Yes Code

Yes to code, no to everything else.

Yes Code is a VS Code extension for agentic software development, built on Anthropic's official Claude Agent SDK. It provides a chat panel that can read, search, edit, and run code in your workspace — and a scope policy that keeps the assistant on software engineering, and nothing else.

Independent project. Yes Code is not affiliated with, sponsored by, or endorsed by Anthropic PBC. "Anthropic", "Claude", and "Claude Code" are trademarks of Anthropic PBC, used here only to describe the underlying SDK and models this extension consumes.

Why Yes Code

The Claude Agent SDK exposes the same agent loop and toolset that powers Anthropic's own coding tools: a capable general-purpose assistant that happens to be pointed at your repository. Yes Code wraps that loop in a VS Code surface and narrows what it is for.

A scope policy is appended to the SDK's built-in claude_code system prompt on every request, in every workspace. It confines the assistant to code, debugging, architecture, and directly-related technical subjects. Personal, social, and sensitive human topics are out of scope — and so is routing them through code. A request for a function, variable name, comment, or string literal whose content is out of scope is declined even when its wrapper is perfectly technical. Anything off-topic gets one answer, and it is always the same one.

The policy is not a hidden filter. It is roughly ten lines of plain English in a single file, src/agent/system-prompt.md, so you can read it, tighten it, or adapt it to your organisation instead of trusting it blindly. It is a strong instruction to the model rather than a hard technical guarantee, and it is written to be audited on that basis.

The result is an agent that is a development tool and nothing else — suited to teams and organisations that want agentic coding assistance without a general-purpose chatbot inside the editor.

Features

• Scoped to development — an auditable policy file keeps the assistant on code and technical subjects, and declines everything else.
• Agentic chat panel in the activity bar (and openable in an editor tab), with the SDK's full toolset (Read, Write, Edit, MultiEdit, Bash, Grep, Glob, Web, TodoWrite, Task/subagents, …).
• Streaming responses with live text and extended-thinking rendering.
• Rich tool cards — every tool call is a collapsible card with inputs, results, and inline diffs for file edits.
• Permission prompts — approve or deny each tool use, with "always allow", plus permission modes: default, acceptEdits, plan (read-only planning), and bypassPermissions.
• Inline diffs & review — accept/reject individual edits or all at once; rejecting reverts the file to its pre-edit snapshot.
• Editor context — automatically shares your active file and selection; add files or selections explicitly via right-click or ⌘⌥K / Ctrl+Alt+K.
• @-file mentions and /slash commands with autocomplete in the composer.
• Model picker — switchable mid-session.
• Usage & cost — per-session token and USD cost indicator.
• Conversation history — browse and resume past sessions.
• Checkpoints — rewind file changes made during a turn.
• Stop / interrupt a running turn at any time.

Keyboard shortcuts

Requirements

• VS Code 1.90+

• Claude Code installed on your machine. Yes Code drives Anthropic's own Claude Code runtime locally; it does not bundle it (the binary is ~250 MB and platform specific). Install it once:

  npm install -g @anthropic-ai/claude-code
  

  The extension auto-detects the executable via PATH, npm global installs, and the native installer, following npm launcher scripts to the real binary. If yours lives somewhere unusual, set yes-code.claudeExecutablePath.

Yes Code must run in a trusted workspace. It edits files, executes shell commands, and starts MCP servers declared in the workspace's .mcp.json — all of which are defined by the repository you have open.

Authentication

Yes Code does not operate a backend. It runs the Claude Agent SDK locally and the SDK talks to Anthropic directly; your credentials never leave your machine. Two methods are available (choose via Yes Code: Sign In, or the yes-code.authMethod setting):

• API key — an Anthropic API key from the Claude Console, stored in VS Code SecretStorage. Also readable from the ANTHROPIC_API_KEY environment variable or the yes-code.apiKey setting. This is the authentication method Anthropic documents for software built on the Agent SDK.
• Claude subscription — signs in with your own Claude account through the bundled Claude runtime's OAuth flow (claude auth login). In this mode the extension does not pass ANTHROPIC_API_KEY to the runtime, so your account login is used rather than Console billing.

Before you rely on subscription mode, read Anthropic's Authentication and credential use policy and satisfy yourself that your usage fits it. As of this writing that policy states that developers building products on the Agent SDK "should use API key authentication", and that Anthropic "does not permit third-party developers to offer Claude.ai login or to route requests through Free, Pro, or Max plan credentials on behalf of their users." Yes Code routes nothing on anyone's behalf — it invokes Anthropic's own runtime with your own local credentials — but if you intend to redistribute Yes Code rather than run it yourself, API-key mode is the unambiguous choice.

Settings

MCP

Yes Code loads MCP servers from your user configuration (claude mcp add) and from the workspace .mcp.json. Run /mcp in the chat to see live connection status for each one. This requires yes-code.loadProjectSettings to be on — it is what enables the settings sources MCP is configured through.

Building from source

Requirements: Node.js 18+ and VS Code 1.90+.

npm install
npm run compile      # builds dist/extension.js and media/webview.js
npm run check-types  # tsc --noEmit

Press F5 in VS Code (or the "Run Extension" launch config) to open an Extension Development Host with the extension loaded, then open Yes Code from the activity bar.

Packaging a VSIX

npm run vsix

The Agent SDK's JavaScript is kept external from the bundle and ships inside the .vsix; its ~250 MB native runtime is not bundled, so the package is ~4 MB and works on every platform. The runtime is discovered at load time from your Claude Code installation.

Architecture

src/
  extension.ts            activation, command registration, context wiring
  panel/chatViewProvider  WebviewViewProvider + editor-tab panel; HTML/CSP/bridge
  agent/                  Agent SDK integration (streaming-input query loop)
  agent/system-prompt.md  the scope policy  ← what makes this Yes Code
  tools/                  canUseTool permission bridge, diff compute & review
  context/                editor context tracking, @-file / slash completions
  history/                session list & resume via the SDK
  shared/protocol.ts      typed message contract shared with the webview  ← frozen
webview-ui/src/           vanilla-TS chat UI (bundled to media/webview.js)
media/                    webview.css, icons, bundled webview.js
docs/SDK-NOTES.md         verified notes on the Agent SDK surface

The extension host holds one long-lived query() per conversation in streaming input mode, translating the SDK's SDKMessage stream into typed HostToWebview messages and forwarding webview actions back. The webview is a dependency-free TypeScript app that renders the transcript and composer using VS Code theme variables, so it matches any color theme.

License

MIT — see LICENSE. The Claude Agent SDK and the Claude runtime it bundles are licensed separately by Anthropic; your use of them is governed by Anthropic's terms.