With Claude

Use OpenCode with your Claude Max subscription.

What this is

An OpenCode plugin that runs Meridian (formerly opencode-claude-max-proxy) for you: start OpenCode once and the proxy comes up with it; quit OpenCode and the proxy stops. No separate proxy CLI or Docker container to manage.

Works with both OpenCode generations: the 1.x line (opencode) and OpenCode 2 (@opencode/cli), from the same package.

Compared to running the proxy yourself:

• One process to think about — OpenCode owns the proxy lifecycle (start/stop) instead of you juggling two things.
• Several OpenCode windows at once — each process gets its own proxy (port 3456 when available, otherwise an OS-assigned port). Project instances within the same process share that proxy, including concurrent plugin initialization.
• Explicit session headers — the plugin adds session tracking on outgoing API calls, so the proxy does not have to infer sessions from fingerprints alone. OpenCode's hidden title and summary requests are kept off the session's turn lease, so the first message of a fresh session does not race them.

How It Works

┌─────────────┐              ┌────────────────────┐       ┌─────────────────┐
│  OpenCode   │─────────────▶│  Claude Max Proxy  │──────▶│    Anthropic    │
│  (TUI/Web)  │ :3456 / auto │   (local server)   │  SDK  │    Claude Max   │
│             │◀─────────────│                    │◀──────│                 │
└─────────────┘              └────────────────────┘       └─────────────────┘

Quick Start

The plugin hooks into OpenCode's plugin system. When OpenCode launches, it starts the proxy, configures the Anthropic provider, and cleans everything up on exit.

1. Install the plugin

With npm:

npm install -g opencode-with-claude

Or with Homebrew (macOS/Linux), which keeps the plugin updated through brew upgrade instead of npm update -g:

brew install ianjwhite99/tap/opencode-with-claude

2. Authenticate with Claude (one-time)

npm install -g @anthropic-ai/claude-code   # or: brew install --cask claude-code
claude auth login

3. Add to your opencode.json

Global (~/.config/opencode/opencode.json) or project-level. The keys differ between OpenCode generations; a block written for the other generation is silently ignored, so make sure you use the right one.

OpenCode 1.x:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-with-claude"],
  "provider": {
    "anthropic": {
      "options": {
        "baseURL": "http://127.0.0.1:3456",
        "apiKey": "dummy"
      }
    }
  }
}

OpenCode 2 (plugins and providers.<id>.settings instead of plugin and provider.<id>.options):

{
  "$schema": "https://opencode.ai/config.json",
  "plugins": ["opencode-with-claude"],
  "providers": {
    "anthropic": {
      "settings": {
        "baseURL": "http://127.0.0.1:3456/v1",
        "apiKey": "dummy"
      }
    }
  }
}

In both cases the baseURL is only a placeholder: the plugin rewrites every Anthropic request to whatever port its own proxy actually got, so several OpenCode instances can run side by side.

If you installed with Homebrew, point the plugin entry at the installed file instead of the package name (the path is stable across upgrades, and brew info opencode-with-claude prints it):

"plugin": ["file:///opt/homebrew/opt/opencode-with-claude/libexec/lib/node_modules/opencode-with-claude/dist/index.js"]

("plugins": [...] on OpenCode 2.) On Linux or Intel macOS replace /opt/homebrew with your Homebrew prefix (brew --prefix, usually /home/linuxbrew/.linuxbrew or /usr/local).

4. Run OpenCode

opencode

Updating

• Homebrew: brew upgrade opencode-with-claude. The release workflow bumps the formula in ianjwhite99/homebrew-tap after every npm publish, so brew update && brew upgrade tracks new releases.
• npm: npm update -g opencode-with-claude. Note that OpenCode caches plugins it installs by package name; if a new version is not picked up, clear ~/.cache/opencode/node_modules/opencode-with-claude and restart.

Profiles and SDK features

The plugin now reads the same Meridian configuration files the meridian CLI uses, so you can maintain multiple Claude accounts and tune SDK behavior without leaving OpenCode.

Profiles (~/.config/meridian/profiles.json)

Define one or more named profiles (for example, a personal Claude Max account, a work account, or an OAuth-token profile). The plugin forwards them to Meridian at startup.

[
  {
    "id": "personal",
    "claudeConfigDir": "/Users/me/.config/meridian/profiles/personal"
  },
  {
    "id": "work",
    "claudeConfigDir": "/Users/me/.config/meridian/profiles/work"
  },
  {
    "id": "headless",
    "type": "oauth-token",
    "oauthToken": "<token from claude setup-token>"
  }
]

Active profile (~/.config/meridian/settings.json)

{ "activeProfile": "work" }

activeProfile selects the default profile for any request that does not send an explicit x-meridian-profile header. If the saved id is not in profiles.json (or the file is missing), the plugin logs a warning and falls back to the first configured profile.

SDK features (~/.config/meridian/sdk-features.json)

Meridian reads this file lazily on every request, so overrides take effect without restarting the proxy. The plugin does not need to do anything special for it to work — just edit the file and the next request picks it up. See Meridian's documentation for the full list of adapter keys.

This plugin does not edit Meridian's SDK feature file. When Meridian's default client prompt pass-through is enabled, the plugin scrubs OpenCode-identifying prompt fingerprints with @rynfar/meridian-plugin-opencode-scrub before forwarding. User context such as AGENTS.md and configured instructions is preserved, while cwd is forwarded to Meridian through the process environment.

{
  "opencode": {
    "memory": true,
    "thinking": "enabled",
    "maxBudgetUsd": 0.5
  }
}

Environment overrides

For parity with the meridian CLI:

• MERIDIAN_PROFILES — JSON array of profile objects; wins over profiles.json.
• MERIDIAN_DEFAULT_PROFILE — profile id; wins over settings.activeProfile.
• MERIDIAN_PATH — run your own Meridian build instead of the bundled one (see Using your own Meridian build).

Malformed or missing files never crash the plugin; all parse/IO failures are logged via OpenCode's plugin log and the plugin falls back to no-profile mode.

Using your own Meridian build

Each plugin release pins one exact @rynfar/meridian version, and Meridian ships faster than this plugin does. Set MERIDIAN_PATH to follow Meridian's releases without waiting for a plugin release:

npm install -g @rynfar/meridian
MERIDIAN_PATH="$(npm root -g)" opencode

MERIDIAN_PATH accepts any of:

• the Meridian package root — .../node_modules/@rynfar/meridian
• any directory Node can resolve @rynfar/meridian from — a global node_modules, or a project that depends on it
• the entry file itself — .../@rynfar/meridian/dist/server.js

Auth, profiles, and the session cache already live on disk (~/.config/meridian, ~/.cache/meridian), so an external build shares all of them with the meridian CLI; only the code version changes.

The bundled copy stays the fallback. A path that does not exist, is not a Meridian install, or exposes no startProxyServer logs a warning and changes nothing else. Either way the plugin logs which build it is running, so a bug report can name it:

meridian 1.79.0 (bundled)
meridian 1.80.0 (external: /opt/homebrew/lib/node_modules/@rynfar/meridian)

A swapped build has to keep the surface the plugin uses: startProxyServer returning { server, config.port, close() }, and a /health response carrying status, error, version, and auth.{daysUntilRenewal,renewalRequiredSoon}.

Switching profiles at runtime

Profile switching through Meridian's HTTP API continues to work — call POST /profiles/active on the proxy URL the plugin prints at startup. The selection is persisted back to settings.json and survives restarts.

Troubleshooting

"Claude Code CLI not found"

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

"Claude not authenticated"

claude auth login
# or (depends of your version)
claude login

This opens a browser for OAuth. Your Claude Max subscription credentials are needed.

"Proxy failed to start"

1. Check Claude auth: claude auth status
2. Ensure your internet connection is working
3. If using a manual port override, check if it's in use: lsof -i :$CLAUDE_PROXY_PORT

Binding the proxy to a non-localhost interface

Meridian binds to 127.0.0.1 by default. If you need it to listen on another interface, set CLAUDE_PROXY_HOST (or Meridian's MERIDIAN_HOST alias) before starting OpenCode:

CLAUDE_PROXY_HOST=0.0.0.0 opencode serve --hostname 0.0.0.0 --port 4098

The plugin still uses loopback internally when you bind to wildcard addresses such as 0.0.0.0 or ::, so local health checks and provider requests remain stable.

Warning

Exposing the proxy beyond localhost makes your authenticated Claude session reachable over the network. Only do this on trusted networks, and prefer firewall rules or other access controls if you open it up.

Development

Project Structure

opencode-with-claude/
├── src/
│   ├── index.ts           # Plugin entry point: v1 server() + v2 setup()
│   ├── headers.ts         # Meridian request-identity headers (shared)
│   ├── proxy.ts           # Proxy lifecycle management
│   ├── meridian-source.ts # Picks the Meridian build (bundled or MERIDIAN_PATH)
│   ├── meridian-config.ts # Reads Meridian's profiles/settings files
│   └── logger.ts          # Plugin loggers
├── test/
│   ├── run.sh             # Launches OpenCode 1.x with the built plugin
│   ├── opencode.json      # Test config
│   └── unit/              # node:test suites (npm run test:unit)
├── scripts/
│   └── update-homebrew-formula.sh # Bumps the Homebrew formula (in ianjwhite99/homebrew-tap) after an npm release
├── package.json
└── tsconfig.json

Build

npm install
npm run build

Test locally

npm run test:unit          # Build, then run the unit suites (v1 hooks and v2 setup)
./test/run.sh              # Build and launch OpenCode 1.x with the plugin
./test/run.sh --clean      # Remove build artifacts

To try the build in OpenCode 2, point a plugins entry at the dist directory, for example "plugins": ["/path/to/opencode-with-claude/dist"].

How the two OpenCode generations are served

dist/index.js has a single default export with id, server() and setup(). OpenCode 1.x calls server() and uses the returned hooks (config, chat.headers, ...). OpenCode 2 calls setup(ctx) and the plugin registers session.hook("model.request") (base URL and Meridian headers), session.hook("http.request") (drops the anthropic-beta header OpenCode's Anthropic transport re-adds after model.request — Meridian talks to the Claude Agent SDK, which refuses custom betas on subscription auth), and the system-prompt hooks on the context. The module deliberately has no other exports: OpenCode 1.17 and 1.18 load every export as a plugin, so a second one would start a second proxy.

FAQ

Do I need an Anthropic API key?

No. Claude Max is not authenticated with API keys here. Run claude login once; the proxy uses that session (Agent SDK via OAuth). OpenCode still expects an apiKey field in the Anthropic provider config, so set a placeholder such as "dummy" in opencode.json — it is not used for real auth.

What if my Claude Max subscription lapses?

The proxy will fail to authenticate. Run claude auth status. You need an active Claude Max plan; see claude.ai for current options and pricing.

Does this work with OpenCode 2?

Yes. The same package loads on OpenCode 1.x and OpenCode 2; only the opencode.json keys differ (see Quick Start). OpenCode 2 gives plugins no log API, so on that generation the plugin's startup and health messages go to the server's stderr instead of the OpenCode log (visible with --print-logs).

Can I run several OpenCode instances at once?

Yes. The first instance uses port 3456 by default; others get a free OS-assigned port, so nothing extra to configure.

Is this the same as using the Anthropic API directly?

Not exactly. OpenCode speaks Anthropic-style HTTP to the local proxy; the proxy maps requests to the Claude Agent SDK and your Claude Max session. Usage limits follow your Max subscription, not Anthropic API billing tiers.

Disclaimer

This project is an unofficial wrapper around Anthropic's publicly available Claude Agent SDK and OpenCode. It is not affiliated with, endorsed by, or supported by Anthropic or OpenCode.

Use at your own risk. The authors make no claims regarding compliance with Anthropic's Terms of Service. It is your responsibility to review and comply with Anthropic's Terms of Service and Authorized Usage Policy. Terms may change at any time.

This project calls publicly available npm packages using your own authenticated account. No API keys are intercepted, no authentication is bypassed, and no proprietary systems are reverse-engineered.

Credits

Built on top of Meridian by @rynfar, which provides the core proxy that bridges the Anthropic Agent SDK to the standard API.

Powered by the Claude Agent SDK by Anthropic and OpenCode.

License

MIT