Add or update a kanji modification spec under `targets/` and rebuild. Recognizes the user's terse input format:
"漢字 N[,N2,...] 横|縦 [start|end]" → extend op(s)
"漢字 糸偏|糸編|竹冠|女偏|<part>" → compose op (compose then optional extends)
Combine forms like "漢字 9,10 横 + 糸偏" stack both compose and extend in the same JSONL file (compose first, then extends). Use when the user types a line matching that shape during the per-kanji modification workflow.
2026-05-11