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Code RoomBorrow checker churn
HardPrep Room Coding #4502

Borrow checker churn

Vibe & agenticAlgorithms & data structuresSenior–Staff~22 min

Deep into a long agent session building a Rust networking module, the agent fixes one borrow-checker error and reintroduces a different one it fixed an hour ago, then starts churning — each edit fixes one thing and breaks another. The context window is full of prior attempts. Why is it failing now, and how do you re-steer versus reset?

Implement
churn_reset_index(errors: list[str], tolerance: int) → int
Examples
in[["E0502","E0106","E0502"],1]out3
in[["E0502","E0502","E0502"],1]out0
in[["E0502","E0106","","E0106","E0502","E0106"],2]out0
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it (tests, edge cases, reading critically), and how you’d re-prompt or decompose to get it right.

0:00 of about 22 min

Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.

Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.