This loses something important about Keybase sigchains: on Keybase, a sigchain represents an identity and not a single key, which makes it possible to add separate keys for different devices and to seamlessly replace and revoke keys over time. (Non-key-specific sigchains let the Keybase client do interesting things like automatically re-encrypting shared data when someone revokes an old key.)

Tying sigchains to keys seems limiting, and I'm curious if there's a reason for it. Otherwise, I like this a bunch.