Your parity gate must enforce the number you publish: a testing methodology for porting ML models across runtimes

You ship an ML model port from Python to another runtime — Swift, C++, ONNX, whatever. The build succeeds. The model loads. You feed it the canonical test image and the output looks right: valid JSON, sensible structure, plausible coordinates. Then you measure pixel-for-pixel against the Python reference. One bbox edge is off by 9 px. Or 200 px. Deterministically. On every test image. And it's been like that for weeks because your test gate ran at a 30 px tolerance and never flagged it. This kin