more audit work

src/__Libraries/StellaOps.HybridLogicalClock/InMemoryHlcStateStore.cs

@@ -4,8 +4,6 @@
 // Task: HLC-004 - Implement IHlcStateStore interface and InMemoryHlcStateStore
 // -----------------------------------------------------------------------------
 
-using System.Collections.Concurrent;
-
 namespace StellaOps.HybridLogicalClock;
 
 /// <summary>
@@ -17,7 +15,8 @@ namespace StellaOps.HybridLogicalClock;
 /// </remarks>
 public sealed class InMemoryHlcStateStore : IHlcStateStore
 {
-    private readonly ConcurrentDictionary<string, HlcTimestamp> _states = new(StringComparer.Ordinal);
+    private readonly Dictionary<string, HlcTimestamp> _states = new(StringComparer.Ordinal);
+    private readonly object _lock = new();
 
     /// <inheritdoc/>
     public Task<HlcTimestamp?> LoadAsync(string nodeId, CancellationToken ct = default)
@@ -25,10 +24,13 @@ public sealed class InMemoryHlcStateStore : IHlcStateStore
         ArgumentException.ThrowIfNullOrWhiteSpace(nodeId);
         ct.ThrowIfCancellationRequested();
 
-        return Task.FromResult(
-            _states.TryGetValue(nodeId, out var timestamp)
-                ? timestamp
-                : (HlcTimestamp?)null);
+        lock (_lock)
+        {
+            return Task.FromResult(
+                _states.TryGetValue(nodeId, out var timestamp)
+                    ? timestamp
+                    : (HlcTimestamp?)null);
+        }
     }
 
     /// <inheritdoc/>
@@ -36,14 +38,21 @@ public sealed class InMemoryHlcStateStore : IHlcStateStore
     {
         ct.ThrowIfCancellationRequested();
 
-        _states.AddOrUpdate(
-            timestamp.NodeId,
-            timestamp,
-            (_, existing) =>
+        lock (_lock)
+        {
+            if (_states.TryGetValue(timestamp.NodeId, out var existing))
             {
                 // Only update if new timestamp is greater (maintain monotonicity)
-                return timestamp > existing ? timestamp : existing;
-            });
+                if (timestamp > existing)
+                {
+                    _states[timestamp.NodeId] = timestamp;
+                }
+            }
+            else
+            {
+                _states[timestamp.NodeId] = timestamp;
+            }
+        }
 
         return Task.CompletedTask;
     }
@@ -52,10 +61,24 @@ public sealed class InMemoryHlcStateStore : IHlcStateStore
     /// Gets all stored states (for testing/debugging).
     /// </summary>
     public IReadOnlyDictionary<string, HlcTimestamp> GetAllStates() =>
-        new Dictionary<string, HlcTimestamp>(_states);
+        GetAllStatesSnapshot();
 
     /// <summary>
     /// Clears all stored states (for testing).
     /// </summary>
-    public void Clear() => _states.Clear();
+    public void Clear()
+    {
+        lock (_lock)
+        {
+            _states.Clear();
+        }
+    }
+
+    private IReadOnlyDictionary<string, HlcTimestamp> GetAllStatesSnapshot()
+    {
+        lock (_lock)
+        {
+            return new Dictionary<string, HlcTimestamp>(_states);
+        }
+    }
 }