## Description I had the 1M context window working with `claude-opus-4-6` for the past several days (confirmed via `/context` showing 1M). Today it reverted back to 200k with no changes on my end. ## Environment - **Product:** Claude Code Desktop (GUI, macOS) - **Model:** claude-opus-4-6 - **Platform:** macOS Darwin 25.3.0 ## What I tried - Setting `ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m]` in `~/.claude/settings.json` under `env` — no effect - Restarting Claude Code Desktop — still

Opus 4.6 1M context window disappeared — was working, now gone

Status Fixed / completed

Maintainer reply None cached

Activity 6 comments · opened Mar 20, 2026 · closed Mar 20, 2026

Description

I had the 1M context window working with claude-opus-4-6 for the past several days (confirmed via /context showing 1M). Today it reverted back to 200k with no changes on my end.

Environment

Product: Claude Code Desktop (GUI, macOS)
Model: claude-opus-4-6
Platform: macOS Darwin 25.3.0

What I tried

Setting ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m] in ~/.claude/settings.json under env — no effect
Restarting Claude Code Desktop — still 200k
/context confirms 200k context window

Expected behavior

1M context window should still be available as it was in previous days.

Questions

Is there a known issue or rollback affecting 1M availability?
Is there a correct way to opt back in from Claude Code Desktop?
Is 1M context supported in Claude Code Desktop, or only CLI?

View original on GitHub ↗

6 Comments

github-actions[bot] · 5 months ago

Found 3 possible duplicate issues:

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🤖 Generated with Claude Code

kylehuirevvision · 5 months ago

anentropic · 5 months ago

Same here - what happened?

Dup: https://github.com/anthropics/claude-code/issues/34585

RealmX1 · 5 months ago

when in terminal mode, trying /model opus[1m] command would claim that
⎿ Opus 4.6 with 1M context is not available for your account. Learn more: https://code.claude.com/docs/en/model-config#extended-context-with-1m
despite max subscription still being active

github-actions[bot] · 4 months ago

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.