Ai Coding And Product Systems hard
In your code assistant's chat, a user working in a monorepo of about 30M tokens asks why payment retries double-charge. The model has a 200K-token window, and answer quality and latency both matter. How should context be assembled?
- A Feed the entire repository across several turns in chunks so the model builds a complete picture of the codebase before answering.
- B Rank files using open tabs, the symbol and call graph, and embedding search, then pack only the top results into a token budget.
- C Include every file under the current directory recursively, since colocated code is most relevant and this avoids retrieval misses.
- D Fill the full 200K-token window with the highest-similarity chunks, since supplying more relevant context always improves accuracy.
Answer: B. Rank files using open tabs, the symbol and call graph, and embedding search, then pack only the top results into a token budget.
Repo context is a **retrieval and ranking problem**. Blending structural signals like the call graph with semantic search finds the retry path, but it costs indexing work and risks missing a file. Filling the window (D) adds latency and cost and buries the key code where attention is weakest, and similarity alone misses callers that use different wording. Maxing out context only pays off for small repos that fit comfortably.
One system design question a day, with spaced repetition so the ones you miss come back.
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