Поисковая строка была слишком короткой, чтобы туда поместился весь адрес, поэтому я написала его короче.

After быть in the past tense, Russian often uses a full adjective in the instrumental when the adjective is part of the predicate:

• строка была короткой
• он был уставшим
• она была довольной

So была слишком короткой is a very normal pattern.

Other options do exist:

• была короткая — possible, more colloquial in some contexts
• была коротка — short-form adjective, a bit more concise or literary

In this sentence, была слишком короткой is the most neutral and natural choice.

After чтобы, Russian normally uses the same verb form that looks like the past tense, but here it does not mean past time.

So:

• чтобы поместился = so that it would fit
• чтобы я написал = so that I would write
• чтобы стало лучше = so that it would become better

This is the normal way Russian builds a clause of purpose or intended result. Historically, the бы element is built into чтобы, which is why the verb appears in that past-like form.

So чтобы туда поместился весь адрес means something like:

• so that the whole address would fit there

not

• after the whole address fit there

Because the subject of that clause is весь адрес.

• адрес is masculine singular
• therefore the verb must be masculine singular: поместился

Even though строка earlier in the sentence is feminine, it is not the subject of this clause.

Compare:

• весь адрес поместился — the whole address fit
• вся ссылка поместилась — the whole link fit
• всё сообщение поместилось — the whole message fit

Because туда suggests direction or placement into that space, while там just means there as a location.

With поместиться, Russian often treats the idea as fitting into somewhere:

• поместиться в коробку
• поместиться в строку
• поместиться туда

So:

• туда = into there / in there
• там = there

In this sentence, туда sounds more natural because the idea is that the address could not fit into the search bar.

You could also say чтобы в неё поместился весь адрес, where неё refers directly to строку.

Because весь адрес is the subject of поместился.

Russian expresses this idea as:

• адрес поместился = the address fit

So the thing that fits is in the nominative case.

That is why you get:

• весь адрес поместился

not

• всего адреса поместился

The adjective весь agrees with адрес in masculine singular nominative.

Both verbs refer to a single completed result, so perfective is the natural choice.

поместился

The point is whether the whole address would fit completely. That is a result, so perfective поместиться works well.

• чтобы поместился весь адрес = so that the whole address would fit

Using imperfective помещался would sound wrong here unless you meant something repeated or habitual.

написала

The speaker finished rewriting the address in a shorter form.

• я написала его короче = I wrote it shorter / in a shorter form

If you used писала, it would suggest process or repetition:

• I was writing
• I used to write

not the finished result.

In the past tense, singular Russian verbs agree with the speaker or subject in gender.

So:

• я написал — said by a man
• я написала — said by a woman

This sentence uses написала, so the speaker is female.

Его is the direct object pronoun meaning it, referring back to адрес.

So:

• я написала его короче = I wrote it shorter

This is the accusative form of the pronoun. For masculine and neuter pronouns, the accusative form его looks the same as the genitive form его, so learners often notice that and get confused.

If you repeated the noun instead of using a pronoun, you could say:

• я написала адрес короче

But using его sounds more natural because it avoids repetition.

Here короче functions adverbially, modifying the verb написала.

It means:

• more briefly
• in a shorter form
• shorter

So я написала его короче means that the speaker wrote the address in a shortened way, not that the object itself physically became shorter.

This is very common in Russian:

• сказать короче — to say it more briefly
• объяснить понятнее — to explain more clearly
• написать проще — to write more simply

So even though короче comes from the adjective короткий, here it behaves like a comparative adverb.

Normally, no. In this sentence, it means in a shorter form, not with smaller letters.

If you wanted to say I wrote it in smaller handwriting, Russian would usually express that differently, for example with words related to smaller rather than shorter.

So here the idea is that the address was abbreviated, shortened, or written in a more compact form.

Yes. Russian word order is flexible, and several versions are possible:

• чтобы туда поместился весь адрес
• чтобы весь адрес туда поместился
• чтобы весь адрес поместился туда

The basic meaning stays the same, but the emphasis changes.

The original version places focus on the limited space first:

• туда — into there
• поместился — fit
• весь адрес — the whole address

That ordering sounds natural because the sentence is about the search bar being too short.

Because поэтому connects two clauses:

• the problem: Поисковая строка была слишком короткой, чтобы туда поместился весь адрес
• the result: поэтому я написала его короче

In Russian, when поэтому links clauses like this, a comma is normally used before it.

So the structure is:

• problem, therefore result

which is exactly what the punctuation marks here.