Newlines in command should be preserved in ACP mode

[feisuzhu]

Description

ACP command argument parsing in agent.ts destroys newlines. When an ACP client sends a command like /pivot prometheus\nmy multi-line prompt, the argument text arrives with all newlines replaced by spaces.

Plugins

oh-my-openagent

OpenCode version

1.14.21

Steps to reproduce

1. Send a /command foo bar\n\nbaz\n\nquux in ACP mode, and the arguments are joined together.

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Operating System

Ubuntu 24.04

Terminal

Alacritty