Handing an agent a 128 MB and 10-second execution contract made generated code up to 3.1x faster and cut peak memory in 13 of 14 comparisons

arXiv·medium signalXBlueskyLinkedInCopy link

The paper names 'substrate blindness' as the absence of execution context from an agent's planning state, and tests it by having Claude Opus 5, GPT-5.6-Sol and Gemini 3.7 Flash generate a high-dimensional pairwise Euclidean distance routine either from the task alone or with an explicit 128 MB RAM and 10.0 s wall-time contract. Disclosure reduced peak process memory in 13 of 14 executable index-aligned comparisons and mean wall time in all three cohorts, up to 3.1x faster. The mechanism is structural, not cosmetic: contract-aware runs adopted bounded blocking, float32 retention, upper-triangle traversal and in-place or memory-mapped buffers.