plano/skills/rules/routing-default.md

title	impact	impactDescription	tags
Always Set Exactly One Default Model Provider	HIGH	Without a default provider, Plano has no fallback when routing preferences do not match — requests with unclassified intent will fail	routing, defaults, model-providers, reliability

Always Set Exactly One Default Model Provider

When a request does not match any routing preference, Plano forwards it to the default: true provider. Without a default, unmatched requests fail. If multiple providers are marked default: true, Plano uses the first one — which can produce unexpected behavior.

Incorrect (no default provider set):

version: v0.3.0

model_providers:
  - model: openai/gpt-4o-mini     # No default: true anywhere
    access_key: $OPENAI_API_KEY
    routing_preferences:
      - name: summarization
        description: Summarizing documents and extracting key points

  - model: openai/gpt-4o
    access_key: $OPENAI_API_KEY
    routing_preferences:
      - name: code_generation
        description: Writing new functions and implementing algorithms

Incorrect (multiple defaults — ambiguous):

model_providers:
  - model: openai/gpt-4o-mini
    default: true               # First default
    access_key: $OPENAI_API_KEY

  - model: openai/gpt-4o
    default: true               # Second default — confusing
    access_key: $OPENAI_API_KEY

Correct (exactly one default, covering unmatched requests):

version: v0.3.0

model_providers:
  - model: openai/gpt-4o-mini
    access_key: $OPENAI_API_KEY
    default: true               # Handles general/unclassified requests
    routing_preferences:
      - name: summarization
        description: Summarizing documents, articles, and meeting notes
      - name: classification
        description: Categorizing inputs, labeling, and intent detection

  - model: openai/gpt-4o
    access_key: $OPENAI_API_KEY
    routing_preferences:
      - name: code_generation
        description: Writing, debugging, and reviewing code
      - name: complex_reasoning
        description: Multi-step math, logical analysis, research synthesis

Choose your most cost-effective capable model as the default — it handles all traffic that doesn't match specialized preferences.

Reference: https://github.com/katanemo/archgw