ext field
A platform-specific value kept outside the shared schema.
What it means
A shared schema cannot cover everything one platform offers. An extension area holds the extras so they are not lost, while making clear they are not part of the cross-platform contract.
How Onekey handles it
ext is one flat level of camelCase names on each endpoint, for example ext.karma on a Hacker News user. A name is stable for that endpoint, but the same name on another endpoint is not guaranteed to mean the same thing. Code that must work across platforms should read fixed-schema fields only. A name that proves useful on many platforms can be promoted into the schema.