OpenCode

Adapters for the **OpenCode** multi-provider AI coding agent from anomalyco/opencode.

⚠️ **Important**: This is **not** the same as the deprecated opencode-ai/opencode project (now charmbracelet/crush). Agent-mux specifically supports the anomalyco/opencode implementation.

Adapter Variants

Agent-mux provides two OpenCode adapters:

• **opencode** (subprocess) — Default CLI-based integration
• **opencode-http** (remote) — HTTP server with SSE streaming for enhanced performance

Choosing an Adapter

**Recommendation**: Use opencode-http for production workloads or when performance is critical. Use opencode for simple use cases or debugging.

Install

# Install the CLI (required for both adapters)
amux install opencode

Install methods:

• npm: npm install -g @anomalyco/opencode
• brew (macOS): brew install --cask opencode
• curl: curl -fsSL https://opencode.ai/install | bash

Supported on macOS, Linux and Windows.

Auth

OpenCode supports multiple AI providers. Configure authentication using:

opencode auth

Or set environment variables directly:

• ANTHROPIC_API_KEY — for Claude models
• OPENAI_API_KEY — for GPT models
• GOOGLE_API_KEY — for Gemini models

Config file: ~/.config/opencode/config.json.

Minimal run

CLI Examples

# Subprocess adapter (default)
amux run opencode --prompt "Add error handling to this function"

# HTTP adapter (enhanced performance)
amux run opencode-http --prompt "Add error handling to this function"

Programmatic Examples

import { createClient } from '@a5c-ai/agent-mux';
const client = createClient();

// Subprocess adapter
const handle1 = await client.run({ agent: 'opencode', prompt: 'Refactor this code' });
for await (const ev of handle1.events()) console.log(ev);

// HTTP adapter
const handle2 = await client.run({ agent: 'opencode-http', prompt: 'Refactor this code' });
for await (const ev of handle2.events()) console.log(ev);

Notable flags

The adapter forwards these RunOptions to the CLI:

• --format json (always, for structured output parsing)
• --model <id> — e.g. claude-3-5-sonnet-20241022 or gpt-4o
• --session <id> — create or resume a session
• --continue — continue an existing session
• --fork <id> — fork from an existing session
• --max-turns <n> — limit conversation length
• --system <prompt> — set system prompt

Session files

• Location: ~/.config/opencode/sessions/*.jsonl
• Format: JSONL with OpenCode event structure
• Resume and fork are both supported (canResume, canFork)

Plugins

Plugin support: **yes** — MCP server integration.

MCP Servers

amux mcp install opencode <mcp-server>
amux mcp list opencode

Registry: https://modelcontextprotocol.io for MCP servers.

Models

OpenCode supports multiple AI providers:

Additional models available via provider configuration.

Capabilities

Shared Capabilities (both adapters)

• **Text streaming** with real-time output
• **Tool calling** with parallel execution support
• **JSON mode** and structured output
• **Image input** and file attachments
• **Multi-turn conversations** with session persistence
• **Subagent dispatch** (up to 5 parallel tasks)
• **Interactive mode** with stdin injection
• **Skills** and AGENTS.md support
• **MCP server** plugin integration

HTTP Adapter Enhancements (`opencode-http`)

• **Server-Sent Events (SSE)** streaming for reduced latency
• **HTTP REST API** for direct integration
• **Automatic server management** with health monitoring
• **Enhanced connection pooling** for multiple concurrent sessions

HTTP Adapter Details

The opencode-http adapter manages an OpenCode server automatically:

Server Management

• **Automatic startup**: Server starts via opencode serve when first connection is made
• **Health monitoring**: Regular health checks ensure server availability
• **Graceful shutdown**: Server cleanup on adapter disposal
• **Port management**: Automatic port allocation to avoid conflicts

Connection Details

• **Endpoint**: Typically http://localhost:<dynamic-port>
• **SSE Streaming**: /api/chat/stream endpoint for real-time events
• **Authentication**: Inherits OpenCode's configured auth providers
• **Session persistence**: Maintains session state across requests

When to Use

• **High throughput**: Multiple concurrent conversations
• **Low latency**: Direct HTTP eliminates subprocess overhead
• **Integration**: REST API for custom tooling
• **Production**: Enhanced reliability and monitoring

Known limitations

Both Adapters

• **No thinking streams** — OpenCode doesn't expose internal reasoning
• **No image output** — text-only responses
• **Tool approval required** — use approvalMode: 'yolo' to auto-approve in trusted environments

Subprocess Adapter (`opencode`)

• **No PTY support** — runs in standard subprocess mode

HTTP Adapter (`opencode-http`)

• **Server dependency** — requires successful opencode serve startup
• **Port requirements** — needs available TCP port for server