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Screen flash (OSC 555)
ESC ] 555 BELOSC 555 triggers a visual bell — the terminal briefly flashes its background color, drawing the user's attention without playing an audible bell. The sequence is
ESC ] 555 BEL and is foot-specific. Visual bells are commonly bound to shell error events, IRC/chat notifications, or completion of long-running commands. Most terminals expose visual bell behavior through preferences rather than an escape sequence; foot is unusual in giving applications direct control. Other terminals silently consume OSC 555 (no flash) or pass it through unchanged.How this is testedpartial
Send
Send
OSC 555 BEL and verify the terminal consumes the sequence (cursor position unchanged).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 4 tested terminals — universal adoption. Part of the Rich TUI baseline.
Supported by 6 of 14 backends (43%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | |
| Terminal.app | 2.15 | ✓ yes | |
| Kitty | 0.46.2 | ✓ yes | |
| VS Code | 1.113.0 | ? unknown | |
| Warp | 0.2026.03.18.08.24.03 | ? unknown | |
| Cursor | 2.6.21 | ? unknown |