The builder reads tag-asks for the candidate's repository and head (versions.TagFor), numbers only its packages under the tag below the next version, keeps each with its repository for the branch's end, and says numbered with the head; the same fingerprint claimed again keeps its number (design 51 *Tagged versions*). Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig