[BUG] [Bug] Cowork Desktop only shows Sonnet 4.6 (1M) — no standard 200K option, triggers usage credits error on Max plan

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?

Claude Cowork Desktop only presents a single Sonnet 4.6 option in the model picker. It silently defaults to the 1M context variant, which requires usage credits even on a fresh session at ~9% plan usage on a Max (5x) plan.

Anthropic's Fin support agent confirmed: "This is different from the documented behavior where sonnet and sonnet[1m] should appear as separate options. The desktop app isn't currently giving you a way to select standard 200K context for Sonnet 4.6."

Error received:
API Error: Usage credits required for 1M context · turn on usage credits at claude.ai/settings/usage, or use --model to switch to standard context

What Should Happen?

The model picker should display two separate Sonnet 4.6 options: standard (200K context, included in Max plan) and sonnet[1m] (extended context, requires usage credits). Users should be able to select standard 200K context without being forced into usage credits billing.

Error Messages/Logs

API Error: Usage credits required for 1M context · turn on usage credits at claude.ai/settings/usage, or use --model to switch to standard context

Steps to Reproduce

1. Open Claude Cowork Desktop app
2. Start a new session (fresh, no prior context loaded)
3. Open the model picker
4. Observe: only one Sonnet 4.6 option appears (no standard vs [1m] split)
5. Select Sonnet 4.6
6. Send any message
7. Error fires immediately: "Usage credits required for 1M context"

Note: Error occurs on fresh sessions with minimal usage (~9% of Max 5x plan limit). Starting a new session does not resolve it.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Related GitHub issues filed this week for similar 1M context errors: #61869, #62100, #61692