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Sixel geometry report (CSI ? Pi;Pa;Pv S)
CSI ? Pi ; Pa ; Pv SQueries 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
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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 3 of 14 backends (21%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| VS Code | ✗ no | ||
| Warp | ✗ no | ||
| Cursor | ✗ no | ||
| Terminal.app | ✗ no | ||
| iTerm2 | 3.6.9 | ? unknown | |
| Ghostty | 1.3.1 | ? unknown |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| vt100.js | 0.2.1 | ✓ yes | |
| vterm | 0.2.0 | ✓ yes | |
| xterm.js | 5.5.0 | ✓ yes | |
| Alacritty | 0.26.0 | ✗ no | Sixel geometry report not supported |
| Kitty | 0.40.0 | ✗ no | Sixel geometry report not supported |
| WezTerm | 0.1.0-fork.5 | ✗ no | Sixel geometry report not supported |