OpenHands/openhands/llm/router

Model Routing Module

⚠️ Experimental Feature: This module is experimental and under active development.

Overview

Model routing enables OpenHands to switch between different LLM models during a conversation. An example use case is routing between a primary (expensive, multimodal) model and a secondary (cheaper, text-only) model.

Available Routers

• noop_router (default): No routing, always uses primary LLM
• multimodal_router: A router that switches based on:
  • Routes to primary model for images or when secondary model's context limit is exceeded
  • Uses secondary model for text-only requests within its context limit

Configuration

Add to your config.toml:

# Main LLM (primary model)
[llm]
model = "claude-sonnet-4"
api_key = "your-api-key"

# Secondary model for routing
[llm.secondary_model]
model = "kimi-k2"
api_key = "your-api-key"
for_routing = true

# Enable routing
[model_routing]
router_name = "multimodal_router"

Extending

Create custom routers by inheriting from BaseRouter and implementing set_active_llm(). Register in ROUTER_REGISTRY.