Curating what a repository's labels mean

Labels are a shared vocabulary, and every change to one changes the meaning of every issue already carrying it. This is a repository-wide edit dressed up as a small one.

Sequence

1. See the whole set at once. list_label returns every label ordered by issue count, most used first. That ordering is the audit: the tail is where the dead vocabulary lives.
2. Find out what is actually in use. For anything you are considering changing, list_issues filtered by that label, omitting state to include open and closed issues, shows what carries it. A label with no issues has no cost to retire; one with two hundred is load-bearing.
3. Read the one you are about to change. get_label returns its exact name, colour and description. Names are case-sensitive in ways that are easy to get wrong, and the description is often the only record of what the label was meant to distinguish.
4. Make the change. label_write with method set to create, update or delete. Renaming is update with new_name.
5. Report what moved, including how many issues were affected by each change.