SlopCodeBench

SlopCodeBench evaluates coding agents the way real software actually gets built: through repeated requirement changes and extensions. Each problem is a sequence of checkpoints — the agent implements an initial version, then extends its own solution as new requirements arrive. Evaluation is black-box: only a CLI or API contract is given, with no prescribed architecture, function signatures, or module boundaries, so early design decisions compound across the run. Beyond correctness, we measure code erosion — verbosity, dead branches, and redundant structure — to surface the agents that stay clean under sustained change instead of patching their way into slop.