false, 'error' => 'conversation_id or user_id required']); exit; } try { $db = Database::getInstance(); if ($conversationId) { $db->execute('DELETE FROM conversations WHERE id = ?', [$conversationId]); } if ($userId) { $db->execute('DELETE FROM conversations WHERE user_id = ?', [$userId]); } echo json_encode(['success' => true]); } catch (Exception $e) { http_response_code(500); echo json_encode(['success' => false, 'error' => $e->getMessage()]); }