react-doctor/redux-useselector-returns-new-collection

useSelector that returns a fresh object/array literal re-renders on every action; return a primitive, split into multiple useSelector calls, or pass shallowEqual.

Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

Fires on a CallExpression whose callee resolves to react-redux useSelector: either the imported name (or a renamed import of useSelector) or a same-file rebinding chain like const useAppSelector = useSelector / export const useAppSelector: TypedUseSelectorHook<RootState> = useSelector: when called with exactly ONE inline arrow/function-expression selector whose result is an ObjectExpression or ArrayExpression: a concise body that is (after stripping parens) {...} or [...] (including spread forms like ({ ...state.user, fullName: state.user.name })), or a block body whose LAST statement is return { ... } / return [ ... ]. False positives a reviewer would suppress: selectors returning a primitive/scalar like (state) => state.count or (state) => state.user.name (NOT flagged); any call that already passes a second equality argument such as shallowEqual or a custom (a, b) => a.x === b.x (NOT flagged); a hoisted selector passed by reference like useSelector(selectActiveUsers), which usually pairs with a memoized createSelector and is intentionally skipped; useSelector imported from a non-react-redux module or a local helper function of the same name; and a react-redux import renamed to something that is NOT useSelector (e.g. import { useDispatch as useAppSelector }). Cross-file typed wrappers (useAppSelector defined in a separate hooks.ts) are out of scope and will not be detected here.

Evidence boundary

The diagnostic proves only that the detector’s modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, repository policy, exceptions, and required rendered or runtime evidence before deciding the occurrence.

Record one outcome:

• Confirmed failure: The required evidence establishes the violation.
• Rejected: A documented exception or false-positive predicate applies.
• Needs evidence: Named evidence can still be collected.
• Unavailable: Required evidence cannot be collected in this run.
• Waived with evidence: An authorized, scoped exception applies to an established failure.
• Observation: The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review condition. It is not a pass or false positive.

Default severity is registry metadata. Use the occurrence’s JSON severity after repository configuration when ordering real findings.

Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

useSelector compares the selector result to the previous one with === (Object.is) by default, so a freshly allocated literal always differs and the component re-renders on every dispatched action, not just when the data changed. Pick one: return a primitive and split the collection into separate calls, e.g. replace const { name, email } = useSelector(s => ({ name: s.user.name, email: s.user.email })) with const name = useSelector(s => s.user.name); const email = useSelector(s => s.user.email); OR pass an equality fn as the second arg, useSelector(s => ({ name: s.user.name, email: s.user.email }), shallowEqual) importing shallowEqual from react-redux; OR for derived/aggregated shapes, memoize the selector with createSelector from reselect so it returns a stable reference. See https://react-redux.js.org/api/hooks#equality-comparisons-and-updates

Repository-wide copy prompt

Use this repository-wide prompt only after validating each occurrence. For one occurrence, use the guidance above.