OpenCode

OpenCode is a flexible AI coding agent that supports 85+ providers from models.dev. Unlike other agents that are locked to a single provider, OpenCode lets you connect multiple AI providers and switch between models freely.

Key Features

85+ Providers: Access models from Anthropic, OpenAI, Google, Mistral, Groq, and many more
OAuth Support: Use your Claude Pro/Max or ChatGPT Plus/Pro subscription instead of API keys
Multi-Provider: Connect multiple providers and switch models per-task
Dynamic Models: Model list updates automatically from models.dev

Getting Started

1. Open Provider Management

When creating a task, select OpenCode as the agent
Click Manage Providers next to the model dropdown
You'll see a list of all available providers

2. Connect a Provider

For each provider, you can authenticate with either:

Subscription (OAuth): Use your existing Claude Pro/Max or ChatGPT Plus/Pro subscription
API Key: Traditional pay-per-token authentication

Using OAuth (Recommended for Anthropic/OpenAI)

Click Connect on Anthropic or OpenAI
Select Use Subscription (default when OAuth is available)
Click Sign in with [Provider]
Complete the authentication flow:
- Anthropic: Visit the URL, copy the code, paste it back
- OpenAI: Visit the URL, enter the device code shown
Once authenticated, you're connected!

Using API Key

Click Connect on any provider
Select Use API Key
Enter your API key
Click Connect

3. Select a Model

After connecting at least one provider, you can select models from the dropdown:

Models are grouped by provider
Only models from connected providers are shown
The list updates dynamically from models.dev

OAuth Authentication

Claude Pro/Max (Anthropic)

Supported subscriptions: Claude Max ($200/mo), Claude Pro ($20/mo)

The OAuth flow for Anthropic uses a "code" method:

Click Sign in with anthropic
A browser window opens to Anthropic's authorization page
Log in and authorize the application
Copy the authorization code shown
Paste it back in Sesame
Click Submit Code

ChatGPT Plus/Pro (OpenAI)

Supported subscriptions: ChatGPT Plus ($20/mo), ChatGPT Pro ($200/mo)

The OAuth flow for OpenAI uses a "device code" method:

Click Sign in with openai
You'll see a URL and a device code (e.g., ABCD-1234)
Visit the URL in your browser
Enter the device code when prompted
Authorize the application
Sesame automatically detects completion and connects

OAuth tokens are stored encrypted and may expire. If authentication fails, disconnect and reconnect the provider.

Provider Management

Viewing Connected Providers

The provider dialog shows:

Connected section: Providers you've authenticated
Available section: Providers you can connect
Each provider shows the number of available models

Disconnecting a Provider

Open Manage Providers
Find the connected provider
Click the trash icon to disconnect
Both API key and OAuth credentials are removed

Multiple Providers

You can connect multiple providers simultaneously:

Use Anthropic for Claude models
Use OpenAI for GPT models
Use Groq for fast inference
Switch between them per-task via the model dropdown

Advanced: JSON Configuration (Legacy)

For advanced users, OpenCode also supports raw JSON configuration. This is useful for:

Custom model parameters
Provider-specific settings
MCP server configuration

JSON configuration is a legacy feature. For most users, the provider management UI is simpler and recommended.

Using JSON Config

In the Agent Credentials dialog, select OpenCode
Toggle to JSON Configuration mode
Enter your configuration:

{
  "$schema": "https://opencode.ai/config.json",
  "model": "anthropic/claude-sonnet-4-5",
  "provider": {
    "anthropic": {
      "apiKey": "{env:ANTHROPIC_API_KEY}"
    }
  }
}

Environment Variable Substitution

Use {env:VAR_NAME} to reference API keys stored in Settings:

{
  "provider": {
    "anthropic": {
      "apiKey": "{env:ANTHROPIC_API_KEY}"
    },
    "openai": {
      "apiKey": "{env:OPENAI_API_KEY}"
    }
  }
}

MCP Server Integration

OpenCode supports Model Context Protocol (MCP) servers. Any MCP servers configured in Sesame are automatically available to OpenCode tasks.

You can also add MCP servers in JSON config:

{
  "mcp": {
    "filesystem": {
      "type": "local",
      "command": ["npx", "-y", "@modelcontextprotocol/server-filesystem", "/workspace"],
      "enabled": true
    }
  }
}

Check your subscription is active
Ensure you're logged into the correct account
For Anthropic: make sure you copy the full authorization code
For OpenAI: wait for the device code flow to complete automatically

Token Expired

OAuth tokens may expire over time. Disconnect and reconnect the provider to refresh.

Model Not Available

Verify the provider is connected (check for green checkmark)
Some models require specific subscription tiers
Model availability updates from models.dev; try refreshing

"OpenCode CLI not found"

The sandbox must have OpenCode installed. Check your sandbox configuration includes the OpenCode CLI.