[killerstorm]

   type ProfileSpec = Frond.NodeSpec<{
     readonly args: Frond.Args.None;
     readonly key: Frond.Key.Singleton;
     readonly deps: {
       readonly http: Frond.Dep<typeof HttpTransportNode>;
     };
    readonly result: Profile;
   }>;

This begs to be its own DSL rather than TypeScript-type-meta-programming.

[eyelidlessness]

I generally agree. But FWIW it does feel fairly idiomatic in terms of code written with Effect/API design in the Effect ecosystem. (Disclaimer: my Effect usage so far has been mostly casual, this observation is based on following the project and ecosystem pretty closely.)