model runner

Scheduling step n+1 before step n's tokens exist sounds impossible. The answer shows the placeholder trick that makes it work, what it costs at an end-of-sequence token, and the configurations where vLLM switches it off for you.

The scheduler did not change; the code that turns its decisions into GPU tensors did. The answer covers where per-request state now lives, why Triton became a hard dependency, and the feature list that silently puts you back on the old runner.