Carry the distinction.
A writing system can preserve one contrast and merge another. Route a Sanskrit transliteration through two different stops, then bring it home unchanged.
Choose your stops
Plan your route from the notes above.
What exactly are we testing?
IAST is a romanization used for Sanskrit. Sanscript maps writing conventions; it does not translate meanings or judge a language. A script can preserve some contrasts and use one sign for others. Once two payloads map to the same sign, a later stop cannot reconstruct their original distinction.
These checks demand an exact round trip for the displayed study text. The bundled mapping may choose a conventional reverse spelling that differs even when a reader could infer a sound from context. Read the returned IAST row, not just whether two shapes look similar.
Real engine: Sanscript 1.3.3 and common_maps 1.0.2. Scope: the six listed mappings and short Sanskrit transliteration studies.