GitHub Actions Composite Actions

Reference for writing and debugging composite actions (action.yml files with runs.using: composite).

For debugging failures in composite action runs, apply the github-actions-debugging skill.

Critical Limitations (Know Before You Code)

uses: Does NOT Support Expressions

The uses: field is evaluated at parse time — expressions like ${{ inputs.ref }} or ${{ env.VERSION }} will not be evaluated. All references must be literal strings.

# WRONG — will not work
uses: my-org/actions/my-action@${{ inputs.version }}