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Microsoft previews Copilot harness, bills compute hourly

Microsoft turned its own agent harness into a managed service in public preview on Foundry Agent Service, and from December 1 the compute agents use in the sandbox is billed by the hour. Microsoft's October 28 developer blog says Copilot harness is an optional managed execution system in Foundry Agent Service: Microsoft runs the agent loop and the sandbox, and developers plug in a model Foundry supports. An agent's cost now includes a compute-hour charge on top of tokens, and it grows with how long and how heavy the run is. Microsoft gives no performance figures and no comparison with a self-built harness. The four building blocks are reusable skill packs, connected tools, execution and delegation to built-in sub-agents, and version-controlled agent definitions. From December 1, sandbox compute costs US$0.0994 per vCPU-hour and US$0.0118 per GiB-hour of memory, free until then, with model inference billed separately; for supported models and regions, the post gives only links and no list (Microsoft Foundry, 2026-10-28). How we checked →

Concept illustration: on a pale green background, a tall light-grey panel shows a four-colour square icon (orange, green, blue, yellow) beside the lettering "MICROSOFT FOUNDRY", a blue banner reading "COPILOT HARNESS", and a left column of icons: a cardboard box, a wrench, a small window with a chat bubble, and a document with a branching symbol. In the middle, a panel labelled "MODEL" holding a speech bubble with grey lines sits above a panel labelled "SANDBOX", with two curved blue arrows forming a loop between them, while on the right edge two hooks hold a grey tag above and a red tag below, whose string a hand reaching in from the right is holding.

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This item ran in the brief of Oct 29, 2026, alongside 16 other items. How we checked it, the quote checks and what was still missing that day are on that issue's How we checked page.

Cite this item

SecondSource (2026). "Microsoft previews Copilot harness, bills compute hourly." https://secondsource.io/en/product/2026-10-29-1/. Accessed access date.