# `react-doctor/jotai-select-atom-in-render-body`

Lift selectAtom to module scope, or wrap it: const a = useMemo(() => selectAtom(base, fn), [deps])

- **Status:** Active
- **Category:** State & Effects
- **Assessment:** Evidence-required risk
- **Required evidence:** source code
- **Default configuration:** Enabled
- **Default severity:** error
- **Scope:** All supported frameworks
- **Active when:** always
- **Requirements:** react
- **Priority:** 72 (P1)
- **Source:** oxlint-plugin-react-doctor
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://jotai.org/docs/utilities/select)

## Validation prompt

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

Fires on a CallExpression whose callee is an Identifier that resolves (via import tracking) to the named export selectAtom from "jotai/utils" or "jotai": alias imports like {selectAtom as makeSlice} still count: when the nearest enclosing function-like node is NOT the first argument of a memoizing hook (useMemo/useCallback) and some outer enclosing function is a component (name matches /^[A-Z]/) or hook (name matches /^use[A-Z]/), resolving the binding through transparent memo()/forwardRef() wrappers; it also fires for selectAtom inside a helper arrow/function nested in a component since that runs at render time.

Suppress when: do NOT flag selectAtom called at module scope, inside a useMemo/useCallback callback (the first-arg memoized form), imported from a non-jotai source like a homegrown ./my-utils helper of the same name, or called inside a lowercase non-hook helper such as function buildSliceAtom() that is itself defined at module scope.

## 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, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.

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

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 or expiry condition. It is not a pass or false positive.

## Fix prompt

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

selectAtom(base, fn) returns a brand-new derived atom on every call, so calling it in a component or hook body makes useAtomValue re-subscribe to a fresh atom each render and loop forever. If the base atom and selector are static, lift the call to module scope: const sliceAtom = selectAtom(baseAtom, (s) => s.foo) outside the component. If it depends on props/state, memoize it: const sliceAtom = useMemo(() => selectAtom(baseAtom, (s) => s[field]), [field]), keeping the selector function stable too. See https://jotai.org/docs/utilities/select

## Repository-wide copy prompt

Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.

````text
Fix every confirmed `react-doctor/jotai-select-atom-in-render-body` diagnostic in the current repository.

Required change:
- selectAtom(base, fn) returns a brand-new derived atom on every call, so calling it in a component or hook body makes useAtomValue re-subscribe to a fresh atom each render and loop forever. If the base atom and selector are static, lift the call to module scope: const sliceAtom = selectAtom(baseAtom, (s) => s.foo) outside the component. If it depends on props/state, memoize it: const sliceAtom = useMemo(() => selectAtom(baseAtom, (s) => s[field]), [field]), keeping the selector function stable too. See https://jotai.org/docs/utilities/select.

Validation before editing:
Fires on a CallExpression whose callee is an Identifier that resolves (via import tracking) to the named export selectAtom from "jotai/utils" or "jotai": alias imports like {selectAtom as makeSlice} still count: when the nearest enclosing function-like node is NOT the first argument of a memoizing hook (useMemo/useCallback) and some outer enclosing function is a component (name matches /^[A-Z]/) or hook (name matches /^use[A-Z]/), resolving the binding through transparent memo()/forwardRef() wrappers; it also fires for selectAtom inside a helper arrow/function nested in a component since that runs at render time.

Suppress when: do NOT flag selectAtom called at module scope, inside a useMemo/useCallback callback (the first-arg memoized form), imported from a non-jotai source like a homegrown ./my-utils helper of the same name, or called inside a lowercase non-hook helper such as function buildSliceAtom() that is itself defined at module scope.

Constraints:
- Make the smallest change that fixes the root cause.
- Preserve behavior and interfaces unrelated to this diagnostic.
- Reuse existing project components, utilities, and conventions.
- Do not introduce render-phase side effects, render-phase state updates, or Hooks rule violations.
- Adapt identifiers and framework details instead of copying blindly.
- Do not disable the rule or suppress matching code.

Assessment:
- Record detector evidence, applicability facts, assumptions, missing evidence, and the rule class for this occurrence.
- Return one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.
- A waiver records the established failure, scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

Verification:
- Run focused tests for the changed behavior.
- Run React Doctor and confirm this diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report the files changed and any checks you could not run.
````