The operator on sindra-nude-final: "the images look blurry until they're
selected and blown up." The cap was 512px on the LONGEST side, which the
comment called "comfortably above any tile size", and it was, for a square. A
gallery tile is sized by its WIDTH, though, and a 704x1408 portrait got 256px
of width for a tile Chromium renders at 361 CSS px. That is 1.4x stretched at
1x density and 2.8x on a 2x screen. The review stage serves the original,
which is why it looked sharp once opened.
- THUMB_WIDTH = 768: the widest desktop tile (3 columns, 1440px and up,
measured at 321-361 CSS px across viewports) doubled for a 2x screen.
THUMB_HEIGHT_MAX = 4096 stops a long screenshot going through at full height.
- An original that fits the bounds is served as-is only when it is also light
(<= 64 KB; 768-wide thumbnails average 39 KB over the 381 live images) or
animated, since a thumbnail is one frame. Fitting a tile in pixels is not
being cheap in bytes: these portraits are ~1.1 MB PNGs.
- The size rule is in the cache name (`<rel>.768w.webp`). The live 512-cap
thumbnails are newer than their sources, so the mtime check alone would have
served them forever. The old files are orphans, swept with their booth.
- tests/test_thumbs_browser.py holds THUMB_WIDTH against the rendered grid at
1440, 1920 and 2560. The constant is a layout number, and a redesign that
widens the tiles turns it red instead of soft.
Measured cost, all 381 live images: 4.8 MB -> 14.2 MB of thumbnails, still ~27x
under the 386 MB of originals. Known limit: the 2-column (<=472px) and 1-column
(<=650px) reflows are softer than 768 covers at 2x. tests/mutations/thumbs.toml
proves 7 falsifiers.
