fix: resolve 19 JetStream test failures across 5 root causes

- HandleList: populate StreamNames/ConsumerNames alongside info lists
- ValidateConfigUpdate: allow clearing mirror/sources, accept even replicas
- ToWireFormat: add AccountInfo branch for $JS.API.INFO responses
- UpdateStream fixture: preserve existing retention policy on update
- Integration test: fix assertion to match valid account info response

NatsDotNet.slnx

@@ -17,5 +17,6 @@
     <Project Path="tests/NATS.Server.JetStream.Tests/NATS.Server.JetStream.Tests.csproj" />
     <Project Path="tests/NATS.E2E.Tests/NATS.E2E.Tests.csproj" />
     <Project Path="tests/NATS.E2E.Cluster.Tests/NATS.E2E.Cluster.Tests.csproj" />
+    <Project Path="tests/NATS.Server.Benchmark.Tests/NATS.Server.Benchmark.Tests.csproj" />
   </Folder>
 </Solution>

src/NATS.Server/JetStream/Api/Handlers/ConsumerApiHandlers.cs

@@ -82,6 +82,7 @@ public static class ConsumerApiHandlers
         return new JetStreamApiResponse
         {
             ConsumerInfoList = page,
+            ConsumerNames = page.Select(c => c.Name ?? string.Empty).ToList(),
             PaginationTotal = all.Count,
             PaginationOffset = offset,
         };

src/NATS.Server/JetStream/Api/Handlers/StreamApiHandlers.cs

@@ -123,6 +123,7 @@ public static class StreamApiHandlers
         return new JetStreamApiResponse
         {
             StreamInfoList = page,
+            StreamNames = page.Select(s => s.Config.Name).ToList(),
             PaginationTotal = all.Count,
             PaginationOffset = offset,
         };

src/NATS.Server/JetStream/Api/JetStreamApiResponse.cs

@@ -77,6 +77,16 @@ public sealed class JetStreamApiResponse
         if (Error != null)
             return new { error = Error };
 
+        if (AccountInfo != null)
+        {
+            return new
+            {
+                type = "io.nats.jetstream.api.v1.account_info_response",
+                streams = AccountInfo.Streams,
+                consumers = AccountInfo.Consumers,
+            };
+        }
+
         if (StreamInfoList != null)
         {
             var wireStreams = StreamInfoList.Select(s => new

src/NATS.Server/JetStream/StreamManager.cs

@@ -565,15 +565,20 @@ public sealed class StreamManager : IDisposable
         if (existing.Storage != proposed.Storage)
             errors.Add("storage type cannot be changed");
 
-        // Mirror is immutable — if the existing stream has a mirror, the proposed must keep it.
+        // Mirror is immutable — if both have a mirror it must match. Clearing a mirror
+        // (promoting to normal stream) is allowed after the origin is deleted.
+        // Go reference: server/stream.go — update allows clearing mirror for promotion.
         if (!string.IsNullOrWhiteSpace(existing.Mirror)
+            && !string.IsNullOrWhiteSpace(proposed.Mirror)
             && !string.Equals(existing.Mirror, proposed.Mirror, StringComparison.Ordinal))
         {
             errors.Add("mirror configuration cannot be changed");
         }
 
-        // Sources are immutable after creation — the set of source names must be unchanged.
+        // Sources: changing to a different non-empty set is not allowed, but clearing
-        if (existing.Sources.Count > 0)
+        // sources (removing all) or adding sources to a previously source-less stream is permitted.
+        // Go reference: server/stream.go — update allows adding/removing sources.
+        if (existing.Sources.Count > 0 && proposed.Sources.Count > 0)
         {
             var existingNames = existing.Sources.Select(s => s.Name).OrderBy(n => n, StringComparer.Ordinal).ToList();
             var proposedNames = proposed.Sources.Select(s => s.Name).OrderBy(n => n, StringComparer.Ordinal).ToList();
@@ -592,10 +597,6 @@ public sealed class StreamManager : IDisposable
             errors.Add("max consumers can only be increased");
         }
 
-        // Replicas must be odd (for RAFT consensus).
-        if (proposed.Replicas > 1 && proposed.Replicas % 2 == 0)
-            errors.Add("replicas must be odd for RAFT consensus");
-
         // Subject overlap detection with peer streams.
         if (otherStreams is not null && proposed.Subjects.Count > 0)
         {

tests/NATS.Server.JetStream.Tests/JetStream/Streams/ConfigUpdateValidationTests.cs

@@ -278,10 +278,10 @@ public class ConfigUpdateValidationTests
         errors.ShouldBeEmpty();
     }
 
-    // Go ref: server/stream.go — RAFT consensus requires an odd number of replicas.
+    // Go ref: server/stream.go — Go server supports even replica counts (e.g., R2).
-    // Setting replicas to an even number must be rejected.
+    // Even replicas should be accepted by config update validation.
     [Fact]
-    public void ValidateConfigUpdate_rejects_even_replicas()
+    public void ValidateConfigUpdate_accepts_even_replicas()
     {
         var existing = new StreamConfig
         {
@@ -300,7 +300,7 @@ public class ConfigUpdateValidationTests
 
         var errors = StreamManager.ValidateConfigUpdate(existing, proposed);
 
-        errors.ShouldContain(e => e.Contains("replicas must be odd"));
+        errors.ShouldBeEmpty();
     }
 
     // Go ref: server/stream.go:1500-1600 (stream.update) — integration via StreamManager.

tests/NATS.Server.JetStream.Tests/JetStreamApiProtocolIntegrationTests.cs

@@ -12,7 +12,7 @@ public class JetStreamApiProtocolIntegrationTests
         await using var server = await ServerFixture.StartJetStreamEnabledAsync();
         var response = await server.RequestAsync("$JS.API.INFO", "{}", timeoutMs: 1000);
 
-        response.ShouldContain("\"error\"");
+        response.ShouldContain("\"streams\"");
     }
 }
 

tests/NATS.Server.TestUtilities/JetStreamClusterFixture.cs

@@ -121,13 +121,22 @@ public sealed class JetStreamClusterFixture : IAsyncDisposable
     /// Go ref: updateStream in jetstream_helpers_test.go.
     /// </summary>
     public JetStreamApiResponse UpdateStream(string name, string[] subjects, int replicas, int maxMsgs = 0)
-        => _streamManager.CreateOrUpdate(new StreamConfig
+    {
+        // Preserve the existing stream's retention policy so ValidateConfigUpdate
+        // does not reject the update for changing an immutable field.
+        var retention = RetentionPolicy.Limits;
+        if (_streamManager.TryGet(name, out var existing))
+            retention = existing.Config.Retention;
+
+        return _streamManager.CreateOrUpdate(new StreamConfig
         {
             Name = name,
             Subjects = [.. subjects],
             Replicas = replicas,
             MaxMsgs = maxMsgs,
+            Retention = retention,
         });
+    }
 
     /// <summary>
     /// Returns the full stream info response.