[FEATURE] Opusplan[1m] for using opus for planning, and sonnet[1m] together

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I currently use opusplan as a model, but I'm not sure if theres anyway to configure the sonnet use to use sonnet[1m] instead of the default sonnet.

Proposed Solution

Can we configure a mode for opusplan[1m] to use sonnet[1m] when not using plan mode?

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_