Merge a branch

A merge brings another line of history into the current branch.

First, make sure the working tree is clean and switch to the branch that should receive the work:

git status
git switch main
git merge add-search

The direction matters. This command merges add-search into main because main is the current branch.

Git finds the common ancestor and compares both histories. If main has not moved, Git can fast-forward its reference. If both branches have new commits, Git usually creates a merge commit after combining compatible changes.

Verify the result:

git status
git log --oneline --decorate --graph --all

After a successful merge, main reaches the feature commits. The add-search reference still exists until you delete it.

If Git reports a conflict, stop and inspect git status. You can resolve the files and continue, or return to the pre-merge state with git merge --abort before making unrelated changes.

Exercise: merge a one-commit branch into an unchanged main. Draw the graph before and after, and explain why no merge commit was necessary.