feat(gamecli): add JSON protocol DTOs with source-gen context

GameCli.Tests/ProtocolTests.cs

@@ -0,0 +1,81 @@
+using System.Text.Json;
+using GameCli;
+using Xunit;
+
+namespace GameCli.Tests;
+
+public class ProtocolTests
+{
+    [Fact]
+    public void StepInput_ParsesActionAndTarget()
+    {
+        var json = """{"action":2,"target":[0.35,0.60]}""";
+        var input = JsonSerializer.Deserialize(json, ProtocolJsonContext.Default.StepInput);
+        Assert.NotNull(input);
+        Assert.Equal(2, input!.Action);
+        Assert.NotNull(input.Target);
+        Assert.Equal(0.35f, input.Target![0]);
+        Assert.Equal(0.60f, input.Target![1]);
+        Assert.Null(input.Cmd);
+    }
+
+    [Fact]
+    public void StepInput_ParsesResetCommand()
+    {
+        var json = """{"cmd":"reset","seed":12345}""";
+        var input = JsonSerializer.Deserialize(json, ProtocolJsonContext.Default.StepInput);
+        Assert.NotNull(input);
+        Assert.Equal("reset", input!.Cmd);
+        Assert.Equal(12345, input.Seed);
+    }
+
+    [Fact]
+    public void StepInput_ParsesResetCommandWithoutSeed()
+    {
+        var json = """{"cmd":"reset"}""";
+        var input = JsonSerializer.Deserialize(json, ProtocolJsonContext.Default.StepInput);
+        Assert.NotNull(input);
+        Assert.Equal("reset", input!.Cmd);
+        Assert.Null(input.Seed);
+    }
+
+    [Fact]
+    public void StepOutput_SerializesAllFields()
+    {
+        var output = new StepOutput
+        {
+            Obs = new[] { 0.1f, 0.2f, 0.3f, 0.4f, 0.5f, 0.6f, 0.7f },
+            State = new ShipStateDto { X = 0.5f, Y = 0.6f, Angle = 0.1f, Engine = 2 },
+            Reward = -0.42f,
+            Done = false,
+            Step = 137,
+        };
+        var json = JsonSerializer.Serialize(output, ProtocolJsonContext.Default.StepOutput);
+        Assert.Contains("\"obs\":", json);
+        Assert.Contains("\"state\":", json);
+        Assert.Contains("\"reward\":", json);
+        Assert.Contains("\"done\":false", json);
+        Assert.Contains("\"step\":137", json);
+        Assert.Contains("\"engine\":2", json);
+    }
+
+    [Fact]
+    public void InitMessage_SerializesExpectedShape()
+    {
+        var init = new InitMessage
+        {
+            Init = new InitPayload
+            {
+                World = new[] { 1.0f, 1.0f },
+                Dt = 0.02f,
+                ObsDim = 7,
+                NActions = 4,
+            },
+        };
+        var json = JsonSerializer.Serialize(init, ProtocolJsonContext.Default.InitMessage);
+        Assert.Contains("\"world\":[1,1]", json);
+        Assert.Contains("\"dt\":0.02", json);
+        Assert.Contains("\"obs_dim\":7", json);
+        Assert.Contains("\"n_actions\":4", json);
+    }
+}