Microsoft put the harness that runs Copilot Code, Studio, the CLI and VS Code into Microsoft Foundry
AspireAI community · Microsoft Foundry Blog
Microsoft moved the agent harness that already powers Copilot Code, Copilot Studio, the GitHub Copilot app, the CLI and VS Code into Microsoft Foundry Agent Service, where it entered public preview on October 28. Developers can either download the Copilot SDK or run the harness in the cloud, and the preview bundles reusable skills, MCP-connected tools, subagent delegation and source-controlled agent definitions, with Microsoft running the agent loop and sandbox while the customer supplies instructions, tools and model choice. It is a preview, and an agent's harness cannot be swapped after creation, so this is a commitment to a Microsoft-owned execution layer rather than a drop-in library.
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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.