Grapheme Cluster Break - Glue After Zwj

Glue After Zwj is a special value that forces a grapheme cluster boundary to be suppressed after a Zero Width Joiner (ZWJ) in certain script contexts, primarily for emoji sequences and complex South Asian scripts. When a character carries this value, it acts like a bonding agent, ensuring that the preceding ZWJ and the following character remain tightly linked as a single visual unit, even if the following character would normally start a new cluster. This prevents unintended breaks in sequences like family emojis or conjunct consonants, where the ZWJ explicitly signals that components should be rendered together. However, it does not override explicit break opportunities, such as spaces or control characters; it only applies in the absence of stronger break-forcing conditions. This ensures that text rendering stays predictable while still supporting intricate ligature and composition rules.