Summary of significant accounting policies - Other receivables, net (Details) - USD ($) |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Jun. 30, 2025 |
|
| Summary of significant accounting policies | |||
| Credit loss on other receivable | $ 10,500 | $ 3,375 | $ 13,875 |
| Other receivable charged against the allowance | $ 0 | $ 0 | $ 2,582,761 |