How to access reference in reusable workflow

Question

Context

A reusable workflow in public repos may be called by appending a reference which can be a SHA, a release tag, or a branch name, as for example: {owner}/{repo}/.github/workflows/{filename}@{ref}

Githubs documentation states:

When a reusable workflow is triggered by a caller workflow, the github context is always associated with the caller workflow.

The problem

Since the github context is always associated with the caller workflow, the reusable workflow cannot access the reference, for example the tag v1.0.0. However, knowing the reference is important when the reusable workflow needs to checkout the repository in order to make use of composite actions.

Example

Assume that the caller workflow is being executed from within the main branch and calls the ref v1.0.0. of a reusable workflow:

name: Caller workflow
on:
  workflow_dispatch:

jobs:
  caller:
    uses: owner/public-repo/.github/workflows/[email protected]

Here is the reusable workflow that uses a composite action:

name: reusable workflows
on:
  workflow_call:

jobs:
  first-job:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/[email protected]
        with:
          repository: owner/public-repo
          ref: ${{ github.ref_name }}

      - name: composite action
        uses: ./actions/my-composite-action

In the above code snippet, ${{ github.ref_name }} is main instead of v1.0.0 because github context is always associated with the caller workflow. Therefore, the composite actions code is based on main and not on v1.0.0. However, the caller wanted v1.0.0. Hence my question: how is the reusable workflow able to access the reference given by the caller?