GitHub Copilot introduced Agent Plugins 1.0 for portable agent extensions

GitHub published its August summary for Copilot in VS Code on 31 August 2026, covering releases v1.132 through v1.135. It includes several capabilities that are worth reading closely, despite the release-notes format, in particular an Agent Plugins 1.0 standard, in-session model switching between Anthropic and Copilot billing, and a full-text search over an entire chat transcript.

Agent Plugins 1.0

The most important line reads: "Install portable agent plugins that follow the Agent Plugins 1.0 standard across VS Code and other compatible agent clients." GitHub does not define what a compatible agent client is in this post, and the specification page is not linked from it, so the standard's scope is not yet public. For now, read the label literally: it is GitHub's name for a portable format, and the promise is that a plugin written for it should install into more than one client. Whether that promise is real depends on which other clients adopt it and how quickly.

In-session model switching

A Claude session in Copilot can now switch model providers mid-conversation, with a choice between models on your Anthropic subscription and models on your Copilot subscription. GitHub does not describe the billing mechanics in the post, so it is unclear whether the Anthropic charge goes to the user's Anthropic account and the Copilot charge to GitHub's or whether both appear on one bill. That answer is probably in a support article rather than the changelog, and it is worth checking before assuming.

Agent Host and side conversations

Agent Host is the layer that manages agent sessions across VS Code windows. In this release it lets multiple windows attach to the same session and continues sessions created in external agent applications. A new command opens a side conversation that keeps the parent's context and prompt cache while the parent continues running, which is meant for the "and by the way" question you would otherwise interrupt a long-running agent to ask.

Other changes in the release

Full-text search now runs across the whole chat transcript, with case matching, whole-word matching, and regular expressions. Token usage is visible per model. The integrated browser can annotate an HTML element to show it to the agent, and auto-reloads on local changes. Two features are behind experimental flags: opening the Agents window without a GitHub sign-in, and a /rubber-duck command that asks a complementary model to review the transcript for missed details.

The interesting item on the list is the Agent Plugins standard, because it is the first attempt at portability across coding-agent clients that has come from a client vendor rather than a plugin marketplace. If you maintain an agent skill or plugin, it is worth reading the specification when GitHub publishes it and deciding whether packaging your work in that format lets more people use it. If you consume plugins, it is worth watching which other clients declare support before you assume the standard is real.

Source

• GitHub Copilot in VS Code, August 2026 releases, GitHub Changelog, 31 August 2026.