3Author and Maintain Actions

• 3.1Creating Custom Actions — Types, Metadata, and I/O

  Understand the three action types (JavaScript, Docker container, composite) and how to choose, the required files and metadata in action.yml (inputs, outputs, runs, branding), using workflow commands within actions, and troubleshooting action execution errors.

• 3.2Distributing, Publishing, and Versioning Actions

  Understand action distribution models (public, private, Marketplace), publishing to the GitHub Marketplace, and versioning/release strategies using tags, releases, a major-version tag, and commit-SHA pinning, plus the concept of immutable actions on hosted runners.