Learn Finnish: Odotatteko te korjaajaa koko tunnin? - Will you wait for the repairer for a whole hour?

Time durations (how long something happens) follow the same case rules as direct objects! Since this sentence has a standard personal subject (te) and isn't a negative sentence or a command, the duration tunti takes the "total object" ending, which looks exactly like the genitive -n to become tunnin.

The verb odottaa is a partitive verb. Shouldn't the time duration also be in the partitive?

No, time duration expressions have their own independent case rules. While odottaa forces the actual object you are waiting for (korjaajaa) to be in the partitive case, the time duration (koko tunnin) follows the standard total object rules. The verb doesn't override how we express the passage of time.

Why is it koko tunnin and not kokon tunnin? Doesn't the modifier usually match the noun's case?

The word koko (whole, entire) is a special exception in Finnish: it is an indeclinable word. This means it never changes its ending to match the noun it describes. So it stays koko even though tunti gets the -n ending.

Just as a refresher, why is the repairer (korjaajaa) in the partitive case?