The body is lean with no preamble explaining concepts Claude already knows; each section and code snippet earns its place, matching the lean-and-efficient anchor.

Provides executable code (the scaleY(progress) snippet), specific CSS properties, named APIs (IntersectionObserver, GSAP ScrollTrigger), explicit attributes (aria-current, scroll-margin), and concrete test widths, rather than vague direction or pseudocode.

"Build the line" is a clearly numbered sequence and the "Verify" section is an explicit checklist with a boundary agreement checkpoint, providing clear sequencing with validation feedback even though the task is not destructive/batch.

Sections are well organized and references (demo/index.html, demo/PROMPT.md, REFERENCES.md) are clearly signaled at one level deep, but the referenced bundle files do not exist, so the disclosed structure is incomplete in practice.

Lists multiple concrete capabilities ("data-driven vertical or horizontal scroll story with a base line, progress fill, active step states, responsive collapse, semantic fallback, and reduced-motion behavior"), matching the comprehensive-actions anchor rather than the partial anchor at 2.

Explicitly answers both what (the scroll-story features) and when via an explicit "Use for..." trigger clause, satisfying the anchor that requires both with explicit triggers rather than merely implying when.

The "Use for onboarding, checkout, roadmaps, recipes, case studies, service processes, histories, or narratives..." clause gives broad natural coverage of terms a user would actually say, beyond just some relevant keywords.

The scroll-driven progress-timeline niche with triggers like onboarding/checkout/roadmaps is clearly distinct and unlikely to fire for unrelated skills, matching the clear-niche anchor.