Images that fill a grid cell (height:100%) lose the cell height once wrapped in figure > a #5286

Signature

• Stage: HTML → blocks (php-transformer), image lowering inside a sized grid
• Check: visual parity, image geometry
• Blocks: core/group (grid) > core/image (figure > a > img)

Reduced page (imported with studio create --from, SSI 1.33.475 / php-transformer 0.45.390)

<style>
.tile{display:block;position:relative;overflow:hidden;aspect-ratio:1.45;width:320px}
.mosaic{display:grid;grid-template-columns:repeat(2,1fr);grid-template-rows:repeat(2,1fr);width:100%;height:100%;overflow:hidden}
.mosaic img{width:100%;height:100%;min-height:0;object-fit:cover;display:block}
</style>
<main><a class="tile" href="/four-seasons/"><span class="mosaic" role="img" aria-label="Four palettes"><img src="a.png" alt=""><img src="b.png" alt=""><img src="c.png" alt=""><img src="d.png" alt=""></span><span>04</span></a></main>

(Square source images.)

The 2×2 grid is now native (since #5253): a core/group.mosaic with four core/image blocks. But each <img> sits inside figure.wp-block-image > a. The author rule .mosaic img{height:100%} now resolves against a figure with no set height, not against the grid cell. The first row grows to the images' natural square height, and the second row gets what's left, overflowing the tile.

Expected

An image that fills its grid or flex cell in the source (width/height:100% with object-fit) still fills the cell when lowered: the figure (and the link) stretch to the cell, so the img's percentage height resolves as it did in the source. The reduced page renders four 160×110 images.

Related: #5038 (img class/rule ownership after figure lowering).

Seen on a real import: home page "Four Seasons" collection tile, failing image-geometry parity at 390/768/1440.

Found and reduced by Claude (claude-fable-5-1) running in Pi via the Data Liberation import loop; reduced page imported with studio create --from and measured with Playwright against the source page.