When a message arrives, two routing decisions are made: which agent should
handle it, and which model class should run the turn. The first is resolved by
the router; the second by model-tier routing. Both happen before the
orchestrator drives the function-calling loop.
Resolving the target agent
The router resolves the target agent in a defined order:
Bindings — an explicit mapping that ties a channel, conversation or
context to a specific agent. This is the primary, deterministic route.
@-mentions — in a group conversation, mentioning an agent by name routes
the message to that agent. This is how group routing works.
Fallback — if nothing else matches, the message goes to a configured
fallback agent so a conversation is never left unanswered.
[!NOTE]
@-mentions are what make multi-agent group chats usable: several agents can
share a conversation, and each message is delivered to the one that was named.
Bindings
A binding is the deterministic backbone of routing. By tying an inbound
context (for example a specific channel or conversation) to an agent, you get
predictable behaviour: the same source always reaches the same agent unless an
@-mention overrides it for a single message.
[!TIP]
Set a binding for every production channel so routing never depends on the
fallback. Reserve the fallback for genuinely unmatched traffic.
Model-tier routing
Independently of which agent is chosen, AiHummer can route a turn to a model
tier based on how demanding it is:
Tier
Intended for
simple
Short, routine turns
standard
Everyday work
complex
Hard, multi-step reasoning
Model-tier routing is configured under the “LLM” router settings. It lets you
serve cheap, fast models for simple turns and reserve a stronger model for
complex ones, controlling cost without hand-tuning every agent.
[!NOTE]
Model-tier routing is separate from an agent’s own per-agent model. The
per-agent model is the agent’s default; tier routing can select a model class
for a given turn. See Agents & personas.
When a message arrives, two routing decisions are made: **which agent** should
handle it, and **which model class** should run the turn. The first is resolved by
the router; the second by model-tier routing. Both happen before the
orchestrator drives the function-calling loop.
## Resolving the target agent
The router resolves the target agent in a defined order:
1. **Bindings** — an explicit mapping that ties a channel, conversation or
context to a specific agent. This is the primary, deterministic route.
2. **`@`-mentions** — in a group conversation, mentioning an agent by name routes
the message to that agent. This is how group routing works.
3. **Fallback** — if nothing else matches, the message goes to a configured
fallback agent so a conversation is never left unanswered.
```text
inbound ─▶ binding? ─▶ @-mention? ─▶ fallback ─▶ agent
```
> [!NOTE]
> `@`-mentions are what make multi-agent group chats usable: several agents can
> share a conversation, and each message is delivered to the one that was named.
## Bindings
A **binding** is the deterministic backbone of routing. By tying an inbound
context (for example a specific channel or conversation) to an agent, you get
predictable behaviour: the same source always reaches the same agent unless an
`@`-mention overrides it for a single message.
> [!TIP]
> Set a binding for every production channel so routing never depends on the
> fallback. Reserve the fallback for genuinely unmatched traffic.
## Model-tier routing
Independently of which agent is chosen, AiHummer can route a turn to a **model
tier** based on how demanding it is:
| Tier | Intended for |
|---|---|
| **simple** | Short, routine turns |
| **standard** | Everyday work |
| **complex** | Hard, multi-step reasoning |
Model-tier routing is configured under the **"LLM"** router settings. It lets you
serve cheap, fast models for simple turns and reserve a stronger model for
complex ones, controlling cost without hand-tuning every agent.
> [!NOTE]
> Model-tier routing is separate from an agent's own per-agent model. The
> per-agent model is the agent's default; tier routing can select a model class
> for a given turn. See [Agents & personas](/en/v1.0/concepts/agents-personas).
## Where to next
- See what the chosen agent does next in
[Orchestration & sub-agents](/en/v1.0/concepts/orchestration-subagents).
- Configure the agents that routing targets in
[Agents & personas](/en/v1.0/concepts/agents-personas).
AiHummer