Learn Hardcore Portuguese (Portugal): Ontem limpei todo o histórico, porque queria começar a semana com a mente mais leve. - Yesterday I cleared all the history because I wanted to start the week with a lighter mind.

Limpei already tells you it is 1st person singular (I).
Eu limpei is also correct, but it adds emphasis (for example, contrasting with someone else: Eu limpei, não tu).

So both are correct:

Ontem limpei todo o histórico… (neutral, very natural)
Ontem eu limpei todo o histórico… (emphatic on I)

Why does the sentence start with Ontem? Could it also be Limpei todo o histórico ontem?

Both word orders are fine:

Ontem limpei todo o histórico…
Limpei todo o histórico ontem…

Placing ontem at the beginning is common when you want to set the time frame first, like saying “Yesterday, I…” in English. Putting it at the end just sounds a bit more neutral. There is no change in meaning.

What tense is limpei, and why not use something like tenho limpo?

Limpei is the pretérito perfeito simples, the simple past for a completed action at a specific time (yesterday).

Ontem limpei… ≈ Yesterday I cleaned/cleared…

In European Portuguese, you do not use tenho limpo to translate English “I have cleaned” in this context. Tenho limpo suggests a repeated or ongoing habit (e.g. lately I have been cleaning it), not a single finished action yesterday. So limpei is the natural choice here.

What exactly does limpei todo o histórico mean? Is limpar really “to clean” here?

Literally, limpar means “to clean,” but in digital contexts it often means to clear / to wipe / to delete data.

limpei todo o histórico → I cleared all the history (e.g. browser history, chat history, search history).

So the verb is the same limpar, but the object (histórico) makes it clear we are talking about deleting data, not washing something.

Why is it todo o histórico and not just todo histórico?

In Portuguese, when todo means “all of the / the whole”, it almost always takes a definite article:

todo o histórico = all of the history / the whole history
toda a semana = the whole week
todos os dias = all the days

Without the article, todo tends to mean “every / each” (more common in Brazilian Portuguese):

todo dia (Br) ≈ every day
In European Portuguese, you usually say todos os dias.

So todo o histórico is the natural way to say “all the history.”

What does histórico mean here? Is it “historic” or “history”?

Histórico can be:

An adjective: um edifício histórico (a historic building).
A noun: o histórico = a record / history of past events.

In this sentence, o histórico is a noun and in a tech context it usually means history log, such as:

browser history
chat history
search history

So todo o histórico is essentially all the (saved) history data.

Why is it porque and not por que, porquê, or por quê?

Portuguese has four forms, with different uses:

porque – conjunction meaning “because” (used here).
por que – “why” or “for which” in questions or some relative clauses.
porquê – noun meaning “the reason” (usually with an article: o porquê).
por quê – “why” only at the end of a sentence or clause.

In …porque queria começar a semana…, porque introduces the reason, so it is the “because” form.

Why is it queria começar and not quis começar or quero começar?

Queria is the imperfect of querer and does two things here:

Refers to a past desire or intention:
- Naquele momento, eu queria começar a semana com a mente mais leve.
Softens the statement; it sounds more polite and less abrupt than quis or quero.

Compare:

Quis começar a semana… – more like “I decided / I wanted (and acted on it),” more factual, completed.
Queria começar a semana… – “I wanted to start the week…,” focusing on the desire, and sounding more natural and gentle in speech.

In this context, queria is the most idiomatic choice.

Why is there no preposition between queria and começar? Could it be queria de começar?

After querer, you use the infinitive directly, with no preposition:

querer fazer, queria começar, queremos mudar

Some other verbs do take a preposition:

gostar de → gosto de ler
tentar → tento aprender
conseguir → consegui acabar

So queria começar is correct; queria de começar is wrong.

Why is it com a mente mais leve and not com mente mais leve?

Portuguese uses the definite article much more than English, especially after prepositions.

com a mente mais leve = with the mind lighter / with a lighter mind
com mente mais leve sounds incomplete or unnatural in standard Portuguese.

The article a shows we are talking about my (the person’s) mind in this situation, not some abstract “mind” in general. This kind of structure (preposition + article + noun) is very typical in Portuguese.

Why is mente feminine? How do I know a mente is correct?

Nouns ending in -e can be either masculine or feminine; you simply have to learn their gender.

o leite (masc.)
a noite (fem.)
a mente (fem.)

We see mente is feminine because it takes:

the feminine article a
and feminine adjectives when they show gender (here leve has the same form for both genders, but the article still shows the gender).

So you say a mente, uma mente aberta, a mente humana.

Could I say começar a semana com a mente mais leve in Brazil too, or is this only European Portuguese?

The sentence works fine in both European and Brazilian Portuguese. A Brazilian might also say:

Ontem apaguei todo o histórico… (using apaguei instead of limpei)
or add a possessive: todo o meu histórico.

But Ontem limpei todo o histórico, porque queria começar a semana com a mente mais leve is perfectly understandable and natural-sounding in Portugal, and also acceptable in Brazil.

Why is there a comma before porque?

The comma separates the main clause from the reason clause:

Main clause: Ontem limpei todo o histórico
Reason clause: porque queria começar a semana com a mente mais leve

In Portuguese, it is common (and usually recommended) to put a comma before porque when it introduces an explanation or reason, especially in writing. In English, you often would not put a comma before because, but in Portuguese this comma is very natural.