05 · Git & Version Control

Phase: 2 · Estimate: 1 week · Prerequisites: none

Why it matters

Almost every developer can commit and push, but panics at a rebase conflict, a detached HEAD, or a "lost" commit. Once you understand Git's object model, no command feels scary anymore.

Concept map

Basics

• init, add, commit, status, log, diff
• Branches, merging, conflict resolution
• Remotes: clone, fetch, pull, push
• VCS hosting: GitHub, GitLab, Bitbucket; pull requests / merge requests

Intermediate

• rebase vs merge, interactive rebase, --fixup + --autosquash
• reset (soft/mixed/hard) vs revert vs restore
• reflog to rescue "lost" commits
• stash, cherry-pick, bisect
• Conventions: Conventional Commits, trunk-based vs Git Flow

Deep dive

• The object model: blob, tree, commit, tag; content-addressable storage
• Refs, HEAD, and the index (staging area) as files
• Packfiles and delta compression
• Merge strategies (ort) and three-way merges

How to learn

1. Create an empty repo, then run find .git -type f after each command to see what changed.
2. Use git cat-file -p <hash> to walk commit → tree → blob by hand.
3. Practice bisect on a repo with a bug planted in commit 37 of 50.
4. Rescue a commit after reset --hard using reflog.

Check your understanding

1. What does a commit actually store? Why does changing one file change the hash of every later commit during a rebase?
2. Why is "don't rebase a shared branch that's already been pushed" a sensible rule?
3. What's the difference between git reset --soft HEAD~1 and git revert HEAD?
4. How does Git know a file was renamed when it only stores snapshots?

Practice projects

Level	Project	What it trains
Basic	Contribute a PR to an open source repo (docs count)	PR workflow
Intermediate	Set up a repo with Conventional Commits + commitlint + an automatic changelog	Conventions, tooling
Deep	Write a mini Git: init, hash-object, cat-file, write-tree, commit-tree	Object model

Primary sources

• Pro Git book, chapter 10: Git Internals
• Write yourself a Git
• Conventional Commits

Related toolkit

• This repo itself uses changesets to version its packages