Feature: Allow /model flag to accept inline prompt

Feature Request

Allow the /model command to optionally accept a prompt, enabling users to both switch models and submit an initial question in one command.

Example Usage

/model opus "explain this code"
/model sonnet --prompt "what's wrong here?"

Current Behavior

The /model flag only accepts the model name:

• /model opus switches to Opus
• Prompts must be submitted separately in a new message

Desired Behavior

Enable submitting a prompt as part of the /model command to:

1. Set the model
2. Start a new thread/question with that model in a single step

This would streamline workflows where you want to quickly ask a question with a specific model without two separate commands.

Use Cases

• Quick model-specific queries from the command line
• Scripting or automation workflows
• Faster iteration when testing model responses