Functional requirements (FR)

• Create, update, retrieve, and remove the records or objects described in the prompt.
• Support the required query, index, eviction, replication, or recovery operations.
• Define behavior for concurrent reads and writes, invalid inputs, and expired or unavailable data.
• Expose operational state such as capacity, health, replication progress, or eviction decisions.

Non-functional requirements (NFR)

• Specify consistency, durability, and recovery guarantees for each operation.
• Set latency, throughput, memory, and storage targets for expected and peak workloads.
• Handle hot keys, skew, resource exhaustion, and node failure without corrupting data.
• Define backup, migration, compatibility, and observability requirements.

Principal-level discussion

• Define the scale, success measures, and operational ownership before committing to an architecture.
• Compare at least two viable approaches and explain the trade-offs, migration path, and failure behavior.
• Identify the riskiest assumptions and how you would validate them with data or a staged rollout.