Fix bug where prompt was sent twice

https://gist.github.com/simonw/59ef2abf59029e80c1e713506cfe9cd3

Author: simonw

gemini-chat.html

@@ -49,7 +49,6 @@
                 userInput.value = "";
 
                 try {
-                    chatHistory.push({ role: "user", parts: [{ text: message }] });
                     const startTime = performance.now();
                     const result = await chat.sendMessageStream(message);
                     let fullResponse = "";
@@ -60,7 +59,11 @@
                     }
                     const endTime = performance.now();
                     const duration = ((endTime - startTime) / 1000).toFixed(2);
+                    
+                    // Add the user's message and the model's response to chatHistory after the interaction
+                    chatHistory.push({ role: "user", parts: [{ text: message }] });
                     chatHistory.push({ role: "model", parts: [{ text: fullResponse }] });
+                    
                     let usage = (await result.response).usageMetadata;
                     console.log("Full result:", result);
                     updateUsageMetadata(usage);