# Multi-seed union-vs-fusion, hard benchmark (0.5B, 3 seeds)

Part of the multi-seed firm-up; full legend and per-seed table in `results/llm_merge_seeds/README.md`
(panel B of its `llm_seeds.png`). Headline: routing beats fusion in every seed (3/3 paired, both
metrics), and one seed exhibited a catastrophic soup failure (0.071 overall / 0.000 worst-family) that
routing was immune to (0.262/0.225). With 3 seeds the variance contrast (sd 0.090 vs 0.023) is an
observation, not an estimate.