[slider] Reduce bundle size

[atomiks]

Reduces the @base-ui/react/slider bundle size without changing behavior or the public API. The bundle bot is authoritative for the current size impact.

The cleanup consolidates control, indicator, thumb, root, and collision-resolution logic. Focused state-machine and enum-sync regressions cover the affected behavior and inlined state-attribute strings.

[pkg-pr-new]

• base-ui-tanstack-start

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@5222
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@5222
  

commit: cc75648

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	▼-1.96KB(-0.43%)	▼-384B(-0.26%)

Details of bundle changes

Performance

Total duration: 1,214.19 ms -83.31 ms^(-6.4%) | Renders: 78 ⁽⁺⁰⁾ | Paint: 1,889.27 ms -109.54 ms^(-5.5%)

Test	Duration	Renders
Scroll Area mount (300 instances)	75.64 ms ▼-23.97 ms(-24.1%)	3 (+0)
Tooltip mount (300 contained roots)	43.27 ms ▼-12.10 ms(-21.9%)	1 (+0)
Dialog mount (300 instances)	44.74 ms ▼-11.42 ms(-20.3%)	1 (+0)

11 tests within noise — details

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Check out the code infra dashboard for more information about this PR.

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[Copilot]

Pull request overview

Behavior-preserving bundle-size reduction pass over @base-ui/react/slider by simplifying small helpers, removing a couple of thin utility wrappers, and switching a few internal hot-path helpers to positional arguments to improve minification. The PR also adds targeted regression tests around swap behavior, indicator parity, and interaction-state cleanup.

Changes:

• Simplify/inline slider internal utilities (map/loops, remove tiny helpers, reuse shared mappings).
• Convert internal helper APIs (resolveThumbCollision, getPushedThumbValues, getMidpoint) to smaller positional signatures and update call sites/tests.
• Add regression tests for swap focus/active index, indicator parity across orientations/directions, enum-to-runtime alignment, and controlled-range growth mid-drag.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/react/src/slider/value/SliderValue.tsx	Simplifies formatting and htmlFor construction for smaller output rendering.
packages/react/src/slider/utils/valueArrayToPercentages.ts	Removes unused/duplicative utility to reduce bundle surface (file deleted).
packages/react/src/slider/utils/validateMinimumDistance.ts	Replaces array allocation + Math.min(...distances) with early-exit loop.
packages/react/src/slider/utils/resolveThumbCollision.ts	Switches to positional args, hoists shared work, and fast-paths push.
packages/react/src/slider/utils/resolveThumbCollision.test.ts	Updates tests to match new resolveThumbCollision signature.
packages/react/src/slider/utils/replaceArrayItemAtIndex.ts	Removes thin wrapper in favor of local inlining (file deleted).
packages/react/src/slider/utils/getSliderValue.ts	Inlines array update/sort logic and simplifies non-range return path.
packages/react/src/slider/utils/getPushedThumbValues.ts	Switches to positional args to improve minification.
packages/react/src/slider/utils/getPushedThumbValues.test.ts	Updates tests to match new getPushedThumbValues signature.
packages/react/src/slider/utils/getMidpoint.ts	Removes Coords object allocation; returns a single axis midpoint.
packages/react/src/slider/thumb/SliderThumb.tsx	Reduces branching and allocations; inlines data-index; updates midpoint usage.
packages/react/src/slider/root/stateAttributesMapping.ts	Reuses a shared nullMapping function to shrink mapping literals.
packages/react/src/slider/root/SliderRootContext.ts	Removes unused pressedInputRef from context surface.
packages/react/src/slider/root/SliderRoot.tsx	Simplifies equality check and trims memo dependencies while preserving stability.
packages/react/src/slider/root/SliderRoot.test.tsx	Adds browser-mode regressions for swap focus/active index and cancel behavior.
packages/react/src/slider/indicator/SliderIndicator.tsx	Consolidates style computation into a single helper while preserving behavior.
packages/react/src/slider/indicator/SliderIndicator.test.tsx	Adds browser-mode parity coverage for keyboard behavior + indicator styling.
packages/react/src/slider/enumSync.test.tsx	Ensures runtime data-index matches the docs enum value.
packages/react/src/slider/control/SliderControl.tsx	Updates collision/midpoint calls, reduces cached refs, and tightens swap focusing.
packages/react/src/slider/control/SliderControl.test.tsx	Adds browser-mode regression to ensure cached interaction state is cleared on range growth mid-drag.

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