[Part 3] A Non-Coder's Dev Environment — The Peace of Mind of "Undo That" with Git

Recap of the Previous Post

In Part 2, we covered Node.js and npm. This time, let's talk about Git — your code insurance policy.

What Is Git — The Ultra-Simple Explanation

Git = a tool that records the change history of your files.

Think of it as save points in a video game. Or a supercharged version of "Undo (Ctrl+Z)" in Word. Every time you make changes, you can save "the state at this point in time," so you can always roll back to any moment you choose.

Why You Need It — "Undo" Is Your Lifeline

When a non-coder writes code (or more accurately, has AI write it), accidents like these happen:

• You ask the AI to "fix this one thing," and it changes completely unrelated files
• You tweak working code and lose track of what the original state was
• You want to go back to where things were 3 hours ago, but Ctrl+Z can't reach that far

With Git, no matter how badly you break things, you can revert to "that point" in an instant.

This is huge psychologically, too. Once you know "I can always undo this," you stop being afraid to experiment.

How to Install

On Windows, just download and install from the official Git for Windows site.

https://git-scm.com/

The installer settings are fine at their defaults. After installation, verify in your terminal:

git --version
# git version 2.47.1.windows.2  ← If you see something like this, you're good

You Only Need 4 Commands

Git has a massive number of commands, but non-coders only need to know 4.

# 1. Initialize Git in your project (just once at the start)
git init

# 2. Stage changed files for the next save
git add filename

# 3. Save (commit)
git commit -m "A note about what you changed"

# 4. View your save history
git log --oneline

How I Actually Use It — Claude Code Does Everything

After all that explanation, here's the thing: I almost never type Git commands myself.

Because Claude Code does it all for me.

Claude Code automatically commits at natural breakpoints during work. It even writes proper commit messages in English. All I do is:

1. Give Claude Code my instructions
2. Claude Code automatically runs git add & commit as it works
3. If something goes wrong, I say "revert the last change"
4. Claude Code runs git revert for me

In other words, for non-coders, Git isn't something you "master yourself" — it's something you "install because Claude Code needs it." But understanding how it works gives you the confidence to say "revert that" without hesitation.

Real Example — How Git Saved Me

The Time clasp push Wiped Everything Out

I was working on the GAS code for the Kagemusha system. I told Claude Code to "fix this function" and ran clasp push to deploy it to GAS.

It didn't work.

And the errors were strange. Not just the function I'd fixed — completely unrelated files were broken too.

The cause: clasp push overwrites everything on the GAS side with the code on your PC. Outdated files were sitting on my PC, and separate changes I'd only made in the GAS editor were all wiped out.

I panicked. And the GAS script editor has virtually no "undo" functionality.

But I had Git.

git log --oneline
# abc1234 fix: Fixed XX
# def5678 feat: Added YY  ← I want to go back to here
git checkout def5678 -- .
clasp push

Recovered in 30 seconds. Without Git, I would have had to manually fix the broken code file by file — or worst case, start over from scratch.

"Try It Out → Never Mind" Becomes Effortless

The real gift of Git is that experimentation stops being scary.

When I tried migrating the Kagemusha system's invoice PDF generation from GAS to Cloudflare Workers — it was a major change, and I wasn't sure it would work.

Because I had Git, I could "go all-in on the migration → roll everything back if it fails." The result: the Workers version was 3x faster, and the migration succeeded. But even if it had failed, a single git checkout would have brought back the stable version.

This peace of mind is bigger than most non-coders can imagine.

Next Time

Next up, we'll introduce Google Apps Script (GAS) — the origin of the Kagemusha system — and clasp, the tool for managing it from your PC. Without these tools, the Kagemusha system would never have been born.