Philox

Philox2x32-10 keyed on the scenario index, mirroring the generator emitted into the CUDA kernel so the two line up path for path.

One instance is a single random stream. Stream 0 is byte-for-byte the historical single-stream generator; a named stream folds its index into the key so its draws are independent of every other stream's. normal() yields a Box-Muller pair per Philox counter (cosine leg for an even draw ordinal, sine leg for the odd one); uniform() takes its own, high-tagged counter range so uniforms never alias normals.