[code-infra] New bundler subcommand for package bundling by brijeshb42 · Pull Request #1083 · mui/mui-public

brijeshb42 · 2026-01-30T09:14:06Z

This PR introduces a new bundle CLI subcommand for @mui/internal-code-infra to build and bundle packages using Rollup with Babel integration.

Changes

New Features

New bundle CLI subcommand (pnpm code-infra bundle)
- Supports building/bundling packages with configurable output formats (ESM, CJS, or both)
- Adapter-based architecture for easy migration to other bundlers in the future
- Automatically determines output file extensions based on "type" field in package.json
- Reads entry points from package.json exports and bin fields
- Supports source maps, and verbose logging
- Option to preserve directory structure in output
- Option to generate package.json in output directory
Rollup adapter implementation (adapter-rollup.mjs)
- Full Babel integration via @rollup/plugin-babel
- Node module resolution with @rollup/plugin-node-resolve
- Environment variable replacement with @rollup/plugin-replace
- TypeScript declaration generation via rollup-plugin-dts
- Directive preservation (e.g., 'use client') via rollup-plugin-preserve-directives
- Automatic externalization of dependencies and peer dependencies
Entry point resolution utilities (resolve-entrypoints.mjs)
- Resolves exports entries from package.json, supporting glob patterns
- Platform detection (node/browser/neutral) based on export conditions
- Support for nested conditions (import, require, types, react-server, etc.)
- Handles bin field entries for CLI tools
Exports field generation (generate-exports-field.mjs)
- Generates proper exports field structure from bundler output
- Correctly maps ESM/CJS outputs with their corresponding type definitions
- Handles bin entries separately

Bug Fixes

Fix side-effect tree-shaking - Improved tree-shaking by properly handling side effects in the bundling process
Babel runtime interop plugin (babel-runtime-interop-plugin.mjs)
- Replaces Rollup's inline interop helper functions with imports from @babel/runtime/helpers
- Deduplicates _interopNamespaceCompat, _interopNamespaceDefault, and _interopNamespace helpers across output files
- Only applies to CJS output format

Other Changes

Migrated babel.config.js to babel.config.mjs (ESM format)
Updated @mui/internal-babel-config with additional configuration options
Added comprehensive test suites for resolve-entrypoints and generate-exports-field utilities (1,430 lines of tests)
New dependencies added to code-infra:
- @rollup/plugin-babel
- @rollup/plugin-node-resolve
- @rollup/plugin-replace
- rollup
- rollup-plugin-dts
- rollup-plugin-preserve-directives
[code-infra] Migrate to rollup based package build base-ui#3901

mui-bot · 2026-01-30T10:16:21Z

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui-components/react	0B^(0.00%)	0B^(0.00%)
@mui/x-charts-pro	0B^(0.00%)	0B^(0.00%)

Details of bundle changes

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

* Handles babel integration * Output file extension based on "type" in package.json * Adapter based so it it simpler to port to another bundler in future

brijeshb42 added the scope: code-infra Involves the code-infra product (https://www.notion.so/mui-org/5562c14178aa42af97bc1fa5114000cd). label Jan 30, 2026

oliviertassinari temporarily deployed to build-package - code-infra-dashboard PR #1083 January 30, 2026 09:14 — with Render Destroyed

oliviertassinari temporarily deployed to build-package - mui-tools-public PR #1083 January 30, 2026 09:14 — with Render Destroyed

brijeshb42 force-pushed the build-package branch from fbe37fa to 022ef04 Compare January 30, 2026 09:15

oliviertassinari deployed to build-package - mui-tools-public PR #1083 January 30, 2026 09:15 — with Render View deployment

brijeshb42 force-pushed the build-package branch from 022ef04 to 9f51ded Compare January 30, 2026 10:15

oliviertassinari temporarily deployed to build-package - mui-tools-public PR #1083 January 30, 2026 10:15 — with Render Destroyed

brijeshb42 changed the title ~~[code-infra] New package for bundler adapter~~ [code-infra] New bundler subcommand for package bundling Jan 30, 2026

brijeshb42 force-pushed the build-package branch from 9f51ded to 6f8240d Compare January 30, 2026 10:17

oliviertassinari deployed to build-package - mui-tools-public PR #1083 January 30, 2026 10:17 — with Render View deployment

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github-actions Bot added the PR: out-of-date The pull request has merge conflicts and can't be merged. label Feb 8, 2026

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brijeshb42 removed the request for review from a team February 24, 2026 05:38

brijeshb42 added 5 commits February 24, 2026 16:06

[code-infra] Create a new bundle subcommand to build/bundle packages

65538c8

* Handles babel integration * Output file extension based on "type" in package.json * Adapter based so it it simpler to port to another bundler in future

Fix side-effect tree-shaking

a47918e

Patch rollup's namespace helper output to instead use babel runtime

a0e08a7

MUI X debug fix

3ce275a

tmp

5388375

brijeshb42 force-pushed the build-package branch from 71b865f to 5388375 Compare February 24, 2026 10:36

oliviertassinari temporarily deployed to build-package - mui-tools-public PR #1083 February 24, 2026 10:36 — with Render Destroyed

github-actions Bot added the PR: out-of-date The pull request has merge conflicts and can't be merged. label Feb 25, 2026

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[code-infra] New bundler subcommand for package bundling#1083

[code-infra] New bundler subcommand for package bundling#1083
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