We close the series by exploring what it means to migrate from CLI to TUI with ratatui: how the interaction model changes, what frictions Rust introduces with ownership and &mut in a persistent event loop, and why hexagonal architecture absorbs the change without surgery.
We design the CLI layer with clap derive, typed argument parsing with ValueEnum and FromStr for UUIDs, subcommands as enums, global –output flag for dual table/json output, and errors propagated through layers down to stderr.
In this part we model the heart of the project: the Task entity, its immutable transitions, and a taxonomy of errors by layers. Less magic, more explicit rules, and fewer surprise bugs.
We kick off the series by building a To-Do CLI in Rust from CodeCrafters’ Project #1, but without turning it into a giant script. We cover architecture decisions, layer boundaries, and why a small project can also teach you serious design.
Reading guide for the Todo CLI in Rust series, featuring the repository’s technical map, recommended reading order, and direct links to files and commits to follow each decision step by step.