Code-quality review on Task 1 (commit a7c9800) flagged an asymmetric
diag gate: the read-before-overwrite block at the top of the dispatcher
was not gated on diag, but the frame-counter increment and BeginQuery
calls were. If a maintainer toggled ACDREAM_WB_DIAG from "1" to "" mid-
session, _gpuQueryFrameIndex would freeze (gated inside if(diag)) while
the read kept firing every frame at the same slot — producing duplicate
stale samples.
Add diag to the read block's outer condition so the read/issue/increment
trio is symmetric. One-line change; behavior under the normal usage
pattern (env var set at launch, never toggled) is unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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