Check your inbox¶

One email is on its way. If it asks you to confirm, tap that; it carries the button back to the course, so you can find your place. That's the only one until the next move is ready.

What happens next

The next move comes by email when it's built. The walls people name on the last page decide which one gets built first.
Did this save you? Reply to the email and tell me, and say if I can quote you. I read every reply.
There are paid things for when you want the whole method. Nothing about them until you ask.

Back to the course The undo button: the five moves, in order.

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MOVE 1 · A SAVE YOU CAN GO BACK TO
Developers say	Plain
`a repository, on GitHub`	A copy of your app on GitHub, under your own accountIt lives outside the platform, so nothing the platform does can write over it. Every commit goes here.
`a commit`	A snapshot of your app: every file as it is at one moment, with a date and a messageThe tool gives each commit a short id like a1b2c3d. Move 2 keeps each one to a single change.
`a tag`	A name you put on a commit, like v1-worksMany commits say “working”. The tag is the one you ask for by name, and still recognise in three weeks.
`“go back to v1-works”`	Go back to a commit, by its tag“Go back to v1-works” puts every file back as it was then. It brings back the app, never the data.
`rollback, revert, restore, rewind`	The platform’s own undoCode only, no name you chose, written over. Not a commit, and not yours.

MOVE 2 · SEE WHAT A CHANGE WILL TOUCH
Developers say	Plain
`the plan`	The list of files a change will touch, before anything changesAsk for it, read it, then say go. A file you never asked about is the one to ask “why?” about.
`small commits`	One change per commitThen “which change broke it” has one answer, and one commit to take out.
`a diff, in plain words`	What changed since a commit, file by fileAsk for it in plain words, with the commit each file came in with. The file name tells you where to look.
`Login.tsx, SignUp.tsx`	One page or part of your app, as a fileUsually named after what it does: Login.tsx is the login. A file name on a plan or a diff is the clue.
`plan mode, Chat mode`	The tool’s button for “show me first”With it on, the plan comes before any change and “wait for my OK” holds.

MOVE 3 · TRY EVERY CHANGE ON A COPY FIRST
Developers say	Plain
`your users`	The people who use your appThey use what you built, get stuck, and leave if it is broken. Everything you try, you try in front of them, unless there is a preview.
`production`	The live copy of your app, the one your users are inWhatever is published here is real. Nothing here is a test.
`a preview, a staging environment`	A second copy of your app at its own address, where nothing countsBuilt from its own branch, with its own test database. Every change goes here before it is published.
`a branch`	The preview’s own line of commitsThe live copy builds from one line of commits and the preview from another, so a change can sit on the preview’s line first.
`publishing, going live, deploying`	Letting a change through to the live copyOnce it is published, your users see it. The preview comes first.
`an environment variable`	A setting that says which database, email service or payment provider a copy of the app usesOne line like DATABASE_URL, set per copy. It decides where a form’s data went; the green tick does not.
`the database`	Where your app keeps what your users typedTables of rows on the platform’s servers. A commit never holds it, so going back to v1-works never touches it.

MOVE 4 · STOP AFTER TWO TRIES
Developers say	Plain
`an attempt`	One fix: your order, and everything the AI changed in answerTwo that fail is the limit. The third is a fix of the fix.
`the error message, the stack trace`	The line the tool printed when it brokeThe closest thing you have to the cause. Read it before you try again.
`reset to the save point`	Go back to v1-works after two failed attemptsThe attempts were never committed, so they go. The original problem is still there, on its own, without the two new ones.
`/clear, a new chat`	A new conversation that has not seen the two failed attemptsIt remembers nothing, so tell it: the commit you are at, the error message, the two attempts, and “don’t repeat those”.
`the loop`	Try, try again, worse each timeEach attempt is built on the last broken one. The way out: stop, reset, new conversation.
`a bug report`	A user’s “it broke”, in their wordsAn error message you did not see yourself. Read it the same way, then the same three moves.

MOVE 5 · A COPY YOU OWN
Developers say	Plain
`the project folder`	Your app as a folder of filesOn the platform’s servers it is theirs to keep or lose. In your repository it is yours.
`a private repository you own`	A repository under your own GitHub account that only you can seeNot an organisation with the platform’s name on it. Check the owner on github.com, signed in as yourself.
`an export, a backup`	The database copied to a file: every table, every rowThe only copy of your users’ data that you hold. Once, to learn what it leaves out, then on a schedule.
`an off-platform backup`	Kept somewhere that is not the platform: your own computer or your own cloud driveA backup that lives on the thing it backs up goes down with it.
`code is versioned, data is not`	Going back to a commit brings back your app, never its dataThe one thing in this course that no undo touches. The export is the answer.

IF YOUR TOOL IS CLAUDE CODE
Developers say	Plain
`CLAUDE.md`	A rule your tool reads at the start of every run“Always commit before a big change.” Written once in CLAUDE.md, followed every time.
`a skill`	A move you write down once and ask for by name“Do the preview check” becomes one word instead of three prompts.
`a hook, CI`	A check that runs by itself, every timeNo one presses anything. The commit, the plan or the preview check happens on its own.
`MCP`	A door from your tool to GitHub, your database or your hostingThe tool walks through it instead of you pasting things across.