A Bitcoin signature doesn't sign the transaction. It signs a message — the sighash — assembled from only the fields its flag chooses to SEE (看). Everything left BLIND (蒙), anyone can change after you sign. A Feynman-style idea-book, from a dinner table to a wall — with a playground you can touch.
▶ Open the SIGHASH playgroundTurn the two sighash dials, watch every field go SEE or BLIND on a real transaction, and tamper a field to prove it. Real BIP-341, no network.
Nine short chapters: a dinner → the paper-strip → covenants → can you see your neighbour's note? → the wall.
九章:一顿饭 → sighash 纸带 → 爸爸的纸条 → 看得见邻座的纸条吗 → 那堵墙。
用纸和剪刀做出来、和孩子一起玩的实体游戏——全书七关。孩子玩明白 = 写成功。