VS Code agent host runs Copilot, Claude, and Codex in a dedicated process
Developers who lean on AI coding agents often keep several editor windows open at once, each tied to its own session. The 1.129 release of Visual Studio Code reworks that setup with a dedicated agent host.
A dedicated process for agent sessions
The agent host is a separate process that runs agent harnesses such as Copilot, Claude, and Codex, built on the Agent Host Protocol. Because a session lives in its own process, one session can connect to and render across several VS Code windows at the same time.
The Copilot agent inside the host draws on the Copilot SDK, so its behavior lines up with the Copilot CLI, the standalone GitHub Copilot app, and other Copilot products. Opting in means enabling the chat.agentHost.enabled setting, which an organization administrator controls, then choosing a harness from a dropdown.
Reviewing an agent’s output in one pane
A redesigned editor panel in the Agents window folds the editor and the detail area into one docked pane with a shared tab bar. Files and diffs open next to the chat, and a Changes view supports inline and side-by-side diffs, expanding or collapsing every file at once, and a compact diff layout that fits more of a change on screen.
The next step, such as Create Pull Request, sits on the editor tab title. Each session restores its side-pane width, open editors, active editor, and per-file collapsed state across window reloads. This layout is experimental and opt-in through the sessions.layout.singlePaneDetailPanel setting, read once when the window starts.
Agents that manage other agents
Agents on the host gain a set of session-management tools. An agent can list your sessions with their status, workspace, and changes, read another session’s recent conversation, create a new session or chat to hand off a sub-task, and send a message to steer that work. VS Code shows an Open Session pill whenever a tool creates or targets a session. Sending a message to another session asks for confirmation first, an agent cannot message its own chat, and a burst of sends is capped so one request stays contained.
Faster new-session setup
The new-session picker in the Agents window remembers your last agent mode and approvals choices and offers them as defaults for the next task. A single New Worktree checkbox now sets Git worktree isolation, which keeps an agent’s changes in a separate folder until you review and merge them.
Terminal commands, keys, and enterprise sign-in
Chat prompts now accept a ! prefix that runs their contents as terminal commands inside agent host sessions. Bring Your Own Key models work in the Agents window under the Copilot harness. Developers whose Copilot access comes through a GitHub Enterprise instance can now sign in against that host, a path the agent host previously blocked because both the OAuth flow and the token request pointed at github.com.
An experimental Modern UI preview updates the look of the editor workbench and ships on by default in Insiders builds. Custom editors also opt out of diff and merge editors by default now, so a file can open in a custom editor and its diffs open in the built-in text editor. A new customEditorPriority API gives extension authors separate priorities for files, diffs, and merge editors, with a never value that keeps an editor available for manual selection only.