One behavioral question before merge: as written, the session field's zero value flips the default from folded-at-40 to show-all — so after this lands every user's diffs dump fully into scrollback and /diff-fold becomes the way to turn folding on. If that flip is intended, say so in the description; otherwise initialize the session value from the configured fold limit so the default stays folded and /diff-fold is the opt-out. One-line change either way. Kicking fork CI now.

One behavioral question before merge: as written, the session field's zero value flips the default from folded-at-40 to show-all — so after this lands every user's diffs dump fully into scrollback and /diff-fold becomes the way to turn folding on. If that flip is intended, say so in the description; otherwise initialize the session value from the configured fold limit so the default stays folded and /diff-fold is the opt-out. One-line change either way. Kicking fork CI now.

You're right. I've changed the default state to folded.

Confirmed the default-state fix — initializing diffMaxLines to diffFoldLimit keeps diffs folded-at-40 by default and makes /diff-fold the expand toggle, which is exactly right. Rename is complete (both diffScrollbackMaxLines refs updated), i18n covers en/zh, and it's wired into help + completion. Thanks for the quick turnaround — merging!