diff --git a/chat_send.php b/chat_send.php
index 425de5a..caf4789 100644
--- a/chat_send.php
+++ b/chat_send.php
@@ -54,29 +54,27 @@ $stmt->execute([$session_id, $message]);
 
 $kb_documents = search_kb($message);
 
-$prompt = "You are a helpful assistant for Extrading, a company that sells construction materials. Please answer in ' . ($lang ?? 'en') . ' language. Answer the user\'s questions based on the provided context. If the answer is not in the context, say you don\'t know.\n\n";
+$messages = [];
+$system_prompt = "You are a helpful assistant for Extrading, a company that sells construction materials. Please answer in ' . ($lang ?? 'en') . ' language. Answer the user\'s questions based on the provided context. If the answer is not in the context, say you don\'t know.";
 
 if (!empty($kb_documents)) {
-    $prompt .= "Context from knowledge base:\n";
+    $system_prompt .= "\n\nContext from knowledge base:\n";
     foreach ($kb_documents as $doc) {
-        $prompt .= "- Title: " . $doc['title'] . "\n";
-        $prompt .= "  Content: " . $doc['content'] . "\n";
+        $system_prompt .= "- Title: " . $doc['title'] . "\n";
+        $system_prompt .= "  Content: " . $doc['content'] . "\n";
     }
-    $prompt .= "\n";
 }
 
-$prompt .= "Conversation history:\n";
+$messages[] = ['role' => 'system', 'content' => $system_prompt];
+
 foreach ($history as $msg) {
-    $prompt .= $msg['sender'] . ": " . $msg['message'] . "\n";
+    $messages[] = ['role' => $msg['sender'], 'content' => $msg['message']];
 }
 
-$prompt .= "user: " . $message . "\n";
-$prompt .= "assistant:";
+$messages[] = ['role' => 'user', 'content' => $message];
 
 $response = LocalAIApi::createResponse([
-    'input' => [
-        ['role' => 'system', 'content' => $prompt]
-    ]
+    'input' => $messages,
 ]);
 
 if (!empty($response['success'])) {
diff --git a/debug_price.log b/debug_price.log
index b879e9b..843c577 100644
--- a/debug_price.log
+++ b/debug_price.log
@@ -11101,3 +11101,101 @@ Product price query executed. Found: {"price_net":"233.20","price_gross":"286.84
 Found product price. Net: 233.2, Gross: 286.84
 FINAL: Returning Net: 233.2, Gross: 286.84
 ---
+---
+START getEffectivePrice for product 1, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"1111.00","price_gross":"1366.53"}
+Found product price. Net: 1111, Gross: 1366.53
+FINAL: Returning Net: 1111, Gross: 1366.53
+---
+---
+START getEffectivePrice for product 2, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"1318.05","price_gross":"1621.20"}
+Found product price. Net: 1318.05, Gross: 1621.2
+FINAL: Returning Net: 1318.05, Gross: 1621.2
+---
+---
+START getEffectivePrice for product 3, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"9.95","price_gross":"12.24"}
+Found product price. Net: 9.95, Gross: 12.24
+FINAL: Returning Net: 9.95, Gross: 12.24
+---
+---
+START getEffectivePrice for product 4, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"9.95","price_gross":"12.24"}
+Found product price. Net: 9.95, Gross: 12.24
+FINAL: Returning Net: 9.95, Gross: 12.24
+---
+---
+START getEffectivePrice for product 5, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"68.00","price_gross":"83.64"}
+Found product price. Net: 68, Gross: 83.64
+FINAL: Returning Net: 68, Gross: 83.64
+---
+---
+START getEffectivePrice for product 6, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"171.60","price_gross":"211.07"}
+Found product price. Net: 171.6, Gross: 211.07
+FINAL: Returning Net: 171.6, Gross: 211.07
+---
+---
+START getEffectivePrice for product 7, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"233.20","price_gross":"286.84"}
+Found product price. Net: 233.2, Gross: 286.84
+FINAL: Returning Net: 233.2, Gross: 286.84
+---
+---
+START getEffectivePrice for product 1, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"1111.00","price_gross":"1366.53"}
+Found product price. Net: 1111, Gross: 1366.53
+FINAL: Returning Net: 1111, Gross: 1366.53
+---
+---
+START getEffectivePrice for product 2, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"1318.05","price_gross":"1621.20"}
+Found product price. Net: 1318.05, Gross: 1621.2
+FINAL: Returning Net: 1318.05, Gross: 1621.2
+---
+---
+START getEffectivePrice for product 3, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"9.95","price_gross":"12.24"}
+Found product price. Net: 9.95, Gross: 12.24
+FINAL: Returning Net: 9.95, Gross: 12.24
+---
+---
+START getEffectivePrice for product 4, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"9.95","price_gross":"12.24"}
+Found product price. Net: 9.95, Gross: 12.24
+FINAL: Returning Net: 9.95, Gross: 12.24
+---
+---
+START getEffectivePrice for product 5, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"68.00","price_gross":"83.64"}
+Found product price. Net: 68, Gross: 83.64
+FINAL: Returning Net: 68, Gross: 83.64
+---
+---
+START getEffectivePrice for product 6, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"171.60","price_gross":"211.07"}
+Found product price. Net: 171.6, Gross: 211.07
+FINAL: Returning Net: 171.6, Gross: 211.07
+---
+---
+START getEffectivePrice for product 7, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"233.20","price_gross":"286.84"}
+Found product price. Net: 233.2, Gross: 286.84
+FINAL: Returning Net: 233.2, Gross: 286.84
+---