Copilot CLI Chat for VS Code

Why This Extension?

VS Code already ships a native Copilot chat — and it's great as a general-purpose tool. This extension takes a different approach: a focused, session-driven workflow designed to keep you in flow while coding.

Think of it as the difference between a Swiss Army knife and a purpose-built tool. Where the native experience covers everything, this extension is optimized for deep think sessions — rich streaming, plan-vs-implement separation, and a Claude Code-inspired UX that stays out of your way.

Your decisions stay where your focus is. When the agent edits a file, you see the diff right in the chat stream — review it, tell the agent what to change, or click through to edit it yourself. No context-switching to scattered inline annotations. No accept/reject popups pulling you out of your conversation. You're already talking to the agent — that's where your decisions should happen.

And you don't have to choose. Sessions created in this extension appear in the official Copilot extension's session list, so you can switch between both seamlessly. Don't worry, this extension will wait. We know you'll be back for the more focused experience.

✨ Features

📌 Activity Bar Sidebar

The extension lives in the VS Code Activity Bar — same location as native Copilot Chat and Claude Code. Click the icon to show/hide, drag between left and right sidebars. Native chat experience with proper lifecycle management and zero memory leaks.

🎯 Focused by Design

• In-Stream Diffs — File edits show compact inline diffs (+/- prefixes) directly in the chat stream. Larger diffs truncate with a "View Diff" button. Review, approve, or redirect the agent without leaving your conversation.
• Plan Mode (ACE-FCA) — Separate planning and implementation into dual sessions. Explore with read-only tools, then hand off a solid plan to your work session. The input area shows a blue outline when plan mode is active.
• Plan Model Selection — Use different AI models for planning vs. implementation. Think with Opus, build with Sonnet, explore with Haiku.
• Reasoning Visibility — Watch the agent think in real-time with streaming reasoning traces.

🔄 Session-First Workflow

• Session Interop — Sessions appear in the official Copilot extension's session list. Switch between both experiences freely.
• Auto-Resume — Picks up where you left off, even after VS Code reloads. Full conversation history loads from Copilot CLI's event log.
• Session Resilience — Smart retry logic handles transient failures automatically (v2.2.3+).
• Session Management — Create, switch, and resume sessions from a dropdown. Filtered by workspace folder.
• Session Fork — Clone the current session at any point with the ⑂ Fork button. The fork starts with the full conversation history and diverges independently — useful for exploring alternate approaches without losing the original thread.
• Usage Metrics — Live context window percentage, token usage, and quota tracking per session.

🤖 Custom Agents

Define named agents as simple Markdown files with YAML frontmatter — drop them in a directory and they're instantly available. Three built-in agents ship out of the box, plus an example Researcher agent:

Agent	Role
Planner	Read-only exploration; writes plan.md. Never edits source files.
Implementer	Reads the plan and executes it. Full file-editing access.
Reviewer	Runs tests, reads changed files, posts a concise review summary. Read-only.

Agent file locations:

• ~/.copilot/agents/ — global agents, available in every workspace
• <workspace>/.copilot/agents/ — project-scoped agents, shared via version control

How to use:

• Open the 🤖 Agents panel in the toolbar to create, edit, or delete agents
• Type @agentName at the start of any message to route that message to a specific agent
• Use /agent <name> to set a sticky agent for the whole session; /agent with no args clears it
• The 🤖 button in the toolbar turns green when an agent is active
• A file of the same name as the built-ins (lowercase) in the locations explained above can override the built-ins.

Agents use Markdown frontmatter for configuration — name, description, allowed tools, and a system prompt in the body. See the Custom Agents Guide for the full format and examples.

🛠️ Rich Agent Experience

• In-Stream Tool Execution — Collapsible tool groups show exactly what the agent is doing, inline with the conversation.
• Color-coded conversation — 🔵 User messages, 🟢 Assistant responses, 🟣 Tool/agent actions each have a distinct left border so you can scan the flow at a glance.
• Mermaid Diagrams — Mermaid code blocks render as interactive diagrams with a toolbar to view source or save as SVG/.mmd.
• Image Attachments — Send screenshots and diagrams to vision-capable models with preview thumbnails.
• Active File Context — The agent always knows which file you're working on, even when chat has focus.
• @file References — Reference files directly in your messages.
• Mid-Session Model Switching — Switch AI models mid-conversation without losing context. Models are grouped by cost tier (Fast/Standard/Premium) with multiplier badges showing request cost. The session resumes with the new model, preserving all messages and tool state.
• 17 AI Models — GPT-5, Claude Sonnet 4.6/4.5, Claude Opus 4.6, Gemini 3 Pro, and more.
• MCP Server Integration — GitHub MCP built-in by default, add custom servers for filesystem, memory, fetch, and more.

⚡ Developer Control

• YOLO Mode — All permissions enabled for fast iteration (default, recommended).
• Granular Permissions — Or lock it down: control tool access, file paths, and URLs individually.
• Enterprise SSO — First-class GitHub Enterprise support for sso authentication.
• Cross-Platform — Linux, macOS, and Windows (PowerShell v6+).

v3.7.1 - Plan Mode Streaming Fix

• Plan mode double-message fix — Fixed a bug where using plan mode would cause chat messages to appear duplicated and produce streaming artifacts.

v3.7.0 - Session Fork and Model Dropdown Fix

• Session Fork — ⑂ Fork button in the input area creates an independent copy of the current session with full conversation history. Diverge, experiment, and switch back to the original any time.
• Model dropdown fix — The model selector dropdown now renders correctly above the input area (was invisibly clipped by overflow: hidden).

v3.6.0 - File-Based Custom Agents, @mention Routing, and Color-Coded Conversation

• File-based custom agents — Define agents as Markdown files with YAML frontmatter. Drop them in ~/.copilot/agents/ (global) or <workspace>/.copilot/agents/ (project-scoped). Three built-in agents ship out of the box: Planner, Implementer, and Reviewer. See the Custom Agents Guide.
• @agentName mentions — Route any message to a specific agent by starting it with @agentName. Mention wins over the sticky agent.
• /agent <name> slash command — Set a sticky agent for the session. The 🤖 button turns green when an agent is active. /agent with no args clears it.
• Color-coded conversation — 🔵 User messages · 🟢 Assistant responses · 🟣 Tool/agent actions. Distinct left border colors let you scan the conversation flow instantly.
• Slash panel reorganized — New "Session" category groups /model, /rename, /agent, /compact. Includes @agent hint for single-shot syntax.

v3.5.0 - Streaming Responses, /compact, and Reasoning Streaming

• Real-time streaming — Assistant responses render word-by-word as they arrive, not all-at-once when the response completes. A safe markdown state machine flushes completed constructs (paragraphs, headings, code blocks, tables) progressively, with a 1.5s inactivity flush so mid-sentence text before a tool call appears immediately.
• Reasoning streaming — When "Show Reasoning" is enabled, the model's thinking process streams in real-time. Previously reasoning only appeared after the full thought was complete.
• /compact slash command — Compact the session context to reduce token usage while preserving key context. Available in both work and plan modes.
• Task complete indicator — A ✓ Task Complete card appears when the agent finishes a multi-step task, providing a clear visual signal that the work is done.
• Suppress broken-sentence bubbles — When the model writes a partial sentence and then immediately calls a tool, the fragment no longer appears as a standalone bubble. It's suppressed until finalized.
• Tool description fallback — Tool cards now show the tool's description when no explicit intent label is available.
• copilotCLI.showReasoning — New config to auto-enable "Show Reasoning" on startup (default false).
• copilotCLI.streaming — New config to disable delta streaming if you prefer responses to appear only when complete (default true).
• SDK 0.2.1 — Upgraded SDK bundling CLI 1.0.17. Structured tool results serialization fixed.

📋 For a complete history of all changes, see the CHANGELOG.md on GitHub.

🧠 Copilot Memory

Copilot learns about your codebase across sessions — coding agent, code review, and CLI all contribute to a shared memory. Memories auto-expire after 28 days and are validated against current code before use.

Status: Public preview (Copilot Pro, Pro+, Business, Enterprise)

How to enable:

1. Enterprise admins enable at the enterprise level
2. Org owners enable for their organization
3. Individual users enable in their Copilot settings

Managing memories: Repository owners can view memories chronologically, delete individual entries, or batch-delete.

See: Copilot Memory documentation

📦 Installation

Prerequisites

⚠️ Important: This extension does not bundle the CLI and requires the new standalone Copilot CLI, NOT the deprecated gh copilot extension.

• Node.js 24+ — The Copilot SDK 0.2.1 and CLI 1.0.17 require Node 24 or later. If sessions don't start, see Troubleshooting.
• VS Code 1.108.1 or higher
• GitHub Copilot CLI (standalone copilot command)
  • Linux/macOS: brew install copilot-cli
  • Windows: winget install GitHub.Copilot
  • Note: Requires PowerShell v6+ on Windows
  • See: Copilot CLI docs
• Active Copilot subscription

From VS Code Marketplace

1. Open VS Code
2. Press Ctrl+Shift+X (or Cmd+Shift+X on Mac)
3. Search for "Copilot CLI Chat"
4. Click Install

From Command Line

code --install-extension darthmolen.copilot-cli-extension

Troubleshooting: Session Won't Start

If the extension hangs on "Starting CLI process..." or times out with "createSession timed out", check these in order:

1. Node.js version (most common)

SDK 0.2.1+ and CLI 1.0.17 require Node.js 24 or later. VS Code's extension host must run Node 24 — this is the Node binary VS Code uses internally, not just what's on your PATH.

# Check what Node version VS Code is using
node --version

If you use nvm, ensure VS Code launches with the correct version:

# Set Node 24 as default
nvm alias default 24
nvm use 24

# On WSL: kill cached VS Code server processes, then relaunch
pkill -f vscode-server
code .

A simple reload (Ctrl+Shift+P → "Developer: Reload Window") will not pick up a new Node binary. You must fully restart the VS Code server.

2. Authentication

After reboots, GitHub auth tokens may expire. Check and fix:

# Check auth status
gh auth status

# Re-authenticate if needed
gh auth login -h github.com

# Also re-auth the Copilot CLI
copilot auth

3. CLI version

Update the CLI to the latest version:

# Update the npm package
npm install -g @github/copilot@latest

# Verify
copilot --version

The Go launcher binary may report a different version than the actual CLI runtime — it reflects the version at the time you first installed it. The launcher auto-downloads newer CLI versions to ~/.copilot/pkg/universal/ and delegates to the latest at runtime.

Authentication

Before using the extension, you must authenticate the Copilot CLI with GitHub.

Option 1: Interactive Login (Recommended)

The extension will automatically guide you if authentication is needed:

1. Open the chat panel (Ctrl+Shift+P → "Copilot CLI: Open Chat")
2. If not authenticated, click "Authenticate Now" in the error dialog
3. The extension opens a terminal with the copilot login command pre-filled
4. Follow the device code flow in your browser to complete authentication
5. Click "Retry" in VS Code to start your session

Manual authentication: You can also run copilot login in any terminal, then restart the extension.

Option 2: Environment Variable

For automation or CI/CD scenarios, set an authentication token as an environment variable:

1. Create a fine-grained Personal Access Token (PAT) with "Copilot Requests" permission
   • Go to: GitHub token settings
   • Generate new token → Select "Copilot Requests" scope
2. Set the environment variable (priority order):
   • COPILOT_GITHUB_TOKEN (highest priority)
   • GH_TOKEN
   • GITHUB_TOKEN (lowest priority)
3. Restart VS Code to pick up the environment variable

Linux/macOS:

export GH_TOKEN="ghp_your_token_here"
code  # Restart VS Code from terminal to inherit env vars

Windows (PowerShell):

$env:GH_TOKEN="ghp_your_token_here"
code  # Restart VS Code

Note: If a token is set but authentication fails, the extension will notify you that the token appears invalid or expired.

GitHub Enterprise with SSO

Only for enterprises with SSO enabled (most enterprises don't need this):

If your GitHub Enterprise organization requires SSO and uses the /enterprises/{slug}/sso authentication path:

1. Get your enterprise slug from your admin (e.g., acme)

2. Configure in VS Code settings:

   • Open Settings (Ctrl+,)
   • Search for "Copilot CLI GH SSO Enterprise Slug"
   • Enter just the slug: acme

3. When authenticating, the extension will automatically generate:

   copilot login --host https://github.com/enterprises/acme/sso
   

When to use this:

• ✅ Your enterprise has SSO enabled and requires /enterprises/{slug}/sso path
• ❌ Using github.com (public GitHub) - leave empty
• ❌ Using GitHub Enterprise Server (self-hosted) - leave empty
• ❌ Using GitHub Enterprise Cloud without SSO - leave empty

Regular GitHub Enterprise (without SSO): Just use the standard copilot login command - no configuration needed.

🚀 Quick Start

Open the Chat Sidebar

Option 1: Activity Bar Icon (NEW in v3.0.0)

1. Look for the Copilot CLI icon in the Activity Bar (left side by default)
2. Click the icon to show/hide the chat sidebar
3. Drag to right sidebar: View → Appearance → Move Side Bar Right (or drag the icon)

Option 2: Command Palette

1. Press Ctrl+Shift+P (or Cmd+Shift+P on Mac)
2. Type "Copilot CLI: Open Chat"
3. Press Enter

Option 3: Status Bar

• Click the "💬 Copilot CLI" item in the status bar

Option 4: Editor Toolbar

• Click the chat icon in the editor toolbar

Start Chatting

1. The chat sidebar opens in the Activity Bar (left or right side)
2. Your last session automatically resumes (if enabled)
3. Type your message and press Enter or click Send
4. View AI responses with full markdown formatting
5. See inline diffs when the agent edits files

Manage Sessions

• Session Dropdown: Select from previous conversations
• New Session (+): Start a fresh conversation
• Auto-resume: Toggle in settings to auto-load last session
• Slash Commands: Type /help to see all available commands

⚙️ Configuration

All Copilot CLI flags are configurable via VS Code settings:

{
  "copilotCLI.yolo": true,                // YOLO mode (all permissions) - recommended
  "copilotCLI.resumeLastSession": true,   // Auto-resume last session on open
  "copilotCLI.cliPath": "copilot",        // Path to copilot executable
  "copilotCLI.model": "",                 // AI model (empty = default claude-sonnet-4.5)
  "copilotCLI.planModel": "",             // AI model for planning mode (empty = use same as work mode)
  "copilotCLI.allowAllTools": false,      // Auto-approve all tools
  "copilotCLI.allowTools": [],            // Specific tools: ["shell(git)", "write"]
  "copilotCLI.denyTools": [],             // Block tools: ["shell(rm)"]
  "copilotCLI.allowUrls": [],             // Specific URLs/domains
  "copilotCLI.denyUrls": [],              // Block URLs/domains
  "copilotCLI.addDirs": [],               // Additional allowed directories
  "copilotCLI.noAskUser": false,          // Autonomous mode (no questions)
  "copilotCLI.showReasoning": false,      // Auto-enable "Show Reasoning" on startup
  "copilotCLI.streaming": true            // Stream responses as they arrive (false = wait for completion)
}

Tool Specification Format

• Shell commands: "shell(COMMAND)" - e.g., "shell(git)", "shell(npm)"
• File writes: "write"
• MCP servers: "MCP_SERVER_NAME(tool_name)"

Available Models

Choose from 17 AI models in settings:

• Claude Sonnet 4.6, Claude Sonnet 4.5 (default), Claude Sonnet 4, Claude Haiku 4.5, Claude Opus 4.5
• Claude Opus 4.6, Claude Opus 4.6 Fast
• GPT-5, GPT-5.1, GPT-5.2, GPT-5 mini, GPT-4.1
• GPT Codex variants (5.1, 5.1 max, 5.1 mini, 5.2)
• Gemini 3 Pro Preview

Plan Mode Model

Use a different AI model for planning mode vs work mode. This allows you to optimize for speed and cost or extensive planning and easy implementation.

If copilotCLI.planModel is not set, planning mode uses the same model as work mode.

Cost Optimization

• Cost optimization: Use cheaper models for planning, premium models for implementation
• Speed: Use faster models for exploratory planning
• Flexibility: Different models may excel at different tasks

{
  "copilotCLI.model": "claude-sonnet-4.5",        // For work mode (implementation)
  "copilotCLI.planModel": "claude-haiku-4.5"      // For plan mode (faster/cheaper exploration)
}

Extensive Planning

• Deep Dive Concepts - Maybe you really want the agent to pull down tons of research and put together the monster roadmap for a product
• Unravel Complex Code - Deep code bases require more thought so having a larger and newer LLM aids in less rework.
• Refactor - it's always best to think more and write less when refactoring.

"Better to plan once well than implement twice"
-- Every experienced developer

{
  "copilotCLI.model": "claude-sonnet-4.5",        // For work mode (faster implementation. might even consider haiku if your plan is good enough)
  "copilotCLI.planModel": "claude-opus-4.5"      // For plan mode (extensive exploration/research/planning)
}

MCP Server Integration

Model Context Protocol (MCP) servers provide pre-built tools for AI agents. The GitHub MCP Server is built-in and enabled by default, giving Copilot access to repositories, issues, and pull requests automatically.

Configure Additional MCP Servers

Add custom MCP servers via settings:

{
  "copilotCLI.mcpServers": {
    "filesystem": {
      "type": "local",
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "${workspaceFolder}"],
      "tools": ["*"]
    },
    "memory": {
      "type": "local",
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-memory"],
      "tools": ["*"]
    }
  }
}

Popular MCP Servers

Official Reference Servers:

• @modelcontextprotocol/server-filesystem - Secure file operations with access controls
• @modelcontextprotocol/server-fetch - Web content fetching and conversion
• @modelcontextprotocol/server-git - Git repository operations and search
• @modelcontextprotocol/server-memory - Knowledge graph-based persistent memory

MCP Server Types:

• Local (stdio): Execute a command locally (e.g., npx, python, node)
• Remote (HTTP/SSE): Connect to a remote server via URL

Browse more servers at the MCP Registry.

Note: Each server can be enabled/disabled via the enabled: false property.

🔧 Architecture

v3.0 Architecture

VS Code Activity Bar
        ↓
  WebviewViewProvider (sidebar integration)
        ↓
Extension Host (Node.js)
  extension.ts orchestrator
       ↓
  Extracted Services (7)
    SessionService, InlineDiffService, fileSnapshotService,
    mcpConfigurationService, modelCapabilitiesService,
    planModeToolsService, messageEnhancementService
       ↓
  ExtensionRpcRouter (typed send/receive)
       ↓ postMessage
Webview (Browser)
  WebviewRpcClient (typed callbacks)
       ↓
  EventBus (decoupled pub/sub)
       ↓
  Components (9)
    MessageDisplay, ToolExecution, InputArea, SessionToolbar,
    AcceptanceControls, StatusBar, ActiveFileDisplay, PlanModeControls,
    SlashCommandPanel
       ↓
  DOM

Shared: TypeScript interfaces in src/shared/ defining the RPC contract
  31 message types with TypeScript interfaces (shared/messages.ts)

Sidebar Integration (v3.0.0):

• WebviewViewProvider: Extension now lives in Activity Bar sidebar (not floating panel)
• Activity Bar Icon: Click to show/hide chat, drag between left/right sidebars
• Native Experience: Proper VS Code sidebar integration with resource management
• MutableDisposable Pattern: Fixes memory leak from accumulating event handlers

Extension Host provides:

• Orchestration: extension.ts coordinates services and routes messages
• Services: 7 extracted services with clear boundaries and independent testability
• Type-Safe RPC: ExtensionRpcRouter with typed send/receive methods replacing raw postMessage
• Session Persistence: Auto-resume, history loading, workspace filtering
• Planning Mode: Separate session for planning with limited tools and alternate model

Webview provides:

• Component Architecture: 9 independent components, each owning its DOM section and lifecycle
• EventBus: Decoupled component communication via pub/sub
• Type-Safe RPC: WebviewRpcClient with typed callback registration
• Inline Diffs: Compact diff display directly in the chat stream
• Slash Commands: 41 commands via CommandParser (type /help for list)

Copilot SDK provides:

• Agent Runtime: Production-tested orchestration engine
• Tool Invocation: File edits, shell commands, web searches, MCP servers
• Model Access: All Copilot CLI models via unified API

🌍 Platform Support

• ✅ Linux - Fully tested
• ✅ macOS - Fully supported
• ✅ Windows - Fully supported (PowerShell v6+)

Session state location:

• Linux/macOS: ~/.copilot/session-state/
• Windows: %USERPROFILE%\.copilot\session-state\

📚 Documentation

• Custom Agents Guide - Create and use custom agents
• Development Guide - Build and test the extension
• Changelog - Version history and release notes
• GitHub Repository - Source code
• Copilot SDK Docs - Official SDK documentation

🤝 Contributing

Contributions welcome! Please see HOW-TO-DEV.md for development setup.

Note: F5 debugging is broken in VS Code 1.100+. We use a VSIX-based development workflow instead.

📝 License

MIT - See LICENSE for details

🐛 Issues & Feedback

• Report bugs: GitHub Issues
• Ask questions: Marketplace Q&A
• Marketplace: VS Code Marketplace

⭐ Support

If you find this extension helpful, please:

• ⭐ Star the GitHub repository
• ✍️ Leave a review on the marketplace
• 🐦 Share with others!

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Made with ❤️ by darthmolen