Everytime that a request is made for the agent to write a document, the IDE throws an error. This is the Debug Info:
```
Trajectory ID: 7a3cdcd7-eb80-4a0a-95ca-fc47fbe8a…
Error: HTTP 400 Bad Request
Sherlog:
TraceID: 0xf9b2c063d3b71…
Headers: {“Alt-Svc”:[“h3=”:443"; ma=2592000,h3-29=“:443”; ma=2592000"],“Content-Length”:[“328”],“Content-Type”:[“text/event-stream”],“Date”:[“Sat, 20 Jun 2026 00:07:41 GMT”],“Server”:[“ESF”],“Server-Timing”:[“gfet4t7; dur=1669”],“Vary”:[“Origin”,“X-Origin”,“Referer”],“X-Cloudaicompanion-Trace-Id”:[“f9b2c063d3b71…”],“X-Content-Type-Options”:[“nosniff”],“X-Frame-Options”:[“SAMEORIGIN”],“X-Xss-Protection”:[“0”]}
{
“error”: {
“code”: 400,
“message”: “{“type”:“error”,“error”:{“type”:“invalid_request_error”,“message”:“This model does not support assistant message prefill. The conversation must end with a user message.”},“request_id”:“req_vrtx_011CcDY9rYd6FWRzQxH4VPo2”}”,
“status”: “INVALID_ARGUMENT”
}
}
```
I don’t know if Opus changed their API or Antigravity changed their request, but they should stop advertising Opus as part of their plans if 70%+ of the requests will fail out of the box (This happens both in the Antigravity app and the IDE)