07-debuggable-state/01-why-reducers-matter.md

Why reducers matter

Reducers are one of the most important tools for keeping Vroq apps understandable and debuggable.

A reducer makes state transitions explicit. Instead of letting state updates happen in many scattered places, reducers centralize how a state slice changes in response to actions.

Why this helps

Reducers make it easier to:

inspect state transitions
understand feature ownership
replay actions during debugging
keep UI code simpler
avoid hidden mutation and special-case updates

This is especially helpful for LLMs, because explicit state transitions are easier to reason about than state updates scattered across UI files.

Reducers as architecture tools

Reducers are not only for state management. They also define boundaries.

A reducer helps answer:

which feature owns this state?
where should this bug be fixed?
what actions are allowed to change this slice?

That clarity reduces hacky fixes.

What goes wrong without reducers

Without clear reducer ownership, apps tend to drift into:

UI files mutating state indirectly
duplicated update logic
hidden assumptions spread across several files
difficult debugging because transitions are not explicit

Final rule

Use reducers to make feature state ownership and transitions explicit, visible, and easy to debug.