Flo
Where Nimble is what you see, Flo is what happens: declarative action sequencing, conditional branching, error handling, and effect dispatch.
Sequencing — order actions declaratively, with HTTP, timer, navigation, and native-OS effects.
Branching and errors — conditional branching and error handling are first-class, not bolted on.
Runs everywhere — Flo source parses to a JSON AST run by Flo interpreters; Nimble UI dispatches it via event handlers.