feat: add auth fields to ServerInfo and ClientOptions protocol types

src/NATS.Server/Protocol/NatsProtocol.cs

@@ -26,6 +26,10 @@ public static class NatsProtocol
     public const string ErrMaxPayloadViolation = "Maximum Payload Violation";
     public const string ErrInvalidPublishSubject = "Invalid Publish Subject";
     public const string ErrInvalidSubject = "Invalid Subject";
+    public const string ErrAuthorizationViolation = "Authorization Violation";
+    public const string ErrAuthTimeout = "Authentication Timeout";
+    public const string ErrPermissionsPublish = "Permissions Violation for Publish";
+    public const string ErrPermissionsSubscribe = "Permissions Violation for Subscription";
 }
 
 public sealed class ServerInfo
@@ -61,6 +65,14 @@ public sealed class ServerInfo
     [JsonPropertyName("client_ip")]
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     public string? ClientIp { get; set; }
+
+    [JsonPropertyName("auth_required")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
+    public bool AuthRequired { get; set; }
+
+    [JsonPropertyName("nonce")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? Nonce { get; set; }
 }
 
 public sealed class ClientOptions
@@ -91,4 +103,19 @@ public sealed class ClientOptions
 
     [JsonPropertyName("no_responders")]
     public bool NoResponders { get; set; }
+
+    [JsonPropertyName("user")]
+    public string? Username { get; set; }
+
+    [JsonPropertyName("pass")]
+    public string? Password { get; set; }
+
+    [JsonPropertyName("auth_token")]
+    public string? Token { get; set; }
+
+    [JsonPropertyName("nkey")]
+    public string? Nkey { get; set; }
+
+    [JsonPropertyName("sig")]
+    public string? Sig { get; set; }
 }

tests/NATS.Server.Tests/AuthProtocolTests.cs

@@ -0,0 +1,56 @@
+using System.Text.Json;
+using NATS.Server.Protocol;
+
+namespace NATS.Server.Tests;
+
+public class AuthProtocolTests
+{
+    [Fact]
+    public void ClientOptions_deserializes_auth_fields()
+    {
+        var json = """{"user":"alice","pass":"secret","auth_token":"mytoken","nkey":"UABC","sig":"base64sig"}""";
+        var opts = JsonSerializer.Deserialize<ClientOptions>(json);
+
+        opts.ShouldNotBeNull();
+        opts.Username.ShouldBe("alice");
+        opts.Password.ShouldBe("secret");
+        opts.Token.ShouldBe("mytoken");
+        opts.Nkey.ShouldBe("UABC");
+        opts.Sig.ShouldBe("base64sig");
+    }
+
+    [Fact]
+    public void ServerInfo_serializes_auth_required_and_nonce()
+    {
+        var info = new ServerInfo
+        {
+            ServerId = "test",
+            ServerName = "test",
+            Version = "0.1.0",
+            Host = "127.0.0.1",
+            Port = 4222,
+            AuthRequired = true,
+            Nonce = "abc123",
+        };
+
+        var json = JsonSerializer.Serialize(info);
+        json.ShouldContain("\"auth_required\":true");
+        json.ShouldContain("\"nonce\":\"abc123\"");
+    }
+
+    [Fact]
+    public void ServerInfo_omits_nonce_when_null()
+    {
+        var info = new ServerInfo
+        {
+            ServerId = "test",
+            ServerName = "test",
+            Version = "0.1.0",
+            Host = "127.0.0.1",
+            Port = 4222,
+        };
+
+        var json = JsonSerializer.Serialize(info);
+        json.ShouldNotContain("nonce");
+    }
+}