# anthropic-proxy

Reverse proxy that lets OpenCode (and similar tools) use a Claude subscription instead of an API key.

## Prerequisites

- Go 1.26+
- **Claude Code CLI** — installed and logged in (`claude auth login`). The proxy reads the OAuth token from `~/.claude/.credentials.json`.

Optional: [Nix](https://nixos.org/) flake for dev shell (`nix develop`).

## Setup

```
cp config.example.yaml config.yaml
```

Edit `config.yaml`:
- `api_keys` — key(s) your clients use to authenticate with the proxy
- `claude_credentials` — path to your Claude credentials file
- `claude_binary` — path to `claude` binary (used on startup to capture request fingerprint)

## Build and run

```
go build -o anthropic-proxy .
./anthropic-proxy
```

## Usage with OpenCode

```
export ANTHROPIC_API_KEY=your-proxy-api-key
export ANTHROPIC_BASE_URL=http://localhost:8082
opencode
```

## Endpoints

| Method | Path | Description |
|--------|------|-------------|
| POST | `/v1/messages` | Anthropic messages API (proxied) |
| POST | `/messages` | Same, without `/v1` prefix |
| GET | `/healthz` | Health check |
| POST | `/reload` | Hot-reload `config.yaml` |

## Request sanitization

The `sanitize` section in config renames tool names and replaces strings in system prompts before forwarding to Anthropic. Responses are de-sanitized before returning to the client.

See `config.example.yaml` for the default rules.

Reload after editing config:

```
curl -X POST localhost:8082/reload
```