Explaining a fork's changes: compare against the right merge-base

When summarizing what a long-lived fork adds, diff from git merge-base <branch> <upstream-main>, not against the current main, or you'll count upstream's newer commits as the fork's deletions. Group the changed paths by directory with git diff --name-only $mb $tip | awk -F/ '{print $1"/"$2}' | sort | uniq -c. Flag noise early: a fork that deletes upstream's CI workflows can show hundreds of 'changed' files under .github that aren't real work. Also check whether the public branch lags the internal CI refs before sharing a compare link.