"Error: cursor-agent exited with code 1" when using Cursor agent integration

Running on Linux, Cursor version 2.1.50, the client's post to http://localhost:5567/agent errors:

```
event: status
data: Thinking...

event: error
data: Error: cursor-agent exited with code 1
```

Not sure how to debug and would be great if the error returned the output from `cursor-agent`!