add chart handler setting

src/Infrastructure/BotSharp.Abstraction/Utilities/StringExtensions.cs

@@ -5,7 +5,7 @@ namespace BotSharp.Abstraction.Utilities;
 
 public static class StringExtensions
 {
-    public static string IfNullOrEmptyAs(this string? str, string defaultValue)
+    public static string? IfNullOrEmptyAs(this string? str, string? defaultValue)
         => string.IsNullOrEmpty(str) ? defaultValue : str;
 
     public static string SubstringMax(this string str, int maxLength)

src/Plugins/BotSharp.Plugin.ChartHandler/ChartHandlerPlugin.cs

@@ -12,7 +12,12 @@ public class ChartHandlerPlugin : IBotSharpPlugin
 
     public void RegisterDI(IServiceCollection services, IConfiguration config)
     {
+        services.AddScoped(provider =>
+        {
+            var settingService = provider.GetRequiredService<ISettingService>();
+            return settingService.Bind<ChartHandlerSettings>("ChartHandler");
+        });
+
         services.AddScoped<IAgentUtilityHook, ChartHandlerUtilityHook>();
     }
-
 }

src/Plugins/BotSharp.Plugin.ChartHandler/Functions/PlotChartFn.cs

@@ -67,8 +67,8 @@ public class PlotChartFn : IFunctionCallback
     {
         try
         {
-            var llmProviderService = _services.GetRequiredService<ILlmProviderService>();
-            var completion = CompletionProvider.GetChatCompletion(_services, provider: "openai", model: "gpt-4.1");
+            var (provider, model) = GetLlmProviderModel();
+            var completion = CompletionProvider.GetChatCompletion(_services, provider: provider, model: model);
             var response = await completion.GetChatCompletions(agent, dialogs);
             return response.Content;
         }
@@ -79,4 +79,21 @@ public class PlotChartFn : IFunctionCallback
             return error;
         }
     }
+
+    private (string, string) GetLlmProviderModel()
+    {
+        var provider = "openai";
+        var model = "gpt-5";
+
+        var state = _services.GetRequiredService<IConversationStateService>();
+        var settings = _services.GetRequiredService<ChartHandlerSettings>();
+        provider = state.GetState("chart_plot_llm_provider")
+                        .IfNullOrEmptyAs(settings.ChartPlot?.LlmProvider)
+                        .IfNullOrEmptyAs(provider);
+        model = state.GetState("chart_plot_llm_model")
+                     .IfNullOrEmptyAs(settings.ChartPlot?.LlmModel)
+                     .IfNullOrEmptyAs(model);
+
+        return (provider, model);
+    }
 }

src/Plugins/BotSharp.Plugin.ChartHandler/Settings/ChartHandlerSettings.cs

@@ -0,0 +1,12 @@
+namespace BotSharp.Plugin.ChartHandler.Settings;
+
+public class ChartHandlerSettings
+{
+    public ChartPlotSetting ChartPlot { get; set; }
+}
+
+public class ChartPlotSetting
+{
+    public string LlmProvider { get; set; }
+    public string LlmModel { get; set; }
+}

src/Plugins/BotSharp.Plugin.ChartHandler/Using.cs

@@ -29,4 +29,5 @@ global using BotSharp.Abstraction.Options;
 global using BotSharp.Core.Infrastructures;
 global using BotSharp.Plugin.ChartHandler.Enums;
 global using BotSharp.Plugin.ChartHandler.LlmContext;
-global using BotSharp.Plugin.ChartHandler.Hooks;
+global using BotSharp.Plugin.ChartHandler.Hooks;
+global using BotSharp.Plugin.ChartHandler.Settings;

src/WebStarter/appsettings.json

@@ -317,6 +317,13 @@
     "Origin": ""
   },
 
+  "ChartHandler": {
+    "ChartPlot": {
+      "LlmProvider": "",
+      "LlmModel": ""
+    }
+  },
+
   "SqlDriver": {
     "MySqlConnectionString": "",
     "SqlServerConnectionString": "",