[mfal]

A re-render of a list's parent, or a refetch that hands List.StaticData a new array of the same items, no longer re-renders the items of a list or tile view. Three changes:

1. Item components read the list model from a stable store. List rebuilds its model on every render, and the model is the list context's value. Every consumer re-rendered with each render, including the ones inside items that skip their own render: ListItemView, and every Button in an item through its size dynamic prop. A second context now holds a store that receives the model once the list has committed. An internal useListSelector reads it and re-renders only when the value it reads changes; ListItemView uses it for the view mode. useList is unchanged.
2. ListItemView and ListItemViewContent build their props contexts once. Both held only constants (tunnels, class names, an OptionsButton element, dynamic props) but were rebuilt on every render, which handed every item's content a new props context. ListItemView keeps one per view mode and hands the item buttons a static size.
3. Items skips rendering while nothing it shows has changed. react-aria re-renders every GridListItem whenever the GridList renders, Flow's item memo or not. Items now returns its last element while these stay equal:
   • loading state, onAction, the infinite scroll trigger, accordion, tileMaxWidth
   • every entry's id and data, and the list props
   • every item rendering the same by the item memo's rule (ItemView.rendersSameFor)

The table counterpart is #3575.

It builds on #3579: without its stable ClearPropsContext, every render of List hands the items a new props context, and they re-render despite the changes here.

Related: #3575

Effect

Measured in mStudio, dev build, React Profiler render time and number of component renders summed over one refetch, median of 7. Baseline is next with #3575 and #3579; after adds this PR.

List	Refetch	before	after
domains, 185 items, List.StaticData	only the list's query	353 ms / 42,617 renders	25 ms / 623 renders
	every query on the page	896 ms / 87,622	320 ms / 3,638
projects, 67 items	every query on the page	690 ms / 40,007	288 ms / 21,767
mail addresses, 35 items	every query on the page	59 ms / 1,409	62 ms / 1,409

Refetching only the projects' or mail addresses' list query was already ~1 ms with #3575, since their loaders keep the same items.

Selecting an item in Nexus' ticket list (list view, 100 entries, selection controlled by the parent), same baseline, dev build, render time summed over all commits of one click, median of 6 real mouse clicks:

	before	after
one click	278 ms / 25,500 renders	127 ms / 3,000 renders

Before, the click rendered every item twice. What remains is mostly the one render of the list and each item's react-aria Button re-rendering on its own state.

Tests

List.browser.test.tsx (Item re-renders): counts react-aria's item renders through an ItemsGridListItem view whose children function runs on each of them, and the item content's renders through a component reading the props context. Two parent re-renders render neither; a change to renderDependencies still renders the item.

The test fails without the Items change and without the stable list store (2 item renders instead of 0, verified by reverting each). A second test toggles a button's size through a nested props context inside an item, which used to change the button's hook count. The existing List tests for filters, saved settings, the date range filter and the view mode cover the useList consumers that still have to follow every change.

NestedFormSubmit.browser.test.tsx now waits for the Modal before typing. Typed into before the remote Field was wired up, the value never reached the remote form, and its required rule blocked the submit. The race is in the test, not in this PR: under CPU load it fails on next as well.

🤖 Generated with Claude Code

[github-actions]

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