I am frequently running agents on a multi-microservice application workspace where I really need the 1M context windows, because they are filled to the brim when implementing features that require changes on several services and APIs.

This works fine with Opus 5.5. But it also works fine with GPT 6.1 Sol, Kimi K3 and MiMo 2.6 Pro.

It doesn't work equally well with Sonnet 5.5, interestingly.