The Structural Gain in Temporal Link Prediction Is Mostly Memory and Recency

Temporal graph networks increasingly encode neighborhood structure, such as neighbors that co-occur in two nodes' recent histories, shared neighbors inside a sliding window, or temporal walks. The premise is that structure reveals who will interact next. We show that a structural feature computed from an event history also carries two other kinds of information: memory, whether the pair has ever interacted, and recency, when its endpoints were last active. The memory part is provable. Distance is the first depth at which two neighborhoods overlap, and the overlap vector is supported on the three depths around it, so a non-zero overlap at three hops certifies that a pair has never met. We measure the three kinds of information on 14 benchmarks under the random and historical negative protocols of DyGLib. Our test admits a structural feature only after memory, and then only after recency, and checks the result against a shuffled control and a second scorer. Under historical negatives, neighborhood overlap, the classical heuristics and DyGFormer's co-occurrence encoding keep a gain above 0.01 AP after memory on 0, 1 and 9 of the 14 benchmarks, and after recency on 0, 0 and 0. Across four structural signals, a gain remains in 14 of 112 benchmark-protocol cells, with median +0.017. Inside a trained model the picture is the same. Nine numbers about the pair's own history, with no neighbor of either node, replace DyGFormer's co-occurrence channel on 10 of 13 benchmarks, and the two exceptions are the two benchmarks on which the test found structure surviving. Structure survives where memory cannot answer: where no pair repeats (on a repeat-free benchmark overlap adds +0.121 and keeps +0.120 after recency), where every pair repeats (a dense trade network), and in the cold part of ordinary benchmarks. Gating a structural feature to the regime the test identifies keeps a median of 98% of its gain on 66% of queries. We release the test as structaudit, together with measurements of three construction mistakes that silently change its answer.