v0.3.18 - the probe cannot report a zero it never measured

v0.3.18

Sensitive to flashing images? See the note in v0.3.13 - it still applies.

The instrument can no longer report a zero it never measured

Both of these were named when the surface probe was built, and both survived into every build since. They are the reason a report could look complete and still be unreadable.

The probe now poisons its readback buffer before every copy. The buffer is allocated once and reused for each measured surface, so a copy that never executed left it as it was allocated - zeros - and the probe reported a perfectly black surface it had never sampled. That is the one failure it cannot tell from a real black frame, which is the thing it exists to diagnose. The sentinel is checked on the raw bytes before any mean is computed, and a buffer still carrying it makes the probe refuse to answer and say so, instead of reporting the zero.

Its failure count now reaches the log, with the totals: the surface probe failed on N of M passes - the means above come from the passes that succeeded, not from every frame. The counter existed and was never printed, so a partial failure was invisible and the printed means silently described an unknown subset of frames. Printed only when it happened, so a healthy report grows no line.

Nothing else changed

The fixes open, the questions waiting on reporters, and the behaviour of the pass are all as they were in v0.3.17. This build is the instrument being made honest, so that the next log - the flicker run with NS_AMD_PROBE_EACH=1, or the interop A/B on the D3D12Core fault - is one we can actually read.

Suite: 165 checks, all green, on an RTX 5070 Ti. Nothing here was run on a Radeon. The new check fails on each of the four properties separately: no poison, poison after the copy, a fall-through on an untouched buffer, and an unprinted failure count.