Enhancement: Migrate from tsup to tsdown

[gander]

Enhancement Description

The project currently uses tsup as the build tool. However, tsup is no longer actively maintained. The official tsup repository now includes a warning recommending migration to tsdown:

This project is not actively maintained anymore. Please consider using tsdown instead.

Proposed Solution

Migrate from tsup to tsdown, which is the recommended successor and offers:

• Blazing fast performance: Powered by Rolldown and Oxc for incredibly fast builds and declaration file generation
• Seamless migration: Compatible with tsup's main options and features with an automated migration tool
• Active maintenance: Maintained by Kevin Deng, who previously co-maintained tsup
• Powerful ecosystem: Supports Rollup, Rolldown, unplugin plugins, and some Vite plugins
• Future-proof: Will be used as the foundation for the next iteration of Vite's library mode

Migration Steps

tsdown provides an automated migration command:

npx tsdown migrate

For monorepos with multiple packages:

npx tsdown migrate packages/*

The migration tool automatically:

• Updates devDependencies in package.json
• Migrates build and dev scripts
• Converts tsup configuration files to tsdown format

You can preview changes without applying them using the --dry-run flag:

npx tsdown migrate --dry-run

Key Differences to Review

After migration, review the following default value changes:

• format: Defaults to esm instead of multiple formats
• clean: Enabled by default, cleans outDir before each build
• dts: Auto-enabled if package.json contains typings or types field
• target: Reads from engines.node field in package.json if available

Additional Resources

• Migration guide: https://tsdown.dev/guide/migrate-from-tsup
• tsdown documentation: https://tsdown.dev
• GitHub repository: https://github.com/rolldown/tsdown

[omachala]

This is now in v0.10.1 🎉 Let me know if everything looks good on your end!