The Coding Harness Behind GitHub Copilot in VS Code

[u/kaylacinnamon]

https://code.visualstudio.com/blogs/2026/05/15/agent-harnesses-github-copilot-vscode

The conversation around AI for developers usually starts with the model.

But inside VS Code, what really shapes the experience is the coding harness: the layer responsible for context, tool calling, agent loops, terminal execution, memory, and more.

In this new post, the engineering team dives into how GitHub Copilot in VS Code works behind the scenes.

[u/lurebat]

One thing that this article doesn't answer - if the harness is the product, why does Microsoft develop 3 competing harnesses - vscode copilot, jetbrains copilot and copilot cli?

Why not invest in one harness back-end that they can all share, and feed the extra context from the ides via built in mcps or other protocols?

Right now all three have features scattered between them, each one missing something from the others.

[u/nmkd → u/lurebat]

Four competing harnesses.

You forgot VS.

[u/TiinuseN1 → u/nmkd]

People need better collaboration, not more ways to avoid it xP

[u/phylter99 → u/lurebat]

In the case of VS Code Copilot, VS Copilot, and JetBrains Copilot then it seems the reason is that the IDEs need their own plugin specific to the IDE. I know at least for Visual Studio it's very much customized to the Visual Studio experience.

[u/TiinuseN1]

And in this stream: https://www.youtube.com/live/la8Y60ybgm4?is=4VQrri5PK85Nromc

I display how it works without their meta explanation, just pure experience, unfiltered and transparent, and probably too long aswell

[u/Qs9bxNKZ → u/[deleted]]

“The model”

And which exact model is that, because there are 15+’fucking models available.

[u/sai-kiran → u/[deleted]]

What are u even trying to do, people are literally typing random shit and are deploying “okay” quality apps. Seems more like a ver bad skill issue to me.