Usage in addons + Embroider build

[bartocc]

Our app uses ember-cli-less, ember-css-modules and an in-repo addon my-ir-addon.

ember-css-modules is configured in my-ir-addon with:

options: {
  cssModules: {
    intermediateOutputPath: "my-ir-addon-modules.less",
    extension: "less"
  },
}

The file my-app/app/styles/app.less contains the line:
@import "../../addon-tree-output/my-ir-addon/__COMPILED_STYLES__/my-ir-addon-modules.less"

This import works under a classic build.
Under Embroider, this fails with the error:

'../../addon-tree-output/my-ir-addon/__COMPILED_STYLES__/my-ir-addon-modules.less' wasn't found.

I understand referencing the build dir addon-tree-output is not ideal, but this allowed us to create a single app.less file since ember-css-modules used in addons produces its output in the addon-tree-output directory.

What could I do to make this work under an Embroider build?

Thx