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Default fg color (SGR 39)
ESC [ 39 mSGR 39 resets the foreground color to the terminal's default, without affecting other attributes. The sequence is
ESC [ 39 m. This is more targeted than SGR 0, which resets all attributes. Useful when you want to clear a color change while preserving bold, underline, or other active attributes.How this is testedautomated
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\x1b[31mX\x1b[39mY, verify the second cell's foreground is reset to default (null).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 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 |