Summary of significant accounting policies - Schedule of property and equipment, net estimated useful lives (Details) |
Dec. 31, 2025 |
|---|---|
| Computer and transmission equipment | |
| Property and equipment, net | |
| Property and equipment, net, estimated useful lives | 3 years |
| Leasehold improvements | |
| Property and equipment, net | |
| Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration] | us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember |
| Furniture and office equipment | |
| Property and equipment, net | |
| Property and equipment, net, estimated useful lives | 5 years |
| Motor vehicles | |
| Property and equipment, net | |
| Property and equipment, net, estimated useful lives | 5 years |