feat: add chat virtualizer options

[segunadebayo]

Closes #

📝 Description

Adds chat-oriented virtualizer options and helpers for end-anchored list experiences.

⛳️ Current behavior (updates)

List virtualization preserves top/start anchors and supports manual prepend compensation, but it does not expose a first-class end anchor, conditional append following, or end-distance helpers for chat UIs.

🚀 New behavior

• Adds anchorTo, followOnAppend, and scrollEndThreshold options.
• Adds scrollToEnd(), getDistanceFromEnd(), and isAtEnd() helpers.
• Keeps end-anchored viewports pinned when the latest row grows.
• Uses the attached scroll element for end-distance and end-scroll calculations when available.
• Hardens key restoration so keyToIndex -1 results are treated as missing keys.
• Adds a full-width Next chat example with auto-load older history, manual load-older history, append/no-yank behavior, streamed replies, and a latest-message control.
• Keeps the chat example pinned to latest when manual history loading is triggered from the latest position, while preserving viewport position for near-top auto history loading.
• Adds unit coverage, virtualizer guide updates, and chat-focused E2E coverage.

💣 Is this a breaking change (Yes/No):

No

📝 Additional Information

Verification:

• pnpm exec vitest packages/utilities/virtualizer/tests/list-virtualizer.test.ts --run
• pnpm --filter @zag-js/virtualizer typecheck
• pnpm build
• FRAMEWORK=react pnpm exec playwright test e2e/virtualizer.e2e.ts -g "(/virtualizer/chat|chat example)"

  

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
zag-nextjs	Ready	Preview	Jun 5, 2026 11:10pm
zag-solid	Ready	Preview	Jun 5, 2026 11:10pm
zag-svelte	Ready	Preview	Jun 5, 2026 11:10pm
zag-vue	Ready	Preview	Jun 5, 2026 11:10pm
zag-website	Ready	Preview	Jun 5, 2026 11:10pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 66d7668

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 89 packages

Name	Type
@zag-js/virtualizer	Minor
@zag-js/anatomy-icons	Minor
@zag-js/anatomy	Minor
@zag-js/core	Minor
@zag-js/docs	Minor
@zag-js/preact	Minor
@zag-js/react	Minor
@zag-js/solid	Minor
@zag-js/svelte	Minor
@zag-js/vanilla	Minor
@zag-js/vue	Minor
@zag-js/accordion	Minor
@zag-js/angle-slider	Minor
@zag-js/async-list	Minor
@zag-js/avatar	Minor
@zag-js/carousel	Minor
@zag-js/cascade-select	Minor
@zag-js/checkbox	Minor
@zag-js/clipboard	Minor
@zag-js/collapsible	Minor
@zag-js/color-picker	Minor
@zag-js/combobox	Minor
@zag-js/date-input	Minor
@zag-js/date-picker	Minor
@zag-js/dialog	Minor
@zag-js/dnd	Minor
@zag-js/drawer	Minor
@zag-js/editable	Minor
@zag-js/file-upload	Minor
@zag-js/floating-panel	Minor
@zag-js/gridlist	Minor
@zag-js/hover-card	Minor
@zag-js/image-cropper	Minor
@zag-js/listbox	Minor
@zag-js/marquee	Minor
@zag-js/menu	Minor
@zag-js/navigation-menu	Minor
@zag-js/number-input	Minor
@zag-js/pagination	Minor
@zag-js/password-input	Minor
@zag-js/pin-input	Minor
@zag-js/popover	Minor
@zag-js/presence	Minor
@zag-js/progress	Minor
@zag-js/qr-code	Minor
@zag-js/radio-group	Minor
@zag-js/rating-group	Minor
@zag-js/scheduler	Minor
@zag-js/scroll-area	Minor
@zag-js/select	Minor
@zag-js/signature-pad	Minor
@zag-js/slider	Minor
@zag-js/splitter	Minor
@zag-js/steps	Minor
@zag-js/switch	Minor
@zag-js/tabs	Minor
@zag-js/tags-input	Minor
@zag-js/timer	Minor
@zag-js/toast	Minor
@zag-js/toc	Minor
@zag-js/toggle-group	Minor
@zag-js/toggle	Minor
@zag-js/tooltip	Minor
@zag-js/tour	Minor
@zag-js/tree-view	Minor
@zag-js/store	Minor
@zag-js/types	Minor
@zag-js/aria-hidden	Minor
@zag-js/auto-resize	Minor
@zag-js/collection	Minor
@zag-js/color-utils	Minor
@zag-js/utils	Minor
@zag-js/date-utils	Minor
@zag-js/dismissable	Minor
@zag-js/dom-query	Minor
@zag-js/file-utils	Minor
@zag-js/focus-trap	Minor
@zag-js/focus-visible	Minor
@zag-js/highlight-word	Minor
@zag-js/hotkeys	Minor
@zag-js/i18n-utils	Minor
@zag-js/interact-outside	Minor
@zag-js/json-tree-utils	Minor
@zag-js/live-region	Minor
@zag-js/popper	Minor
@zag-js/rect-utils	Minor
@zag-js/remove-scroll	Minor
@zag-js/scroll-snap	Minor
@zag-js/stringify-state	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR