Problem Statement

Currently, the list of external modules must be fully defined before executing the bundler.

But defining this list statically is not trivial in the following scenarios:

• imports that "reach into" modules, like import bar from "foo/bar"
• external modules that are aliased to some other name via an import map or some other form of custom resolution logic

Workaround

The current workaround is to add a custom "pre-bundle" phase where the complete codebase is crawled, each import is visited analyzed (usually by a variation of the logic that will be later used to implement the "Resolve" trait), and a list of external modules is gathered.

This list is then fed to the bundler.

Proposed Solution

Other bundlers like Rollup and ESBuild allow "marking" a module as external during the resolution phase. See: https://rollupjs.org/guide/en/#resolveid