Скачать или смотреть This Tiny Java Spring Shell CLI Bug Broke Everything… So I Fixed It.

In this video, I take a tiny but surprisingly tricky part of my CLI — the book new scan flags — and refactor it using clean architecture + DDD thinking. It’s a fast timelapse of me working through a micro-slice: one small, well-defined change that tightens the whole system.

This slice fixes a long-standing issue where the CLI treated flags like strings, causing weird edge cases:
--scan needed a value, null meant something else, and distinguishing single scan from multi scan was… chaos.

So I redesigned the command contract using boolean flags, a truth table, and explicit modes:

Final behavior

book new → manual book creation

book new --scan → single-book scan

book new --scan --multi → multi-book scan

No values. No ambiguity. Clean routing.

Behind that small surface change is a deeper architectural shift:
• separating input semantics from domain logic
• isolating CLI behavior into a crisp mode resolver
• keeping the domain ignorant of flags entirely
• preparing room for a future ScanMode enum + application-layer use case

What’s inside this micro-slice?

✔ Replacing messy string flags with boolean flags
✔ Designing a clean CLI contract
✔ Truth table → behavior mapping
✔ Improving mode routing (NONE, SINGLE, MULTI)
✔ Keeping scanning and manual flows separate
✔ Notes for future refactor hooks (helper methods, enums, better docs)

A focus on teaching myself to build well-structured systems one micro-slice at a time

If you like seeing the real process of building software — messy thinking, incremental design, small guided improvements — this one shows the work.

⏱ Timelapse Format