encoding

Tabular ML is won on features, and this question checks whether you navigate the practical traps: target leakage in encodings, informative missingness, and fitting transforms on the wrong data. The signal is leakage-safe preprocessing. Here is the toolkit.

base64, leetspeak, invisible Unicode, and foreign scripts each let a payload look like gibberish to your filter yet read as a clear instruction to the model. The signal is knowing why the model decodes what the classifier cannot.