nx_spatial_probe.nx

nx_spatial_probe.nx -- STANDING WITNESS for the spatial-safety gap (CWE-787/125). Measures, does not assert. Three cells, each printed with its OWN control: CELL A: [N]T indexed by a COMPILE-TIME CONSTANT -- already compile-time checked (a negative control lives in nx_spatial_negctl_const.nx: it must FAIL TO COMPILE). CELL B: [N]T indexed by a RUNTIME VARIABLE -- the GAP under test. CELL C: *T (raw pointer) indexed out of range -- no length is carried; C-class by construction. A cell prints UNCHECKED when the out-of-range access completed and the program kept running. When the bounds-check rung lands, cell B must instead ABORT -- which this probe cannot print, so the gate asserts on the EXIT CODE, not on this text.