Allow to use subscription rather than API key

[mdbergmann]

This is awesome, I was thinking about doing this myself. :)

But using API key is super expensive, so be able to use subscription would be great.

[murinsel]

I think this is not so easy to accomplish. I would also be happy if I could use my Claude Code subscription for this.

[mdbergmann]

Yeah, I guess that's some sort of OAuth2 process.

[reinauer]

Anthropic does not currently support OAuth2 login for 3rd party clients. I filed a feature request with them referencing this project.

[murinsel]

I have tried to use the OpenCode proxy from https://github.com/rynfar/opencode-claude-max-proxy
This works for chats but has limitations that the AmigaAI tools like shell_command, arexx_command, read_file, write_file, screenshot, etc. are not supported via OAuth. So this is pointless and makes nu fun.
Here is a more detailed description:

Claude Max Proxy Limitations
How the Proxy Works
The opencode-claude-max-proxy uses the Claude Agent SDK to bridge Claude Max subscriptions to the Anthropic Messages API format. Internally, it spawns the claude CLI as a subprocess, which authenticates via OAuth tokens tied to the Max subscription.

Limitation 1: No Custom Tool Support
The proxy cannot pass through custom tool definitions from the client. AmigaAI defines its own tools (shell_command, arexx_command, read_file, write_file, screenshot, etc.) and sends them in the API request JSON. However, the proxy:

Converts all messages to a flat text prompt (discarding tool definitions)
Passes this text to the Claude Agent SDK's query() function
Filters out any tool_use content blocks from the response
Returns only text content to the client
As a result, Claude never sees AmigaAI's tool definitions and cannot request tool calls. AmigaAI works in chat-only mode through the proxy.

Limitation 2: OAuth vs API Key Authentication
Claude Max subscriptions use OAuth-based authentication managed by the Claude CLI. This is fundamentally different from API key authentication:

API Key: A simple bearer token (x-api-key header) that can be used with any HTTP client to call api.anthropic.com directly. Supports the full Messages API including custom tools. Billed per token.
OAuth (Max subscription): Tied to the Claude CLI/SDK session. There is no way to extract a reusable token for direct API calls. The SDK only exposes query() which runs Claude Code internally with its own tool set. Included in the Max subscription fee (no per-token cost).
There is no official way to use a Claude Max subscription for direct, raw API access with custom tools.

What Works Through the Proxy
Simple text conversations (chat without tools)
System prompts are passed through
Model selection (sonnet/opus/haiku) works
Non-streaming JSON responses (with stream: false)
What Does NOT Work Through the Proxy
AmigaAI's Amiga-specific tools (shell, ARexx, file I/O, screenshots, mouse/keyboard)
Tool use loops (the core agent functionality)
Token usage reporting (always returns 0)
Conversation history fidelity (messages are flattened to text)

[sacredbanana]

Yeah I got requests for this and for Google Gemini subscriptions via OAuth for AmigaGPT. I also don't think its an easy task