[atomiks]

This is part of the Codex review sweep

Changes

• Stop grouped Toggle handling immediately when onPressedChange cancels the event.
• Add regression coverage for canceled Toggle and ToggleGroup changes, including the parent callback staying quiet when child cancellation vetoes the change.
• Document data-disabled for Toggle and add accessible labels to the ToggleGroup hero demos.

[pkg-pr-new]

• base-ui-tanstack-start

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@4940
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@4940
  

commit: 9b845e2

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	🔺+17B(0.00%)	🔺+1B(0.00%)

Details of bundle changes

Performance

Total duration: 1,341.78 ms 🔺+252.77 ms^(+23.2%) | Renders: 50 ⁽⁺⁰⁾ | Paint: 2,022.77 ms 🔺+389.29 ms^(+23.8%)

Test	Duration	Renders
Select mount (200 instances)	181.31 ms 🔺+44.53 ms(+32.6%)	3 (+0)
Menu mount (300 instances)	164.94 ms 🔺+43.89 ms(+36.3%)	2 (+0)
Menu open (500 items)	93.24 ms 🔺+31.51 ms(+51.0%)	12 (+0)
Mixed surface mount (app-like density)	97.61 ms 🔺+30.01 ms(+44.4%)	5 (+0)
Select open (500 options)	71.46 ms 🔺+17.48 ms(+32.4%)	14 (+0)

…and 1 more (+6 within noise) — details

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[flaviendelangle]

PR #4940 Review Summary — [toggle] Fix grouped cancelation and JSDoc

The fix itself is correct and well-tested for the headline scenarios. Main gap: the new tests don't cover several adjacent code paths that could regress silently. No blocking issues.

Critical Issues

None.

Important Issues

Test coverage gaps (packages/react/src/toggle/Toggle.test.tsx, packages/react/src/toggle-group/ToggleGroup.test.tsx):

• No test for cancellation in multiple mode — setGroupValue (ToggleGroup.tsx:70-76) has a distinct array-mutation branch that's exercised only in multi mode. A regression there would slip through.
• No test for keyboard activation (Enter/Space) — the existing tests use button.click(). The repo's convention (see ToggleGroup.test.tsx:402-426) tests both paths separately.
• No test asserting onPressedChange is called exactly once in the cancel case. A future bug that skips or double-fires it would still pass assertions on aria-pressed.

Suggestions

• Toggle.tsx:90-91 comment wording: "before the group commits" is slightly imprecise — setGroupValue itself fires onValueChange before committing. Consider tightening to: "before setGroupValue runs, so canceling here also vetoes onValueChange and the group value commit (they share this details object)."
• Toggle.tsx:101-103 (second isCanceled check): still meaningful — guards the case where onValueChange cancels — but could use a mirroring one-line comment so future readers understand why both checks exist.
• Pre-existing silent-failure hazard (not introduced by this PR): if a Toggle inside a ToggleGroup has a falsy value, the group commit is silently skipped in production (the dev-only error() at Toggle.tsx:52-63 doesn't run in prod). Worth tracking separately.

Strengths

• The reorder genuinely fixes the bug: pre-PR, canceling in onPressedChange couldn't veto the group commit because setGroupValue had already run.
• The added comment correctly explains the WHY (shared details object, cancel ordering), not the WHAT — aligned with AGENTS.md guidance.
• data-disabled is already emitted via state.disabled (verified by Toggle.test.tsx:93); this PR just documents the existing attribute appropriately in ToggleDataAttributes.ts, types.md, and page.mdx.
• aria-label="Text alignment" on the ToggleGroup hero demos is a real a11y improvement.
• Tests follow conventions: Vitest matchers, no Chai chains, no unnecessary flushMicrotasks, mirror existing describe structure.
• No new silent failures, no broad catches, exception propagation is unaffected.
• AGENTS.md compliance: no window.setTimeout/useCallback/useLayoutEffect violations.

Recommended Action

1. (Optional) Add a multiple mode cancellation test and a keyboard-activation cancellation test — closest to "important" of any finding here.
2. (Optional) Tighten the Toggle.tsx:90-91 comment wording and mirror it above the second isCanceled check.
3. Approve and merge — the fix is correct and reasonably covered.