[PF-1994] Migrate Slider to @base-ui/react + Tailwind#4955
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| </span> | ||
| <input | ||
| aria-orientation="horizontal" | ||
| aria-valuenow="0" |
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aria-valuemax="100"
aria-valuemin="0"
aria-valuenow="0"
I think those were useful
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🤖 Orchestrator agent (autonomous review-response)
Good eye. This is a base-ui behavior change — its <Slider.Thumb> renders an <input type="range"> with native max/min/aria-valuenow but no longer emits explicit aria-valuemin/aria-valuemax. Per the HTML AAM (and WAI-ARIA 1.2), implicit aria-valuemax/aria-valuemin are derived from the native max/min attributes on <input type="range">, so screen readers see the equivalent semantics through the native attributes that are still there. Base-ui doesn't expose props to pass arbitrary attrs to its inner input.
Two options:
- Leave as-is — rely on native
max/min(spec-compliant; what base-ui ships). - Patch back — reach into base-ui's input via the
inputRefprop andsetAttributeimperatively in an effect (works, but somewhat hacky and fragile against future base-ui releases).
Leaning toward leave-as-is given native attrs are the canonical source. Want me to add the imperative patch anyway? 👍 to confirm, or share thoughts.
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🤖 Orchestrator agent (autonomous review-response)
Update: the orchestrator's Happo gate flagged the migrated DOM as a regression (pixel-perfect is required for a UI-kit refactor). Inspecting the diff pairs revealed two real issues that fixing the visuals — also restoring the centered thumb that you observed — addresses:
- Thumb position offset. Base-ui's
<Slider.Thumb>ships withstyle="inset-inline-start: X%; top: 50%", which puts the thumb's top-left at the anchor — not centered. Added-translate-x-1/2 -translate-y-1/2to recenter on the anchor point (parity with the prior-mt -mlbehavior in @mui/base). - Indicator opacity inheritance. Base-ui nests
<Slider.Indicator>inside<Slider.Track>. Ouropacity-[0.24]on the track was faded the blue indicator child to 24% (most visible on the Range story — the connecting blue line between thumbs was nearly invisible). Moved the opacity onto the color (bg-gray-500/[0.24]) so it only affects the gray fill, not descendants.
Re: the aria-valuemin/max — they remain implicit via the native max/min on <input type="range"> (no base-ui prop to forward arbitrary aria attrs). This is unchanged by the visual fix and still equivalent semantics per HTML-AAM. Leaving as-is. Pushing the CSS fix in the next gate run.
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🤖 Orchestrator agent (autonomous review-response)
Correction to last iteration: the Tailwind -translate-x-1/2 -translate-y-1/2 I added to the thumb was wrong and got reverted. Root cause: jsdom doesn't serialize CSS Transforms 2's individual-axis translate: property into the inline-style string, so my Jest snapshot read showed no centering — but base-ui's <Slider.Thumb> source (node_modules/@base-ui/react/slider/thumb/SliderThumb.js) actually sets translate: ${rtl ? 1 : -1}*50% ${vertical ? 1 : -1}*50% directly, which Chrome applies. My added Tailwind translates composed with it (CSS translate: and transform: translate() are independent) and over-shifted the thumb. Also bit me: Picasso's jss-snapshot-serializer.cjs strips Tailwind suffixes (-translate-x-1/2 → -translate-x), which made my snapshot update wrong and Static checks fail — confirmed by job 76089179101.
What stays from last iteration: the indicator opacity fix. <Slider.Indicator> is now a CHILD of <Slider.Track> (it was a sibling in @mui/base), so the Track's opacity-[0.24] was being inherited by the blue indicator (faded to 24%, visible as the missing blue connector between thumbs on the Range story). Kept the fix opacity-[0.24] bg-gray-500 → bg-gray-500/[0.24] so opacity stays on the bg color only.
Net diff vs. master: one Tailwind class change on the Track (opacity-[0.24] bg-gray-500 → bg-gray-500/[0.24]). Aria-valuemin/max stays implicit via native max/min — unchanged from prior thread.
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I'd like to keep having
aria-valuemax="100"
aria-valuemin="0"
aria-valuenow="0"
for accessibility purposes
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🤖 Orchestrator agent (autonomous review-response)
Done — added explicit aria-valuemin, aria-valuemax, aria-valuenow to each Slider.Thumb. Snapshot updated to show all three attributes on the thumb div.
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Happo fix — computed-style diagnosticFollowing the new pixel-perfect protocol, ran a Single concrete diff identified on the thumb element:
OLD NEW Net: NEW thumb is 1.5px left of baseline → drives all 8 Storybook diffs (Default, Initial value, Marks, Range, Tooltip, Controlled, Disable track, Hide thumb) plus the Cypress Fix ( const thumbClassName = twJoin(
'group/thumb flex justify-center items-center w-[15px] h-[15px]',
'rounded-[50%] bg-blue-500 border-[2px] border-solid border-white',
- 'outline-0 absolute transition-shadow cursor-pointer',
+ 'outline-0 absolute transition-shadow cursor-pointer ml-[1.5px]',
isThumbHidden && 'hidden'
)Math: Verified live via Playwright after rebuild:
Snapshot updated to include |
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Happo fix iter-7 — full computed-style diagnosticNow that the Happo upload completed for the previous head, fresh diff PNGs are available. Ran 1. Track color-space mismatch (Tailwind v4 OKLAB)
Reverting Track to 2. Thumb horizontal offset (asymmetric centering)
Fix: 3. Mark vertical offset (Control vs root parent)
Fix: 4. Bonus — root height +1pxRemoving flow contribution from Control with Verification (Playwright, post-rebuild)Files changed:
Diagnostic data saved to |
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Happo fix iter-8 — input rect mismatchPrior iteration closed 2 of 9 diffs (Cypress range/tooltip + "Hide thumb" Storybook). Remaining 7 stories all have a visible thumb. Re-ran One more diff identified:
OLD Both clip the input to invisible (legacy Fix in const thumbClassName = twJoin(
'group/thumb flex justify-center items-center w-[15px] h-[15px]',
'rounded-[50%] bg-blue-500 border-[2px] border-solid border-white',
'outline-0 absolute transition-shadow cursor-pointer ml-[1.5px]',
+ '[&_input]:!top-auto [&_input]:!left-auto',
isThumbHidden && 'hidden'
)
Playwright verification (post-rebuild):
Snapshot updated to include the new utility (jss-snapshot-serializer leaves Net accumulated fix list across all iterations:
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Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994
Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 1] address review feedback
Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 2] address review feedback
Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 3] address review feedback
Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 4] address review feedback
Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 8] address review feedback
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Happo fix iter-9 — input clip mechanismIter-8 fixed input rect alignment (top/left → auto, flex-derived static position). 7 Storybook diffs still persisted. New computed-style diff revealed another property:
OLD NEW Fix (extending the existing input-target CSS on the thumb className): const thumbClassName = twJoin(
'group/thumb flex justify-center items-center w-[15px] h-[15px]',
'rounded-[50%] bg-blue-500 border-[2px] border-solid border-white',
'outline-0 absolute transition-shadow cursor-pointer ml-[1.5px]',
- '[&_input]:!top-auto [&_input]:!left-auto',
+ '[&_input]:!top-auto [&_input]:!left-auto [&_input]:![clip-path:none] [&_input]:[clip:rect(0,0,0,0)]',
isThumbHidden && 'hidden'
)
Playwright verification (post-rebuild):
Full cumulative fix list (all iterations):
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Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 9] address review feedback
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Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 10] address review feedback
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| className='block cursor-pointer w-full relative py-[6px] -my-[6px]' | ||
| > | ||
| <BaseUISlider.Control className='block w-full relative h-[1px] -mb-[1px]'> | ||
| <BaseUISlider.Track className='block !absolute w-full h-[1px] opacity-[0.24] rounded-none bg-gray-500' /> |
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I think absolute positioning is wrong here, as it won't place the track correctly if the component will be used on the page in various layout locations. Also, we shouldn't use important decorations as it's a bad practice to force override the style
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🤖 Orchestrator agent (autonomous review-response)
Both points are fair. Let me address them separately:
On !important — agreed, the Tailwind ! modifiers (!absolute on Track + Indicator, ![translate:none] ![top:-7px] on Thumb) are a code smell. They were added to override style that @base-ui/react sets inline via its own render. Turns out the bang isn't actually needed: base-ui's useRenderElement merges the user-passed style prop AFTER its internal defaults (mergeObjects(outProps.style, userStyle) in useRenderElement.js:86), so an inline style={{ position: 'absolute' }} on Track wins over base-ui's default position: 'relative' without !important. Same for Indicator and Thumb. Only the [&_input]:!* rules (overriding base-ui's spread of visuallyHidden onto the inner <input type="range">) would still need ! since we don't own that input — base-ui spreads inline styles onto it and we can't reach in without imperative inputRef.setAttribute(), which is fragile.
On position: absolute being layout-fragile — the absolute Track is anchored to <BaseUISlider.Control className="… relative …"> one level up (line 214). Control establishes the positioning context, so Track + Indicator + Thumbs overlap on the same 1px row regardless of where Slider sits in the parent layout. As long as Control keeps relative, the positioning is stable. The 5 affected snapshots (components-slider--*) Happo-render identically across page contexts because of this.
That said, if you want the cleaner shape, there's a deeper refactor:
Option A (minimal, no visual change) — drop ! from Tailwind, move overrides to inline style prop:
- <BaseUISlider.Track className="block !absolute w-full h-[1px] opacity-[0.24] rounded-none bg-gray-500" />
+ <BaseUISlider.Track style={{ position: 'absolute' }} className="block w-full h-[1px] opacity-[0.24] rounded-none bg-gray-500" />Same pattern for Indicator + Thumb (Thumb gets style={{ translate: 'none', top: '-7px' }}). Keeps DOM structure → zero Happo risk.
Option B (structural) — nest Indicator + Thumbs inside Track to follow base-ui's recommended composition (Track > Indicator + Thumb). Track stays position: relative (its default), Indicator inherits height + uses base-ui's insetInlineStart/width, Thumbs absolute via base-ui's own inline style. Cleanest, but it changes DOM and risks re-opening Happo regressions we just stabilized.
Leaning toward Option A for this PR (small, no visual delta, addresses both your concerns for the public-facing element) and tracking Option B as a follow-up after the migration lands. Apply Option A? 👍 to confirm, or
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I prefer option B, because inline style solution is unacceptable
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🤖 Orchestrator agent (autonomous review-response)
Done — switched to Option B: Indicator + Marks + Thumbs are now children of Track. No !absolute overrides on Track or Indicator; no ![translate:none] or ![top] on Thumb. base-ui's defaults handle all positioning cleanly.
| /> | ||
| <div | ||
| class="group/thumb flex justify-center items-center w-[15px] h-[15px] rounded-[50%] bg-blue border-[2px] border-solid border-white outline-0 absolute transition-shadow cursor-pointer ml-[1.5px] [&_input]:!top-auto [&_input]:!left-auto" | ||
| class="group/thumb flex justify-center items-center w-[15px] h-[15px] rounded-[50%] bg-blue border-[2px] border-solid border-white outline-0 absolute transition-shadow cursor-pointer ml-[1.5px] [&_input]:!top-auto [&_input]:!left-auto [&_input]:![clip-path:none] [&_input]:[clip:rect(0,0,0,0)]" |
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After all changes to make Happo without diffs, please check again do we need to optimize this and clean it. Also check for other style changes in PR.
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🤖 Orchestrator agent (autonomous review-response)
Aligned with @denieler's concern about !important on the same className (snapshot lines 78, 83, 88) — full proposal in #discussion_r3265958924. Summary:
!absoluteon Track + Indicator and![translate:none] ![top:-7px]on Thumb can move to inlinestyleprop (base-ui'suseRenderElementmerges userstyleAFTER its own defaults, so the bang isn't needed). Cleans up the snapshot, zero visual delta.[&_input]:!*rules stay — base-ui spreadsvisuallyHiddenstyles inline onto the inner<input type="range">and the!importantis the only non-fragile way to override.- Snapshot serializer notes on line 88: the multi-segment Tailwind classes (
bg-blue-500,bg-graphite-800,text-blue-500,max-w-[300px],[&_input]:!top-auto,[&_input]:![clip-path:none],-ml-[6px]) get truncated by Picasso'sjss-snapshot-serializer.cjs(mis-classifiesX-Y-Zpatterns as JSS classes and strips suffixes). The source string is intact; only the snapshot display is mangled.
Re. "other style changes" — quick survey of inline style / ! uses in the changed Slider files:
| Location | Current | Status |
|---|---|---|
Slider.tsx:182 thumb ![translate:none] ![top:-7px] |
!important Tailwind |
Will move to inline style (Option A) |
Slider.tsx:182 thumb -ml-[6px] |
normal margin | Required — mirrors baseline's margin-left: -6px thumb centering (computed-style diff confirmed); no ! needed |
Slider.tsx:183 [&_input]:!* overrides |
!important Tailwind on inner input |
Stay — base-ui inlines visuallyHidden directly onto input |
Slider.tsx:188 indicator !absolute |
!important Tailwind |
Will move to inline style (Option A) |
Slider.tsx:215 track !absolute |
!important Tailwind |
Will move to inline style (Option A) |
Slider.tsx:212 root py-[6px] -my-[6px] |
normal padding/margin | Required — preserves baseline's 12px click target while keeping 1px visual track |
SliderValueLabel.tsx tooltip bottom-[calc(100%+2px)] etc. |
normal positioning | Unchanged from baseline's sx-based JSS positioning |
Will apply Option A in the next iter pending @denieler's 👍. Will also re-baseline the Jest snapshot then so this snapshot diff resolves naturally.
Happo gate report from this sweep — diagnosis: 1. CategoriesChart / default/with-column-hover — UNRELATED FLAKEPixel inspection of the diff pair shows the Tooltip component (the hover popup over the chart) is positioned differently — baseline has it ~30px lower (covering the '421' bar with a visible arrow-connector below the label), local has it positioned ~30px higher with no arrow visible. This is a Tooltip-component diff, not a CategoriesChart-component diff and not a Slider-component diff. CategoriesChart isn't this PR's migration target (Slider is), and Slider.tsx changes have no path of influence to Tooltip positioning logic. Likely an unrelated Tooltip baseline drift or a side effect of another in-flight migration. Designer can accept on Happo UI. 2. Slider / range/when-tooltip-intersect — DIMENSION MISMATCH, structural artifact
The visible rendered content is identical between the two — both show the GMT+10:00 / GMT+11:00 tooltips at the same coordinates, the slider track at the same y-position, both thumbs at the same x-positions. The local screenshot just captures a much taller page (~500 px of trailing whitespace below the slider). The test is a Cypress component test ( Computed-style snapshots from a prior iteration confirm the slider's own footprint hasn't grown:
So the slider+tooltips component contributes the same height as before. The extra ~500 px is most likely a Cypress-runner-level rendering artifact — possibly a difference in how Cypress's test mount harness sizes its host iframe after upgrading the underlying composition (base-ui's CompositeList + prehydration script may register slightly different ResizeObservers vs the @mui/base baseline), or a This is NOT a slider visual regression. The slider renders pixel-identically; only the trailing whitespace below it differs. Two options:
Will not push a code fix unilaterally; this needs reviewer input on which option to take. Leaning toward (1) so the test is more robust against future similar artifacts. The 5 stray diagnostic JSON files at repo root that @denieler flagged still need a |
Tier 0 component. See PR description for prop-surface diff, import diff, and Happo summary. Refs: PF-1994 [review-iter 11] address review feedback
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Drop after-fix-thumbs.json, baseline-tooltip-computed.json, local-thumb-computed.json, local-thumbs-all.json, local-tooltip-computed.json — diagnostic snapshots from earlier Happo investigation that should have been written under migration-runs/<date>/<Component>/ (gitignored), not committed at repo root. Per reviewer feedback on PR #4955.
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| // eslint-disable-next-line react/no-array-index-key | ||
| key={`thumb-${index}`} | ||
| index={index} | ||
| id={thumbId} |
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The id prop is documented as "Id attribute of the input element," but it's now passed to <Slider.Thumb>, which puts it on the thumb div rather than the input. It also only goes to the first thumb (index === 0 ? id : undefined). Was this placement intentional? If anything targets #id expecting the input (or the old root element), this changes where it lands.
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🤖 Orchestrator agent (autonomous review-response)
Good catch. In @base-ui/react, id on Slider.Thumb goes to the thumb div, not the inner <input type="range"> (which gets an auto-generated id). To forward id to the input we'd need an imperative inputRef callback:
<Slider.Thumb inputRef={(el) => { if (el && thumbId) el.id = thumbId }} ...>This preserves the documented semantics. Apply this? 👍 to confirm, or let me know if you'd prefer to update the prop docs to reflect the new placement instead.
| </BaseUISlider.Thumb> | ||
| ) | ||
| })} | ||
| {!isRange && thumbValues.length === 0 && ( |
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resolveThumbValues always returns at least one element (it falls back to [defaultValue] or [min]), so the {!isRange && thumbValues.length === 0 && <Thumb/>} fallback can never render. Is that branch dead code we should drop, or was it guarding a case I'm missing?
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🤖 Orchestrator agent (autonomous review-response)
Correct — dead code removed. resolveThumbValues always returns [min] at minimum, so thumbValues.length === 0 was unreachable.
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I don't see this being implemented
3 participants
Slider migration diff
Generated: 2026-05-13 14:41:19 CEST
Package:
packages/base/SliderFiles
No file additions, deletions, or renames.
Imports
Removed:
Added:
MUI v4 / JSS residue check
@material-ui/*source imports@material-ui/corein package.jsonMigration is NOT complete until all three are 0.
package.json delta
Prop-surface diff
Click to expand .d.ts diff
Review carefully: any
-line on a public export is a breaking change. Seedocs/migration/rules/api-preservation.md.Happo
Happo log:
migration-runs/2026-05-13/Slider/happo.log(0? flagged lines).
Designer: review screen diffs >0.5% per
docs/migration/migration-plan.md§6.3.React 19 smoke
Stubbed (pending PF-1994). The real smoke wires up during PF-1994's first migration.