diff --git a/ai-assistant/src/langchain/LangChainManager.ts b/ai-assistant/src/langchain/LangChainManager.ts
index ceddb1bb69..bbb47a4805 100644
--- a/ai-assistant/src/langchain/LangChainManager.ts
+++ b/ai-assistant/src/langchain/LangChainManager.ts
@@ -103,69 +103,83 @@ export default class LangChainManager extends AIManager {
   }
 
   private createModel(providerId: string, config: Record<string, any>): BaseChatModel {
+    const sanitize = (value: any) => (typeof value === 'string' ? value.trim() : value);
+    const sanitizedConfig = {
+      ...config,
+      apiKey: sanitize(config.apiKey),
+      endpoint: sanitize(config.endpoint),
+      baseUrl: sanitize(config.baseUrl),
+      deploymentName: sanitize(config.deploymentName),
+      model: sanitize(config.model),
+    };
+
     try {
       switch (providerId) {
         case 'openai':
-          if (!config.apiKey) {
+          if (!sanitizedConfig.apiKey) {
             throw new Error('API key is required for OpenAI');
           }
           return new ChatOpenAI({
-            apiKey: config.apiKey,
-            modelName: config.model,
+            apiKey: sanitizedConfig.apiKey,
+            modelName: sanitizedConfig.model,
             dangerouslyAllowBrowser: true,
             verbose: true,
           });
         case 'azure':
-          if (!config.apiKey || !config.endpoint || !config.deploymentName) {
+          if (
+            !sanitizedConfig.apiKey ||
+            !sanitizedConfig.endpoint ||
+            !sanitizedConfig.deploymentName
+          ) {
             throw new Error('Incomplete Azure OpenAI configuration');
           }
           return new AzureChatOpenAI({
-            azureOpenAIEndpoint: config.endpoint.replace(/\/+\$/, ''),
-            azureOpenAIApiKey: config.apiKey,
-            azureOpenAIApiDeploymentName: config.deploymentName,
+            azureOpenAIEndpoint: sanitizedConfig.endpoint.replace(/\/+$/, ''),
+            azureOpenAIApiKey: sanitizedConfig.apiKey,
+            azureOpenAIApiDeploymentName: sanitizedConfig.deploymentName,
             azureOpenAIApiVersion: '2024-12-01-preview',
-            modelName: config.model,
+            modelName: sanitizedConfig.model,
             dangerouslyAllowBrowser: true,
             verbose: true,
           });
         case 'anthropic':
-          if (!config.apiKey) {
+          if (!sanitizedConfig.apiKey) {
             throw new Error('API key is required for Anthropic');
           }
           return new ChatAnthropic({
-            apiKey: config.apiKey,
-            modelName: config.model,
+            apiKey: sanitizedConfig.apiKey,
+            modelName: sanitizedConfig.model,
             dangerouslyAllowBrowser: true,
             verbose: true,
           });
         case 'mistral':
-          if (!config.apiKey) {
+          if (!sanitizedConfig.apiKey) {
             throw new Error('API key is required for Mistral AI');
           }
           return new ChatMistralAI({
-            apiKey: config.apiKey,
-            modelName: config.model,
+            apiKey: sanitizedConfig.apiKey,
+            modelName: sanitizedConfig.model,
             dangerouslyAllowBrowser: true,
             verbose: true,
           });
         case 'gemini': {
-          if (!config.apiKey) {
+          if (!sanitizedConfig.apiKey) {
             throw new Error('API key is required for Google Gemini');
           }
           return new ChatGoogleGenerativeAI({
-            apiKey: config.apiKey,
-            model: config.model,
+            apiKey: sanitizedConfig.apiKey,
+            model: sanitizedConfig.model,
             dangerouslyAllowBrowser: true,
             verbose: true,
           });
         }
         case 'local':
-          if (!config.baseUrl) {
+          if (!sanitizedConfig.baseUrl) {
             throw new Error('Base URL is required for local models');
           }
           return new ChatOllama({
-            baseUrl: config.baseUrl,
-            model: config.model,
+            baseUrl: sanitizedConfig.baseUrl,
+            model: sanitizedConfig.model,
             dangerouslyAllowBrowser: true,
             verbose: true,
           });
diff --git a/ai-assistant/src/modal.tsx b/ai-assistant/src/modal.tsx
index 1882f20819..3349b72bb6 100644
--- a/ai-assistant/src/modal.tsx
+++ b/ai-assistant/src/modal.tsx
@@ -142,7 +142,7 @@ export default function AIPrompt(props: {
     if (active) {
       setActiveConfig(active);
       // Set the default model for the active provider
-      const defaultModel = getProviderModels(active)[0] || 'default';
+      const defaultModel = resolveSelectedModel(active);
       setSelectedModel(defaultModel);
 
       // Update global state with all providers and active one
@@ -178,7 +178,7 @@ export default function AIPrompt(props: {
           _pluginSetting.setActiveProvider(newActive);
 
           // Set the default model for the new provider
-          const defaultModel = getProviderModels(newActive)[0] || 'default';
+          const defaultModel = resolveSelectedModel(newActive);
           setSelectedModel(defaultModel);
 
           // Clear history and show provider change message
@@ -224,6 +224,20 @@ export default function AIPrompt(props: {
   // Handle changing the active configuration
   const [selectedModel, setSelectedModel] = useState<string>('default');
 
+  const resolveSelectedModel = (config: StoredProviderConfig, explicitModel?: string) => {
+    if (explicitModel && explicitModel.trim().length > 0) {
+      return explicitModel;
+    }
+
+    const savedModel = config.config?.model;
+    if (savedModel && savedModel.trim().length > 0) {
+      return savedModel;
+    }
+
+    const providerModels = getProviderModels(config);
+    return providerModels[0] || 'default';
+  };
+
   const handleChangeConfig = (config: StoredProviderConfig, model?: string) => {
     if (!config) return;
     if (
@@ -233,11 +247,9 @@ export default function AIPrompt(props: {
       JSON.stringify(activeConfig.config) !== JSON.stringify(config.config) ||
       selectedModel !== model
     ) {
-      setPromptHistory([]);
-      setPromptVal('');
       setApiError(null);
       setActiveConfig(config);
-      setSelectedModel(model || getProviderModels(config)[0] || 'default');
+      setSelectedModel(resolveSelectedModel(config, model));
       _pluginSetting.setActiveProvider(config);
       if (aiManager) {
         aiManager.reset();
@@ -245,19 +257,19 @@ export default function AIPrompt(props: {
         setTimeout(() => {
           const providerName =
             config.displayName || getProviderById(config.providerId)?.name || config.providerId;
-          setPromptHistory([
+          setPromptHistory(prev => [
+            ...prev,
             {
               role: 'system',
-              content: `Switched to ${providerName}${
-                model ? ' / ' + model : ''
-              }. History has been cleared.`,
+              content: `Switched to ${providerName}${model ? ' / ' + model : ''}.`,
             },
           ]);
         }, 100);
       } else {
         const providerName =
           config.displayName || getProviderById(config.providerId)?.name || config.providerId;
-        setPromptHistory([
+        setPromptHistory(prev => [
+          ...prev,
           {
             role: 'system',
             content: `Using ${providerName}${model ? ' / ' + model : ''}.`,