v3.26.1
Income tax (Narrative) (Details)
¥ in Thousands, $ in Thousands, $ in Millions
12 Months Ended
Dec. 31, 2025
HKD ($)
Dec. 31, 2024
CNY (¥)
Dec. 31, 2023
Dec. 31, 2025
CNY (¥)
Dec. 31, 2025
USD ($)
Income tax          
Statutory tax rate 25.00% 25.00% 25.00%    
Profits tax rate | $ $ 2        
Profits tax rate, percentage 8.25%        
Applicability of preferential income tax rate 25.00%        
Preferential income tax rate 15.00%        
Operating loss carryforwards   ¥ 2,218,872   ¥ 2,207,677  
Accumulated deficit   (691,785)   (933,885) $ (133,546)
PRC Tax Administration and Collection Law          
Income tax          
Statute of limitations period if underpayment of taxes due to computational errors by taxpayer or withholding agent 3 years        
Statute of limitations extended period under special circumstances 5 years        
Underpayment of tax liability       100  
Statute of limitations under related party transactions 10 years        
Hong Kong          
Income tax          
Statutory tax rate 16.50%        
CAYMAN ISLANDS          
Income tax          
Statutory tax rate 0.00%        
CHINA          
Income tax          
Accumulated deficit   ¥ 2,349,005   ¥ 2,435,538