After ke: -u or a real tense?

After ke: -u for what someone wants

When the main verb wants, asks, orders, permits or requires something, and someone new is to do it, the ke clause takes -u:

English uses an infinitive with its own subject (you to come), which is why learners write ke vi veni. That is not Esperanto. Some verbs of asking and ordering also allow the person plus an infinitive:

• Li petis min resti. - He asked me to stay.

Voli never does: I want you to come is always the ke clause.

Three more points:

• -u has no tense: Mi volis, ke li venu. - I wanted him to come.
• Por ke (so that) takes -u: Mi laboras, por ke miaj infanoj lernu. - I work so that my children learn.
• With the same subject, por takes the infinitive: Mi laboras por vivi. - I work to live.

Report or demand?

-u follows verbs of wanting, not verbs of saying or knowing. A report keeps the real tense. Diri can do either job, so the ending alone tells you which:

The ke clause keeps the tense of what was true at the moment of the main verb: when she was thought to be there, she is there, so estas. Reported speech has the whole rule.

When English would is not -us

English would also reports a future from a past moment: he said he would come. Esperanto uses -os there, because at the moment of saying, the coming was still ahead:

• Li diris, ke li venos. - He said he would come.
• Li diris, ke li venus, se li povus. - He said he would come if he could.