First line: a circular initials avatar — gradient for people, flat colour for agents.

```jsx
<Avatar initials="АИ" />                          {/* person — gradient */}
<Avatar initials="МК" color="var(--accent-pilot)" size={36} />   {/* agent */}
```

Notes
- Default fill is the warm `terracotta→magenta` gradient reserved for human users.
- Give agents/system actors a flat `color` (often the product accent) so people stay visually distinct.
- Sizes in the app: 28 (chat byline), 30 (sidebar), 36 (member lists).