merge-to-main

Merge the current feature branch into local main with a clean, linear history.

0. Check main is current — git fetch origin and confirm local main is not behind origin/main (git rev-list --count main..origin/main must be 0). If it is behind, fast-forward local main first and rebase this branch onto it. Merging — and especially cutting a release — on a stale base means redoing it: the version may already be taken upstream.
1. Squash if too many commits.
2. Rebase onto local main.
3. Verify the diff — run git diff main..HEAD. Confirm it contains only the feature's intended changes and nothing that removes or reverts existing main content. If main changes were dropped during conflict resolution, fix before proceeding.
4. Build — run make all to confirm nothing broke.
5. Update CHANGELOG.md — ensure all commits in the branch have corresponding entries in the [Unreleased] section. Compare git log main..HEAD --oneline --no-merges against existing entries; add any missing ones under the appropriate subsection (Added/Changed/Fixed/Removed). Check the entries are under ## [Unreleased], not merely present: a rebase across a release boundary relocates them into the just-released section with no conflict, and git diff main..HEAD still shows a clean pure-addition diff. Read the top of the file (sed -n '1,40p' CHANGELOG.md) and confirm with your own eyes that each new line sits above the first ## [x.y.z] heading; move any that don't.
6. FF-merge into the main worktree.
7. Build again — run make all from the main worktree to confirm the merge is clean.

At the end ask the user if they want to clean-up by removing the local worktree and branch. Careful, this could be destructive!