LEASE - ROU assets and lease liabilities (Details) - CNY (¥) ¥ in Thousands |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| ROU assets and lease liabilities | ||
| Right-of-use assets | ¥ 35,733 | ¥ 35,635 |
| Operating lease, right-of-use asset, statement of financial position [Extensible List] | Other non-current assets | Other non-current assets |
| Operating lease liabilities-current | ¥ 18,357 | ¥ 27,258 |
| Operating lease, liability, current, statement of financial position [Extensible List] | Accrued expenses and other current liabilities | Accrued expenses and other current liabilities |
| Operating lease liabilities-non current | ¥ 14,326 | ¥ 7,693 |
| Operating lease, liability, noncurrent, statement of financial position [Extensible List] | Other long-term liabilities | Other long-term liabilities |
| Weighted-average remaining lease term | 2 years 10 days | 1 year 4 months 28 days |
| Weighted-average discount rate | 3.27% | 3.77% |