v3.26.3
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of risks (Details) - USD ($)
6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Concentration of risks      
Accounts receivable $ 0   $ 0
Purchase | Vendor | Vendor A      
Concentration of risks      
Concertation risk (in percent) 100.00% 100.00%  
Sales | Customer | Customer A      
Concentration of risks      
Concertation risk (in percent) 82.00%    
Sales | Customer | Customer B      
Concentration of risks      
Concertation risk (in percent) 18.00% 91.00%