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determinism

2 posts

verification

5 min read

The strongest render gate is hash equality

A refactor rerouted the WebGPU frame shell through RHI wrappers and claimed byte-identical rendering. We did not diff pixels against a tolerance — we hashed three captures and got cd3097…9b0f three times. A same-code re-run proved the noise floor was zero, upgrading the gate from diff-below-tolerance to bit equality. Determinism is a property you engineer into the harness; once you have it, verification collapses from statistics to md5sum.

determinism

4 min read

The winner was whoever loaded last

Two overlapping map labels swapped survivors on pan because the collision pass's tie-break was tile-dispatch order — reversed. The fix is a stable identity fed to the greedy allocator, and the gate is a permutation test.