Coding Agents Underestimate the Cost of Code They Own

The author argues that coding agents frequently underestimate the long-term maintenance costs of custom code compared to established libraries. While generating custom plumbing reduces initial effort, it accumulates hidden expenses across testing, comprehension, and future design changes. To measure this trade-off objectively, the author proposes a new benchmark called LongHaul, which tracks the lifetime cost of repeatedly modifying an application over a sequence of tasks. Open article →