Wrote up the best technical conversation I've had in a while: async-first OS design

A weekend back-and-forth with Mohit D. Patel, who's building CharlotteOS (a from-scratch kernel in Rust), turned into one of the better technical conversations I've had in a while. I wrote up where it landed: the case for making asynchrony a kernel's default instead of bolting it on later.

It gets into io_uring as a completion model, why a file descriptor, a Windows HANDLE, and a capability are all the same primitive, the observer and upcall approach CharlotteOS takes, and an honest look at the hard parts and the greenfield costs.