[Bug] Subagent tool output rendering truncated and malformed in CLI display

Question

**Bug Description**
When executing a subagent, tool output is rendered in a very broken, truncated way, making it hard to understand exactly what the subagent is doing.

[![broken subagent tool call rendering](https://bojangl.es/49orcRL)](https://bojangl.es/49orcRL)

**Environment Info**
- Platform: darwin
- Terminal: ghostty
- Version: 2.0.76
- Feedback ID: 9b26f053-f7a1-427d-bd13-43a53496d4ec

**Errors**
```json
[]
```