【Qwen Code】: ACP slash-command error freezes composer input until banner disappears #797

When using Qwen Code as the agent in Codeg, any ACP protocol error (for example /mcp not supported) is shown as a sticky red error banner and blocks the composer. I cannot type or send a new message until the error eventually disappears. Recovery requires waiting instead of retrying or interrupting.

Steps to reproduce

1. Open a workspace and select Qwen Code as the agent (model shown in my session: deepseek-v4-flash, reasoning Medium).
2. Drive a turn so the agent (or Codeg) issues a slash command that ACP does not allow — e.g. /mcp.
3. Observe the red ACP error banner at the bottom of the conversation.
4. Try to type or send the next message.

Actual behavior

• Composer input is disabled/stuck while the error is visible.
• I have to wait for the error to disappear before I can continue the conversation.
• A single unsupported command effectively locks the session UI.

Environment

• OS: Windows (from screenshot)
• Agent: Qwen Code via ACP
• Model: deepseek-v4-flash / Medium
• Branch / commit: main as of filing

Screenshots