Allow persisting model variant settings (effort level, extended context) in config

Problem

Every time I start a new Claude Code session, I have to manually set my preferred model variant settings — specifically the thinking effort level and extended context mode. There's no way to persist these preferences.

The /model command lets you select between variants like normal 200K, 1M context, medium effort, and high effort — but this resets every session.

Proposal

Allow users to configure their preferred model variant settings in ~/.claude/settings.json (global) or .claude/settings.json (project-level), so they persist across sessions. Something like:

{
  "model": "claude-opus-4-6",
  "modelSettings": {
    "thinkingEffort": "high",
    "extendedContext": true
  }
}

Why

Having to manually toggle these every session adds unnecessary friction, especially for users who always want the same configuration.

---
🤖 Authored with Claude Code