v3.26.3
Fair value measurements - Valuation model (Details) - Level-3 Inputs
Jun. 30, 2026
Y
$ / shares
Apr. 30, 2026
$ / shares
Y
Jul. 31, 2025
$ / shares
Y
2025 Debentures | Class A Ordinary Share price      
Fair value measurements      
Measurement input of debentures 6.25    
2025 Debentures | Class A Ordinary Share price | Minimum      
Fair value measurements      
Measurement input of debentures     99.55
2025 Debentures | Class A Ordinary Share price | Maximum      
Fair value measurements      
Measurement input of debentures     117.3
2025 Debentures | Credit-adjusted discount rate | Minimum      
Fair value measurements      
Measurement input of debentures 24.13   16.33
2025 Debentures | Credit-adjusted discount rate | Maximum      
Fair value measurements      
Measurement input of debentures 24.16   16.61
2025 Debentures | Remaining term ( years)      
Fair value measurements      
Measurement input of debentures | Y     4
2025 Debentures | Expected volatility | Minimum      
Fair value measurements      
Measurement input of debentures 164.77   145.75
2025 Debentures | Expected volatility | Maximum      
Fair value measurements      
Measurement input of debentures 164.94   150.16
2025 Debentures | Risk-free interest rate      
Fair value measurements      
Measurement input of debentures 4.15   3.93
April 2026 Debenture | Class A Ordinary Share price      
Fair value measurements      
Measurement input of debentures 6.25 13  
April 2026 Debenture | Credit-adjusted discount rate      
Fair value measurements      
Measurement input of debentures 23.62 17.53  
April 2026 Debenture | Remaining term ( years)      
Fair value measurements      
Measurement input of debentures | Y 3.8 4  
April 2026 Debenture | Expected volatility      
Fair value measurements      
Measurement input of debentures 159.03 158.05  
April 2026 Debenture | Risk-free interest rate      
Fair value measurements      
Measurement input of debentures 4.17 3.86  
June 2026 Debenture | Class A Ordinary Share price      
Fair value measurements      
Measurement input of debentures 6.25    
June 2026 Debenture | Credit-adjusted discount rate      
Fair value measurements      
Measurement input of debentures 23.43    
June 2026 Debenture | Remaining term ( years)      
Fair value measurements      
Measurement input of debentures | Y 4    
June 2026 Debenture | Expected volatility      
Fair value measurements      
Measurement input of debentures 155.7    
June 2026 Debenture | Risk-free interest rate      
Fair value measurements      
Measurement input of debentures 4.12    
June 29, 2026 Debenture | Class A Ordinary Share price      
Fair value measurements      
Measurement input of debentures 6.15    
June 29, 2026 Debenture | Credit-adjusted discount rate      
Fair value measurements      
Measurement input of debentures 23.43    
June 29, 2026 Debenture | Remaining term ( years)      
Fair value measurements      
Measurement input of debentures | Y 4    
June 29, 2026 Debenture | Expected volatility      
Fair value measurements      
Measurement input of debentures 155.7    
June 29, 2026 Debenture | Risk-free interest rate      
Fair value measurements      
Measurement input of debentures 4.12