heading-rhythm (quality): a heading binds to the content it introduces,
so its rendered space above must exceed its space below. Browser-only:
measures real getBoundingClientRect gaps (margin collapsing, flex rows,
and section padding make authored margins untrustworthy), merges eyebrow
labels into the heading cluster, requires same-column edges, and exempts
first-in-container headings, bounded bands, and small cards. Fires only
when 2+ headings on a page invert the rhythm.
blinking-cursor (slop, advisory): a decorative blinking caret (solid
block, underscore bar, or block glyph) bound to an infinite blink
animation in the landing region of a page. Real editable surfaces
(contenteditable, role=textbox, inputs) are exempt; round pulsing dots
stay with the pulsing-dot rule.
Verified against eval corpus repros: heading-rhythm fires on the
val-a18 observability sample Paul flagged (6 headings, 0px above vs
40px below) and blinking-cursor on the val-a19 hero terminal cursor;
10 other samples across both runs stay clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Paul BakausandClaude Fable 5
cc8906ecaa