v3.26.1
Summary of significant accounting policies - Schedule of sales and marketing expenses (Details) - Accounts payable - Customer concentration risk
12 Months Ended
Dec. 31, 2025
CNY (¥)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
CNY (¥)
Customer A      
Concentration of risk, accounts receivable, net      
Company percentage     14.00%
Company     ¥ 6,930,689
Customer B      
Concentration of risk, accounts receivable, net      
Company percentage 16.00% 16.00%  
Company ¥ 12,672,979 $ 1,812,212  
Customer C      
Concentration of risk, accounts receivable, net      
Company percentage     13.00%
Company     ¥ 6,273,190
Customer D      
Concentration of risk, accounts receivable, net      
Company percentage 17.00% 17.00%  
Company ¥ 12,889,482 $ 1,843,171