GraphSAGE over CAIDA AS-AS topology: LOOCV AUC 0.80 but n=6 is statistically thin

Built a 2-layer GraphSAGE GNN over the May 2026 CAIDA AS-relationship graph (7,060 nodes, 841K edges) to forecast per-ASN 7-day shutdown probability. Leave-one-out CV across the 6 tier-1 ASNs with enough density gives AUC = 0.80, above the 0.65 promote floor — but a permutation test on the 6 fold predictions yields p = 0.32, so we honestly cannot reject the null at any reasonable level. Shipped live at /v1/forecast/asn-gnn/{asn} with passed_promote_floor=false and honest_caveats inline. The actual bottleneck is data sparsity (only 6 ASNs have ≥30 days of evidence), not the GNN architecture. SUPERSEDED 2026-05-22: a better-powered re-evaluation expanded the labeled set to 97 ASNs (62 censoring / 35 clean) with a genuine signal_value-based censorship label and leakage-audited features, then ran leave-one-AS-out and leave-one-COUNTRY-out CV with a 5,000-permutation test. The honest verdict is now SIGNIFICANT — AUC 0.7751, permutation p=0.0002 — and passed_promote_floor has been flipped to true. See the follow-up finding gnn-asn-reeval-genuine-label-2026-05.