Features›Extensions›Sixel geometry report (CSI ? Pi;Pa;Pv S)

Sixel geometry report (CSI ? Pi;Pa;Pv S)

Category: extensions · Baseline: rich · Tags: Sixel Graphics, Xterm Extensions · Specification ↗

CSI ? Pi ; Pa ; Pv S

Queries xterm for sixel graphics geometry. Added in xterm patch 402 (2025-06-22). The Pi parameter specifies the item being queried (color registers, geometry, etc.), Pa is the action (read/reset/set), and Pv is the value. The response reports current sixel capability values so applications can size sixel images to match the terminal's maximum supported dimensions. Support: xterm only as of 2026. Mentioned in xterm ChangeLog patch 402.

How this is testedautomated
Send CSI ? 1 ; 1 ; 0 S (read color register count), verify response matches CSI ? 1 ; ... S.

The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.

Supported by 0 of 14 backends (0%)

Terminal Applications

Terminal	Version	Support	Notes
iTerm2	3.6.9	? unknown
Ghostty	1.3.1	? unknown
Terminal.app	2.15	? unknown
Kitty	0.46.2	? unknown	Sixel geometry report not supported
VS Code	1.113.0	? unknown
Warp	0.2026.03.18.08.24.03	? unknown
Cursor	2.6.21	? unknown

Headless Backends

Parser correctness only — a ✓ means the parser accepts the sequence.

Backend	Version	Support	Notes
Alacritty	0.26.0	✗ no	Sixel geometry report not supported
WezTerm	0.1.0-fork.5	✗ no	Sixel geometry report not supported
vt100.js	0.2.1	? unknown
vterm	0.2.0	? unknown
xterm.js	5.5.0	? unknown

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