[FEATURE] Opus 4.8 not available in Claude Code despite API availability

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

Opus 4.8 is available through the Anthropic API (GitHub Copilot
serves it), but Claude Code's model picker only offers Opus 4.6
as the latest option.

claude --model claude-opus-4-8 silently falls back to 4.6.

As a Max subscriber, I'd expect the latest available API model
to be accessible in Claude Code. When will 4.8 be available?

Claude Code version: 2.1.52
Plan: Max

Proposed Solution

Proposed Solution:
When a new Claude model (e.g. Opus 4.8) is available through the
Anthropic API, it should appear in Claude Code's model picker
(/model) and be selectable via claude --model claude-opus-4-8.

Currently, claude --model claude-opus-4-8 silently falls back to
Opus 4.6 with no error or warning. At minimum, it should return an
explicit error like "Model not available" instead of a silent fallback.

Ideally, Max subscribers should have access to the same models in
Claude Code that are available through the API.

Alternative Solutions:
Currently using Opus 4.8 through GitHub Copilot, which accesses it
via the Anthropic API. This works for raw coding but loses all
Claude Code features (CLAUDE.md, hooks, MCP servers, subagents,
workflows, output styles). Not a real alternative for complex projects.

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_