Interaction UI — Before / After

PR #3147 · 19 surfaces and states, captured at 1280px desktop and 390px mobile viewport widths.
Before: PR base 6cdb4ba612 · After: f8dfde99d1.
Every After compact card is one 38px row showing the short label, dot, and caret. Errors use a red dot in compact mode; the full message appears when expanded. Expanded labels remain readable; child-thread links truncate first. Click any screenshot for its original size.