VPI vpiSimTime is in the design's global precision, not the -timescale default: do not hard-code ns in log checks

A VPI library logged event times as vpi_get_time(NULL, &t) with t.type = vpiSimTime, and a test script checked for a line with "t":15000000, meaning 15 ms in ns. That value is in simulation time steps at the global time precision, which is the smallest precision of any compiled module. A command-line -timescale=1ns/1ns (VCS) only applies to files without a timescale directive. If any file in the compile (testbench, UVM, IP) declares timescale 1ns/1ps, the same moment is 15000000000, and the check fails although the event happened.

The safe patterns: - Calibrate from the same run. Take the value the library printed for an event at a known TB time (for example the TB's own n-th call at N ns) and compare later lines against that, or log the ratio as the unit. - In the library, use vpiScaledRealTime with an object handle to get time in that module's units, or read vpi_get(vpiTimePrecision, NULL) and log it once. - Name the column t_simtime, not t_ns, unless the library scales it.

The failure is a false FAIL, not a false PASS, but it can waste a long hardware or licence slot.