Max plan: Claude Code may compress context at 200K instead of using extended context window

[jimvaras-design]

Plan: Max 20x
Model: claude-opus-4-6
Version: 2.1.153

Claude Code triggers context compression ("Transmuting") well before what my Max plan should allow. I suspect the client tracks the context window against the model's base 200K limit and doesn't account for the extended context available on Max plans.

Evidence:

• Session hits "100% context used" and starts compressing during moderate-length conversations
• ~82K tokens of system prompt (startup hooks, CLAUDE.md chain, 9 MCP servers) means only ~118K remains for actual conversation before compression
• On Max 20x, I'd expect access to the full context window, not early compression at 200K

Expected behavior: Claude Code should query the plan's actual context limit from the API and use that as the compression threshold, not a hardcoded model default.

Requested info: Does Max 20x extend the context window for Opus 4.6 beyond 200K? If yes, does Claude Code honor that?

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Max plan: context window stuck at 200K instead of 1M (hasExtraUsageEnabled not updated after Pro → Max upgrade) #47019
2. [Bug] /context command reports 200K max for Claude Opus 4.6 instead of 1M #23432
3. Opus 4.6 (1M context): autocompact triggers at ~76K tokens — 92% of context window wasted #34332

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[jimvaras-design]

Closing as duplicate of #23432 (root cause identified: context window detection function only checks for Sonnet-4, Opus always falls through to 200K). Upvoting the original.

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.