ACP Fails miserably when there's another session elsewhere #39390

Description

When there's another opencode session running, opencode acp --print-logs --pure --log-level=DEBUG fails miserably with an error:

Error: Unexpected error

ServeError

Plugins

irrelevant, fails even with --pure on all sessions

OpenCode version

1.18.5

Steps to reproduce

1. launch opencode acp --pure and leave it running
2. launch another now with logging to see the error opencode acp --print-logs --pure --log-level=DEBUG

you can also reproduce with an ide like Zed, open two instances with the zed agent (uses acp under the hood)

Screenshot and/or share link

Operating System

macos 15.7.7

Terminal

zed term, ghostty