Feature request: session-only model override without changing global default

Problem

Currently, /model <name> saves the model as the global default for all future sessions. There's no way to switch models for just the current session without permanently changing the default.

The --model flag at launch (claude --model <name>) is the only session-scoped option, but it's only available at startup — you can't switch mid-session without affecting your global default.

Requested Behaviour

Either:

• /model <name> should apply only to the current session (and not persist), or
• A separate command/flag for session-scoped overrides, e.g. /model --session <name> or /model --temp <name>

Use Case

Quickly trying a different model for one session (e.g. testing Sonnet vs Opus for a specific task) without having to remember to switch back afterwards.