Three things were wrong on a 390px phone, and all three cost the photo its
screen. The toolbar's six labelled buttons wrapped to three lines (141px of an
844px screen, 17% of it) and now sit on one 30px row of icons; the histogram
read as an empty white plot; and a crop corner was a 9x16px target to a touch,
so a thumb a few pixels off it moved the frame instead of resizing it.
The toolbar keeps its labels in the DOM and only takes them out of the paint —
font-size 0 on the button, the glyph on ::before — so every button keeps the
accessible name it always had, and the two toggles still report their own
state. Verify: measured on a 390x844 viewport with a real P1010256.JPG, the row
is 30px tall, one row, buttons 34x30, `fontSize` 0px, the labels still in the
DOM as text, and hist-toggle still flips aria-pressed both ways.
The histogram was two separate faults, and the first one was invisible to the
DOM. Measured: after upload or after a close/reopen the plot is an empty frame
for ~100ms (4 paths land at 104ms / 126ms) — that is the mount, not a bug. But
the SVG then carried four full-length paths whose own map was flat: the lum
curve sat 0.9 of the panel high on ONE bin and every other bin measured 0.066
or less, so the photo read as a line along the floor. That is real: the
sampled frame has 34% of its pixels on bin 255, and under a linear scale a
blown sky owns the whole panel. The scale is log1p now — an empty bin still
sits exactly on the floor — and the bins go from 1 bin above half to 226.
The second fault was the paint: `.hist-ch` screens its three curves, which is
how light adds up on a dark panel, and it is measured against the backdrop —
so on the light theme (a white plot) it screened every channel straight to
white. Screen is now gated to `[data-theme='dark']`; measured on the light
theme, the plot went from 52 red / 39 green pixels to 931 / 1143 with the grey
fill under them.
The crop corner keeps its 16px square, which is the size a corner reads at,
and grows only its touch target: 44px centred on the node, so the outward half
is clipped by the photo's own layer and the target never overlaps the rect it
would otherwise hand the drag to. Measured: 23x44px reachable around each
node, and a drag from the bottom-right corner's centre still resizes (w 358 ->
297, h 201 -> 167) without moving the frame.
Verified: `npx tsc --noEmit` clean, `npm run build` clean, and every number
above read back off the built bundle in a 390x844 mobile context.
Co-authored-by: PenguinHarness <noreply@penguin.local>
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