Opus 4.6 with 1M context unavailable on Max plan

I have an active Max plan subscription and cannot access Opus 4.6 with 1M context in Claude Code.

Error: Opus 4.6 with 1M context is not available for your account.

Expected: Per Claude Code docs, Max plan includes Opus 4.6 with 1M context automatically.

Verified:

• Max subscription active (confirmed via /status)
• Claude Code on latest version
• CLAUDE_CODE_DISABLE_1M_CONTEXT not set
• No availableModels restriction in ~/.claude/settings.json or project .claude/settings.json
• Regular Opus 4.6 works; only opus[1m] is blocked

Failed commands:

/model opus[1m]
/model claude-opus-4-6[1m]
claude --model opus[1m]

Appears to be a server-side entitlement issue.