The chart note (and the 2-row mobile chip legend) lived inside the fixed 360px/420px chartBox and competed with the canvas for it, so a longer caption — e.g. the new KS4 gap note — shrank the mobile canvas to ~178px and tripped the e2e >220px guard. The canvas now owns a definite height (280px mobile / 380px desktop) with chips above and the note flowing below at natural size, so neither can eat the plot. Verified on staging: patched canvas renders 280px vs the squashed 178px. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB