[FEATURE] Feature request: Add 1M context window option for Opus 4.6

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 4.6 is currently the default model in Claude Code and, in my experience, the most capable for complex reasoning and code tasks. However, it's the only Opus model without a 1M context window option.

Opus 4.8 has a 1M context variant. Opus 4.7 also has one (legacy). But Opus 4.6 — the model I rely on most — only has the standard context option.

When working on large codebases or long sessions, I hit context limits and am forced to switch to 4.7 or 4.8 to get 1M context, which feels like a downgrade in output quality.

Proposed Solution

Add an "Opus 4.6 (1M context)" option to the model selector, matching the existing 1M variants for 4.7 and 4.8.

Current state:

• Opus 4.8 → Standard ✅, 1M context ✅
• Opus 4.7 → Standard ✅, 1M context ✅
• Opus 4.6 → Standard ✅, 1M context ❌

Expected state:

• Opus 4.6 → Standard ✅, 1M context ✅

This would let users who prefer 4.6's reasoning quality also benefit from extended context without being forced to switch to a different model version.

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_