fix: add xhigh reasoning effort for GitHub Copilot GPT-5 models

[Arthur742Ramos]

Summary

• Add xhigh reasoning effort variant for GitHub Copilot provider for GPT-5.1 codex and GPT-5.2 models
• Previously only low, medium, high were available; now xhigh is included for supported models

Changes

• Updated @ai-sdk/github-copilot case in ProviderTransform.variants() to include xhigh for:
  • Models containing 5.1-codex in the ID
  • Models containing 5.2 in the ID
• Added tests for GitHub Copilot variant behavior

Models affected

Model	Reasoning efforts
gpt-5.1-codex-max	low, medium, high, xhigh
gpt-5.2	low, medium, high, xhigh
gpt-5.2-codex	low, medium, high, xhigh
Other models	low, medium, high

Fixes #9818

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found

[dkraemerwork]

Yeah I had to change my opencode.json manually to get all variants. Should be there per default if the provider exists

[AdrianAcala]

Yeah I had to change my opencode.json manually to get all variants. Should be there per default if the provider exists

Thank you! I didn't know this was possible until I read this thread. For anyone else that ran into this, here's how to add to your opencode.json file:

{
  "$schema": "https://opencode.ai/config.json",
  "model": "github-copilot/gpt-5.2-codex",
  "provider": {
    "github-copilot": {
      "models": {
        "gpt-5.2-codex": {
          "variants": {
            "xhigh": {
              "reasoningEffort": "xhigh"
            }
          }
        }
      }
    }
  }
}