Before choosing a state-management package, ask who owns the information and how long it should live. A password visibility toggle, a shopping basket, and a signed-in session may all change the interface, but they should not necessarily live in the same object.

Separate four different questions

  • Local interaction: is a panel expanded or a tab selected?
  • Feature state: which results, filters, and request status does this screen show?
  • Shared data: what must several screens observe consistently?
  • Persistence: what should survive process termination or sign-out?

Flutter describes both local state and state shared across an application. There are several supported approaches, and the useful choice depends on the boundaries in your product. A simple local interaction can use setState; sharing important data needs a clear owner and a predictable update path.

Design complete states

A catalog that contains only isLoading and a list has unanswered questions. Can old results remain visible during refresh? Is an empty list a successful response or the initial value? Did pagination fail after the first page succeeded? Write the actual combinations you support before building the widget tree.

For example, a loaded catalog can retain items, a selected filter, a refresh flag, and an optional recoverable error. An initial failure may have no items and a full-page retry action. Naming these situations makes both design reviews and tests more precise.

Keep updates observable

Prefer replacing a state value through one update path to letting several widgets mutate shared collections. Derive values such as item count from the authoritative collection when practical. Storing both independently creates extra ways for the interface to disagree with itself.

Plan reset behavior

Signing out should clear account-specific data, but it should not necessarily reset a user's theme preference. Switching accounts must not briefly show the previous account's basket. Put these rules next to the owner of the data, then exercise them with two separate test accounts.

A useful review exercise is to write an ownership list for one feature: value, owner, readers, lifetime, and reset trigger. If two objects claim to own the same value, resolve that disagreement before adding another dependency.

Official reference: Flutter state management introduction.