Opus 4.6 1M context model unusable on Max plan - immediate rate limit error

Description

The Opus 4.6 with 1M context window (claude-opus-4-6[1m]) is completely unusable on the Max subscription plan. Every request immediately returns a rate limit error, making it impossible to even test the model.

Environment

• Plan: Max (highest tier)
• Session usage: 54% used
• Weekly usage: 38% used
• Extra usage: Unlimited
• Model selected: claude-opus-4-6[1m] via /model

Steps to Reproduce

1. Select Opus 4.6 1M via /model
2. Send any message
3. Immediately get: API Error: Rate limit reached

Expected Behavior

With over 40% session capacity remaining and unlimited extra usage, the 1M context variant should be usable — or at minimum, there should be a clear message explaining the limitation rather than a generic rate limit error.

Notes

• Standard Opus 4.6 (non-1M) works fine with the same quota
• /upgrade confirms already on highest plan
• The rate limit appears to be a per-minute API throttle specific to the 1M model, separate from subscription quotas
• This effectively makes the 1M context feature inaccessible to Max plan users