.NET: Honor disabled recent search memory (#9013)

Co-authored-by: LEN5010 <191021661+LEN5010@users.noreply.github.com>

Author: LEN5010

dotnet/src/Microsoft.Agents.AI/TextSearchProvider.cs

@@ -150,9 +150,10 @@ protected override ValueTask<IEnumerable<ChatMessage>> InvokingCoreAsync(Invokin
     /// <inheritdoc />
     protected override async ValueTask<IEnumerable<ChatMessage>> ProvideMessagesAsync(InvokingContext context, CancellationToken cancellationToken = default)
     {
-        // Retrieve recent messages from the session state.
-        var recentMessagesText = this._sessionState.GetOrInitializeState(context.Session).RecentMessagesText
-            ?? [];
+        // Retrieve recent messages from the session state only when memory is enabled.
+        var recentMessagesText = this._recentMessageMemoryLimit > 0
+            ? this._sessionState.GetOrInitializeState(context.Session).RecentMessagesText ?? []
+            : [];
 
         // Aggregate text from memory + current request messages.
         var sbInput = new StringBuilder();

dotnet/tests/Microsoft.Agents.AI.UnitTests/Data/TextSearchProviderTests.cs

@@ -602,6 +602,79 @@ public async Task InvokedAsync_CustomStorageInputFilter_OverridesDefaultAsync()
 
     #region Recent Message Memory Tests
 
+    [Theory]
+    [InlineData(false, false, false, 0)]
+    [InlineData(false, false, false, 2)]
+    [InlineData(false, false, true, 0)]
+    [InlineData(false, false, true, 2)]
+    [InlineData(false, true, false, 0)]
+    [InlineData(false, true, false, 2)]
+    [InlineData(false, true, true, 0)]
+    [InlineData(false, true, true, 2)]
+    [InlineData(true, false, false, 0)]
+    [InlineData(true, false, false, 2)]
+    [InlineData(true, false, true, 0)]
+    [InlineData(true, false, true, 2)]
+    [InlineData(true, true, false, 0)]
+    [InlineData(true, true, false, 2)]
+    [InlineData(true, true, true, 0)]
+    [InlineData(true, true, true, 2)]
+    public async Task InvokingAsync_WithConfiguredMemoryLimit_HonorsSavedStateAsync(bool restore, bool messageOnly, bool populated, int limit)
+    {
+        // Arrange
+        var session = new TestAgentSession();
+        string? capturedInput = null;
+        Task<IEnumerable<TextSearchProvider.TextSearchResult>> SearchAsync(string input, CancellationToken ct)
+        {
+            capturedInput = input;
+            return Task.FromResult<IEnumerable<TextSearchProvider.TextSearchResult>>([]);
+        }
+
+        if (populated)
+        {
+            var originalProvider = new TextSearchProvider(SearchAsync, new TextSearchProviderOptions { RecentMessageMemoryLimit = 2 });
+            await originalProvider.InvokedAsync(new(s_mockAgent, session, [new ChatMessage(ChatRole.User, "Previous")], []));
+        }
+
+        if (restore)
+        {
+            session = new TestAgentSession(AgentSessionStateBag.Deserialize(session.StateBag.Serialize()));
+        }
+
+        string originalState = session.StateBag.Serialize().GetRawText();
+        var provider = new TextSearchProvider(SearchAsync, new TextSearchProviderOptions { RecentMessageMemoryLimit = limit });
+
+        // Act
+        await InvokeSearchAsync(provider, "Current");
+
+        // Assert
+        Assert.Equal(populated && limit > 0 ? "Previous\nCurrent" : "Current", capturedInput);
+
+        if (limit == 0)
+        {
+            await provider.InvokedAsync(new(s_mockAgent, session, [new ChatMessage(ChatRole.User, "Disabled turn")], []));
+            Assert.Equal(originalState, session.StateBag.Serialize().GetRawText());
+
+            var enabledProvider = new TextSearchProvider(SearchAsync, new TextSearchProviderOptions { RecentMessageMemoryLimit = 2 });
+            await InvokeSearchAsync(enabledProvider, "Reenabled");
+            Assert.Equal(populated ? "Previous\nReenabled" : "Reenabled", capturedInput);
+        }
+
+        async Task InvokeSearchAsync(TextSearchProvider instance, string text)
+        {
+            ChatMessage[] messages = [new(ChatRole.User, text)];
+            if (messageOnly)
+            {
+                await instance.InvokingAsync(new MessageAIContextProvider.InvokingContext(s_mockAgent, session, messages));
+            }
+            else
+            {
+                await instance.InvokingAsync(new AIContextProvider.InvokingContext(s_mockAgent, session, new AIContext { Messages = messages }));
+            }
+        }
+    }
+
+
     [Fact]
     public async Task InvokingAsync_WithPreviousFailedRequest_ShouldNotIncludeFailedRequestInputInSearchInputAsync()
     {