# Function getFallbackChain

- getFallbackChain(
  cli: "claude" | "gemini" | "codex" | "opencode",
  ): readonly (
  | "claude-opus"
  | "claude-sonnet"
  | "claude-haiku"
  | "gemini-3-pro"
  | "gemini-pro"
  | "gemini-3-flash"
  | "gemini-flash"
  | "codex-5.3"
  | "codex-5.2"
  | "codex-5.1-mini"
  | "opencode-default"
  | "opencode-custom-opus"
  | "opencode-custom-sonnet"
  | "openrouter-nemotron-super"
  | "openrouter-qwen-coder"
  )[]

  Get the fallback chain for a CLI tool.

  #### Parameters

  - cli: "claude" | "gemini" | "codex" | "opencode"

  #### Returns readonly (
  | "claude-opus"
  | "claude-sonnet"
  | "claude-haiku"
  | "gemini-3-pro"
  | "gemini-pro"
  | "gemini-3-flash"
  | "gemini-flash"
  | "codex-5.3"
  | "codex-5.2"
  | "codex-5.1-mini"
  | "opencode-default"
  | "opencode-custom-opus"
  | "opencode-custom-sonnet"
  | "openrouter-nemotron-super"
  | "openrouter-qwen-coder"
  )[]

  - Defined in packages/nexus-agents/src/config/model-availability.ts:168