PROBE measured coding agents against 2,457 real maintainer-fixed bugs and found recall below 21 percent and precision below 9 percent
AspireAI community · arXiv (LogicStar.ai, ETH Zurich)
*Coding agents are widely deployed for proactive bug discovery, but their ability to find the bugs human maintainers would actually repair across a repository had not been studied.* PROBE is a benchmark of all 2,457 bugs fixed over 18 months across 20 GitHub repositories, together with a method for matching candidate findings to that partial reference set.
Across frontier models the agents all achieved recall below 21 percent and precision below 9 percent against the reference set. Stronger models increased recall substantially from 8 to 17 percent but did not improve precision. Despite the low precision, LLM and human evaluators still judged 85 percent of findings valid. The key finding is distributional: the bugs agents find look similar across agents, but differ substantially from the bugs maintainers actually fix - which makes PROBE a useful measure of what these tools do and do not cover.
Read the story and explore more from the AspireAI community.
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.