# Ask for a plan before code

Course: Vibe Coding 101 — https://zero2vibecode.com/learn/vibe-coding-101
Canonical URL: https://zero2vibecode.com/learn/vibe-coding-101/2-2-ask-for-a-plan-first

A plan is a paragraph you can reject in ten seconds — this lesson shows what to ask for, what a good plan contains, and the two questions that catch a bad one.

For anything larger than a small change, do not ask for code. Ask for the plan.

```text
Before you write anything: how would you add tags to Readlist?
List the steps and which files you would change. No code yet.
```

Ten seconds to read. Ten seconds to reject. Compare that with reading four modified files and trying to work out what happened.

## What a good plan contains

```text
Plan for tags:

1. Change the saved item shape from a plain string to an object
   with a url and a tags array. Add a migration so existing saved
   items still load.
2. Add a second text box next to the URL box for comma-separated tags.
3. Show tags as small labels under each list item.
4. Add a filter row at the top: clicking a tag shows only matching items.

Files: readlist.html only.
Not doing: editing tags after saving, tag autocomplete, tag colours.
Open question: should an item with no tags be hidden when a filter
is active, or always shown?
```

Four things make this a good plan, and you can check all of them without knowing a line of code:

- **Ordered steps** in plain language.
- **Which files** get touched.
- **What it is deliberately not doing** — this is the line that catches scope creep before it exists.
- **An open question** where a real decision is needed.

That last one is worth its weight. The plan surfaced a decision you had not thought about, at the only moment when answering it is free.

## The two questions that catch a bad plan

**"Which files will you change?"**

If the plan for a delete button mentions the save logic, the styling and a new file, one of two things is true: it understood something different from what you meant, or it is bundling in work you did not ask for. Both are worth a sentence right now.

**"What could go wrong with this approach?"**

Asked directly, agents are surprisingly good at naming the weak point of their own plan. They rarely volunteer it, because nothing rewards volunteering doubt — but they will answer honestly when asked.

For the tags plan above, the honest answer is the migration: everyone who already has links saved will break if the loading code does not handle both the old shape and the new one.

## Approving, redirecting, restarting

Three responses, all short.

**Approve:**

```text
Plan looks right. Items with no tags stay visible when a filter is on.
Go ahead, and do step 1 first so I can check the migration.
```

**Redirect:**

```text
Steps 1-3 yes, step 4 no — no filtering yet. And do not change how
items are stored; keep the plain string and put tags in a separate list.
```

**Restart:**

```text
That is more than I want. Simplest possible version: one optional
tag per link, shown as text. No filtering, no data migration.
```

Every one of those is cheaper than reading the code that would have come from the wrong plan.

If a plan has more than about five steps, it is probably two tasks. Ask for the first one only. Plans that grow past a handful of steps produce changes nobody reviews properly.

## When to skip the plan

Not every request needs one. Skip it for:

- Cosmetic changes — colours, labels, spacing.
- Anything you can verify by looking at the screen in two seconds.
- Fixes where you already know the cause and the change is one line.

Ask for one for:

- Anything touching how data is stored.
- Anything touching more than one file.
- Anything involving money, accounts, permissions or deletion.
- Anything you would find hard to undo.

The rule of thumb: if being wrong would cost you more than five minutes, spend thirty seconds on a plan.

## Some tools have this built in

A few agents ship a mode that plans first and waits for approval before touching anything. If yours has one, use it for anything structural — it makes the good habit the default.

If yours does not, the sentence "plan first, no code yet" does the same job. This is a habit, not a feature.

## Try it yourself

A plan arrives. Read it, question it, or skip it — and see where each choice lands.