pixelshot clamped the page height to `body.getBoundingClientRect().bottom`,
which only bounds the document when the page lets the body size to its
content. Sites that pin it to the viewport — `html, body { height: 100% }`,
as Wikipedia's Vector 2022 skin does — leave the content overflowing a
one-viewport box, so a 19,951px article measured 1,568px and captured a
single tile with `complete: true` (issue #124).
The rect was also read as a document coordinate while being
viewport-relative. A URL with a `#fragment` loads already scrolled, where
the bottom edge is negative and `Math.max(bottom, 1)` floors the whole page
to 1px.
Measure the lowest edge among the body and its element children instead, and
add the scroll offset back. That reads the same as before on a self-sizing
body, so the clamp still drops the blank tail an inflated
`documentElement.scrollHeight` would otherwise buy (root padding, trailing
margin), while surviving a pinned body.
Both capture paths carried their own copy of the probe; the snippet now
lives in one module so they can't drift apart.
Verified in stock Chrome, standard and turbo probes agreeing on every page:
page before after scrollHeight
wikipedia (#124) 1568 19951 19951
wikipedia #fragment 1 19951 19951
simonwillison.net 18252 18252 18252
ourworldindata.org 8713 8713 8713
Closes#124
Zhifei Li
ae809153b5