determinism

Temperature zero removes the sampling randomness and leaves the floating-point kind. The batch your request lands in changes the reduction order, the logits move in the last bits, and a near-tie flips a token. The fix has a cost.

A tokenizer moves about a megabyte of text per second per core, which makes this a seven-hundred-core-day batch job rather than something to run during training. The throughput arithmetic per stage, the shard format the loader needs, and the determinism requirements that let you resume without corrupting a run.