Remove sx props and Box from Truncate

[liuliu-dev]

Migrates the Truncate component away from BoxWithFallback components and sx prop support to use CSS modules, Closes #4822

• Note: Multiple repos are using Truncate with sx props including github/github-ui.

Rollout strategy

• Major release; if selected, include a written rollout or migration plan

[changeset-bot]

🦋 Changeset detected

Latest commit: a5bd7a9

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

This PR includes changesets to release 2 packages

Name	Type
@primer/react	Major
@primer/styled-react	Major

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[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	89.74 KB (-0.03% 🔽)
packages/react/dist/browser.umd.js	90.12 KB (+0.13% 🔺)

[primer-integration]

👋 Hi from github/github! Your integration PR is ready: https://github.com/github/github/pull/397797

[primer-integration]

🔴 golden-jobs completed with status failure.

[Copilot]

Pull Request Overview

This PR migrates the Truncate component from using BoxWithFallback and sx props to CSS modules as part of the design system modernization effort. This is a breaking change that removes styled-system dependencies.

• Removes sx prop support and MaxWidthProps from Truncate component
• Replaces BoxWithFallback with direct component rendering using polymorphic as prop
• Creates a styled wrapper in @primer/styled-react package to maintain backward compatibility

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/react/src/Truncate/Truncate.tsx	Main component migration removing sx props and BoxWithFallback
packages/styled-react/src/index.ts	Adds styled wrapper for Truncate to maintain backward compatibility
packages/react/src/ActionList/Description.tsx	Removes sx prop usage from Truncate component
packages/react/src/Truncate/Truncate.stories.tsx	Removes sx prop from Storybook controls
packages/react/src/Truncate/Truncate.docs.json	Updates documentation to reflect API changes
packages/styled-react/src/__tests__/__snapshots__/exports.test.ts.snap	Updates test snapshot for export changes
.changeset/lucky-facts-obey.md	Changeset documenting the breaking change

[liuliu-dev]

integration checks manually ran here: https://github.com/github/github-ui/pull/1180