A terminal pane draws the kitty graphics its program places, so yazi's image and PDF previews show

yazi asks the pane XTVERSION, and ghostty-vt answers "libghostty": yazi
takes it for Ghostty and sends its previews by the kitty graphics protocol
with Unicode placeholders (a=T,U=1, then U+10EEEE cells). ghostty-vt stored
the images, but nothing drew them: the placeholders showed as tofu in the
GUI and as raw codepoints in the tty, in every build since terminal panes
answered queries (vkznsvzs, 2026-07-01). Before that no query was answered
and yazi fell back to chafa's text art.

Each frame, TerminalImages.zig reads the active screen's images and
placements (virtual ones through their placeholder runs, and ones placed on
a cell), cuts each into the cell rows it covers, maps those rows through
the body's own row walk, clips them to the pane, and hands them on as
ImagePlaces with exact geometry (NativePlacement.exact). The GUI draws
them as textures; the tty passes them to an outer terminal with kitty
graphics as one placement per row, its source cropped to whole cells.
Placeholder cells draw no text. Scrolling, a delete, a resize, the
alternate screen and a closed pane all fall out of reading the emulator's
state every frame.

A pane now knows its size in pixels: CSI 14/16/18 t are answered, the
emulator's width_px/height_px follow the shell's cells, and the pty's
winsize carries pixels (host_io.ptyWinsize), so yazi and a nested pardes
size their images right. ghostty-vt's image store is 64 MiB per screen
(its library default, 10 MB, refused a large preview), PNG transmissions
are decoded with stb_image, and RGB images are converted only while shown.

test/yazi_preview.py runs yazi in a hidden window on a PNG and a PDF and
checks the captures, also through a tty pardes nested in the pane.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

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