[BUG] /model fable shows Fable as selected-but-disabled when logged out, instead of prompting to log in

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When not logged in, selecting Fable via /model fable shows it as selected but disabled/greyed out, with the error:

Model 'fable' is not currently available for your account.
Claude Fable 5 is currently unavailable. Learn more: https://www.anthropic.com/news/fable-mythos-access

This is misleading. The actual cause was that I wasn't logged in — running /login and re-selecting Fable resolved it immediately. But the error message is identical to the one shown for genuinely unavailable/unentitled models (e.g. plan restrictions, ZDR orgs, regional rollout), so there's no way to distinguish "you're logged out" from "your account doesn't have access" from the UI alone.

What Should Happen?

When a model is selected while the user is unauthenticated, Claude Code should either:

1. Prompt the user to /login directly, or
2. Show a distinct error message (e.g. "You're not logged in — run /login to continue") rather than the generic "not available for your account" message used for actual entitlement failures.

Error Messages/Logs

Steps to Reproduce

1. Log out of Claude Code (or start a fresh session without auth)
2. Run /model fable
3. Observe: Fable is shown as selected/highlighted but disabled, with the unavailability error above
4. Run /login, then repeat step 2 — Fable now selects successfully

Claude Model

Other

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.205

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Xterm

Additional Information

This is easy to misdiagnose as a plan, version, or ZDR-related restriction (see related issues #73333, #68578) when the actual cause is much simpler — the user just isn't authenticated. A clearer error would save significant troubleshooting time.