Interview prompt
Problem context
A storage fleet must move from a custom binary protocol to a versioned protocol with stronger authentication and streaming. Clients and servers upgrade independently across regions, long-lived connections span deployments, and some embedded clients update rarely.
Skills being evaluated
protocol evolutioncapability negotiationmixed-version designsecurity migration
The full reasoning guide is part of Pro
The scenario and evaluation focus above remain public. Pro unlocks the structured answer, trade-off analysis, follow-up probes, common weak answers, rubric, related reasoning, and any architecture diagram.
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Clarify the decision
Establish scale assumptions
Functional and non-functional requirements
High-level architecture
Data model and flow
Consistency and transaction boundaries
Failure modes and recovery
Security and privacy
Observability and SLOs
Capacity and cost
Alternatives and trade-offs
Evolution and migration
What Staff and Principal candidates should emphasize