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Secondary Device Attributes (DA2)
ESC [ > cDA2 (CSI > c) returns the terminal's type, firmware version, and ROM cartridge registration number. Modern terminals use DA2 to identify themselves — e.g., xterm returns CSI > 41 ; version ; 0 c. This is commonly used for terminal detection.
How this is testedautomated
Send CSI > c, check for a CSI > Pp ; Pv ; Pc c response via onResponse callback.
Send CSI > c, check for a CSI > Pp ; Pv ; Pc c response via onResponse callback.
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 11 of 12 terminals (92%). Not supported by: vt100.js. Part of the Modern TUI baseline. Notes: vt100.js: No output stream — pure TypeScript emulator.
Supported by 10 of 14 backends (71%)
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 |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| vterm | 0.2.0 | ✓ yes | |
| xterm.js | 5.5.0 | ✓ yes | |
| Alacritty | 0.26.0 | ~ partial | Headless mode has no output stream for DA2 responses |
| Kitty | 0.40.0 | ~ partial | Headless mode has no output stream for DA2 responses |
| WezTerm | 0.1.0-fork.5 | ~ partial | Headless mode has no output stream for DA2 responses |
| vt100.js | 0.2.1 | ✗ no | No output stream — pure TypeScript emulator |