MAX 5x subscriber stuck at 200K context window instead of 1M

Bug Description

MAX 5x subscriber with correct credentials showing subscriptionType: "max" and rateLimitTier: "default_claude_max_5x" in .credentials.json, but Claude Code enforces effectiveWindow=180000 (200K) instead of the expected 1M context window.

Additionally, the debug log repeatedly shows:

Fast mode unavailable: Fast mode requires extra usage billing · /extra-usage to enable

This message is incorrect for MAX plan users — MAX includes fast mode and extended context.

Steps to Reproduce

1. Subscribe to MAX 5x plan
2. Launch Claude Code CLI (v2.1.100)
3. Check debug log — effectiveWindow=180000 in every autocompact entry
4. Status line meter shows 200K context window, not 1M

Trigger Context

User was on 1M, switched model to Haiku mid-session, cancelled a compaction (didn't want auto-compact), and context window got stuck at 200K. Restarting Claude Code did not fix it. The issue persists across all new sessions.

Debug Evidence

autocompact: tokens=39627 threshold=167000 effectiveWindow=180000

attribution header x-anthropic-billing-header: cc_version=2.1.100.ff4; cc_entrypoint=cli; cch=00000;

Fast mode unavailable: Fast mode requires extra usage billing · /extra-usage to enable

Credentials (redacted)

{
  "subscriptionType": "max",
  "rateLimitTier": "default_claude_max_5x"
}

Expected Behavior

• effectiveWindow should be ~950000 (1M context)
• Fast mode should be available without "extra usage billing" prompt
• MAX 5x plan should not be treated as base Pro

Environment

• OS: Fedora 41 (Linux 6.11.4)
• Claude Code: v2.1.100
• Model: Opus 4.6
• Plan: MAX 5x
• Shell: bash

Additional Context

All debug logs on this machine (dating back to March 22, 2026) show effectiveWindow=180000. The billing header cch=00000 may indicate the plan entitlements are not being read correctly from the OAuth token.

Attempted fix: claude logout && claude login to refresh token — not yet confirmed if this resolves.