How would you decide whether to build, fine-tune, or buy an LLM for a feature?
Build / Fine-tune / Buy Decision TreeDriven by differentiation, latency, cost, and data moat.
What a strong answer covers
- What's the user job and what level of quality is 'good enough'?
- Is the differentiator the model or the workflow around the model?
- Latency, cost per request, and privacy constraints.
- Data: do you have proprietary data that would make fine-tuning win?
- Recommend: foundation API → RAG → fine-tune → train, only as needed.
How do you measure quality for a generative AI feature?
Eval Stack: Offline + Online + HumanNo single metric. Layer automated evals, online behaviour, and human review.
What a strong answer covers
- Offline: golden set, rubric-based scoring, regression suite per release.
- Online: implicit signals (regen, edit, abandon), explicit (thumbs).
- Human-in-the-loop: weekly sample review with a quality rubric.
- Guardrails: hallucination rate, safety, latency budget.
- How you'd ship a model upgrade safely (shadow → canary → ramp).
Your AI feature is hallucinating. How do you fix it?
Diagnose → Mitigate → MeasureHallucination has many root causes. Fix the right one.
What a strong answer covers
- Diagnose: prompt issue, retrieval gap, model capability, or stale context?
- Mitigate (in order of cost): prompt fix → RAG → tool use → fine-tune → model swap.
- Add UX guardrails: citations, confidence display, easy correction.
- Track hallucination rate as a first-class metric.
- Decide acceptable rate by use case (medical vs marketing copy ≠ same bar).
How would you price an AI feature with high variable inference cost?
Unit Economics + Tiered PricingInference cost shows up in COGS. Pricing must protect the margin.
What a strong answer covers
- Model the variable cost per request and cost per power user.
- Choose pricing shape: usage-based, tiered with caps, or freemium with upsell.
- Identify abuse vectors and design fair-use limits.
- Migration: how you handle legacy customers when costs shift.
- Long-run: as model costs fall, do you cut price or expand value?
Walk me through how you'd ship an agentic workflow safely to enterprise customers.
Agent Safety StackAgents take actions. Errors are no longer just bad text — they're bad outcomes.
What a strong answer covers
- Scope the agent: tasks, tool surface, blast radius if it goes wrong.
- Permissions: read vs write tools, human-in-the-loop checkpoints.
- Observability: full action traces, replay, audit logs.
- Reversibility: undo, sandboxes, dry-run mode for destructive actions.
- Rollout: design partners → opt-in beta → GA, with clear kill switch.