feat: add jetstream config validation models

src/NATS.Server/JetStream/Models/ConsumerConfig.cs

@@ -0,0 +1,18 @@
+namespace NATS.Server.JetStream.Models;
+
+public sealed class ConsumerConfig
+{
+    public string DurableName { get; set; } = string.Empty;
+    public string? FilterSubject { get; set; }
+    public AckPolicy AckPolicy { get; set; } = AckPolicy.None;
+    public int AckWaitMs { get; set; } = 30_000;
+    public int MaxDeliver { get; set; } = 1;
+    public bool Push { get; set; }
+    public int HeartbeatMs { get; set; }
+}
+
+public enum AckPolicy
+{
+    None,
+    Explicit,
+}

src/NATS.Server/JetStream/Models/StreamConfig.cs

@@ -0,0 +1,9 @@
+namespace NATS.Server.JetStream.Models;
+
+public sealed class StreamConfig
+{
+    public string Name { get; set; } = string.Empty;
+    public List<string> Subjects { get; set; } = [];
+    public int MaxMsgs { get; set; }
+    public int Replicas { get; set; } = 1;
+}

src/NATS.Server/JetStream/Validation/JetStreamConfigValidator.cs

@@ -0,0 +1,26 @@
+using NATS.Server.JetStream.Models;
+
+namespace NATS.Server.JetStream.Validation;
+
+public static class JetStreamConfigValidator
+{
+    public static ValidationResult Validate(StreamConfig config)
+        => string.IsNullOrWhiteSpace(config.Name) || config.Subjects.Count == 0
+            ? ValidationResult.Invalid("name/subjects required")
+            : ValidationResult.Valid();
+}
+
+public sealed class ValidationResult
+{
+    public bool IsValid { get; }
+    public string Message { get; }
+
+    private ValidationResult(bool isValid, string message)
+    {
+        IsValid = isValid;
+        Message = message;
+    }
+
+    public static ValidationResult Valid() => new(true, string.Empty);
+    public static ValidationResult Invalid(string message) => new(false, message);
+}

tests/NATS.Server.Tests/JetStreamConfigValidationTests.cs

@@ -0,0 +1,15 @@
+using NATS.Server.JetStream.Models;
+using NATS.Server.JetStream.Validation;
+
+namespace NATS.Server.Tests;
+
+public class JetStreamConfigValidationTests
+{
+    [Fact]
+    public void Stream_requires_name_and_subjects()
+    {
+        var config = new StreamConfig { Name = "", Subjects = [] };
+        var result = JetStreamConfigValidator.Validate(config);
+        result.IsValid.ShouldBeFalse();
+    }
+}