feat(m6b): add playable menu and save flow

[Change Nature]
- This commit adds the M6b desktop menu and persistence integration.

[New Capability]
- Provide new game, continue, settings, controls, load error, save, load, and exit flows.
- Provide a bounded autoplay flow covering menu navigation and persistence.

[Implementation]
- Add pure menu state transitions and focused M6b coverage.
- Connect menu commands to simulation controls, WorldSave, view resets, and rendering.

[Impact]
- Desktop runtime gains the playable M6b front end without changing out-of-scope files.
- Release focused and solution test suites remain passing.

1 files changed, 289 insertions, 78 deletions

diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index 232930d..5465ba2 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -116,6 +116,7 @@ module PixelText =
           ':', [| "00000"; "00110"; "00110"; "00000"; "00110"; "00110"; "00000" |]
           ';', [| "00000"; "00110"; "00110"; "00000"; "00110"; "00100"; "01000" |]
           '/', [| "00001"; "00010"; "00010"; "00100"; "01000"; "01000"; "10000" |]
+          '>', [| "10000"; "01000"; "00100"; "00010"; "00100"; "01000"; "10000" |]
           '?', [| "01110"; "10001"; "00001"; "00010"; "00100"; "00000"; "00100" |] ]
         |> Map.ofList
 
@@ -137,8 +138,13 @@ type LivingVillageGame() as this =
     inherit Game()
 
     let autoplay = Environment.GetEnvironmentVariable("LV_AUTOPLAY") = "1"
-    let titleSuffix = if autoplay then " [AUTOPLAY]" else ""
-    let modeName = if autoplay then "autoplay" else "keyboard"
+    let autoplayFlow = Environment.GetEnvironmentVariable("LV_AUTOPLAY_FLOW") = "1"
+    let automated = autoplay || autoplayFlow
+    let titleSuffix = if automated then " [AUTOPLAY]" else ""
+    let modeName =
+        if autoplayFlow then "autoplay-flow"
+        elif autoplay then "autoplay"
+        else "keyboard"
     let configuredStepsPerFrame =
         match Environment.GetEnvironmentVariable("LV_STEPS_PER_FRAME") with
         | null | "" -> 1
@@ -167,6 +173,9 @@ type LivingVillageGame() as this =
     let mutable m5View = M5Interaction.initial
     let mutable simulationControl = initialSimulationControl
     let mutable legacyStepsPerFrame = initialLegacyStepsPerFrame
+    let mutable menu = MenuState.create initialSimulationControl false
+    let mutable autoplayFrames = 0
+    let mutable flowStep = 0
 
     do
         graphics.PreferredBackBufferWidth <- 1280
@@ -174,7 +183,7 @@ type LivingVillageGame() as this =
         graphics.SynchronizeWithVerticalRetrace <- true
         this.IsFixedTimeStep <- true
         this.TargetElapsedTime <- TimeSpan.FromTicks(TimeSpan.TicksPerSecond / 60L)
-        this.Window.Title <- if autoplay then "Living Village M6 [AUTOPLAY]" else "Living Village M6"
+        this.Window.Title <- $"Living Village M6{titleSuffix}"
         printfn $"mode={modeName} seed=42"
         printfn "controls=WASD move E interact 1-6 choose Q observe Tab needs C chronicle L relations P pause F1/F2/F3 speed F6 save F7 load Esc close/exit"
     member private this.CenterCamera() =
@@ -188,107 +197,246 @@ type LivingVillageGame() as this =
         let y = MathHelper.Clamp(world.Avatar.Pos.Y + half - vh / 2.0f, 0.0f, max 0.0f (worldH - vh))
         camera <- Vector2(x, y)
 
-    override this.Initialize() =
-        base.Initialize()
-        prevKb <- Keyboard.GetState()
+    member private this.ResetWorldView() =
+        relationView <- false
+        relationSnapshot <- None
+        m5View <- M5Interaction.initial
+        this.CenterCamera()
 
-    override _.LoadContent() =
-        spriteBatch <- new SpriteBatch(this.GraphicsDevice)
-        atlas <- Atlas.build this.GraphicsDevice
-        pixel <- new Texture2D(this.GraphicsDevice, 1, 1)
-        pixel.SetData([| Color.White |])
+    member private this.StartNewGame() =
+        world <- Sim.initialWorldN 42UL Sim.npcCount
+        this.ResetWorldView()
+        menu <- menu |> MenuState.setCurrentWorld true |> MenuState.enterGame
+        printfn $"new-game=ok seed=42 npcs={Sim.npcCount}"
 
-    override this.Update(gameTime: GameTime) =
-        let kb = Keyboard.GetState()
-        let pressed (key: Keys) = kb.IsKeyDown(key) && not (prevKb.IsKeyDown(key))
+    member private this.SaveWorld (prefix: string) : bool =
+        try
+            WorldSave.saveToFile savePath world
+            printfn $"{prefix}=ok path={savePath} tick={world.Tick}"
+            true
+        with
+        | ex ->
+            printfn $"{prefix}=error path={savePath} message={ex.Message}"
+            false
+
+    member private this.LoadWorld (prefix: string) : Result<int64, string> =
+        match WorldSave.loadFromFile savePath with
+        | Ok nextWorld ->
+            world <- nextWorld
+            this.ResetWorldView()
+            printfn $"{prefix}=ok path={savePath} tick={world.Tick}"
+            Ok world.Tick
+        | Error failure ->
+            printfn $"{prefix}=error path={savePath} message={failure}"
+            Error failure
+
+    member private this.OpenMainMenu() =
+        relationView <- false
+        relationSnapshot <- None
+        m5View <- M5Interaction.initial
+        menu <- menu |> MenuState.setCurrentWorld true |> MenuState.openMain
+        printfn $"menu=open tick={world.Tick}"
+
+    member private this.ApplyMenuCommand (command: MenuCommand) =
+        match command with
+        | NoCommand -> ()
+        | ContinueGame ->
+            menu <- menu |> MenuState.setCurrentWorld true |> MenuState.enterGame
+            printfn $"continue=ok tick={world.Tick}"
+        | StartNewGame -> this.StartNewGame()
+        | LoadGame ->
+            match this.LoadWorld "load" with
+            | Ok _ ->
+                menu <- menu |> MenuState.setCurrentWorld true |> MenuState.enterGame
+            | Error failure ->
+                menu <- menu |> MenuState.showLoadError failure
+        | ApplySettings nextControl ->
+            simulationControl <- nextControl
+            legacyStepsPerFrame <- None
+            menu <- menu |> MenuState.setSettings nextControl
+            printfn $"simulation={M6Presentation.clockLabel simulationControl}"
+        | ExitGame ->
+            printfn "menu=exit"
+            this.Exit()
+
+    member private this.DispatchMenuInput (input: MenuInput) =
+        let nextMenu, command = MenuState.update input menu
+        menu <- nextMenu
+        this.ApplyMenuCommand command
+
+    member private this.UpdateMenu (pressed: Keys -> bool) =
         let pressedAny (keys: Keys list) = keys |> List.exists pressed
+        let input =
+            if pressedAny [ Keys.Up; Keys.W ] then Some Up
+            elif pressedAny [ Keys.Down; Keys.S ] then Some Down
+            elif pressed Keys.Enter then Some Confirm
+            elif pressed Keys.Escape then Some Back
+            else None
+        match input with
+        | Some nextInput -> this.DispatchMenuInput nextInput
+        | None when autoplay && not autoplayFlow && menu.Page = MainMenu && not menu.HasCurrentWorld ->
+            autoplayFrames <- autoplayFrames + 1
+            if autoplayFrames >= 15 then
+                this.DispatchMenuInput Confirm
+        | None -> ()
+
+    member private this.UpdatePlaying (gameTime: GameTime) (kb: KeyboardState) (pressed: Keys -> bool) (pressedAny: Keys list -> bool) =
+        let mutable loadFailed = false
+        let mutable leftGame = false
         let lPressed = pressed Keys.L
         let escapePressed = pressed Keys.Escape
         if pressed Keys.P then
             simulationControl <- SimulationControl.togglePause simulationControl
+            menu <- MenuState.setSettings simulationControl menu
             printfn $"simulation={M6Presentation.clockLabel simulationControl}"
         if pressed Keys.F1 then
             simulationControl <- SimulationControl.setSpeed OneX simulationControl
             legacyStepsPerFrame <- None
+            menu <- MenuState.setSettings simulationControl menu
             printfn $"simulation={M6Presentation.clockLabel simulationControl}"
         if pressed Keys.F2 then
             simulationControl <- SimulationControl.setSpeed TwoX simulationControl
             legacyStepsPerFrame <- None
+            menu <- MenuState.setSettings simulationControl menu
             printfn $"simulation={M6Presentation.clockLabel simulationControl}"
         if pressed Keys.F3 then
             simulationControl <- SimulationControl.setSpeed FiveX simulationControl
             legacyStepsPerFrame <- None
+            menu <- MenuState.setSettings simulationControl menu
             printfn $"simulation={M6Presentation.clockLabel simulationControl}"
         if pressed Keys.F6 then
-            try
-                WorldSave.saveToFile savePath world
-                printfn $"save=ok path={savePath} tick={world.Tick}"
-            with
-            | ex -> printfn $"save=error path={savePath} message={ex.Message}"
+            this.SaveWorld "save" |> ignore
         if pressed Keys.F7 then
-            match WorldSave.loadFromFile savePath with
-            | Ok nextWorld ->
-                world <- nextWorld
-                relationView <- false
-                relationSnapshot <- None
-                m5View <- M5Interaction.initial
-                this.CenterCamera()
-                printfn $"load=ok path={savePath} tick={world.Tick}"
-            | Error failure -> printfn $"load=error path={savePath} message={failure}"
-        if escapePressed then
+            match this.LoadWorld "load" with
+            | Ok _ -> menu <- MenuState.setCurrentWorld true menu
+            | Error failure ->
+                menu <- menu |> MenuState.setCurrentWorld true |> MenuState.showLoadError failure
+                loadFailed <- true
+        if not loadFailed && escapePressed then
             if m5View.Panel <> WorldPanel then
                 let nextWorld, nextView = M5Interaction.apply ClosePanel world m5View
                 world <- nextWorld
                 m5View <- nextView
                 printfn $"m5 panel={M5Interaction.panelName m5View} status={m5View.Status} tick={world.Tick}"
+            elif relationView then
+                relationView <- false
+                relationSnapshot <- None
+                printfn $"relation view=off tick={world.Tick}"
             else
-                this.Exit()
-        if lPressed then
-            relationView <- not relationView
-            if relationView then relationSnapshot <- Some(Sim.relationMatrix world)
-            let state = if relationView then "on" else "off"
-            printfn $"relation view={state} tick={world.Tick}"
-        let m5Command =
-            if pressed Keys.E then Some Interact
-            elif pressedAny [ Keys.D1; Keys.NumPad1 ] then Some Intent1
-            elif pressedAny [ Keys.D2; Keys.NumPad2 ] then Some Intent2
-            elif pressedAny [ Keys.D3; Keys.NumPad3 ] then Some Intent3
-            elif pressedAny [ Keys.D4; Keys.NumPad4 ] then Some Intent4
-            elif pressedAny [ Keys.D5; Keys.NumPad5 ] then Some Intent5
-            elif pressedAny [ Keys.D6; Keys.NumPad6 ] then Some Intent6
-            elif pressed Keys.Q then Some Observe
-            elif pressed Keys.Tab then Some ToggleNeeds
-            elif pressed Keys.C then Some ShowChronicle
-            else None
-        match m5Command with
-        | Some command ->
-            let nextWorld, nextView = M5Interaction.apply command world m5View
-            world <- nextWorld
-            m5View <- nextView
-            printfn $"m5 panel={M5Interaction.panelName m5View} status={m5View.Status} tick={world.Tick}"
-        | None -> ()
-        let panelOpen = m5View.Panel <> WorldPanel
-        if not relationView && not panelOpen then
-            let input =
-                if autoplay then
-                    let t = float32 world.Tick
-                    { MoveX = MathF.Sin(t / 60.0f) * 0.8f
-                      MoveY = MathF.Cos(t / 90.0f) * 0.6f }
-                else
-                    { MoveX =
-                        (if kb.IsKeyDown(Keys.D) then 1.0f
-                         elif kb.IsKeyDown(Keys.A) then -1.0f
-                         else 0.0f)
-                      MoveY =
-                        (if kb.IsKeyDown(Keys.S) then 1.0f
-                         elif kb.IsKeyDown(Keys.W) then -1.0f
-                         else 0.0f) }
-            let ts = { Input = input }
-            let stepCount = SimulationControl.stepsPerFrameWithLegacy legacyStepsPerFrame simulationControl
-            if stepCount > 0 then
-                for _ in 1 .. stepCount do
-                    world <- Sim.step ts world
-            this.CenterCamera()
+                this.OpenMainMenu()
+                leftGame <- true
+        if not loadFailed && not leftGame then
+            if lPressed then
+                relationView <- not relationView
+                if relationView then relationSnapshot <- Some(Sim.relationMatrix world)
+                let state = if relationView then "on" else "off"
+                printfn $"relation view={state} tick={world.Tick}"
+            let m5Command =
+                if pressed Keys.E then Some Interact
+                elif pressedAny [ Keys.D1; Keys.NumPad1 ] then Some Intent1
+                elif pressedAny [ Keys.D2; Keys.NumPad2 ] then Some Intent2
+                elif pressedAny [ Keys.D3; Keys.NumPad3 ] then Some Intent3
+                elif pressedAny [ Keys.D4; Keys.NumPad4 ] then Some Intent4
+                elif pressedAny [ Keys.D5; Keys.NumPad5 ] then Some Intent5
+                elif pressedAny [ Keys.D6; Keys.NumPad6 ] then Some Intent6
+                elif pressed Keys.Q then Some Observe
+                elif pressed Keys.Tab then Some ToggleNeeds
+                elif pressed Keys.C then Some ShowChronicle
+                else None
+            match m5Command with
+            | Some command ->
+                let nextWorld, nextView = M5Interaction.apply command world m5View
+                world <- nextWorld
+                m5View <- nextView
+                printfn $"m5 panel={M5Interaction.panelName m5View} status={m5View.Status} tick={world.Tick}"
+            | None -> ()
+            let panelOpen = m5View.Panel <> WorldPanel
+            if not relationView && not panelOpen then
+                let input =
+                    if automated then
+                        let t = float32 world.Tick
+                        { MoveX = MathF.Sin(t / 60.0f) * 0.8f
+                          MoveY = MathF.Cos(t / 90.0f) * 0.6f }
+                    else
+                        { MoveX =
+                            (if kb.IsKeyDown(Keys.D) then 1.0f
+                             elif kb.IsKeyDown(Keys.A) then -1.0f
+                             else 0.0f)
+                          MoveY =
+                            (if kb.IsKeyDown(Keys.S) then 1.0f
+                             elif kb.IsKeyDown(Keys.W) then -1.0f
+                             else 0.0f) }
+                let ts = { Input = input }
+                let stepCount = SimulationControl.stepsPerFrameWithLegacy legacyStepsPerFrame simulationControl
+                if stepCount > 0 then
+                    for _ in 1 .. stepCount do
+                        world <- Sim.step ts world
+                this.CenterCamera()
+
+    member private this.RunAutoplayFlow() =
+        let moveDown count =
+            for _ in 1 .. count do
+                this.DispatchMenuInput Down
+        match flowStep with
+        | 0 ->
+            printfn "flow=main-menu"
+            this.DispatchMenuInput Confirm
+            printfn "flow=new-game"
+            flowStep <- 1
+        | 1 when menu.Page = Playing ->
+            this.OpenMainMenu()
+            printfn "flow=return-menu"
+            flowStep <- 2
+        | 2 when menu.Page = MainMenu ->
+            moveDown 3
+            this.DispatchMenuInput Confirm
+            printfn "flow=settings=open"
+            this.DispatchMenuInput Down
+            this.DispatchMenuInput Confirm
+            this.DispatchMenuInput Back
+            printfn "flow=settings=back"
+            flowStep <- 3
+        | 3 when menu.Page = MainMenu ->
+            moveDown 4
+            this.DispatchMenuInput Confirm
+            printfn "flow=controls=open"
+            this.DispatchMenuInput Back
+            printfn "flow=controls=back"
+            flowStep <- 4
+        | 4 when menu.Page = MainMenu ->
+            this.DispatchMenuInput Confirm
+            this.SaveWorld "flow=save" |> ignore
+            flowStep <- 5
+        | 5 when menu.Page = Playing ->
+            this.LoadWorld "flow=load" |> ignore
+            flowStep <- 6
+        | 6 ->
+            this.OpenMainMenu()
+            printfn "flow=exit"
+            this.Exit()
+            flowStep <- 7
+        | _ -> ()
+
+    override this.Initialize() =
+        base.Initialize()
+        prevKb <- Keyboard.GetState()
+
+    override _.LoadContent() =
+        spriteBatch <- new SpriteBatch(this.GraphicsDevice)
+        atlas <- Atlas.build this.GraphicsDevice
+        pixel <- new Texture2D(this.GraphicsDevice, 1, 1)
+        pixel.SetData([| Color.White |])
+
+    override this.Update(gameTime: GameTime) =
+        let kb = Keyboard.GetState()
+        let pressed (key: Keys) = kb.IsKeyDown(key) && not (prevKb.IsKeyDown(key))
+        let pressedAny (keys: Keys list) = keys |> List.exists pressed
+        if autoplayFlow then
+            this.RunAutoplayFlow()
+        elif menu.Page = Playing then
+            this.UpdatePlaying gameTime kb pressed pressedAny
+        else
+            this.UpdateMenu pressed
         fpsFrames <- fpsFrames + 1
         fpsSeconds <- fpsSeconds + gameTime.ElapsedGameTime.TotalSeconds
         if fpsSeconds >= 1.0 then
@@ -305,8 +453,15 @@ type LivingVillageGame() as this =
                 | Day -> "DAY"
                 | Night -> "NIGHT"
             let viewTag = if relationView then " | [RELATIONS]" else ""
+            let pageName =
+                match menu.Page with
+                | MainMenu -> "MAIN MENU"
+                | Settings -> "SETTINGS"
+                | Controls -> "CONTROLS"
+                | Playing -> "PLAYING"
+                | LoadError -> "LOAD ERROR"
             this.Window.Title <-
-                $"Living Village M6{titleSuffix} | fps {fps:F1} | tick {world.Tick} | {dayNight} | {M6Presentation.clockLabel simulationControl} | npc {npcAction}{viewTag} | panel {M5Interaction.panelName m5View} | {M5Interaction.titleText m5View}"
+                $"Living Village M6{titleSuffix} | {pageName} | fps {fps:F1} | tick {world.Tick} | {dayNight} | {M6Presentation.clockLabel simulationControl} | npc {npcAction}{viewTag} | panel {M5Interaction.panelName m5View} | {M5Interaction.titleText m5View}"
             printfn $"fps={fps:F1} tick={world.Tick} pos=({world.Avatar.Pos.X:F0},{world.Avatar.Pos.Y:F0})"
         prevKb <- kb
 
@@ -350,12 +505,68 @@ type LivingVillageGame() as this =
         spriteBatch.End()
 
     override this.Draw(gameTime: GameTime) =
-        if relationView then
+        if menu.Page <> Playing then
+            this.DrawMenu()
+        elif relationView then
             this.DrawRelationView()
             this.DrawM5Overlay()
         else
             this.DrawWorldView()
 
+    member private this.DrawMenu() =
+        this.DrawWorldView()
+        let viewport = this.GraphicsDevice.Viewport
+        let width = viewport.Width
+        let height = viewport.Height
+        let panelWidth = min 720 (max 1 (width - 64))
+        let panelHeight = min 640 (max 1 (height - 48))
+        let panelX = (width - panelWidth) / 2
+        let panelY = (height - panelHeight) / 2
+        let innerX = panelX + 32
+        let textScale = 3
+        let lineHeight = 30
+        let selectedColor = Color(245, 222, 120)
+        let textColor = Color(210, 226, 220)
+        let mutedColor = Color(140, 170, 170)
+        let drawText (x: int) (y: int) (color: Color) (text: string) =
+            PixelText.draw spriteBatch pixel x y textScale color text
+        let drawSelection (index: int) (label: string) (y: int) =
+            let selected = index = menu.Selected
+            let prefix = if selected then ">" else " "
+            drawText innerX y (if selected then selectedColor else textColor) (sprintf "%s %s" prefix label)
+        spriteBatch.Begin()
+        spriteBatch.Draw(pixel, Rectangle(0, 0, width, height), Color(4, 9, 14, 190))
+        spriteBatch.Draw(pixel, Rectangle(panelX, panelY, panelWidth, panelHeight), Color(11, 19, 27, 245))
+        spriteBatch.Draw(pixel, Rectangle(panelX, panelY, panelWidth, 6), Color(92, 180, 190))
+        drawText innerX (panelY + 28) (Color(235, 246, 232)) "LIVING VILLAGE"
+        let contentY = panelY + 100
+        match menu.Page with
+        | MainMenu ->
+            drawText innerX (panelY + 70) mutedColor "MAIN MENU"
+            MenuState.items menu
+            |> List.iteri (fun index item -> drawSelection index (MenuState.itemLabel item) (contentY + index * lineHeight))
+            drawText innerX (panelY + panelHeight - 54) mutedColor "UP DOWN SELECT ENTER CONFIRM"
+        | Settings ->
+            drawText innerX (panelY + 70) mutedColor "SETTINGS"
+            MenuState.settings
+            |> List.iteri (fun index setting -> drawSelection index (MenuState.settingsLabel setting) (contentY + index * lineHeight))
+            drawText innerX (panelY + panelHeight - 84) mutedColor (sprintf "ACTIVE %s" (M6Presentation.clockLabel menu.Settings))
+            drawText innerX (panelY + panelHeight - 54) mutedColor "ENTER APPLY ESC BACK"
+        | Controls ->
+            drawText innerX (panelY + 70) mutedColor "CONTROLS"
+            MenuState.controlRows
+            |> List.iteri (fun index row ->
+                drawText innerX (contentY + index * 25) textColor (sprintf "%s %s" row.Keys row.Action))
+            drawText innerX (panelY + panelHeight - 28) mutedColor "ESC BACK"
+        | LoadError ->
+            drawText innerX (panelY + 70) (Color(240, 130, 120)) "LOAD ERROR"
+            let message = menu.Error |> Option.defaultValue "NO SAVE AVAILABLE" |> fun value -> value.ToUpperInvariant()
+            let visible = if message.Length > 34 then message.Substring(0, 34) else message
+            drawText innerX contentY textColor visible
+            drawText innerX (contentY + lineHeight * 2) mutedColor "ENTER OR ESC BACK"
+        | Playing -> ()
+        spriteBatch.End()
+
     member private this.DrawWorldView() =
         let profile = M6Presentation.profileAtTick world.Tick
         this.GraphicsDevice.Clear(profile.Background)