Decomposition
Splitting a big job into pieces small enough to be done and checked alone, in an order where each piece builds on something already known to work.
Given everything at once, an agent can run out of room halfway and leave the next session a half-built feature. With small pieces, a break shows up at the piece that caused it. Too small has a cost as well, because every piece has its own overhead.
Say it to your agent
“Split this into steps that each end with something I can run. Give me the list, with the check for each step. Do step 1 only, show me the check passing, and then carry on to step 2.”