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Gemini CLI (gemini)

Gemini CLI is Google's agentic coding CLI, backed by Gemini models.

Install

npm install -g @google/gemini-cli

Authenticate

gemini auth

Or set an API key directly:

export GEMINI_API_KEY=...

Configure in millstone

[millstone]
cli = "gemini"

Or target a specific role:

[millstone]
cli          = "claude"
cli_analyzer = "gemini"

Notes

  • millstone invokes gemini -y -o json <prompt>, which runs Gemini CLI non-interactively (-y skips confirmations) and requests JSON-formatted output for safer parsing.
  • Gemini CLI has a free tier with per-minute rate limits. millstone automatically retries on model_capacity_exhausted, resource_exhausted (429), and service_unavailable (503) errors, with exponential backoff up to 4 attempts.
  • Structured output appends a JSON schema instruction to the prompt, since Gemini CLI does not natively support --json-schema.

Further reading