Mods: let the Image element draw Sixel in Windows Terminal
Problem
The mods Image element draws real pixels only in kitty and Ghostty. On Windows, neither is available, while Windows Terminal (the default terminal on Windows 11) has supported Sixel in its stable channel since 1.21 (2024).
As a result, every image-preview mod falls back to block characters on Windows. That includes community ones such as claude-image-view, as well as ours: thumbnails of pasted images above the prompt, and a zoomable large view in a pane. The best we can do there is a chafa-style fit (an 8×8 sub-cell grid per cell, choosing among block glyphs). That is readable, but it is still an approximation of the image the user is about to send.
Proposed solution
When the terminal reports Sixel support (DA1 attribute 4), render the Image element as Sixel. Keep the alt fallback, as with the kitty path.
Why it matters
- Enterprise users on Windows. Many of them run Claude Code there. Pasting screenshots is a daily gesture, and seeing exactly what you paste before sending prevents mistakes, such as sending the wrong image or one showing personal data.
- Exact previews. Mods already let users remove a pasted image before sending. Sixel would make the preview itself pixel-exact.
Related
#32005 (image paste preview), #2266 and #79706 (terminal graphics protocols for inline images in general).