Appearance
CUD stops at bottom
CUD (Cursor Down, CSI Pn B) should stop at the bottom margin of the scroll region, or the last row if no scroll region is set. Moving down with a count exceeding the remaining rows should clamp to the last row rather than scrolling or wrapping. Unlike a linefeed at the bottom margin, CUD never triggers scrolling — it simply stops.
How this is testedautomated
Position at row 0, send
Position at row 0, send
\x1b[999B (CUD with count 999), verify cursor stopped at the last row.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.
Analysis2026-04-06
Supported by all 12 tested terminals — universal adoption. Part of the Core TUI baseline.
Supported by 13 of 14 backends (93%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | cursor at row 25 |
| Ghostty | 1.3.1 | ✓ yes | cursor at row 119 |
| VS Code | ✓ yes | ||
| Warp | ✓ yes | ||
| Cursor | ✓ yes | ||
| Terminal.app | ✓ yes |