The route was clipping at three places: top and bottom of hovered
cards (the track was only 460 tall) and at the left/right viewport
edges (first card half-off-screen at scrollLeft 0, last card off the
right at scrollEnd).
Track height: default trackHeight in roadmap-layout 460 → 580; .rr-track
inline-style and the SVG height matched. midY now 290. Path centreline
stays in the visual centre and gains 60px breathing room above + 60px
below — which is exactly the room a hovered card needs to expand into.
Scroll-container padding: .rr-scroll gains 140px of horizontal padding
plus matching scroll-padding-left/right so snap-stops land cleanly.
The 140 figure is 220px card-width / 2 + 30px buffer, so the first and
last cards have a full card-width of clear space inside the viewport
at the scroll extremes.
Layout helper test verifies midY === 290.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Pure math, no DOM. computeRouteLayout(opts) takes itemCount + viewport
width and returns trackWidth, pathD, itemX, itemY, cardSide, midY:
- itemX evenly distributes items between padding and viewport-padding,
expanding the canvas beyond the viewport when itemCount * minSpacingX
exceeds the available width. Single-item case centres the dot.
- itemY puts the first item on the centreline; subsequent items
alternate +amplitude / -amplitude so the path snakes gently up and
down. The route reads as a river rather than a saw-tooth because the
cubic-bezier control points use the segment midpoint x — that holds
the tangent flat at each milestone.
- cardSide alternates 'below' / 'above' starting from 'below' on item 0.
Cards hang from their dot via a thin vertical connector in the
consuming component.
Also adds travelledStopFor(statuses) — the stop position on the path
stroke gradient where 'travelled' fades into 'ahead'. Clamps to 0.98
even when every item is shipping so the fade is always visible.
9 unit tests cover itemCount 1/2/3/7/20 plus the travelledStop edge
cases (no shipping → 0; all shipping → ≤ 0.98; mixed → exact midpoint).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
