diff --git a/public/src/uncloseai-embed-modal.js b/public/src/uncloseai-embed-modal.js
index d1844e6..79c5249 100644
--- a/public/src/uncloseai-embed-modal.js
+++ b/public/src/uncloseai-embed-modal.js
@@ -1915,7 +1915,12 @@ You have complete knowledge of this page content and can reference any details,
 			// Get user's preferred language and localize the system prompt
 			const userLang = getUserLanguagePreference();
 			const languageName = NATIVE_LANGUAGE_NAMES[userLang] || "English";
-			
+
+			// Build explicit language instruction for non-English languages
+			const langInstruction = userLang !== "en"
+				? `\n\nCRITICAL: You MUST write your ENTIRE response in ${languageName}. Do NOT write in English. Every word of your introduction must be in ${languageName}.`
+				: "";
+
 			const introSystemPrompt = `${getUIText("systemPromptIntro")}
 
 PAGE INFORMATION:
@@ -1930,9 +1935,11 @@ ${getUIText("systemPromptTask1")}
 ${getUIText("systemPromptTask2")}
 ${getUIText("systemPromptTask3")}
 
-${getUIText("systemPromptInstructions")} ${languageName}.`;
+${getUIText("systemPromptInstructions")} ${languageName}.${langInstruction}`;
 
-			const introPrompt = "Generate the welcoming introduction message now.";
+			const introPrompt = userLang !== "en"
+				? `Generate the welcoming introduction message now. Remember: Write ONLY in ${languageName}, not English.`
+				: "Generate the welcoming introduction message now.";
 
 			// Create temporary chat history for intro generation
 			const introHistory = [