emaui/node_modules/@reduxjs/toolkit/skills/model-redux-state/design-state-ownership/references/state-ownership.md

State Ownership Heuristics

Choose the owner, then the tool

Kind of state	Default owner	Typical tool
Editable form fields	Component	useState
Shared mutable app data	Redux	Slice state
Server cache	RTK Query	createApi
URL, pathname, search params	Router	Router APIs plus selector inputs
Browser-only authority like localStorage	External source	Read at boundaries, then dispatch events

Good reasons to move data into Redux

• Multiple distant parts of the UI need the same mutable data.
• You need time-travel debugging or a stable action history.
• The reducer should own transitions because they mix old store state with new inputs.

Reasons to keep data out of Redux

• Another system already owns it, such as the router.
• It only matters during editing inside one component tree.
• It is server cache and RTK Query fits the use case better.

Re-evaluate slice size

• If data is constantly stitched together outside reducers, it may belong closer together.
• If unrelated updates keep touching the same slice, split the slice by domain ownership.