[Bug] Usage credits required for 1M context on Max 5x plan — standard model selected, Cowork + Claude Code

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?

Bug Description

Getting "API Error: Usage credits required for 1M context" in both
Cowork and Claude Code, even with standard models selected
(Opus 4.8, Sonnet 4.6 — no [1m] variant).

Max 5x plan. Weekly usage at 0%. Session at 3%.
Credits being drained ($7.09) from prepaid balance instead
of counting against Max plan quota.

Steps to Reproduce

1. Open Cowork or Claude Code
2. Select any standard model (not 1M)
3. Send any message
4. Error appears immediately

Expected

Standard context, billed against Max plan.

Actual

1M context forced internally. Requires usage credits.

Environment

• Plan: Max 5x
• OS: Windows
• Claude Desktop version: Version 1.10628.0 (b4f860)
• Claude Code version: 2.1.158 (Claude Code)

Related Issues

#63634, #63761, #64544, #62063

What Should Happen?

Standard context model (Opus 4.8, Sonnet 4.6) should use standard 200K context and bill against Max 5x plan quota — not require usage credits for 1M context.

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 Cowork or Claude Code
2. Select standard model (Opus 4.8 or Sonnet 4.6 — NOT 1M variant)
3. Send any message
4. Error: "Usage credits required for 1M context"
5. Enabling usage credits drains prepaid balance ($7.09) instead of Max plan quota
6. Plan usage dashboard shows 0% weekly, 3% session — Max plan not being used

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.158

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Max 5x plan. Usage credits toggle was OFF, got error. Turned ON, credits drained from prepaid balance ($7.09) instead of Max plan. Weekly usage still 0%.

Affects both Cowork and Claude Code CLI.

Screenshots attached.

Related: #63634, #63761, #64544, #62063, #62199

<img width="919" height="529" alt="Image" src="https://github.com/user-attachments/assets/59f1303b-ed63-4c9c-a7ec-e0cdffa515d8" />