How to add new custom model variants with extended options?

How can I create a new custom model variant (e.g., gpt-5-high) that extends an existing model (gpt-5) with different options, without overwriting the original model configuration?

I want to have multiple configurations of the same base model with different options. For example:

gpt-5: Default configuration with medium reasoning effort
gpt-5-high: Same model but with reasoningEffort: "high"

Attempted to add a custom model in ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "opencode": {
      "models": {
        "gpt-5-high": {
          "options": {
            "reasoningEffort": "high",
            "textVerbosity": "low",
            "reasoningSummary": "auto"
          }
        }
      }
    }
  }
}

But I'm getting an error: AI_APICallError: Model gpt-5-high not supported

Is it possible to create custom model aliases/variants that extend existing models with different options?

hmm this isn't currently supported but this is a good idea, it would look more like this tho:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "opencode": {
      "models": {
        "gpt-5-high": {
          "id": "gpt-5",
          "options": {
            "reasoningEffort": "high",
            "textVerbosity": "low",
            "reasoningSummary": "auto"
          }
        },
        "gpt-5-low": {
          "id": "gpt-5",
          "options": {
            "reasoningEffort": "low",
            "textVerbosity": "low",
            "reasoningSummary": "auto"
          }
        }
      }
    }
  }
}

Support for thsi should be in next release

Just merged change so you could do that^^^ note the "id" field

will be in next release

docs: add documentation for anomalyco#2833 anomalyco#2829

fix: use 'id' field for custom GLM-4.7 model aliases

Is it now preferred to use it via "variants" feature?

yes!

There's very little docs on variants. Can it be used in an agent's frontmatter to always use that variant for an agent?

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How to add new custom model variants with extended options? #2829

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How to add new custom model variants with extended options? #2829

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rekram1-node commented on Sep 27, 2025

rekram1-node commented on Sep 27, 2025

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