Issue: OAuth + claude-opus-4-5 returns HTTP 500

[sucruf111]

Description

I was using Opencode with my Claude Max Subscription (OAuth) for a few days now and getting Internal Server Errors when its doing some work.

ERROR service=llm providerID=anthropic modelID=claude-opus-4-5 agent=build error={ "name": "AI_APICallError", "url": "https://api.anthropic.com/v1/messages", "statusCode": 500 }

Notes:

• OAuth authentication succeeds
• Error occurs when making LLM request
• Same issue with fresh session after /clear
• Sonnet models may work (untested)

OpenCode version

Version 1.0.218

Steps to reproduce

1. Authenticate via OAuth (/connect anthropic)
2. Set model to claude-opus-4-5
3. Send any prompt
4. Receive "Internal Server Error"

Screenshot and/or share link

Operating System

macOS 26.1 (25B78)

Terminal

Opencode TUI