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OSC 133;C command executed (FTCS_COMMAND_EXECUTED)
ESC ] 133 ; C BELOSC 133;C (also known as FTCS_COMMAND_EXECUTED) marks the transition from the command line to command output. Shells emit this immediately after the user presses Enter and before the command begins producing output. It tells the terminal: everything from here until 133;D is the command's output.
This marker lets the terminal group output blocks for selection, scrolling, and folding. Features like "copy command output" and "scroll by command" depend on knowing where output begins. Combined with 133;D, it enables the terminal to compute command duration and show success/failure decorations.
How this is testedpartial
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OSC 133 ; C BEL and verify the terminal consumes the sequence (cursor doesn't advance, terminal remains responsive).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 9 tested terminals — universal adoption. Part of the Rich TUI baseline.
Supported by 11 of 14 backends (79%)
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 |