Learn Hardcore Indonesian: Agenda rapat sudah disimpan di lemari. - The meeting agenda has already been stored in the cupboard.

sudah is a perfect‐aspect marker. It shows that the action of storing the agenda has been completed. In English you’d say “already” or use the present perfect (“has been stored”).

Why is the verb disimpan passive instead of active?

Indonesian often uses passive to focus on the object (the agenda) rather than the doer. Here, we care about where the agenda ended up, not who stored it. Passive is formed by the prefix di- on the verb.

What exactly does the prefix di- do in disimpan?

di- marks a verb as passive. disimpan literally means “is/was stored.” If you remove di- you get the active form simpan (“to store”), and with the active verbal prefix meny- you get menyimpan (“to store [something]”).

Could I turn this into an active‐voice sentence?

Yes. You simply pick an agent and use menyimpan. For example:
Saya sudah menyimpan agenda rapat di lemari.
(“I have stored the meeting agenda in the cupboard.”)

Why is the location phrase di lemari at the end? Can it move?

In Indonesian, location phrases often follow the verb phrase. You could also say Di lemari, agenda rapat sudah disimpan, for emphasis on location. The default neutral word order is Subject–Predicate–Location.

What’s the difference between di lemari and di dalam lemari?

Both mean “in the cupboard,” but di dalam lemari is more explicit (“inside the cupboard”). di lemari is perfectly natural and generally understood as “in/at the cupboard.”

Can I swap sudah with telah here?

Yes. telah is more formal or literary but has the same meaning as sudah.
So Agenda rapat telah disimpan di lemari is also correct.

Is agenda rapat one phrase or two? How is it structured?

It’s a noun phrase where agenda (agenda) is modified by rapat (meeting). Literally “agenda of the meeting,” equivalent to “meeting agenda” in English.