Module model_router 

Smart model routing based on query complexity.

Classifies user messages into tiers using keyword heuristics (no LLM call required) and selects the appropriate model configuration for each tier.

• Cheap: Simple greetings, yes/no, short acknowledgements. Nano models.
• Mid: Tool-calling messages (search, email, calendar, etc.).
• Expensive: Complex reasoning (analysis, comparison, code review, etc.).

Structs

ModelRouter

Smart model router that picks cheap / mid / expensive models based on message complexity.

Enums

ModelTier

The complexity tier for a user message.