# ADR 2: @mention-Based Routing

**Date**: 2026-04-28

### Decision
Agents are triggered exclusively by Zulip @mentions. No topic-based assignment. Users @mention an agent in any topic, and the agent's bot responds.

### Context
Topic-based routing is too rigid — it requires users to know which topic maps to which agent. @mention routing is natural in Zulip (users already know how to @mention). It also enables multi-agent conversations in a single topic.

### Consequences
- Each bot must parse @mentions from every message in `#agent-hub`
- Routing complexity moves from topic name matching to @mention resolution
- Users can freely create topics and involve agents ad-hoc