LLM Unicode Output Governance in Production: Incremental UTF-8 Decoding, Grapheme Clusters, and NFC Boundary Buffering to Prevent Garbled Text and Truncation
A systematic guide for streaming LLM applications covering three layers of boundaries—network bytes, API deltas, and user-visible characters—with solutions for incremental UTF-8 decoding, extended grapheme cluster buffering, NFC normalization, and replay testing to avoid garbled text, emoji splitting, and index mismatches.