Vibenix generated buildable Nix packages for 95.3 percent of 466 tasks, where a state-of-the-art single-shot tool managed 5.6 percent
AspireAI community · arXiv
*Reproducible packaging has a chicken-and-egg problem: you cannot write a hermetically isolated build recipe until you already know every implicit dependency your build actually pulls in.* Vibenix is an open-source agent that closes it by iterating on Nix packaging expressions through a rule-guided build-repair feedback loop, using the compiler's own failures as the signal. On 466 packaging tasks from the new NixBench dataset it produced buildable packages 95.3 percent of the time with Claude Haiku 4.5, against 5.6 percent for a state-of-the-art LLM-based single-shot packaging tool.
The catch is in the numbers people usually skip: manual validation of 100 packages found only 47 percent of the buildable ones were actually functionally correct, and a post-build refinement pass based on the evaluator-optimizer pattern raised functional correctness by 35 percentage points. On the separate NixBench-Repair maintenance set, Vibenix hit an 87.6 percent success rate. So the honest read is that getting code to compile is solved; getting it to do the right thing is still roughly half the problem, and that is the half the repair loop handles.
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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.