Push

1. Check where you are. Run git status -sb and git remote -v.
   • Detached HEAD: stop. You can't push without a branch.
   • No remote: stop, and tell the user to add one with git remote add origin <url>.
2. No upstream yet (git rev-parse --abbrev-ref @{u} fails): run git push -u origin HEAD. If there's no origin but exactly one other remote, use that one. If there are several remotes and none of them is origin, ask the user which to use.
3. Upstream exists: run git fetch, then git rev-list --left-right --count @{u}...HEAD. This prints <behind> <ahead>.
   • ahead = 0: say there's nothing to push, and stop.
   • behind > 0: the remote has commits that aren't here, so the push would be rejected. Stop and suggest /sync.
   • Otherwise, save the list with git log --oneline @{u}..HEAD and run git push.
4. HTTPS auth failure (could not read Username, Authentication failed, Device not configured): the remote is HTTPS, but there are no stored credentials for it. Many machines still have an SSH key for the same host. Retry the same command over SSH without changing the repo config:

   git -c url."git@github.com:".insteadOf=https://github.com/ push -u origin HEAD

   Use the remote's own host in place of github.com. Upstream stays origin/<branch>. If this works, mention that git remote set-url origin git@<host>:<owner>/<repo>.git makes SSH permanent. If SSH also fails, stop and tell the user to run ! git push -u origin HEAD so git can prompt for credentials in their terminal, or to set up gh auth login.
5. Never force-push (--force, --force-with-lease) unless the user explicitly asked in the arguments. A force-push can silently delete other people's work. If the push is rejected, explain why and suggest /sync.
6. Report the branch, the remote, and the pushed commits. If uncommitted changes remain, mention them; they weren't pushed.