INITIAL_AT_CAP

capinit.wat (82 bytes) — declares memory 16 16: an initial and a max sitting exactly on the default 16-page cap. Wholly legal, so it must load and run.

It is the only vector whose initial touches the boundary, and so the only one that can tell initial > cap from initial >= cap. REVERSE declares 1 16, which pins the max boundary (an impl rejecting max >= cap reds every happy-path property) and pins nothing about the initial one — its initial is 1, sixteen pages clear of the edge. See WasmRuntimeConformanceSuite.loadAcceptsInitialMemoryExactlyAtTheCap.