Use when changes to src/ or examples/ need compile verification before committing, when asked to build or verify the library, or when arduino-cli is not installed on this machine ("arduino-cli not found").
Use when a public method is added, removed, or its signature changed, before committing API changes, or when asked to audit consistency between the header, cpp, README and keywords.txt.
Use when publishing a new library version — bumping the version, tagging, creating a GitHub release — or when asked what remains before a release can be tagged.