Putting It All Together

You now have all the moving parts:

The full git CLI sits on top of these primitives. Plumbing commands map 1:1: git hash-object, git cat-file, git ls-tree, git update-ref, git read-tree, git write-tree, git commit-tree. Porcelain commands (git add, git commit, git checkout, git merge) are convenience layers over the plumbing.

What we glossed over:

• Packfiles — efficient storage of millions of objects via delta chains
• The smart protocol — git fetch / git push over HTTP / SSH
• Hooks — pre-commit, post-merge, pre-push scripts
• Stash — saves working tree as commits on a special ref
• Bisect — binary search for the bad commit
• Worktrees — multiple checkouts of the same repo
• submodules — embedded repos pinned by SHA
• LFS — large-file storage outside object DB
• The reflog — local history of HEAD/branch movements (recovery!)

But these are all built on the same five primitives: blobs, trees, commits, refs, and SHA-1. You now understand what makes Linus's design so elegant — and why every other VCS that came after has tried to copy it.