Variants

Variants are named payload presets for a model, allowing you to quickly switch between different LLM parameters — like reasoning effort — without changing the model itself.

Built-in Variants

ECA ships with built-in variants for some known models via the variantsByModel config which has a good default.

AnthropicOpenAI

Applies to models matching sonnet-4-6, opus-4-5, opus-4-6 (any separator: -, ., _).

Variant	Payload
low	{"output_config": {"effort": "low"}, "thinking": {"type": "adaptive"}}
medium	{"output_config": {"effort": "medium"}, "thinking": {"type": "adaptive"}}
high	{"output_config": {"effort": "high"}, "thinking": {"type": "adaptive"}}
max	{"output_config": {"effort": "max"}, "thinking": {"type": "adaptive"}}

Applies to models matching gpt-5-3-codex, gpt-5-2. Excluded for github-copilot provider.

Variant	Payload
none	{"reasoning": {"effort": "none"}}
low	{"reasoning": {"effort": "low", "summary": "auto"}}
medium	{"reasoning": {"effort": "medium", "summary": "auto"}}
high	{"reasoning": {"effort": "high", "summary": "auto"}}
xhigh	{"reasoning": {"effort": "xhigh", "summary": "auto"}}

Custom Variants

You can define your own variants per model under providers.<provider>.models.<model>.variants. Custom variants are merged with built-in ones — if names clash, your definition wins.

Global config fileLocal config file

~/.config/eca/config.json

{
  "providers": {
    "anthropic": {
      "models": {
        "claude-sonnet-4-6": {
          "variants": {
            "creative": {"temperature": 1, "top_p": 0.95}
          }
        }
      }
    }
  }
}

.eca/config.json

{
  "providers": {
    "anthropic": {
      "models": {
        "claude-sonnet-4-6": {
          "variants": {
            "creative": {"temperature": 1, "top_p": 0.95}
          }
        }
      }
    }
  }
}

To disable a specific built-in variant, set it to {}:

~/.config/eca/config.json

{
  "providers": {
    "openai": {
      "models": {
        "gpt-5.2": {
          "variants": {
            // removes the "none" and "xhigh" built-in variants
            "none": {},
            "xhigh": {}
          }
        }
      }
    }
  }
}

Agent Default Variant

You can set a default variant for an agent so it starts with that variant pre-selected:

~/.config/eca/config.json

{
  "agent": {
    "code": {
      "variant": "medium"
    }
  }
}

If the configured variant doesn't exist for the current model, it will be ignored.