Learn Hardcore Swedish: Kom ihåg att stänga dörren så att katten stannar inne. - Remember to close the door so that the cat stays inside.

Kom ihåg is the imperative: a direct instruction meaning Remember.
Kommer ihåg is present tense: (I/you/he) remember(s).
So Kom ihåg att stänga … = Remember to close …, while Jag kommer ihåg att stänga … = I remember to close … (a statement, not a command).

What do the two att’s do here?

They’re two different things that happen to look the same:

att before stänga is the infinitive marker (English to): att stänga = to close.
att in så att is part of the subjunction så att (English so that), introducing a subordinate clause: … så att katten stannar inne.

Why is it stänga and not stäng?

Because it follows att (the infinitive marker). After att, you use the infinitive stänga. If you gave a direct command without kom ihåg, you’d use the imperative: Stäng dörren!

Do I need a comma before så att?

No comma is required in Swedish before a following subordinate clause. The given sentence without a comma is standard: Kom ihåg att stänga dörren så att katten stannar inne. Writers may add a comma for a deliberate pause in longer sentences, but it’s not necessary here.

What’s the difference between så att, så, and för att?

så att + clause = so that / with the result that. Example: Stäng dörren så att katten stannar inne.
så + main clause (no att) often means then/so (consequence) and triggers inversion in the next clause: Stäng dörren, så stannar katten inne.
för att + infinitive expresses purpose: Kom ihåg att stänga dörren för att hålla katten inne.
You can also use för att + clause with ska for purpose: … för att katten ska stanna inne.

Why is the word order … så att katten stannar … and not … så att stannar katten …?

Because så att introduces a subordinate clause. In Swedish subclauses, the subject comes before the finite verb (no V2 inversion). So it’s att katten stannar, not att stannar katten. With negation, you’d get: … så att katten inte stannar/går ut (the sentence adverb inte comes before the verb in subclauses).

Why are dörren and katten definite?

dörren = the door (the one relevant in context, e.g., the apartment door).
katten = the (specific) cat everyone knows about. That matches English here (the door, the cat). Using en dörr / en katt would feel odd unless you meant some random, unspecified door/cat.

What’s the nuance of stanna inne vs vara inne?

stanna inne = stay inside (don’t go out). It implies remaining rather than leaving.
vara inne = be inside (a simple state). Here, stanna inne is right because the point is to keep the cat from going out.

Why inne and not in?

Swedish distinguishes motion vs location:

in = motion towards the inside (go in): gå in.
inne = location/state (be/stay inside): vara/stanna inne. Since it’s about the cat staying inside (state), you need inne.

Could I say hålla katten inne instead?

Yes, as a purpose construction:

Kom ihåg att stänga dörren för att hålla katten inne. That’s very natural and directly mirrors English to keep the cat inside.

Why is it present tense stannar and not future ska stanna?

Swedish often uses present tense for future meaning when context makes the time clear. … så att katten stannar inne naturally means the cat will stay inside as a result. … så att katten ska stanna inne is possible but can sound more like an intended/required outcome.

Is Kom ihåg too blunt? How can I make it softer?

It’s fine, but you can soften:

Glöm inte att stänga dörren … (Don’t forget to close …)
Tänk på att stänga dörren … (Keep in mind to close …)
Kan du stänga dörren så att katten stannar inne? (Could you …)

What is ihåg? Can I use it elsewhere?

ihåg is a fossilized element meaning roughly “memory,” used almost only in komma ihåg (to remember). There is a formal verb ihågkomma (to remember), but in modern speech komma ihåg is the normal choice. You don’t use ihåg by itself.

Can I drop att before stänga?

Not after kom ihåg. You need att: Kom ihåg att stänga …. Swedish does drop att after modal verbs like kan/måste/vill (e.g., Du måste stänga dörren), but kom ihåg isn’t a modal.

Some people say Kom ihåg och stäng dörren. Is that okay?

That och is colloquial/dialectal. Standard Swedish uses att before the infinitive: Kom ihåg att stänga dörren.

Where would negation go if I wanted to say “so the cat doesn’t go out”?

In the så att subclause, put inte before the verb:

Kom ihåg att stänga dörren så att katten inte går ut. In a main clause with så (no att), you’d have inversion after så and place inte after the verb:
Stäng dörren, så går katten inte ut.

Can I move inne elsewhere, like … så att katten inne stannar?

No. stanna inne is a verb + particle/adverb combination, and inne stays right after the verb: stannar inne. You can split particle verbs before object pronouns in some cases, but here there’s no object, so keep them together.

How do I pronounce tricky bits here?

ihåg: long å sound; stress on ihåg in Kom ihåg.
stänga: the äng is like the “eng” in English “length” (a nasal sound).
dörren: ö is like the vowel in French deux; double rr keeps the vowel short.
så: long å.
katten/inne: double consonants mean the preceding vowel is short.
Also, att is usually very short and weak in speech.