hardOpenAI

Build a time-based KV store, write three real unit tests for it, then defend a locking strategy

The OpenAI variant where the data structure is the warm-up: the round is graded on whether your tests control time and whether you can argue global vs per-key vs optimistic locking with actual reasons. Most candidates ace part one and lose the round in parts two and three.

Updated Aug 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.

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