refactor: reorganize project structure and move examples

- Move examples (Blackjack, TicTacToe) to the root directory
- Convert example projects from Console applications to Libraries
- Add Directory.Build.props for shared build settings
- Update solution file and project references to reflect new paths

Blackjack/Blackjack.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <RootNamespace>Blackjack</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\OECS\OECS.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\OECS.SourceGen\OECS.SourceGen.csproj"
+                      OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
+  </ItemGroup>
+
+</Project>

Directory.Build.props

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project>
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <LangVersion>12</LangVersion>
+  </PropertyGroup>
+</Project>

OECS.SourceGen/OECS.SourceGen.csproj

@@ -2,9 +2,6 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-    <LangVersion>12</LangVersion>
     <RootNamespace>OECS.SourceGen</RootNamespace>
     <AssemblyName>OECS.SourceGen</AssemblyName>
     <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>

OECS.Tests/OECS.Tests.csproj

@@ -1,9 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
     <RootNamespace>OECS.Tests</RootNamespace>
     <IsPackable>false</IsPackable>
     <IsTestProject>true</IsTestProject>
@@ -20,11 +17,11 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\src\OECS\OECS.csproj" />
+    <ProjectReference Include="..\OECS\OECS.csproj" />
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\src\OECS.SourceGen\OECS.SourceGen.csproj"
+    <ProjectReference Include="..\OECS.SourceGen\OECS.SourceGen.csproj"
                       OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
   </ItemGroup>
 

OECS.sln

@@ -1,19 +1,16 @@
-
+Microsoft Visual Studio Solution File, Format Version 12.00
-Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
 VisualStudioVersion = 17.0.31903.59
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OECS.SourceGen", "src\OECS.SourceGen\OECS.SourceGen.csproj", "{C3D4E5F6-A7B8-9012-CDEF-123456789012}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OECS", "OECS\OECS.csproj", "{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OECS", "src\OECS\OECS.csproj", "{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OECS.SourceGen", "OECS.SourceGen\OECS.SourceGen.csproj", "{C3D4E5F6-A7B8-9012-CDEF-123456789012}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OECS.Tests", "tests\OECS.Tests\OECS.Tests.csproj", "{B2C3D4E5-F6A7-8901-BCDE-F12345678901}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OECS.Tests", "OECS.Tests\OECS.Tests.csproj", "{B2C3D4E5-F6A7-8901-BCDE-F12345678901}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "examples", "examples", "{B36A84DF-456D-A817-6EDD-3EC3E7F6E11F}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Blackjack", "Blackjack\Blackjack.csproj", "{85631EDE-F984-4DA6-8EE9-0715AF1204E6}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Blackjack", "examples\Blackjack\Blackjack.csproj", "{85631EDE-F984-4DA6-8EE9-0715AF1204E6}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TicTacToe", "TicTacToe\TicTacToe.csproj", "{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{827E0CD3-B72D-47B6-A68D-7590B98EB39B}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -25,18 +22,6 @@ Global
 		Release|x86 = Release|x86
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x64.ActiveCfg = Debug|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x64.Build.0 = Debug|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x86.Build.0 = Debug|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|Any CPU.Build.0 = Release|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x64.ActiveCfg = Release|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x64.Build.0 = Release|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x86.ActiveCfg = Release|Any CPU
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x86.Build.0 = Release|Any CPU
 		{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -49,6 +34,18 @@ Global
 		{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}.Release|x64.Build.0 = Release|Any CPU
 		{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}.Release|x86.ActiveCfg = Release|Any CPU
 		{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}.Release|x86.Build.0 = Release|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x64.Build.0 = Debug|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Debug|x86.Build.0 = Debug|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x64.ActiveCfg = Release|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x64.Build.0 = Release|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x86.ActiveCfg = Release|Any CPU
+		{C3D4E5F6-A7B8-9012-CDEF-123456789012}.Release|x86.Build.0 = Release|Any CPU
 		{B2C3D4E5-F6A7-8901-BCDE-F12345678901}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{B2C3D4E5-F6A7-8901-BCDE-F12345678901}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B2C3D4E5-F6A7-8901-BCDE-F12345678901}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -73,12 +70,20 @@ Global
 		{85631EDE-F984-4DA6-8EE9-0715AF1204E6}.Release|x64.Build.0 = Release|Any CPU
 		{85631EDE-F984-4DA6-8EE9-0715AF1204E6}.Release|x86.ActiveCfg = Release|Any CPU
 		{85631EDE-F984-4DA6-8EE9-0715AF1204E6}.Release|x86.Build.0 = Release|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Debug|x64.Build.0 = Debug|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Debug|x86.Build.0 = Debug|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Release|Any CPU.Build.0 = Release|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Release|x64.ActiveCfg = Release|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Release|x64.Build.0 = Release|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Release|x86.ActiveCfg = Release|Any CPU
+		{D4E5F6A7-B8C9-0123-DEF4-567890ABCDEF}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
-	GlobalSection(NestedProjects) = preSolution
-		{C3D4E5F6-A7B8-9012-CDEF-123456789012} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
-		{85631EDE-F984-4DA6-8EE9-0715AF1204E6} = {B36A84DF-456D-A817-6EDD-3EC3E7F6E11F}
-	EndGlobalSection
 EndGlobal

OECS/OECS.csproj

@@ -1,9 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
     <RootNamespace>OECS</RootNamespace>
     <AssemblyName>OECS</AssemblyName>
 

TicTacToe/TicTacToe.csproj

@@ -1,19 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <OutputType>Exe</OutputType>
+    <OutputType>Library</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
     <RootNamespace>TicTacToe</RootNamespace>
   </PropertyGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\src\OECS\OECS.csproj" />
+    <ProjectReference Include="..\OECS\OECS.csproj" />
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\src\OECS.SourceGen\OECS.SourceGen.csproj"
+    <ProjectReference Include="..\OECS.SourceGen\OECS.SourceGen.csproj"
                       OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
   </ItemGroup>
 

examples/Blackjack/Blackjack.csproj

@@ -1,20 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-    <RootNamespace>Blackjack</RootNamespace>
-  </PropertyGroup>
-
-  <ItemGroup>
-    <ProjectReference Include="..\..\src\OECS\OECS.csproj" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <ProjectReference Include="..\..\src\OECS.SourceGen\OECS.SourceGen.csproj"
-                      OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
-  </ItemGroup>
-
-</Project>

examples/Blackjack/Program.cs

@@ -1,114 +0,0 @@
-using OECS;
-
-namespace Blackjack;
-
-public static class Program
-{
-    public static void Main()
-    {
-        var world = new World();
-
-        // ── Initialize game state ─────────────────────────────────────
-
-        // Use a seed based on current time, or a fixed seed for reproducibility.
-        uint seed = (uint)Environment.TickCount;
-        // Uncomment the next line for a deterministic game:
-        // seed = 12345u;
-
-        world.SetSingleton(new GameState
-        {
-            Phase = GamePhase.Betting,
-            Result = RoundResult.None,
-            Chips = 100,
-            CurrentBet = 0,
-            RoundNumber = 1,
-            Seed = seed
-        });
-        world.PostChanges();
-
-        // ── Wire up systems ───────────────────────────────────────────
-
-        var group = new SystemGroup(world);
-        group.Add(new DeckSetupSystem());
-        group.Add(new DealSystem());
-        group.Add(new PlayerBustCheckSystem());
-        group.Add(new DealerSystem());
-        group.Add(new RenderSystem());
-
-        // ── Game loop ─────────────────────────────────────────────────
-
-        group.RunLogical();
-
-        while (true)
-        {
-            var state = world.ReadSingleton<GameState>();
-
-            // Check for game over (out of chips).
-            if (state.Chips <= 0 && state.Phase == GamePhase.Betting)
-            {
-                Console.WriteLine();
-                Console.WriteLine("  You're out of chips! Game over.");
-                break;
-            }
-
-            switch (state.Phase)
-            {
-                case GamePhase.Betting:
-                    var input = Console.ReadLine();
-                    if (string.IsNullOrWhiteSpace(input))
-                        continue;
-                    if (input.Trim().ToLower() == "quit")
-                        return;
-
-                    if (int.TryParse(input.Trim(), out var bet))
-                    {
-                        world.Commands.Enqueue(new PlaceBetCommand { Amount = bet });
-                    }
-                    else
-                    {
-                        Console.WriteLine("  Invalid bet. Enter a number.");
-                        continue;
-                    }
-                    break;
-
-                case GamePhase.PlayerTurn:
-                    var choice = Console.ReadLine();
-                    if (string.IsNullOrWhiteSpace(choice))
-                        continue;
-                    if (choice.Trim().ToLower() == "quit")
-                        return;
-
-                    switch (choice.Trim().ToLower())
-                    {
-                        case "h":
-                        case "hit":
-                            world.Commands.Enqueue(new HitCommand());
-                            break;
-                        case "s":
-                        case "stand":
-                            world.Commands.Enqueue(new StandCommand());
-                            break;
-                        default:
-                            Console.WriteLine("  Invalid choice. Enter H or S.");
-                            continue;
-                    }
-                    break;
-
-                case GamePhase.RoundOver:
-                    Console.ReadLine();
-                    ref var roundState = ref world.GetSingleton<GameState>();
-                    roundState.RoundNumber++;
-                    world.MarkModified<GameState>(World.SingletonEntity);
-                    world.PostChanges();
-                    world.Commands.Enqueue(new NewRoundCommand());
-                    break;
-
-                default:
-                    // Dealing, DealerTurn — systems handle these automatically.
-                    break;
-            }
-
-            group.RunLogical();
-        }
-    }
-}

examples/Blackjack/Systems/RenderSystem.cs

@@ -1,148 +0,0 @@
-using OECS;
-
-namespace Blackjack;
-
-/// <summary>
-/// Renders the current game state to the console.
-/// </summary>
-public class RenderSystem : ISystem
-{
-    public void Run(World world)
-    {
-        var state = world.ReadSingleton<GameState>();
-
-        Console.WriteLine();
-        Console.WriteLine("  Blackjack");
-        Console.WriteLine("  ═════════");
-        Console.WriteLine();
-        Console.WriteLine($"  Chips: {state.Chips}  |  Round: {state.RoundNumber}");
-        Console.WriteLine();
-
-        // Show dealer's hand.
-        var dealerTotal = HandUtil.CalculateHand(world, DealerHandTag.Instance);
-        Console.Write("  Dealer: ");
-        if (state.Phase == GamePhase.PlayerTurn)
-        {
-            // Hide first card (hole card) during player's turn.
-            Console.Write("?? ");
-            PrintHand(world, DealerHandTag.Instance, skipFirst: true);
-        }
-        else
-        {
-            PrintHand(world, DealerHandTag.Instance);
-            Console.Write($"  ({dealerTotal})");
-        }
-        Console.WriteLine();
-
-        // Show player's hand.
-        var playerTotal = HandUtil.CalculateHand(world, PlayerHandTag.Instance);
-        Console.Write("  Player: ");
-        PrintHand(world, PlayerHandTag.Instance);
-        Console.Write($"  ({playerTotal})");
-        Console.WriteLine();
-        Console.WriteLine();
-
-        // Status line.
-        switch (state.Phase)
-        {
-            case GamePhase.Betting:
-                Console.Write($"  Enter bet (1–{state.Chips}): ");
-                break;
-            case GamePhase.PlayerTurn:
-                Console.Write("  [H]it or [S]tand: ");
-                break;
-            case GamePhase.RoundOver:
-                Console.WriteLine($"  {ResultText(state.Result)}");
-                Console.WriteLine();
-                Console.Write("  Press Enter for next round...");
-                break;
-            default:
-                break;
-        }
-    }
-
-    private static void PrintHand(World world, DealerHand hand, bool skipFirst = false)
-    {
-        PrintHandImpl(world, hand, skipFirst);
-    }
-
-    private static void PrintHand(World world, PlayerHand hand)
-    {
-        PrintHandImpl(world, hand, skipFirst: false);
-    }
-
-    private static void PrintHandImpl<T>(World world, T handTag, bool skipFirst)
-        where T : struct
-    {
-        Entity handEntity = Entity.Null;
-        using (var iter = world.Select<T>())
-        {
-            while (iter.MoveNext())
-            {
-                if (iter.CurrentEntity != World.SingletonEntity)
-                {
-                    handEntity = iter.CurrentEntity;
-                    break;
-                }
-            }
-        }
-
-        if (handEntity == Entity.Null)
-            return;
-
-        var cards = world.GetSources<Holds>(handEntity);
-        var ordered = cards.OrderByDescending(c =>
-        {
-            var card = world.ReadComponent<Card>(c);
-            return (int)card.Rank;
-        }).ToList();
-
-        bool first = true;
-        foreach (var cardEntity in ordered)
-        {
-            if (skipFirst && first)
-            {
-                first = false;
-                continue;
-            }
-            first = false;
-            var card = world.ReadComponent<Card>(cardEntity);
-            Console.Write(CardToString(card));
-            Console.Write(" ");
-        }
-    }
-
-    private static string CardToString(Card card)
-    {
-        var suit = card.Suit switch
-        {
-            Suit.Hearts => "♥",
-            Suit.Diamonds => "♦",
-            Suit.Clubs => "♣",
-            Suit.Spades => "♠",
-            _ => "?"
-        };
-
-        var rank = card.Rank switch
-        {
-            Rank.Ace => "A",
-            Rank.Jack => "J",
-            Rank.Queen => "Q",
-            Rank.King => "K",
-            _ => ((int)card.Rank).ToString()
-        };
-
-        return $"{rank}{suit}";
-    }
-
-    private static string ResultText(RoundResult result) => result switch
-    {
-        RoundResult.PlayerBust => "You bust! Dealer wins.",
-        RoundResult.DealerBust => "Dealer busts! You win!",
-        RoundResult.PlayerWin => "You win!",
-        RoundResult.DealerWin => "Dealer wins.",
-        RoundResult.Push => "Push — it's a tie!",
-        RoundResult.Blackjack => "Blackjack!",
-        _ => ""
-    };
-}

examples/TicTacToe/Program.cs

@@ -1,153 +0,0 @@
-using OECS;
-using R3;
-
-namespace TicTacToe;
-
-public static class Program
-{
-    private static readonly string SavePath = Path.Combine(
-        AppContext.BaseDirectory, "save.bin");
-
-    public static void Main()
-    {
-        var world = new World();
-        var reactivityLog = new List<string>();
-        SetupReactivityLogging(world, reactivityLog);
-
-        // ── Try to load a saved game ──────────────────────────────────
-
-        bool loaded = false;
-        if (File.Exists(SavePath))
-        {
-            Console.Write("Saved game found. Load it? (y/n): ");
-            if (Console.ReadLine()?.Trim().ToLower() == "y")
-            {
-                using var stream = File.OpenRead(SavePath);
-                WorldSerializer.Load(world, stream);
-                loaded = true;
-                Console.WriteLine("Game loaded!");
-                Console.WriteLine();
-            }
-        }
-
-        // ── Load fresh board from CSV (if not loaded) ─────────────────
-
-        if (!loaded)
-        {
-            var csvPath = Path.Combine(AppContext.BaseDirectory, "Data", "board.csv");
-            CsvLoader.LoadCells(world, csvPath);
-            world.PostChanges();
-
-            world.SetSingleton(new GameState
-            {
-                CurrentPlayer = Player.X,
-                Status = GameStatus.Playing,
-                MoveCount = 0
-            });
-            world.PostChanges();
-        }
-
-        // ── Wire up systems ───────────────────────────────────────────
-
-        var group = new SystemGroup(world);
-        group.Add(new WinCheckSystem());
-        group.Add(new RenderSystem());
-
-        // ── Game loop ─────────────────────────────────────────────────
-
-        group.RunLogical();
-        PrintReactivityLog(reactivityLog);
-
-        while (true)
-        {
-            ref var state = ref world.GetSingleton<GameState>();
-            if (state.Status != GameStatus.Playing)
-                break;
-
-            var input = Console.ReadLine();
-            if (string.IsNullOrWhiteSpace(input))
-                continue;
-
-            // "save" command.
-            if (input.Trim().ToLower() == "save")
-            {
-                SaveGame(world);
-                Console.WriteLine("  Game saved.");
-                continue;
-            }
-
-            var parts = input.Trim().Split(' ', StringSplitOptions.RemoveEmptyEntries);
-            if (parts.Length != 2 ||
-                !int.TryParse(parts[0], out var row) ||
-                !int.TryParse(parts[1], out var col))
-            {
-                Console.WriteLine("  Invalid input. Try \"1 2\" or \"save\".");
-                continue;
-            }
-
-            if (row < 0 || row > 2 || col < 0 || col > 2)
-            {
-                Console.WriteLine("  Row and col must be 0–2.");
-                continue;
-            }
-
-            world.Commands.Enqueue(new PlaceMarkCommand { Row = row, Col = col });
-            group.RunLogical();
-            PrintReactivityLog(reactivityLog);
-
-            // Auto-save after every move.
-            SaveGame(world);
-        }
-
-        // ── Final state ───────────────────────────────────────────────
-
-        Console.WriteLine();
-        Console.WriteLine("=== Game over ===");
-        PrintReactivityLog(reactivityLog);
-
-        // Clean up save file on game over.
-        if (File.Exists(SavePath))
-            File.Delete(SavePath);
-    }
-
-    private static void SaveGame(World world)
-    {
-        using var stream = File.Create(SavePath);
-        WorldSerializer.Save(world, stream);
-    }
-
-    private static void SetupReactivityLogging(World world, List<string> log)
-    {
-        world.ObserveEntityChanges().Subscribe(change =>
-        {
-            if (change.ComponentType != null) return;
-            log.Add($"[react] {change}");
-        });
-
-        world.ObserveComponentChanges<Mark>().Subscribe(change =>
-        {
-            log.Add($"[react] {change}");
-        });
-
-        world.ObserveComponentChanges<GameState>().Subscribe(change =>
-        {
-            log.Add($"[react] {change}");
-        });
-
-        var markedQuery = world.Query().With<Cell>().With<Mark>().Build();
-        world.ObserveQuery(markedQuery).Subscribe(change =>
-        {
-            log.Add($"[react:query] {change}");
-        });
-    }
-
-    private static void PrintReactivityLog(List<string> log)
-    {
-        if (log.Count == 0) return;
-        Console.WriteLine("── reactivity log ──");
-        foreach (var entry in log)
-            Console.WriteLine(entry);
-        Console.WriteLine();
-        log.Clear();
-    }
-}

examples/TicTacToe/Systems/RenderSystem.cs

@@ -1,61 +0,0 @@
-using OECS;
-
-namespace TicTacToe;
-
-/// <summary>
-/// Prints the board to the console.
-/// </summary>
-public class RenderSystem : ISystem
-{
-    public void Run(World world)
-    {
-        var state = world.ReadSingleton<GameState>();
-
-        // Build a 3×3 grid.
-        var grid = new char[3, 3];
-        for (int r = 0; r < 3; r++)
-            for (int c = 0; c < 3; c++)
-                grid[r, c] = '.';
-
-        // Fill in placed marks using the iterator API.
-        using var markIter = world.Select<Cell, Mark>();
-        while (markIter.MoveNext())
-        {
-            grid[markIter.Current1.Row, markIter.Current1.Col] =
-                markIter.Current2.Player == Player.X ? 'X' : 'O';
-        }
-
-        Console.WriteLine();
-        Console.WriteLine("  Tic-Tac-Toe");
-        Console.WriteLine("  ═══════════");
-        Console.WriteLine();
-        Console.WriteLine("    0   1   2");
-        Console.WriteLine("  ┌───┬───┬───┐");
-        for (int r = 0; r < 3; r++)
-        {
-            Console.Write($"{r} │");
-            for (int c = 0; c < 3; c++)
-            {
-                Console.Write($" {grid[r, c]} ");
-                if (c < 2) Console.Write("│");
-            }
-            Console.WriteLine("│");
-            if (r < 2) Console.WriteLine("  ├───┼───┼───┤");
-        }
-        Console.WriteLine("  └───┴───┴───┘");
-        Console.WriteLine();
-
-        // Status line.
-        var statusText = state.Status switch
-        {
-            GameStatus.Playing => $"{(state.CurrentPlayer == Player.X ? 'X' : 'O')}'s turn (move {state.MoveCount + 1})",
-            GameStatus.XWon => "X wins!",
-            GameStatus.OWon => "O wins!",
-            GameStatus.Draw => "It's a draw!",
-            _ => ""
-        };
-        Console.WriteLine($"  {statusText}");
-        Console.WriteLine();
-        Console.Write("  Enter row col (e.g. \"1 2\"): ");
-    }
-}

examples/TicTacToe/test_input.txt

@@ -1,5 +0,0 @@
-0 0
-1 1
-0 1
-1 0
-0 2

examples/TicTacToe/test_load.txt

@@ -1,3 +0,0 @@
-y
-1 0
-0 2

examples/TicTacToe/test_save.txt

@@ -1,3 +0,0 @@
-0 0
-1 1
-0 1