Features›Text›CJK wide chars (2 cols)

CJK wide chars (2 cols)

Category: text · Baseline: core · Tags: Unicode · Specification ↗

Tests whether CJK (Chinese, Japanese, Korean) ideographs correctly occupy two terminal columns. The Unicode Standard Annex #11 defines East Asian Width properties. Terminals must account for this in cursor positioning — after rendering a CJK character, the cursor advances by 2 columns, not 1. Incorrect width handling breaks TUI layouts and cursor alignment.

How this is testedautomated
Write U+4E2D (CJK character), verify the cell has wide=true (occupies 2 columns).

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 Core TUI baseline. Notes: vt100.js: Not in VT100/VT220 — ASCII only, no Unicode width.

Supported by 12 of 14 backends (86%)

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
Alacritty	0.26.0	✓ yes
Kitty	0.40.0	✓ yes
vterm	0.2.0	✓ yes
WezTerm	0.1.0-fork.5	✓ yes
xterm.js	5.5.0	✓ yes
vt100.js	0.2.1	✗ no	Not in VT100/VT220 — ASCII only, no Unicode width

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