FAIR VALUE MEASUREMENTS - Estimated fair value of Convertible Notes (Details) - Level 3 - Recurring |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Series A-1 Convertible Notes | Expected volatility | ||
| FAIR VALUE MEASUREMENTS | ||
| Debt Instrument, Measurement Input | 1.031 | 1.042 |
| Series A-1 Convertible Notes | Risk-free interest rate | ||
| FAIR VALUE MEASUREMENTS | ||
| Debt Instrument, Measurement Input | 0.0397 | 0.0348 |
| Series B-1 Convertible Notes | Expected volatility | ||
| FAIR VALUE MEASUREMENTS | ||
| Debt Instrument, Measurement Input | 1.016 | 0.996 |
| Series B-1 Convertible Notes | Risk-free interest rate | ||
| FAIR VALUE MEASUREMENTS | ||
| Debt Instrument, Measurement Input | 0.04 | 0.0347 |