## Why
MultiAgent V2 workers can be reviewed after the root conversation has received
new user authorization that is absent from the worker's own transcript. Guardian
reviews need that genuine user context without treating forwarded or
assistant-authored claims as authorization.
## What changed
- Add the bounded root conversation to Guardian prompts for worker reviews.
- Preserve user and assistant roles, and explicitly treat only root user messages
as authorization evidence.
- Exclude summaries, review artifacts, and assistant commentary from the root
conversation evidence.
- Apply the same evidence to both core Guardian prompts and Guardian V2
classification.
## Testing
Add an integration test covering late root-user authorization, forged role text,
forwarded agent claims, and filtered synthetic authorization.
GitOrigin-RevId: 8846de69ba214a88f58f70675798d324e213427c
d12a7f3fd8