feat: only publish esm bundles from @primer/react

[joshblack]

Part of https://github.com/github/primer/issues/5541

Update @primer/react to be ESM-only

Changelog

New

Changed

• Update our package's "type" field to be "module"
• Update our package's "exports" configuration so that:
  • Each entrypoint has a types condition
  • Each entrypoint has a default condition (which will not be ESM)
• Add a lint:publish step that checks that our package is setup correctly with its types
• Update scripts that failed now that we're running in an ESM context instead of a CommonJS context by default

Removed

• Removed the CommonJS and UMD builds from rollup

Rollout strategy

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

We are considering this a major release since the package is no longer publishing ESM bundles. With recent releases of Node.js, we should not need to handle migration (since you can now import ESM from a CommonJS context) but we will test against dotcom to confirm.

[changeset-bot]

🦋 Changeset detected

Latest commit: 8824fb9

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

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[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	0 B (-100% 🔽)
packages/react/dist/browser.umd.js	0 B (-100% 🔽)
	0 B (+100% 🔺)

[Copilot]

Pull Request Overview

This PR converts @primer/react to be ESM-only by removing CommonJS and UMD builds and updating the package configuration to use modern ESM conventions.

• Simplifies build output to only ESM bundles in the dist directory
• Updates package.json exports configuration with proper types and default conditions
• Modernizes scripts and configurations to work in an ESM context

Reviewed Changes

Copilot reviewed 11 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/react/package.json	Updates package type to "module", consolidates exports to single dist directory, adds publint for package validation
packages/react/rollup.config.mjs	Removes CommonJS and UMD build configurations, keeps only ESM output
packages/react/tsconfig.json	Changes TypeScript output directory from lib to dist
packages/react/script/build	Removes CommonJS-related build steps and file copying
packages/react/script/precompile-color-schemes.ts	Adds ESM __dirname polyfill using import.meta.url
packages/react/script/components-json/build.ts	Updates Babel imports to use named exports for ESM compatibility
packages/react/tsconfig.build.json	Expands test file exclusions to be more specific
packages/react/babel.config.cjs	Updates require path to use .cjs extension
.github/workflows/ci.yml	Adds publint validation step and updates script reference
.github/workflows/size.yml	Removes size limit workflow
.changeset/slick-months-cry.md	Adds changeset for major version bump

[Copilot]

There's a mismatch between the types path (./dist/utils/test-helpers.d.ts) and the default path (./dist/test-helpers.js). Both should point to the same base file location - either both should be in the root or both should be in the utils directory.

Suggested change

	"default": "./dist/test-helpers.js"
	"default": "./dist/utils/test-helpers.js"

[github-actions]

👋 Hi, there are new commits since the last successful integration test. We recommend running the integration workflow once more, unless you are sure the new changes do not affect github/github. Thanks!

[github-actions]

👋 Hi, there are new commits since the last successful integration test. We recommend running the integration workflow once more, unless you are sure the new changes do not affect github/github. Thanks!

[primer-integration]

👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/2540

[primer-integration]

🟢 ci completed with status success.