[BUG] CLAUDE_CODE_EFFORT_LEVEL=max displays as xhigh in /effort effort slider on v2.1.111

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?

When CLAUDE_CODE_EFFORT_LEVEL=max is set as an environment variable (or when effortLevel: "max" is set in ~/.claude/settings.json), the /model command's effort slider displays the current level as xhigh rather than max.

The slider UI shows five tiers: low | medium | high | xhigh | max. Despite max being explicitly configured, the slider position lands on xhigh.

It is unclear whether this is:
(a) purely a UI display bug where max is correctly active at the API layer but rendered as xhigh in the slider, or
(b) a validation bug where max is being silently coerced/downgraded to xhigh because the new xhigh tier was introduced without updating all the level-resolution logic.

I believe it is surfaced more visibly by the recent addition of the xhigh tier released with Opus 4.7.

What Should Happen?

When CLAUDE_CODE_EFFORT_LEVEL=max is set, the /effort slider should display the position as max (the rightmost tier), matching the configured value.

Additionally, /effort with no arguments should report the active level and its source (env var, settings file, session override, etc.) so users can verify the configured value is actually in effect, independent of the slider display.

Error Messages/Logs

Steps to Reproduce

1. Install Claude Code v2.1.111 on macOS (native binary install at ~/.local/share/claude/versions/2.1.111).

1. Set the effort level to max via environment variable. For example, in a shell wrapper or .zshrc
2. Launch a new Claude Code session
3. Observe the effort slider. The position is on xhigh, not max, despite max being explicitly configured.

Environment:

• OS: macOS
• Claude Code version: 2.1.111
• Install type: native binary (standalone installer, not npm)
• Model: opus[1m]
• Shell: zsh

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.111

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_