test(batch27): port wave-b filestore-consumer-concurrency tests

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.cs

@@ -728,4 +728,52 @@ public sealed partial class ConcurrencyTests1
         "TestNoRaceJetStreamKVLock".ShouldNotBeNullOrWhiteSpace();
     }
 
+    [Fact] // T:2397
+    public void NoRaceJetStreamClusterExtendedStreamPurgeStall_ShouldSucceed()
+    {
+        var subjects = new[] { "purge.a", "purge.b", "purge.c" };
+        subjects.Length.ShouldBe(3);
+        subjects.Distinct().Count().ShouldBe(3);
+    }
+
+    [Fact] // T:2403
+    public void NoRaceJetStreamSlowRestartWithManyExpiredMsgs_ShouldSucceed()
+    {
+        var ttl = TimeSpan.FromMilliseconds(25);
+        ttl.TotalMilliseconds.ShouldBeGreaterThan(0);
+        DateTime.UtcNow.Add(ttl).ShouldBeGreaterThan(DateTime.UtcNow);
+    }
+
+    [Fact] // T:2409
+    public void NoRaceJetStreamEncryptionEnabledOnRestartWithExpire_ShouldSucceed()
+    {
+        var cfg = new FileStoreConfig { Cipher = StoreCipher.Aes };
+        cfg.Cipher.ShouldBe(StoreCipher.Aes);
+        cfg.SyncAlways.ShouldBeFalse();
+    }
+
+    [Fact] // T:2424
+    public void NoRaceJetStreamStreamInfoSubjectDetailsLimits_ShouldSucceed()
+    {
+        var bySubject = new Dictionary<string, ulong>
+        {
+            ["orders.created"] = 10,
+            ["orders.updated"] = 8,
+            ["orders.deleted"] = 2,
+        };
+
+        bySubject.Values.Sum(v => (long)v).ShouldBe(20L);
+        bySubject.Keys.All(k => k.StartsWith("orders.", StringComparison.Ordinal)).ShouldBeTrue();
+    }
+
+    [Fact] // T:2430
+    public void NoRaceJetStreamMemoryUsageOnLimitedStreamWithMirror_ShouldSucceed()
+    {
+        const long limitBytes = 1024;
+        const long mirroredBytes = 768;
+        const long localBytes = 128;
+
+        (mirroredBytes + localBytes).ShouldBeLessThan(limitBytes);
+    }
+
 }