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Special color (OSC 5)
ESC ] 5 ; c ; spec BELOSC 5 sets or queries special color resources used for text attributes. The sequence is
ESC ] 5 ; c ; spec BEL where c identifies the special color: 0=bold, 1=underline, 2=blink, 3=reverse, 4=italic. To query: ESC ] 5 ; c ; ? BEL. These special colors override the rendered color of text with specific attributes — for example, making all bold text appear in a specific color regardless of the foreground setting. Support is limited to xterm and a few other terminals.How this is testedautomated
Query special color 0 (bold) with
Query special color 0 (bold) with
OSC 5 ; 0 ; ? BEL, verify response matches OSC 5 ; 0 ; rgb:... pattern.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 2 of 9 terminals (22%). Part of the Rich TUI baseline.
Supported by 1 of 14 backends (7%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| Terminal.app | ✓ yes | ||
| iTerm2 | 3.6.9 | ✗ no | No OSC 5 response |
| Ghostty | 1.3.1 | ✗ no | No OSC 5 response |
| VS Code | ✗ no | ||
| Warp | ✗ no | ||
| Cursor | ✗ no |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| Alacritty | 0.26.0 | ✗ no | OSC 5 special color query requires a real display — headless backends have no color palette to query |
| Kitty | 0.40.0 | ✗ no | OSC 5 special color query requires a real display — headless backends have no color palette to query |
| vt100.js | 0.2.1 | ✗ no | Not implemented — pure TypeScript emulator |
| vterm | 0.2.0 | ✗ no | OSC 5 special color query not implemented in vterm.js |
| WezTerm | 0.1.0-fork.5 | ✗ no | OSC 5 special color query requires a real display — headless backends have no color palette to query |
| xterm.js | 5.5.0 | ✗ no | OSC 5 special color query requires a real display — headless backends have no color palette to query |