if is a fork in the road — and AI uses it to encode every business rule

If you've ever asked Cursor only run this when the user is signed in, charge a fee if the order is over $100, show the warning when the score is below 60 — the thing AI reaches for is an if statement. This is how every conditional rule in your code gets expressed.

if is the entire grammar of business logic. Once you can read one, you can read every signup flow, every pricing rule, every permissions check Cursor will ever write you.

The mental model: ordered checks, exactly one branch wins

if score >= 90:
    print("excellent")
elif score >= 70:
    print("good")
else:
    print("needs work")

Read this top-to-bottom, like a flowchart:

1. if is checked first. Python evaluates score >= 90. If True, it runs that block and skips the rest entirely.
2. elif is checked next, but only if the previous condition was false. You can stack as many elifs as you want.
3. else is the catch-all. It runs only if every condition above failed. It has no condition of its own — just a colon.

The hard rule: exactly one branch runs per trip. The first condition that's true wins. Everything below it gets skipped, even if its condition would also be true.

A worked example

The editor on the right has score = 92. Trace what happens:

Step	Condition	Result	What runs
1	score >= 90	True	print("excellent")
2	elif score >= 70	(skipped)	—
3	else	(skipped)	—

Output: excellent. The elif would have been true too — 92 >= 70 is True — but Python never checked it, because the if already won.

Why ordering matters more than people expect

Look what happens if you flip the conditions:

if score >= 70:
    print("good")
elif score >= 90:
    print("excellent")

Now every score 70 or higher prints "good". The excellent branch is unreachable, because anything that matches >= 90 also matches >= 70, and the first true branch wins.

This is a real bug in real AI-generated code. When Cursor writes if chains over numeric ranges, it sometimes orders them lowest-to-highest when they should be highest-to-lowest. The script "works" — no crash — but the output is silently wrong.

Where AI specifically gets if wrong

Three patterns to flag in code Cursor writes:

1. Forgetting the colon. if score >= 90 (no colon) is a SyntaxError. AI almost never makes this mistake, but you might, so it's worth knowing what the error message looks like.

2. Indenting the body wrong. Python decides what's "inside" the if purely by indentation. Mix tabs and spaces, or under-indent one line, and the block silently means something different. Cursor almost always uses 4 spaces; trouble starts when you copy-paste code from somewhere else and the indentation doesn't match.

3. Conditions in the wrong order. The flip we just walked through. When you read AI-generated if/elif chains over numeric ranges, read them top to bottom and ask: "could a value in branch 2 also match branch 1?" If yes, the order is fragile — branch 2 might never run.

Run the editor. With score = 92, only excellent prints. The other branches are silent — they were never even checked.