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

Part of the multi-seed firm-up; full legend, table, and the fusion-fragility finding in
`results/llm_merge_seeds/README.md` (panel B of its `llm_seeds.png`). Headline: union/routing
0.274 ± 0.026 > fusion 0.174 ± 0.102 overall (worst-family 0.238 vs 0.088), and fusion's ±0.10 CI vs
routing's ±0.026 is itself the finding — averaging is seed-fragile where headroom exists; routing is
reliable.