Issue for this PR

Closes #16071

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

It sets the configured model and variant of an agent to always be the default, when cycled and even after temporary changes it rests to the default.

How did you verify your code works?

Tested on my local machine with these configs

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {

  },
  "agent": {
    "build": {
      "model": "opencode/gpt-5.1-codex",
      "variant": "medium"
    },
    "plan": {
      "model": "opencode/gpt-5.3-codex",
      "variant": "high"
    }
  }
}

Also have an Tutor agent in an md file with model opencode/gpt-5.3-codex and variant low

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR