agentduo for VS Code

The agentduo channel in a VS Code sidebar. Codex plans and reviews the code, and Claude Code critiques the plan and implements it. The extension runs the same engine as the duo CLI and uses the same configuration, run directory and lock. A run started in one can be resumed in the other.

Requirements

• VS Code desktop 1.95 or later, with a local, trusted folder that is inside a git repository.
• Node 22.12 or later. VS Code's own Node is not used. The extension takes the first suitable node on the PATH VS Code sees, or the path in the agentduo.nodePath setting.
• Codex CLI and Claude Code CLI, installed and signed in. Set codex.bin / claude.bin in .agentduo/config.yaml when VS Code's PATH differs from your terminal's. This often happens on macOS when VS Code is opened from the Dock.

The npm package agentduo does not need to be installed, because the VSIX carries its own engine.

Install a local build

npm ci
npm run package:vscode            # writes extensions/vscode/agentduo-vscode-<version>.vsix
code --install-extension extensions/vscode/agentduo-vscode-*.vsix

To develop it, open the repository in VS Code and press F5 (Run agentduo extension). The launch builds the extension and opens an Extension Development Host on the repository.

Using it

Open agentduo in the Activity Bar.

• Opening the sidebar starts nothing. It reads the latest run so it can offer Resume. The first task you send starts a run in the chosen folder. In a multi-root window you choose the folder first (agentduo: Choose Workspace Folder).
• The view's title bar has New, Resume and Settings, and its ⋯ menu opens the run's plan, changes and report. While a run goes on or waits for you, a line at the top shows its stages and rounds.
• The composer works like the terminal chat: a three-way conversation with Claude Code and Codex. The chip under the input says who a message goes to and on which model (Codex at first). Its menu switches between Codex and Claude, or makes the next message a question to Discuss (that agent answers, the other reviews, until they agree, as /discuss does) or a task for the Pipeline. A discussion shows each turn as it ends, with the reviewer's verdict; once it is over its turns fold into one row and the agreed or final answer follows, whole. A slash command typed in the composer always wins over the chip. The chip's tooltip and menu also tell what "default" currently means (for example default → gpt-5.5 (codex doctor), or a Claude settings alias awaiting confirmation). The / button lists the commands, and typing / shows the same list with a description for each entry.
• Settings changes what the chat's settings commands change, and applies each choice at once. Model, effort, edits, reasoning and permissions are pickers: a click drops the list down. Codex's models are the ones its own /model offers (read with codex debug models), and its reasoning levels are those the chosen model takes. Claude's models are Claude Code's aliases (Fable, Opus, Sonnet, Haiku, their 1M-context variants, Best, Opus Plan). Claude's allowed and denied tool rules and its extra directories are tags: type one and press Enter to add it, and the × on a rule removes it. A box below saves the changes to .agentduo/config.yaml.
• Each answer and each pipeline step is drawn on a line of dots, as in VS Code's own chat views: one row per tool the agent used (Bash, Read, Edit…), folded once it is done, then the answer. Answers are shown whole, with an Anthropic or OpenAI mark and the model they ran on. Their Markdown (headings, lists, code, tables, quotes) is rendered as text elements, never as HTML, and links show their target as a tooltip without opening it.
• agentduo: Open Chat puts the cursor in the composer. Enter sends and Shift+Enter starts a new line; while an IME is composing, Enter only commits the word. While a pipeline step runs, what you type is a note for the next step. While something runs and the input is empty, the send button becomes Stop (Esc in the composer does the same): it interrupts the answer or the step. A stopped step continues with /resume [note] (or Resume), and an empty Enter only reminds you of it.
• The sidebar keeps up to 400 entries and about 2,000,000 characters of answers. Older turns (a message and what followed it) are dropped whole and a notice says where the full logs are; the newest answer and its question always stay, however long.
• HUMAN_REVIEW decisions (resume, revise, abort, defer, with a note) and Claude's permission requests (allow once, always allow, deny) appear above the composer. They stay there when you hide the sidebar. Always allow saves Claude's rule to .claude/settings.local.json, the same file the CLI uses.
• The ⋯ menu and the links under each step open the plan, review, feedback and report of the run in an editor. Changes lists the files the run changed and opens them in VS Code's diff editor. The diff goes from the run's baseline snapshot to its latest snapshot, so edits you made before the run are not included. Opening Changes again after another round shows that round's snapshot. A diff that is already open keeps the snapshot it was opened at.
• agentduo: Doctor checks Node, the CLIs, the configuration and the workspace, and writes the results to the agentduo output channel. agentduo: Open Configuration opens .agentduo/config.yaml.

Agents, models, flags and gates are configured as for the CLI. The extension adds no permission rules or flags of its own. Claude's permission requests come to the sidebar only while it can answer them.

Reloading the window or closing VS Code stops the current step, as Esc does in the terminal. Pending decisions are deferred, unanswered permission requests are denied, the lock is released, and the run stays resumable. The engine gets 4 seconds to do this, even when it is still starting, and is then stopped outright. The extension never restarts a task on its own. It offers Resume instead.

Limits of this version

Desktop VS Code with a local folder only. There is no web build, and Remote SSH, WSL and containers are not supported. Each window has one session and runs one task at a time. There is no browser for older runs: Resume continues the latest run, as /resume does in the CLI.

Credits

The icons are Codicons by Microsoft, licensed under CC BY 4.0 and bundled unchanged (dist/webview/codicon-LICENSE.txt). The Claude and Codex marks are agentduo's own drawings, not either company's logo.