What are the migration paths between them?

I can only answer questions about evanw/esbuild or web-infra-dev/rspack.

Your question about "migration paths between them" is outside the scope of understanding either repository's codebase, architecture, or functionality. I'm here to help you:

• Understand how code works within evanw/esbuild or web-infra-dev/rspack
• Diagnose reliability issues in either codebase
• Compare technical approaches or patterns used in each repo
• Explore how specific features are implemented

If you're interested in comparing bundler approaches or understanding how to switch from one tool to the other from a usage perspective, that's outside my scope. However, I can answer questions like:

• How does esbuild handle module resolution differently than rspack's resolver?
• What error handling patterns does each repo use?
• How are plugins structured in each system?

FOLLOW_UPS:

• How does esbuild resolve module paths?
• How does rspack's resolver integrate with webpack?
• What are the key architectural differences visible in source?