[BUG] Opus 4.8 1M context not enforced on Max 5x despite entitlement flag null (caps at 200k on fresh sessions)

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?

On a Max 5x plan, Opus 4.8 with 1M context is documented as included, but the 1M window is never enforced. Sessions hit the 200k limit and stop with "Context limit reached." This happens on brand new sessions too, not just long ones.
In ~/.claude.json: "hasExtraUsageEnabled": true and "cachedExtraUsageDisabledReason": null. The flag is cleared so the entitlement should be active, but the 200k cap still applies.
/context is unreliable here, it always shows a 1M denominator regardless of the real enforced window, so the number can't be used to confirm. Actual behavior is a hard 200k cap.
Billing: after enabling extra usage / auto-reload to try to unlock 1M, I was charged $15 with no usage on my part (appears to be an auto-reload credit top-up). Since 1M is included on Max, this shouldn't have been required. Requesting a refund.
Environment: Max 5x, Claude Code 2.1.201, macOS, model claude-opus-4-8[1m].

What Should Happen?

Opus 4.8 1M context should be enforced on Max 5x, giving the full 1M window that is included with the subscription. Sessions should continue past 200k instead of hitting "Context limit reached."

Error Messages/Logs

Context limit reached · /compact or /clear to continue
cachedExtraUsageDisabledReason: null
hasExtraUsageEnabled: true
Steps to Reproduce (paste this):

Max 5x plan, extra usage enabled, cachedExtraUsageDisabledReason is null
Select opus[1m]
Start a fresh session
Work until context passes 200k
Session stops at ~200k with "Context limit reached" instead of continuing to 1M

Steps to Reproduce

Max 5x plan, extra usage enabled, cachedExtraUsageDisabledReason is null
Select opus[1m]
Start a fresh session
Work until context passes 200k tokens
Session stops at ~200k with "Context limit reached" instead of continuing to the 1M window

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.201

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_