Description

Description

When using acpx (ACP client) to connect to opencode via ACP protocol on Windows, the session/new method returns "Internal error".

Environment

• OS: Windows 11
• opencode version: 1.2.25
• acpx version: 0.3.0
• Node.js: v22.17.0

Steps to Reproduce

1. Install opencode: npm install -g opencode-ai
2. Install acpx: npm install -g acpx
3. Run: acpx --format json opencode exec "test"

Expected Behavior

session/new should succeed and return a session ID.

Actual Behavior

The initialize succeeds, but session/new fails with "Internal error".

Additional Context

• Authentication is configured (zhipuai and lenovo providers)
• opencode works normally in interactive mode
• The issue only occurs with ACP mode (opencode acp)

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response