feat(tables): add tree support

[tenphi]

Summary

• add opt-in nested rows to ItemTable and DataTable with controlled and uncontrolled expansion
• add React Aria treegrid semantics, disclosure controls, roving focus, typeahead, and hierarchy keyboard navigation
• make client sorting, search, pagination, virtualization, ranges, selection, and row drops hierarchy-aware
• add cascading ItemTable selection, recursive DataTable sorting, stories, docs, localization, browser coverage, and a minor changeset
• raise the complete bundle budget from 505 kB to 510 kB; the measured bundle is 508.04 kB and the Button tree-shaking budget is unchanged

Verification

• pnpm test — 97 files, 2,079 passed, 1 skipped
• pnpm test:browser — 8 files, 110 passed
• pnpm audit-docs --component=ItemTable
• pnpm audit-docs --component=DataTable
• pnpm audit-defaults
• pnpm build
• pnpm size

---

Note

Medium Risk
Touches the shared table renderer, selection, keyboard focus, and virtualization. Behavior is opt-in via getRowChildren, but bugs here can affect accessibility and selection in both tables.

Overview
Adds opt-in nested rows to ItemTable and DataTable via getRowChildren, with controlled/uncontrolled expansion (expandedKeys / defaultExpandedKeys / onExpand) and a disclosure column (treeColumnKey).

A shared immutable tree model recursively sorts siblings, paginates roots (keeping subtrees together), and flattens only expanded rows for render and virtualization. ItemTable client search keeps ancestor paths and temporarily opens matching branches. Multiple selection cascades by default (treeSelectionBehavior); DataTable cell ranges and row numbers follow visible descendants. Flat reorder is ignored in tree mode; dropOnRow rejects self/descendant cycles.

The native table becomes role="treegrid" with React Aria keyboard/typeahead, virtualized focus handoff, and TreeContent / TreeToggle / TreeValue styling. Bundle budget rises 505→510 kB; Button tree-shaking is unchanged.

^{Reviewed by Cursor Bugbot for commit 8b84560. Bugbot is set up for automated code reviews on this repo. Configure here.}

[changeset-bot]

🦋 Changeset detected

Latest commit: 8b84560

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

This PR includes changesets to release 1 package

Name	Type
@cube-dev/ui-kit	Minor

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[vercel]

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Project	Deployment	Actions	Updated (UTC)
cube-ui-kit	Ready	Preview	Aug 20, 2026 7:51pm

[github-actions]

📦 NPM canary release

Deployed canary version 0.0.0-canary-7475904.

[github-actions]

🧪 Storybook is successfully deployed!

• 👀 Review changes: https://www.chromatic.com/build?appId=626ee6db91d1c8004a912249&number=3930
• 👨‍🎨 Preview storybook: https://626ee6db91d1c8004a912249-jkvtrtmbgi.chromatic.com/

[github-actions]

🏋️ Size limit report

Name	Size	Passed?
All	496.35 KB (+0.79% 🔺)	Yes 🎉
Tree shaking (just a Button)	120.73 KB (0% 🟰)	Yes 🎉

Compared against main at 11e8319 — run 32383738012, 2026-08-20T15:02:21Z.

To see which modules changed, download the size-limit-statoscope-report artifact from this run and open report.html.

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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