[BUG] Heavily degraded model performance during off peak business hours (March 17, 2026)

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?

Heavily degraded model performance during off peak business hours (March 17, 2026)

This started happening recently, maybe last week.

What Should Happen?

Claude Code should make sure to use Opus 4.6 with high effort if the user's settings are set up that way.

Error Messages/Logs

N/A

Steps to Reproduce

Repro steps:

1. Link a high quality Figma, and use existing .claude/ markdown context files including standards and best practices.
2. Claude one shots this with no issues during peak business hours. Claude has astronomical failures for this same task during non peak business hours where I need to spend 1 hour babysitting and fixing all the bugs, despite all of this being in my context files and standards already.

Note: repro steps are for pure UI code only (no non UI code is included in this workflow)
Note: if it matters, I am using Figma MCP

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.77 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_