OpenCode for GitHub Copilot Chat

Use OpenCode models directly in GitHub Copilot Chat — no Copilot Pro/Enterprise subscription needed. Just bring your own API key (BYOK).

What Is This?

OpenCode for GitHub Copilot Chat is a VS Code extension that registers models from OpenCode — both OpenCode Go (paid) and OpenCode Zen (free) — into GitHub Copilot Chat via the official VS Code Language Model Chat Provider API.

This lets you pick and use OpenCode models directly from the Copilot Chat model picker, just like selecting GPT-4 or Claude — no extra Copilot Pro/Enterprise subscription required. Simply enter your OpenCode API key.

✨ Features

• BYOK — configure OpenCode Go and OpenCode Zen independently with separate API keys, both active at the same time
• Live model list — fetches available Go models and Zen free models directly from OpenCode on every startup
• Bundled fallback — works offline or if the API is unreachable, using a curated model table with accurate token limits
• Per-model token limits — precise context window and max output token values per model, not a single global cap
• Tool-calling support — forwards tool schemas using OpenAI-compatible or Anthropic-compatible request shapes automatically based on the model endpoint
• Dual endpoint routing — routes standard models to /chat/completions and MiniMax M2 models to /messages transparently
• Diagnostics command — one-click markdown report showing exactly which models VS Code has registered

Requirements

• VS Code 1.120.0 or higher with the Language Model Chat Provider API
• GitHub Copilot Chat extension — install from marketplace (required — this extension only adds models into Copilot Chat)
• Sign in to GitHub Copilot Chat (a personal GitHub account is sufficient — no Copilot Pro/Enterprise needed for BYOK)
• An OpenCode Go API key for Go models, or an OpenCode Zen API key for Zen free models — get one at opencode.ai

⚡ Quick Start

1. Install GitHub Copilot Chat from the marketplace if you haven't already.
2. Install this extension (or press F5 in the repo to launch an Extension Development Host).
3. Open GitHub Copilot Chat (click the Copilot icon in the sidebar or press Cmd+Shift+I / Ctrl+Shift+I).
4. Click the model picker (current model name) → Manage Models…
5. Select OpenCode Go or OpenCode Zen.
6. Press Enter to accept the default Group Name.
7. Enter your OpenCode API Key when prompted — VS Code stores it securely as a secret.
8. Choose the models you want available.
9. Select any OpenCode model from the picker and start chatting.

💡 Tips:

• Registered models are automatically available in the Copilot Chat model picker — no extra setup needed.
• If a model appears in the Language Models view but not in the chat picker, hover its row and click the eye icon (👁) to enable visibility.
• Go and Zen are separate provider groups, so both can be active at the same time. Switch between them anytime from the model picker.

Commands

Once installed, OpenCode models appear directly in the GitHub Copilot Chat model picker — no special commands needed. The easiest way to manage your API key is via Settings → Language Models (gear icon ⚙).

For advanced usage, you can also run these commands via the Command Palette (Cmd+Shift+P / Ctrl+Shift+P):

Note: The native BYOK flow via Language Models (gear icon ⚙) is recommended. VS Code will ask for a group name, then the matching API key. Go and Zen are separate provider groups, so both can be active at the same time.

Settings

Models

The extension fetches the live model lists from:

https://opencode.ai/zen/go/v1/models   (OpenCode Go — paid)
https://opencode.ai/zen/v1/models       (OpenCode Zen — free)

The Go provider exposes all OpenCode Go models. The Zen provider filters the live Zen list to free chat-completions-compatible models (*-free plus big-pickle) so paid Zen models do not appear unless support is added intentionally.

Because the endpoints return model IDs only, a bundled metadata table provides context window and max output tokens per model. If the live fetch fails, the bundled list is used as a fallback.

VS Code and Copilot read separate input/output metadata fields for UI display. OpenCode models can have very large output limits, so the extension advertises a small response reserve to keep the Language Models table, model picker tooltip, and chat context indicator consistent while still sending each model's full bundled max output limit to the OpenCode API.

Bundled model limits

Set opencodego.maxInputTokens or opencodego.maxTokens to a non-zero value to override the bundled defaults globally.

Endpoint routing

Most models use the OpenAI-compatible chat completions endpoint:

https://opencode.ai/zen/go/v1/chat/completions   (Go)
https://opencode.ai/zen/v1/chat/completions       (Zen)

OpenCode Go MiniMax M2 models (minimax-m2.*) are automatically routed to the Anthropic-compatible messages endpoint:

https://opencode.ai/zen/go/v1/messages

Development

# Install dependencies
npm install

# Compile TypeScript
npm run compile

# Watch mode
npm run watch

Press F5 in VS Code to launch an Extension Development Host with the extension loaded.

To package a .vsix for local install:

npm run package

Contributing

Issues and pull requests are welcome. Please open an issue first for significant changes so we can discuss the approach.

License

MIT — see LICENSE for details.