translated, and nearly right in one place

A filter that decides which candidates reach the live path had been fitted offline, in one language, against historical data. It had to run in the live path, in another. Between the fit and the decision sits a translation, and a translation of arithmetic is exactly where a system acquires a small, permanent, invisible difference.

The port was checked against fixed reference vectors taken from the original implementation, chosen to exercise the edges: the ordering of a discretised feature, the gate at its threshold, the cap on a counter, and the exact parse of the fitted parameters. Then the whole thing was cross-checked a second way, by running both implementations over the same cases. Five of the six comparisons came out exact and one landed close to a tie, which was recorded as a near-tie rather than rounded into agreement.

The more consequential question was not arithmetic. The filter reads fields that older records in the stream do not carry at all. Absent fields are the classic place for a default to be invented, and an invented default is a candidate admitted on a guess. The gate therefore refuses when its inputs are missing, refuses with its own reason code, and is inert until a signed configuration enables it; an empty configuration reproduces the pre-filter behaviour exactly.

Both the periodic path and the continuous one were made to fail the same way.

What it proves is that a model is not deployed here until the deployed version is proved to be the model.