[toast] Reduce bundle size

[atomiks]

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

This removes dead context members and selectors, deduplicates Title and Description logic, consolidates store and effect logic, and inlines internal CSS-variable enum values. Regression and enum-sync tests cover the retained behavior and 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@5219
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@5219
  

commit: db97bd5

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	▼-1.62KB(-0.35%)	▼-316B(-0.21%)

Details of bundle changes

Performance

Total duration: 1,290.32 ms +106.81 ms^(+9.0%) | Renders: 78 ⁽⁺⁰⁾ | Paint: 1,994.85 ms +153.47 ms^(+8.3%)

Test	Duration	Renders
Checkbox mount (500 instances)	96.30 ms 🔺+20.52 ms(+27.1%)	1 (+0)
Mixed surface mount (app-like density)	80.98 ms 🔺+19.57 ms(+31.9%)	5 (+0)

12 tests within noise — details

Metric alarms

Test	Metric	Change
Mixed surface mount (app-like density)	bench:paint	🔺 +29.64 ms

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

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[Copilot]

Pull request overview

This PR is part of the toast bundle-size minimization effort, refactoring @base-ui/react/toast internals to remove dead/duplicate code paths, inline CSS var enum values (with a new sync test), and simplify store/component logic while aiming for no behavior changes.

Changes:

• Simplifies toast state/store APIs (signature tightening, helper removal, deduped logic) and updates affected call sites/tests.
• Deduplicates Toast.Title/Toast.Description via a shared hook and streamlines several parts to return useRenderElement(...) directly.
• Inlines CSS variable names in toast parts and adds an enum-sync test to keep runtime strings pinned to the documented enums.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/react/src/toast/viewport/ToastViewport.tsx	Merges global listener effects, removes enum indirection for CSS var, and simplifies hover/leave logic.
packages/react/src/toast/utils/useToastLabelPart.ts	New shared hook to dedupe Title/Description logic and ID registration.
packages/react/src/toast/useToastManager.ts	Uses the shared provider context hook instead of direct context access.
packages/react/src/toast/title/ToastTitle.tsx	Refactors to use useToastLabelPart and simplifies render flow.
packages/react/src/toast/description/ToastDescription.tsx	Refactors to use useToastLabelPart and simplifies render flow.
packages/react/src/toast/store.ts	Shrinks store surface area and simplifies several internal flows (timers, updates, focus scan).
packages/react/src/toast/store.test.ts	Updates tests to match new store method signatures.
packages/react/src/toast/root/ToastRootContext.ts	Removes unused context members to reduce bundle surface.
packages/react/src/toast/root/ToastRoot.tsx	Inlines CSS var names, simplifies swipe logic/context memo, and adjusts height recalculation behavior.
packages/react/src/toast/provider/ToastProvider.tsx	Updates provider sync call to match new store API.
packages/react/src/toast/positioner/ToastPositioner.tsx	Inlines CSS var name and removes unnecessary memoization.
packages/react/src/toast/enumSync.test.tsx	New test that pins inlined CSS var strings to the exported enums.
packages/react/src/toast/content/ToastContent.tsx	Simplifies to return useRenderElement directly (no behavior change intended).
packages/react/src/toast/close/ToastClose.tsx	Simplifies to return useRenderElement directly and relies on root context for expanded.
packages/react/src/toast/arrow/ToastArrow.tsx	Simplifies to return useRenderElement directly.
packages/react/src/toast/action/ToastAction.tsx	Uses enabled to avoid rendering when not needed, reducing branching.

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