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Routing Modes

Each model alias can be assigned one of three routing modes:
ModeBehavior
autoUse direct provider if a key and implementation are available; fall back to OpenRouter
directForce direct provider; fall back to OpenRouter with a warning if unavailable
openrouterAlways route through OpenRouter regardless of available keys
The default mode is auto.

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Configuration

Set default_mode to apply a mode to all models, then override per-alias as needed: 
[routing]
default_mode = "auto"
claude = "direct"
gpt = "openrouter"

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Auto Mode (Default)

In auto mode, the router checks whether a direct provider implementation exists for the model’s vendor and whether an API key is configured for that vendor. If both are true, the request goes direct. Otherwise it falls back to OpenRouter. Currently, Anthropic is the only vendor with a direct provider implementation. So in auto mode:
  • claude-opus, claude → direct Anthropic API (if ANTHROPIC_API_KEY is set), otherwise OpenRouter
  • gpt, gemini, grok, nemotron → OpenRouter

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Per-Alias Routing

Override routing for specific models: 
[routing]
default_mode = "auto"
claude = "direct"      # Force direct even if OpenRouter key is also present
gpt = "openrouter"     # Always use OpenRouter even if a direct key exists

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Routing Decisions in Transcripts

Every ModelResponse includes a routing field that records the vendor, mode, and whether OpenRouter was used for that specific call. Use this to audit which provider handled each response. 
{
  "routing": {
    "vendor": "anthropic",
    "mode": "auto",
    "via_openrouter": false
  }
}