v3.26.3
Summary of significant accounting policies (Details)
6 Months Ended 12 Months Ended
Jun. 01, 2026
Mar. 23, 2026
Mar. 11, 2026
May 23, 2025
Jun. 30, 2026
CNY (¥)
segment
$ / ¥
Jun. 30, 2026
USD ($)
segment
Jun. 30, 2025
CNY (¥)
segment
Dec. 31, 2025
CNY (¥)
Jun. 30, 2026
USD ($)
$ / ¥
Dec. 31, 2025
USD ($)
Dec. 31, 2024
CNY (¥)
Summary of significant accounting policies                      
Transfer of assets from level 1 to level 2         ¥ 0     ¥ 0      
Transfer of assets from level 2 to level 1         0     0      
Transfer of assets in and out of level 3         0     0      
Transfer of liabilities from level 1 to level 2         0     0      
Transfer of liabilities from level 2 to level 1         0     0      
Transfer of liabilities in and out of level 3         0     0      
Credit loss for accounts receivable         1,430,109 $ 210,772 ¥ 1,550,481        
Deferred revenue         625,320     ¥ 40,942 $ 92,161 $ 6,034 ¥ 620,000
Impairment of long-lived assets         0   0        
Short term operating lease expense         ¥ 51,574,000 $ 7,601,000 0        
VAT rate         6.00% 6.00%          
Penalties or interest relating to income taxes         ¥ 0   0        
Employee welfare contribution expenses         ¥ 465,232 $ 68,567 ¥ 481,920        
Number of reportable segments | segment         4 4 3        
Number of operating segments | segment         4 4 3        
Dilutive securities         ¥ 0   ¥ 0        
Stock split, conversion ratio 0.1 0.04 0.04 0.125              
Exchange rate | $ / ¥         6.7851       6.7851    
Research and development expenses         ¥ 1,547,422 $ 228,062 ¥ 873,959