What problem does this feature solve?

https://rollupjs.org/configuration-options/#output-amd-id

An ID to use for AMD/UMD bundles

Context: we're trying to migrate the leaflet build process to rolldown in Leaflet/Leaflet#10011 and found that output.amd.id is not supported in rolldown v1.0.0-beta.58.

Rollup with output.amd.id = 'leaflet' yields

typeof define === 'function' && define.amd ? define('leaflet', ['exports'], factory) :

Rolldown does not support this option and yields

typeof define === 'function' && define.amd ? define(['exports'], factory) :

Spec: https://requirejs.org/docs/whyamd.html#namedmodules

What does the proposed API look like?

https://rollupjs.org/configuration-options/#output-amd-id