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instalilyAI·AI Engineer·Onsite - System Design / Architecture·Senior

Senior
May 2026

Summary

The final stretch of the instalilyAI onsite was a live demo and Q&A on an AI app you built earlier that same day, which is a brutal format if anything in your build went sideways. Less about polished answers and more about how you hold up when things aren't clean.

Questions Asked (3)

Q1

Walk us through the design decisions you made while building the AI app today.

System DesignTechnical Trade-offsAdaptability & Ambiguity
Author's notes

This is where I felt the pressure most.

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AI HintsAI Generated

Suggested Approach

Start with a high-level overview of the app's purpose and constraints, then dive into 2-3 key design decisions, explaining the trade-offs and why you chose that path. Conclude by reflecting on what you learned and how you would iterate.

Pro tip: Frame your decisions as hypotheses validated through rapid prototyping and user feedback, showing you balance technical rigor with business impact. Also, acknowledge any limitations and how you'd address them with more time.

1. Set the Context

Briefly describe the app's goal, target users, and any constraints (time, data, compute) that shaped your approach.

2. Highlight Key Decisions

Select 2-3 critical design choices (e.g., model selection, architecture, data pipeline) and explain the rationale behind each.

3. Discuss Trade-offs

For each decision, articulate the alternatives considered and the trade-offs (e.g., accuracy vs. latency, cost vs. scalability).

4. Show Adaptability

Describe how you handled ambiguity or changes during development, such as pivoting based on new information or user feedback.

5. Reflect and Iterate

Summarize lessons learned and outline next steps or improvements you would make with more time or resources.

Key Points to Mention

  • Model selection criteria (e.g., trade-offs between LLMs, fine-tuning vs. prompting)
  • System architecture (e.g., microservices, serverless, real-time vs. batch processing)
  • Data handling (e.g., preprocessing, augmentation, privacy considerations)
  • Evaluation metrics and validation strategy (e.g., A/B testing, offline metrics)
  • Scalability and cost optimization (e.g., caching, model quantization)
  • Collaboration and iteration process (e.g., cross-functional teamwork, agile sprints)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q2

What are the architectural limitations of what you built, and what would you change with more time?

System DesignTechnical Trade-offs
Author's notes

Easier to answer than I expected because I actually knew where my app was weak.

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AI HintsAI Generated

Suggested Approach

Acknowledge the limitations honestly, framing them as conscious trade-offs made under constraints. Then, for each limitation, propose a concrete improvement, showing you've thought deeply about the system's evolution. Balance technical depth with business impact, and tie your changes to scalability, reliability, or performance gains.

Pro tip: Focus on 2-3 high-impact limitations rather than listing many minor ones; depth over breadth demonstrates senior-level prioritization. Also, mention any monitoring or metrics you'd add to validate the improvements.

1. Set the context

Briefly describe the system you built, its purpose, and the constraints (time, resources, scale) that shaped your decisions.

2. Highlight key limitations

Select 2-3 significant architectural limitations, explaining why they exist and their impact on performance, scalability, or maintainability.

3. Propose improvements

For each limitation, outline a specific change you would make, such as adopting a new technology, refactoring a component, or adding a layer.

4. Quantify the benefits

Explain how each improvement would enhance the system, using metrics like reduced latency, increased throughput, or lower cost.

5. Conclude with learnings

Summarize what you learned from the experience and how it would influence your future architectural decisions.

Key Points to Mention

  • Trade-offs between speed of delivery and long-term scalability
  • Specific technical debt incurred and its consequences
  • Alternative technologies or patterns considered (e.g., microservices vs. monolith, batch vs. streaming)
  • Scalability bottlenecks and how to address them (e.g., horizontal scaling, caching, sharding)
  • Observability and monitoring gaps that hindered debugging or performance tuning
  • Cost implications of current vs. proposed architecture

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q3

How did you handle the parts of the app you didn't finish in time?

Adaptability & AmbiguityRoadmap Prioritization
Author's notes

Awkward question to get in a live demo setting.

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AI HintsAI Generated

Suggested Approach

Acknowledge that not finishing everything is normal in fast-paced AI development, then focus on how you prioritized, communicated, and delivered value. Show that you made deliberate trade-offs, kept stakeholders informed, and set up a clear path for the unfinished work.

Pro tip: Frame unfinished work as a strategic decision, not a failure—explain what you learned from shipping the core and how that informed the roadmap for the rest. This shows product thinking and ownership.

1. Set the context

Briefly describe the project, your role, and the constraint (e.g., tight deadline, shifting requirements) that led to unfinished parts.

2. Explain your prioritization

Detail how you decided what to build first—e.g., focusing on core user value, technical dependencies, or MVP scope—and what you consciously deferred.

3. Describe communication and mitigation

Explain how you kept stakeholders informed, managed expectations, and any interim solutions (e.g., feature flags, manual workarounds) you put in place.

4. Share the outcome and learnings

Highlight what was delivered successfully, the impact, and what you learned that improved future planning or execution.

5. Outline the follow-up plan

Describe how you handed off or scheduled the remaining work, ensuring it wasn't forgotten and had a clear owner and timeline.

Key Points to Mention

  • Prioritization based on user impact and business value (e.g., MVP approach)
  • Transparent communication with stakeholders about scope and trade-offs
  • Use of feature flags or modular design to ship partial functionality safely
  • Documentation of unfinished work and creation of follow-up tickets
  • Metrics or feedback from the delivered portion that validated priorities
  • Retrospective learnings that improved future estimation and planning

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.