[Bug] Opus 4.6 default model alias not using 1M context window

[DannyMichaud]

Bug Description
On Claude 2.1.76 with the Max plan, Opus 4.6 is supposed to default to 1M context window. However, my agents that use Opus by default (model:opus) still use the 200K context window, I have to change it to opus[1M] to enable the full window. This seems unintuitive considering this is now "default".

Environment Info

• Platform: linux
• Terminal: kitty
• Version: 2.1.76
• Feedback ID: 16c3d467-cf1d-4a02-94d2-5617c50541e9

Errors

[]

[github-actions]

Found 3 possible duplicate issues:

1. Opus 4.6 shows 200K context instead of 1M on Claude Max plan (v2.1.75) #34143
2. Max plan: 1M context window shows 200k, Remote Control unavailable #34083
3. [Bug] /context command reports 200K max for Claude Opus 4.6 instead of 1M #23432

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

[ln-north]

Workaround: bypass the client-side check with an env var.

ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m] claude

/model opus[1m] is rejected client-side (s1mAccessCache), but the server actually accepts it on Max 20x after the March 13 GA. Env vars are passed to the provider as-is, so they skip that check.

Banner confirms Opus 4.6 (1M context). Tested on v2.1.76, Max 20x, macOS.

Add to ~/.zshrc to make it permanent:

export ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m]

[PandasProperty]

@ln-north from the bottom of my heart I thank you

[ahundt]

Here is a minimal binary patch that restores 1M context, /remote-control, and /btw when DISABLE_TELEMETRY=1 or CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 is set. Tested on v2.1.76, Max 20x, macOS: https://gist.github.com/ahundt/158d498f07a10fec4955a70bf475a20b

[jose-notte]

Confirmed working on v2.1.76, Max 5x, macOS. Thanks @ln-north!
ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m] claude
Banner shows Opus 4.6 (1M context) immediately.

[lucasmen9527]

Workaround: bypass the client-side check with an env var.解决方法：使用环境变量绕过客户端检查。

ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m] claude
/model opus[1m] is rejected client-side (s1mAccessCache), but the server actually accepts it on Max 20x after the March 13 GA. Env vars are passed to the provider as-is, so they skip that check./model opus[1m] 在客户端被拒绝（ s1mAccessCache ），但服务器实际上在 3 月 13 日正式版发布后在 Max 20x 上接受了它。环境变量按原样传递给提供程序 ，因此它们跳过了该检查。

Banner confirms Opus 4.6 (1M context). Tested on v2.1.76, Max 20x, macOS.横幅确认 Opus 4.6 (1M context) 。已在 v2.1.76、Max 20x、macOS 上测试。

Add to ~/.zshrc to make it permanent:将其添加到 ~/.zshrc 文件中以使其永久生效：

export ANTHROPIC_DEFAULT_OPUS_MODEL=claude-opus-4-6[1m]

It really worked, thank you.