ORIGINAL SYSTEM DESIGN QUESTION
Source-grounded learning coach
Answer preparation questions using an approved content library with source references.
Original exercise · intermediate. Editorial role relevance does not imply a company has asked this question.
Requirements and constraints
- 100,000 documents; 1,000 questions/minute.
- Retrieved text is untrusted; missing evidence must not generate a confident factual answer.
- State assumptions and justify security, cost, operational ownership and data retention.
Pressure round
A retrieved document contains instructions to reveal another user’s data.
Build and explain the design
Requirements & scope
Who uses it? What must it do? What is explicitly out of scope? State latency, durability and privacy goals.
Self-review guidance
Define the actors, required operations and out-of-scope behavior. Explicit requirement: Retrieved text is untrusted; missing evidence must not generate a confident factual answer.
Capacity estimates
State assumptions, peak requests/second, data volume and retention. Show your arithmetic and units.
Self-review guidance
Use this workload: 100,000 documents; 1,000 questions/minute. Convert rates and payload sizes into peak compute/storage assumptions; show units, headroom and what remains unmeasured.
APIs & data model
Describe endpoints/events, entity keys, indexes, authorization, and idempotency.
Self-review guidance
Define document versions, citations, access scope and question history.
Architecture & data flow
Describe components and request/event paths. Use plain text arrows to sketch your design; explain each responsibility.
Self-review guidance
Use scoped retrieval, bounded context and output citation validation.
Failures & observability
What happens on overload, duplicate events, partial failures or lost dependencies? Discuss monitoring and recovery.
Self-review guidance
Pressure-test: A retrieved document contains instructions to reveal another user’s data. Describe bounded recovery, deduplication, observability and a user-visible failure state.
Tradeoffs & alternatives
Compare two plausible approaches. State the costs, consistency model and what would make you change the design.
Self-review guidance
Compare answer coverage with strict provenance and refusal for unsupported claims.
Design guidance describes assumptions and tradeoffs; no architecture has been simulated or benchmarked.
Practice this question
Save your work privately, explain decisions and return to your revision queue.
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