## Summary
EPUBs that use ISO 639-2 three-letter language codes in their
`dc:language` metadata (e.g. `<dc:language>eng</dc:language>`) got no
hyphenation. The hyphenator registry only matched ISO 639-1 two-letter
codes (`"en"`, `"fr"`, etc.), so `"eng"` produced a null hyphenator and
every word in the book was treated as unhyphenatable.
Added a normalization step in `hyphenatorForLanguage` that maps ISO
639-2 codes (both bibliographic and terminological variants) to their
two-letter equivalents before the registry lookup.
Discovered via *Project Hail Mary* (Random House), which uses
`<dc:language>eng</dc:language>`.
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### AI Usage
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