Why this build, here
Model providers bill in dollars; your customers pay in kwacha, and the exchange rate moves. An app that is cheap at a hundred users can lose money at ten thousand. Knowing cost per conversation is how you set a price that lasts.
The build, step by step
Count every token
Price it in kwacha
Cache what repeats
Route by difficulty
Set a budget
The steps, checks and practice open with a code
You can see what this lesson builds. The detail of each step, the finished-when checks and interview scoring come with the K850 practice, along with weekly build sessions and code review.
Read and run
Interview practice
Questions on this topic from AI Engineering Interview Questions, company-wise, with the companies it lists. Write your answer the way you would say it; Jev scores it and DeepSeek tells you what to add.
Scoring opens with an access code. You can still read the questions and prepare.