour * 3L / 4L, M6Presentation.resolveStartTick (Some 20.75) false)
        // Explicit hour overrides the daylight bootstrap.
        Assert.AreEqual<int64>(12L * ticksPerHour, M6Presentation.resolveStartTick (Some 12.0) true)
        // No override: daylight -> 6:00, otherwise midnight.
        Assert.AreEqual<int64>(6L * ticksPerHour, M6Presentation.resolveStartTick None true)
        Assert.AreEqual<int64>(0L, M6Presentation.resolveStartTick None false)

    [<TestMethod>]
    member _.TitleEntranceProgressIsDeterministicAndCompleteAfterTwoSeconds () =
        // 120 frames at the fixed 60Hz step = 2s entrance, pure function of frame count.
        Assert.AreEqual<float32>(1.0f, TitleScreen.entranceProgress 0L)
        Assert.AreEqual<float32>(0.5f, TitleScreen.entranceProgress 60L)
        Assert.AreEqual<float32>(0.0f, TitleScreen.entranceProgress 120L)
        Assert.AreEqual<float32>(0.0f, TitleScreen.entranceProgress 1000L)
        Assert.AreEqual<float32>(TitleScreen.entranceProgress 37L, TitleScreen.entranceProgress 37L)

    [<TestMethod>]
    member _.ProceduralMapGeneratesByteIdenticalTerrainFromSameSeed () =
        let first = ProceduralMap.generate (uint64 4242)
        let second = ProceduralMap.generate (uint64 4242)
        Assert.AreEqual<int>(first.Tiles.Length, second.Tiles.Length)
        let snapshot = Array.copy first.Tiles
        let mutable diverged = -1
        for i in 0 .. snapshot.Length - 1 do
            if snapshot.[i] <> second.Tiles.[i] then diverged <- i
        Assert.AreEqual<int>(-1, diverged)

        // Different seed must produce different terrain (sanity).
        let other = ProceduralMap.generate (uint64 777)
        let differs = [0 .. snapshot.Length - 1] |> List.tryFind (fun i -> other.Tiles.[i] <> snapshot.[i])
        Assert.IsTrue(differs.IsSome, "different seed should carve different terrain")

        // Village core stays walkable: no water/peat inside the handcrafted core rect.
        let coreBad =
            [ for y in ProceduralMap.villageCoreMinY .. ProceduralMap.villageCoreMaxY do
                for x in ProceduralMap.villageCoreMinX .. ProceduralMap.villageCoreMaxX do
                    let code = first.Tiles.[y * ProceduralMap.width + x]
                    if code = ProceduralMap.GroundTile.Water || code = ProceduralMap.GroundTile.Peat then yield (x, y, code) ]
        Assert.AreEqual<(int * int * int) list>([], coreBad)

    [<TestMethod>]
    member _.WorldPanelDoesNotRenderA永久KeyList () =
        let world = Sim.initialWorldN 42UL 0
        let lines = M5Interaction.panelLines world M5Interaction.initial
        Assert.AreEqual<string list>([], lines)
        Assert.IsFalse(lines |> List.exists (fun line -> line = "Q 观察" || line = "TAB 需求" || line = "C 年鉴" || line = "L 关系"))

    [<TestMethod>]
    member _.WorldPanelStatusIsTransientAndExpiresAfterTwoAndAHalfSeconds () =
        let world = Sim.initialWorldN 42UL 0
        let _, interacted = M5Interaction.apply ClosePanel world M5Interaction.initial
        let stamped = { interacted with StatusTick = Some world.Tick }
        Assert.AreEqual<string list>([ "E 进屋"; "面板已关闭" ], M5Interaction.panelLines world stamped)

        let expired = { stamped with StatusTick = Some (world.Tick - M5Interaction.statusDisplayDurationTicks) }
        Assert.AreEqual<string list>([ "E 进屋" ], M5Interaction.panelLines world expired)

    [<TestMethod>]
    member _.DialogueCompletionReturnsToTheLightweightWorldPanel () =
        let world = Sim.initialWorldN 42UL 4 |> fun value -> { value with Avatar = { value.Avatar with Pos = value.Npcs.[0].Pos } }
        let openedWorld, opened = M5Interaction.apply Interact world M5Interaction.initial
        Assert.AreEqual<M5Panel>(DialoguePanel, opened.Panel)
        Assert.IsTrue(opened.Menu.IsSome)

        let nextWorld, view = M5Interaction.apply Intent1 openedWorld opened
        Assert.AreEqual<M5Panel>(WorldPanel, view.Panel)
        Assert.AreEqual<DialogueMenu option>(None, view.Menu)
        Assert.AreEqual<int64 option>(Some nextWorld.Tick, view.StatusTick)
        Assert.IsTrue(M5Interaction.statusText view |> fun text -> text.Contains("对话完成"))
        Assert.IsTrue(M5Interaction.transientStatusLine nextWorld.Tick view |> Option.map (fun line -> line.Contains("对话完成")) |> Option.defaultValue false)

    [<TestMethod>]
    member _.InteractionRangeAndTargetSelectionStayDeterministicAtTheBoundary () =
        let avatar : Vec2 =
            { X = float32 (32 * Sim.tilePixels + Sim.tilePixels / 2)
              Y = float32 (24 * Sim.tilePixels + Sim.tilePixels / 2) }
        let baseWorld = Sim.initialWorldN 42UL 4

        let withNpcPositions (positions: (int * Vec2) list) =
            let npcs = Array.copy baseWorld.Npcs
            for index in 0 .. npcs.Length - 1 do
                npcs.[index] <- { npcs.[index] with Pos = ({ X = 2000.0f; Y = 1400.0f } : Vec2) }
            for index, position in positions do
                npcs.[index] <- { npcs.[index] with Pos = position }
            { baseWorld with
                Avatar = { baseWorld.Avatar with Pos = avatar }
                Npcs = npcs }

        let atBoundary = withNpcPositions [ 0, { X = avatar.X + Sim.chatRangePx; Y = avatar.Y } ]
        let beyondBoundary = withNpcPositions [ 0, { X = avatar.X + Sim.chatRangePx + 0.1f; Y = avatar.Y } ]
        let competing =
            withNpcPositions
                [ 0, { X = avatar.X + 72.0f; Y = avatar.Y }
                  1, { X = avatar.X + 48.0f; Y = avatar.Y } ]
        let switched =
            { competing with
                Avatar = { competing.Avatar with Pos = { X = avatar.X + 64.0f; Y = avatar.Y } } }

        Assert.AreEqual<InteractionAction option>(Some(TalkTo(NpcId 0)), InteractionResolver.resolve atBoundary Outside |> Option.map (fun target -> target.Action))
        Assert.AreEqual<InteractionAction option>(None, InteractionResolver.resolve beyondBoundary Outside |> Option.map (fun target -> target.Action))
        Assert.AreEqual<InteractionAction option>(Some(TalkTo(NpcId 1)), InteractionResolver.resolve competing Outside |> Option.map (fun target -> target.Action))
        Assert.AreEqual<InteractionAction option>(Some(TalkTo(NpcId 0)), InteractionResolver.resolve switched Outside |> Option.map (fun target -> target.Action))

    [<TestMethod>]
    member _.CjkGlyphAtlasHasAStableCharacterTableAndGeometry () =
        Assert.AreEqual<int>(345, characters.Length)
        CollectionAssert.AreEqual(characters, characters |> Array.sort)
        Assert.AreEqual<int>(characters.Length, characters |> Array.distinct |> Array.length)
        Assert.AreEqual<int>(16, columns)
        Assert.AreEqual<int>(24, cellPixels)
        Assert.AreEqual<int>(22, rowCount)
        Assert.AreEqual<int>(384, pixelWidth)
        Assert.AreEqual<int>(528, pixelHeight)
        Assert.AreEqual<string>("Assets/cjk-glyph-atlas.png", assetRelativePath)
        Assert.AreEqual<string>("Assets/cjk-glyphs.txt", manifestRelativePath)

    [<TestMethod>]
    member _.RequiredUiLabelsAreFullyCoveredByTheGlyphTable () =
        let labels = ChineseText.requiredUiLabels

        Assert.IsTrue(labels |> List.forall PixelText.isRenderable)
        Assert.IsTrue(labels |> List.contains "时间")
        Assert.IsTrue(labels |> List.contains "E 出屋")
        Assert.IsTrue(labels |> List.contains "E 进屋")
        Assert.IsTrue(labels |> List.contains "E 交谈")
        Assert.IsTrue(PixelText.isRenderable "时间 白天")
        Assert.IsTrue(PixelText.isRenderable "2倍速")
        Assert.IsTrue(PixelText.isRenderable "E 出门")
        Assert.IsTrue(PixelText.isRenderable "E 交谈")
        Assert.IsFalse(PixelText.isRenderable "龘")

    [<TestMethod>]
    member _.CjkGlyphAtlasMatchesThePackagedManifestAndRejectsUnknownCharacters () =
        Assert.IsTrue(ChineseText.requiredUiLabels |> List.forall PixelText.isRenderable)
        Assert.IsTrue(contains '江')
        Assert.IsTrue(contains '间')
        Assert.IsTrue(contains '门')
        Assert.IsTrue(contains '谈')
        Assert.IsTrue(contains '体')
        Assert.IsTrue(contains '龘' |> not)
        Assert.AreEqual<int>(0, sourceRectangle '龘' |> Option.toList |> List.length)
        let manifestPath = runtimeManifestPath ()
        Assert.IsTrue(File.Exists manifestPath, sprintf "Missing atlas manifest: %s" manifestPath)
        let manifestLines = File.ReadAllLines manifestPath
        Assert.AreEqual<int>(characters.Length, manifestLines.Length)
        Assert.IsTrue(manifestLines |> Array.forall (fun line -> line.Length = 1), "The CJK manifest must contain exactly one character per line.")
        CollectionAssert.AreEqual(characters, manifestLines |> Array.map (fun line -> line.[0]))
        Assert.IsTrue(File.Exists(runtimeAssetPath ()), sprintf "Missing atlas PNG: %s" (runtimeAssetPath ()))

    [<TestMethod>]
    member _.WorldDigestIsCanonicalAcrossSaveFormatVersions () =
        // The digest must bind to simulation state only: a world presented as a
        // legacy V1 save text and as the new V2 save text must share one digest.
        let world = Sim.initialWorldN (uint64 42) 4
        let v2Text = WorldSave.save world

        let firstPipe = v2Text.IndexOf('|')
        let secondPipe = v2Text.IndexOf('|', firstPipe + 1)
        let thirdPipe = v2Text.IndexOf('|', secondPipe + 1)
        let v1Text = ("LV_WORLD_SAVE_V1" + v2Text.Substring(thirdPipe))

        // v1/v2 same-world digest equality (RED before canonical digest exists).
        let digestOfV1 = PerformanceProbe.WorldDigestOfText v1Text
        Assert.AreEqual<string>(digestOfV1, PerformanceProbe.WorldDigestOfText v2Text)
        // 953775FA 硬对齐由 --performance-baseline 于 finalWorld 支线证据。

    [<TestMethod>]
    member _.HouseFacadeVariantsAlternateAlongTheVillage () =
        // P26：512 大图上两种民居立面都要出现，且按位置确定性交替（纯函数）。
        let map = MapGen.generateWithSize 512 384 (uint64 4242)
        let variants = map.Buildings |> List.map VillageArt.houseFacadeVariant
        Assert.IsTrue(Set.ofList variants |> Set.contains 0, "variant A must appear")
        Assert.IsTrue(Set.ofList variants |> Set.contains 1, "variant B must appear")
        let repeated = MapGen.generateWithSize 512 384 (uint64 4242)
        Assert.AreEqual<(int list)>(variants, repeated.Buildings |> List.map VillageArt.houseFacadeVariant)
        // Neighbouring buildings along the same river bank must flip variant, i.e. not one solid run.
        let flipped =
            variants
            |> List.pairwise
            |> List.filter (fun (a, b) -> a <> b)
            |> List.length
        Assert.IsTrue(flipped > 0, "facades must alternate, not stay one variant")

    [<TestMethod>]
    member _.JiangnanArtAssetsArePackagedAsRealPngFiles () =
        let requiredAssets =
            [ "Assets/jiangnan-world.png"
              "Assets/jiangnan-characters.png"
              "Assets/jiangnan-interior.png" ]

        let missing =
            requiredAssets
            |> List.filter (fun relativePath -> not (File.Exists(Path.Combine(AppContext.BaseDirectory, relativePath))))

        Assert.AreEqual<string list>([], missing, sprintf "Missing Jiangnan PNG assets: %s" (String.concat ", " missing))

        // The baked world atlas must match the 32-slot layout the renderer indexes into
        // (P17 added 石灯笼/水缸/摊贩摊位 as slots 25..27; P26 added the variant-B house
        // parts 屋檐挑出/木格栅窗/院门 as slots 28..30 and 护岸石垒 as slot 31).
        Assert.AreEqual<int>(32, VillageArt.worldTileCount)
        let worldPath = Path.Combine(AppContext.BaseDirectory, "Assets/jiangnan-world.png")
        let header = File.ReadAllBytes worldPath
        let be32 offset =
            (int header.[offset] <<< 24)
            ||| (int header.[offset + 1] <<< 16)
            ||| (int header.[offset + 2] <<< 8)
            ||| int header.[offset + 3]
        let atlasWidth : int = be32 16
        let atlasHeight : int = be32 20
        Assert.IsTrue((atlasWidth = VillageArt.worldAtlasWidth), "world atlas width must match 32 x 32px slots")
        Assert.IsTrue((atlasHeight = VillageArt.worldAtlasHeight), "world atlas height must stay 32px")

    /// P28：防复发。第二变体（P26）在 512 整图 ~2px/tile 下不可辨，根因是挑檐与第一变体同为
    /// 近黑黛瓦。此回归直接解码 world 图集，断言变体 B 的挑檐（slot 28）平均亮度显著高于
    /// 变体 A 的屋脊（slot 8），保证「配色差异」不会在后续编辑中被悄悄抹平。
    [<TestMethod>]
    member _.VariantBRoofPaletteIsClearlyLighterThanVariantA () =
        let worldPath = Path.Combine(AppContext.BaseDirectory, "Assets/jiangnan-world.png")
        let bytes = File.ReadAllBytes worldPath
        let be32 offset =
            (int bytes.[offset] <<< 24)
            ||| (int bytes.[offset + 1] <<< 16)
            ||| (int bytes.[offset + 2] <<< 8)
            ||| int bytes.[offset + 3]
        Assert.AreEqual<int>(0x89504E47, be32 0)
        let width = be32 16
        let height = be32 20
        Assert.AreEqual<int>(VillageArt.worldAtlasWidth, width)
        Assert.AreEqual<int>(VillageArt.worldAtlasHeight, height)
        // Collect IDAT and inflate; the baked atlas is 8-bit RGBA, non-interlaced, filter 0.
        let mutable offset = 8
        use idat = new MemoryStream()
        while offset < bytes.Length do
            let length = be32 offset
            let tag = System.Text.Encoding.ASCII.GetString(bytes, offset + 4, 4)
            if tag = "IDAT" then idat.Write(bytes, offset + 8, length)
            offset <- offset + 12 + length
        idat.Position <- 0L
        use inflater = new System.IO.Compression.ZLibStream(idat, System.IO.Compression.CompressionMode.Decompress)
        use raw = new MemoryStream()
        inflater.CopyTo raw
        let data = raw.ToArray()
        let stride = width * 4 + 1
        let pixel (x: int) (y: int) =
            let rowStart = y * stride
            Assert.AreEqual<byte>(0uy, data.[rowStart])
            let p = rowStart + 1 + x * 4
            (int data.[p], int data.[p + 1], int data.[p + 2], int data.[p + 3])
        let slotMeanBrightness (slot: int) =
            let mutable sum = 0.0
            let mutable count = 0
            for y in 0 .. height - 1 do
                for x in slot * 32 .. slot * 32 + 31 do
                    let (r, g, b, a) = pixel x y
                    if a > 0 then
                        sum <- sum + float (r + g + b) / 3.0
                        count <- count + 1
            Assert.IsTrue(count > 0, sprintf "slot %d must have opaque pixels" slot)
            sum / float count
        let roofA = slotMeanBrightness 8   // RoofRidgeSprite: variant A near-black 黛瓦
        let roofB = slotMeanBrightness 28  // RoofEaveOverhangSprite: variant B light blue-grey 瓦
        Assert.IsTrue(
            roofB > roofA + 15.0,
            sprintf "variant B roof must be clearly lighter than variant A (A=%.1f B=%.1f)" roofA roofB)

    [<TestMethod>]
    member _.CjkGlyphManifestIsUniqueAndMatchesAtlasGrid () =
        // 防复发：图集用字增长时，清单必须非空、每行恰 1 个字符、字符唯一，
        // 且与 16 列图集网格自洽（打包脚本不再硬编码行数）。
        let assets = Path.Combine(AppContext.BaseDirectory, "Assets")
        let manifestPath = Path.Combine(assets, "cjk-glyphs.txt")
        let atlasPath = Path.Combine(assets, "cjk-glyph-atlas.png")
        Assert.IsTrue(File.Exists manifestPath, "missing cjk-glyphs.txt")
        Assert.IsTrue(File.Exists atlasPath, "missing cjk-glyph-atlas.png")

        let lines = File.ReadAllLines manifestPath
        Assert.IsTrue(lines.Length > 0, "CJK manifest must not be empty")
        for index in 0 .. lines.Length - 1 do
            Assert.AreEqual<int>(1, lines.[index].Length)
        Assert.AreEqual<int>(lines.Length, (Set.ofArray lines).Count)

        let header = File.ReadAllBytes atlasPath
        let be32 offset =
            (int header.[offset] <<< 24)
            ||| (int header.[offset + 1] <<< 16)
            ||| (int header.[offset + 2] <<< 8)
            ||| int header.[offset + 3]
        let cell = 24
        let width = be32 16
        let height = be32 20
        Assert.AreEqual<int>(0, width % cell)
        Assert.AreEqual<int>(0, height % cell)
        let columns = width / cell
        let capacity = columns * (height / cell)
        Assert.AreEqual<int>(16, columns)
        Assert.IsTrue(capacity >= lines.Length, "CJK atlas grid must cover every manifest character")
        Assert.IsTrue(capacity - lines.Length < columns, "CJK atlas must not keep an extra empty row")