diff --git a/src/Infrastructure/BotSharp.Abstraction/Agents/Models/AgentLlmConfig.cs b/src/Infrastructure/BotSharp.Abstraction/Agents/Models/AgentLlmConfig.cs
index 6ed259a3..be75a01e 100644
--- a/src/Infrastructure/BotSharp.Abstraction/Agents/Models/AgentLlmConfig.cs
+++ b/src/Infrastructure/BotSharp.Abstraction/Agents/Models/AgentLlmConfig.cs
@@ -35,6 +35,21 @@ public class AgentLlmConfig
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     public int? MaxOutputTokens { get; set; }
 
+    /// <summary>
+    /// Sampling temperature override for this agent. <c>null</c> (the default) inherits the
+    /// conversation state / provider settings, so an unset field never changes global behavior.
+    /// </summary>
+    [JsonPropertyName("temperature")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public float? Temperature { get; set; }
+
+    /// <summary>
+    /// Nucleus sampling (top-p) override for this agent. <c>null</c> inherits the defaults.
+    /// </summary>
+    [JsonPropertyName("top_p")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public float? TopP { get; set; }
+
     /// <summary>
     /// Reasoning effort level
     /// </summary>
diff --git a/src/Plugins/BotSharp.Plugin.AzureOpenAI/Providers/Chat/ChatCompletionProvider.cs b/src/Plugins/BotSharp.Plugin.AzureOpenAI/Providers/Chat/ChatCompletionProvider.cs
index dc9a0fbc..62d2d18c 100644
--- a/src/Plugins/BotSharp.Plugin.AzureOpenAI/Providers/Chat/ChatCompletionProvider.cs
+++ b/src/Plugins/BotSharp.Plugin.AzureOpenAI/Providers/Chat/ChatCompletionProvider.cs
@@ -565,23 +565,33 @@ public class ChatCompletionProvider : IChatCompletion
         var settingsService = _services.GetRequiredService<ILlmProviderService>();
         var settings = settingsService.GetSetting(Provider, _model);
 
+        // Sampling: an explicit conversation state wins, then the agent's own override, then the
+        // model's configured reasoning defaults. Unset everywhere keeps the historical 0.0 fallback.
+        float? temperature = null;
+        if (state.ContainsState("temperature") && float.TryParse(state.GetState("temperature"), out var stateTemperature))
+            temperature = stateTemperature;
+        temperature ??= agent?.LlmConfig?.Temperature;
+        temperature ??= settings?.Reasoning?.Temperature;
+        temperature ??= 0.2f;
+
+        float? topP = null;
+        if (state.ContainsState("top_p") && float.TryParse(state.GetState("top_p"), out var stateTopP))
+            topP = stateTopP;
+        topP ??= agent?.LlmConfig?.TopP;
+
         // Reasoning effort
         ChatReasoningEffortLevel? reasoningEffortLevel = null;
-        float? temperature = float.Parse(state.GetState("temperature", "0.0"));
-        if (settings?.Reasoning != null)
-        {
-            temperature = settings.Reasoning.Temperature;
-            var level = state.GetState("reasoning_effort_level")
-                         .IfNullOrEmptyAs(agent?.LlmConfig?.ReasoningEffortLevel)
-                         .IfNullOrEmptyAs(settings?.Reasoning?.EffortLevel);
-            reasoningEffortLevel = ParseReasoningEffortLevel(level);
-        }
+        var level = state.GetState("reasoning_effort_level")
+                     .IfNullOrEmptyAs(agent?.LlmConfig?.ReasoningEffortLevel)
+                     .IfNullOrEmptyAs(settings?.Reasoning?.EffortLevel);
+        reasoningEffortLevel = ParseReasoningEffortLevel(level);
 
         // Web search
         ChatWebSearchOptions? webSearchOptions = null;
         if (settings?.WebSearch != null)
         {
             temperature = null;
+            topP = null;
             reasoningEffortLevel = null;
             webSearchOptions = new();
         }
@@ -593,6 +603,7 @@ public class ChatCompletionProvider : IChatCompletion
         return new ChatCompletionOptions()
         {
             Temperature = temperature,
+            TopP = topP,
             MaxOutputTokenCount = maxTokens,
             ReasoningEffortLevel = reasoningEffortLevel,
             WebSearchOptions = webSearchOptions
diff --git a/src/Plugins/BotSharp.Plugin.DeepSeekAI/Providers/Chat/ChatCompletionProvider.cs b/src/Plugins/BotSharp.Plugin.DeepSeekAI/Providers/Chat/ChatCompletionProvider.cs
index eebc64d1..bb684dbc 100644
--- a/src/Plugins/BotSharp.Plugin.DeepSeekAI/Providers/Chat/ChatCompletionProvider.cs
+++ b/src/Plugins/BotSharp.Plugin.DeepSeekAI/Providers/Chat/ChatCompletionProvider.cs
@@ -691,23 +691,33 @@ public class ChatCompletionProvider : IChatCompletion
         var settingsService = _services.GetRequiredService<ILlmProviderService>();
         var settings = settingsService.GetSetting(Provider, _model);
 
+        // Sampling: an explicit conversation state wins, then the agent's own override, then the
+        // model's configured reasoning defaults. Unset everywhere keeps the historical 0.0 fallback.
+        float? temperature = null;
+        if (state.ContainsState("temperature") && float.TryParse(state.GetState("temperature"), out var stateTemperature))
+            temperature = stateTemperature;
+        temperature ??= agent?.LlmConfig?.Temperature;
+        temperature ??= settings?.Reasoning?.Temperature;
+        temperature ??= 0.2f;
+
+        float? topP = null;
+        if (state.ContainsState("top_p") && float.TryParse(state.GetState("top_p"), out var stateTopP))
+            topP = stateTopP;
+        topP ??= agent?.LlmConfig?.TopP;
+
         // Reasoning effort
         ChatReasoningEffortLevel? reasoningEffortLevel = null;
-        float? temperature = float.Parse(state.GetState("temperature", "0.0"));
-        if (settings?.Reasoning != null)
-        {
-            temperature = settings.Reasoning.Temperature;
-            var level = state.GetState("reasoning_effort_level")
-                         .IfNullOrEmptyAs(agent?.LlmConfig?.ReasoningEffortLevel)
-                         .IfNullOrEmptyAs(settings?.Reasoning?.EffortLevel);
-            reasoningEffortLevel = ParseReasoningEffortLevel(level);
-        }
+        var level = state.GetState("reasoning_effort_level")
+                     .IfNullOrEmptyAs(agent?.LlmConfig?.ReasoningEffortLevel)
+                     .IfNullOrEmptyAs(settings?.Reasoning?.EffortLevel);
+        reasoningEffortLevel = ParseReasoningEffortLevel(level);
 
         // Web search
         ChatWebSearchOptions? webSearchOptions = null;
         if (settings?.WebSearch != null)
         {
             temperature = null;
+            topP = null;
             reasoningEffortLevel = null;
             webSearchOptions = new();
         }
@@ -719,6 +729,7 @@ public class ChatCompletionProvider : IChatCompletion
         return new ChatCompletionOptions()
         {
             Temperature = temperature,
+            TopP = topP,
             MaxOutputTokenCount = maxTokens,
             ReasoningEffortLevel = reasoningEffortLevel,
             WebSearchOptions = webSearchOptions
diff --git a/src/Plugins/BotSharp.Plugin.OpenAI/Providers/Chat/ChatCompletionProvider.cs b/src/Plugins/BotSharp.Plugin.OpenAI/Providers/Chat/ChatCompletionProvider.cs
index 7ab149e2..cfe655c0 100644
--- a/src/Plugins/BotSharp.Plugin.OpenAI/Providers/Chat/ChatCompletionProvider.cs
+++ b/src/Plugins/BotSharp.Plugin.OpenAI/Providers/Chat/ChatCompletionProvider.cs
@@ -534,23 +534,33 @@ public class ChatCompletionProvider : IChatCompletion
         var settingsService = _services.GetRequiredService<ILlmProviderService>();
         var settings = settingsService.GetSetting(Provider, _model);
 
+        // Sampling: an explicit conversation state wins, then the agent's own override, then the
+        // model's configured reasoning defaults. Unset everywhere keeps the historical 0.0 fallback.
+        float? temperature = null;
+        if (state.ContainsState("temperature") && float.TryParse(state.GetState("temperature"), out var stateTemperature))
+            temperature = stateTemperature;
+        temperature ??= agent?.LlmConfig?.Temperature;
+        temperature ??= settings?.Reasoning?.Temperature;
+        temperature ??= 0.2f;
+
+        float? topP = null;
+        if (state.ContainsState("top_p") && float.TryParse(state.GetState("top_p"), out var stateTopP))
+            topP = stateTopP;
+        topP ??= agent?.LlmConfig?.TopP;
+
         // Reasoning effort
         ChatReasoningEffortLevel? reasoningEffortLevel = null;
-        float? temperature = float.Parse(state.GetState("temperature", "0.0"));
-        if (settings?.Reasoning != null)
-        {
-            temperature = settings.Reasoning.Temperature;
-            var level = state.GetState("reasoning_effort_level")
-                         .IfNullOrEmptyAs(agent?.LlmConfig?.ReasoningEffortLevel)
-                         .IfNullOrEmptyAs(settings?.Reasoning?.EffortLevel);
-            reasoningEffortLevel = ParseReasoningEffortLevel(level);
-        }
+        var level = state.GetState("reasoning_effort_level")
+                     .IfNullOrEmptyAs(agent?.LlmConfig?.ReasoningEffortLevel)
+                     .IfNullOrEmptyAs(settings?.Reasoning?.EffortLevel);
+        reasoningEffortLevel = ParseReasoningEffortLevel(level);
 
         // Web search
         ChatWebSearchOptions? webSearchOptions = null;
         if (settings?.WebSearch != null)
         {
             temperature = null;
+            topP = null;
             reasoningEffortLevel = null;
             webSearchOptions = new();
         }
@@ -562,6 +572,7 @@ public class ChatCompletionProvider : IChatCompletion
         return new ChatCompletionOptions()
         {
             Temperature = temperature,
+            TopP = topP,
             MaxOutputTokenCount = maxTokens,
             ReasoningEffortLevel = reasoningEffortLevel,
             WebSearchOptions = webSearchOptions