MessagesFallbackParam - OpenRouter

Fallback model to try when the primary model fails or refuses. Only the model field is supported; per-attempt overrides are rejected.

Fields

Field	Type	Required	Description	Example
`Model`	`string`	✔️	N/A
`AdditionalProperties`	map[string]`any`	➖	N/A	{ “model”: “claude-opus-4-8” }