AI System Design Case Studies and the Interview Framework

Eleven mock interviews and one kitchen routine

Divya has an AI Solutions Architect interview in two weeks. Her mentor, Kabir, runs one mock interview every evening, each with a different open-ended prompt: "Design an enterprise ChatGPT." "Design a coding assistant." (Divya, Kabir and the scenarios are made up for teaching.)

On the first evening, Divya freezes. She knows RAG, agents and serving, but under pressure she jumps straight to vector databases and forgets to ask who the users are. Kabir, who cooks, gives her a rule: "A good chef has a routine. The same steps every time, in the same order, so the salt never gets forgotten when the heat is on."

These questions have no single right answer. Interviewers want to see that you:

• clarify the problem,
• choose a model strategy deliberately,
• build the data and inference paths,
• then cover safety, evaluation, reliability and cost.

The building blocks are covered in earlier guides: RAG, vector search, agents, serving, security, reliability and cost and evals. This guide is Divya's routine, then her eleven evenings of practice.

1. The routine: the eight-step AI design framework

flowchart LR
    A@{ icon: "algomi:svc-cube", label: "1 Product requirements", pos: "b", h: 52 }
    B@{ icon: "algomi:svc-spark", label: "2 Model strategy", pos: "b", h: 52 }
    A --> B
    C@{ icon: "algomi:async-pipeline", label: "3 Data pipeline", pos: "b", h: 52 }
    B --> C
    D@{ icon: "algomi:svc-cube", label: "4 Inference architecture", pos: "b", h: 52 }
    C --> D
    E@{ icon: "algomi:svc-cube", label: "5 Safety", pos: "b", h: 52 }
    D --> E
    F@{ icon: "algomi:svc-cube", label: "6 Evaluation", pos: "b", h: 52 }
    E --> F
    G@{ icon: "algomi:svc-cube", label: "7 Reliability", pos: "b", h: 52 }
    F --> G
    H@{ icon: "algomi:svc-cube", label: "8 Cost", pos: "b", h: 52 }
    G --> H

Reading the diagram. It's a left-to-right order, and the order matters:

• Steps 1–2 decide what you're building. Skip them, and everything after is guesswork. That is where Divya went wrong on evening one.
• Steps 3–4 are the system itself: how knowledge gets in, and how a question becomes an answer.
• Steps 5–8 are what makes it production-worthy. Interviewers often judge seniority here.

In kitchen terms: what's the dish and who's eating (1–2), prepare the ingredients (3), cook (4), taste for safety (5) and quality (6), have a backup plan if the stove dies (7), and keep track of what it all costs (8).