description = Rebase all branches on top of the main branch, so that the commits are in alphabetical order, and then point the main branch to the top commit.

[setup]

git commit --allow-empty -m A
git commit --allow-empty -m B
git commit --allow-empty -m C

git switch -c side1 main~1
git commit --allow-empty -m D
git commit --allow-empty -m E

git switch -c side2 main~2
git commit --allow-empty -m F

git checkout main

[win]

diff <(git log --pretty=%s main) <(echo -e "F\nE\nD\nC\nB\nA")