## Why
A user restriction such as “Cancel the deployment” can fall outside the recent-message window after unrelated status questions. Guardian reviews need that restriction when assessing delegated actions.
## What changed
- Preserve root user messages during handoff relevance filtering, subject to the existing shared message cap.
- Apply handoff filtering during heartbeats while retaining saved heartbeat instructions and the active turn's trusted skills.
- Mark assistant context as incomplete when handoff filtering omits it, so ordinary user replies are not interpreted without their missing context.
## Testing
Add regression coverage for restrictions followed by status questions, bounded user history, omitted assistant questions, and trusted skills across first and repeated heartbeats. Update the delegation request-history snapshot.
GitOrigin-RevId: 67f77313572dc54225713cd7cdb90f06b0fbe030