react-doctor/activity-wraps-effect-heavy-subtree

Audit the `<Activity>` subtree: every hide/show cycle tears down and recreates every `useEffect`/`useLayoutEffect` inside, so move subscriptions and effect-driven setState chains outside the boundary or pre-resolve the data above it.

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Fires only on React 19.2+ when a JSX element resolving to React's Activity/unstable_Activity (named import, alias like unstable_Activity as UA, or <React.Activity> where the namespace object is React's default import or * as React binding) has a mode prop whose value is a NON-static, toggleable expression such as mode={open ? "visible" : "hidden"}, AND it wraps at least one capitalized same-file child component (collected from JSXOpeningElement JSXIdentifier names, excluding the locally-bound Activity name) whose function body contains one or more useEffect/useLayoutEffect calls. False positive — suppress when: (1) mode is a static literal (mode="hidden", mode="visible", mode={"hidden"}) or absent (default visible), since a pinned boundary has no hide/show cycle; (2) the wrapped child is a member-expression tag like <Charts.Bar />, which is skipped during child collection (the trailing identifier is never looked up) even when a same-file Bar helper with effects exists, because such children resolve through an external namespace; (3) the boundary element ITSELF is a member-expression like <Calendar.Activity> whose namespace object (import * as Calendar from "./calendar") is not React's default/* as React binding — the detector rejects it at boundary detection so it never fires even though its same-file <Entry /> child is effectful; (4) the wrapped component is imported from another module (v1 is same-file only); (5) the children have no effect hooks; or (6) the tag is a user component named Activity imported from a non-react module. Toggling the effects intentionally on hide/show (a subscription that genuinely should pause while hidden) is benign-by-design and should be suppressed.

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Decide whether the inner Effects belong inside the Activity boundary at all: a toggleable <Activity mode={open ? "visible" : "hidden"}> tears down and recreates every wrapped useEffect/useLayoutEffect on each hide/show, causing a remount storm on dense screens. Lift subscriptions, observers, and effect-driven setState chains into a parent that stays mounted across the toggle, or pre-resolve the data above the boundary and pass it down as props so the hidden subtree holds state without re-running effects; reserve effects that truly must restart on show inside the boundary. Alternatively pin the mode statically if the subtree never actually toggles. See https://react.dev/reference/react/Activity