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OSC 633;C pre-execution
ESC ] 633 ; C BELOSC 633;C is VS Code's pre-execution marker, emitted just before a command begins executing. It mirrors OSC 133;C and marks the boundary between the command line and command output.
VS Code uses this marker to start tracking command duration, group output for the run-recent-command picker, and prepare command decoration UI. When combined with OSC 633;D, it gives VS Code precise timing for each command execution.
How this is testedautomated
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OSC 633 ; 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 14 of 14 backends (100%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | |
| VS Code | ✓ yes | ||
| Warp | ✓ yes | ||
| Cursor | ✓ yes | ||
| Terminal.app | ✓ yes |