Correct setup for subpath-imports for internal and external packages

[mgandolfi7]

I have internal and external packages (published to npm but also consumed internally) in my monorepo and I'm confused about the correct way to setup subpath imports with tsdown. In my internal packages that are not published to npm, I am using tsc and setup my package.json like so:

{
	"name": "@repo/internal-package",
	"private": true,
	"version": "0.0.0",
	"type": "module",
	"scripts": {
		"dev": "tsc --watch",
		"build": "tsc"
	},
	"imports": {
		"#*": "./dist/*" 
	},
	"exports": {
		"./*": {
			"types": "./src/*.ts",
			"default": "./dist/*.js"
		}
	},
}

For external packages that are consumed and published to npm, I'm using tsdown with the following configs:

{
	"name": "@morpheus-sdk/contracts",
	"private": false,
	"version": "0.0.0",
	"type": "module",
	"scripts": {
		"build": "tsdown",
		"dev": "tsdown --watch"
	},
	"imports": {
		"#*": "./src/*"
	},
}

and my tsdownconfig.ts:

export default defineConfig({
	entry: ["src/**/*.ts"],
	format: ["esm"],
	dts: {
		sourcemap: true,
	},
	ignoreWatch: [".turbo"],
	sourcemap: true,
	clean: false,
	target: "esnext",
	platform: "node",
	shims: false,
	exports: true,
});

The above config works but I have a few questions:

1. How come we dont set the imports to resolve to /dist but instead /src like we do with tsc?
2. is there any better way to do what I am trying to accomplish? My builds seem a bit wonky and I’m not sure if some way I’m configuring tsdown is causing it or if its an underlying issue I need to keep looking for with my turborepo or typescript configs.
3. Would it make sense to use tsdown for internal packages that are currently using tsc for performance gains?

Thanks!