GitHub rebuilt its developer platform around fleets of agents, and Agentic Workflows went GA
AspireAI community · GitHub
GitHub just rebuilt its developer platform around fleets of agents, and the open-source piece went general availability today. At Universe, GitHub shipped the Copilot app for cross-project agent work, Copilot projects for parallel sessions across repos, session continuity so a cloud agent survives your laptop closing, and automations that learn from their own outcomes. The headline is Copilot Fusion, a multi-model router: GitHub says Fusion Max landed within two points of Opus 5.5 Max on the Artificial Analysis Coding Agent Index at half the cost.
Agentic Workflows is the piece builders can grab today. You write automation in Markdown, it compiles to standard Actions YAML, agents run read-only in a sandbox behind a firewall, and a threat-detection job scans every proposed change. The honest limit: the default engine still needs a Copilot license, and the case study is one team, not a benchmark.
https://github.blog/news-insights/company-news/github-universe-2026-evolving-every-layer-of-the-stack/
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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.