You'll notice
Import resolution now also tries .mts and .cts file extensions for .mjs and .cjs imports
What
When resolving an import path, Claude Code's module resolver now also tries a .mts file if the import ends in .mjs, and a .cts file if it ends in .cjs. This joins the existing mapping that tries .tsx for a .jsx import.
Why
This lets imports resolve correctly to TypeScript source files (.mts, .cts) even when the import specifier uses the compiled JavaScript extension (.mjs, .cjs).
Names in the bundle.mts.cts
Documented inclaude-code/agent-sdk/hosting