Features›Extensions

Extensions

Modern terminal extensions beyond the traditional VT specification: Kitty keyboard protocol, Kitty graphics protocol, sixel inline images, OSC 8 hyperlinks, text reflow on resize, and semantic prompt markers (OSC 133). These features represent the cutting edge of terminal capability and vary widely in adoption across terminals. Modern extensions push terminals beyond the 1978 VT100 model. The Kitty keyboard protocol solves a 45-year-old input ambiguity — before it, terminals couldn't distinguish Escape from Alt+[ or Ctrl+I from Tab. OSC 8 brings clickable hyperlinks to terminal output — ls can now link filenames to the actual files. Sixel graphics (from DEC, 1987) are having a renaissance: an image format from the Reagan era is now the most widely supported way to display inline images in a terminal. The Kitty graphics protocol is more capable, but Sixel has the installed base advantage of being 39 years old.

79 features in this category

Analysis2026-04-06

The Extensions category covers 79 features. Common gaps: iTerm2 Cell Size Reporting (OSC 1337) (11 terminals fail), iTerm2 Capability Reporting (OSC 1337) (11 terminals fail), OSC 5522 advanced clipboard (11 terminals fail).

Terminal Applications

Feature	iTerm2	Ghostty	VS Code	Warp	Cursor	Terminal.app
System clipboard paste	?	?	?	?	?	?
Font ligatures	?	?	?	?	?	?
iTerm2 Inline Images (OSC 1337)	✓	✓	✓	✓	✓	✓
Kitty graphics protocol	✓	✓	✗	✓	✗	✓
Kitty graphics: animation	✓	✓	✓	✓	✓	✓
Kitty graphics: display	✓	✓	✗	✓	✗	✓
Kitty graphics: transmit	✓	✓	✓	✓	✓	✓
Kitty graphics: Unicode placeholders	✗	✗	✗	✗	✗	✓
Kitty keyboard protocol	✓	✓	✓	✓	✗	✗
Kitty keyboard: DISAMBIGUATE (flag 1)	✓	✓	✓	✓	✗	✗
Kitty keyboard: REPORT_ALL_KEYS (flag 8)	✓	✓	✓	✓	✗	✗
Kitty keyboard: REPORT_ALTERNATE (flag 4)	✓	✓	✓	✓	✗	✗
Kitty keyboard: REPORT_EVENTS (flag 2)	✓	✓	✓	✓	✗	✗
Kitty keyboard: REPORT_TEXT (flag 16)	✓	✓	✓	✓	✗	✗
Desktop Notifications (OSC 9/777)	✓	✓	✓	✓	✓	✓
VS Code Shell Integration (OSC 633)	✓	✓	✓	✓	✓	✓
Icon and title (OSC 0)	✓	✓	✓	✓	✓	✓
Icon name (OSC 1)	✓	✓	✓	✓	✓	✓
Foreground color query (OSC 10)	✓	✓	✓	✓	✓	✓
Reset color palette (OSC 104)	✓	✓	✓	✓	✓	✓
Background color query (OSC 11)	✓	✓	✓	✓	✓	✓
Reset foreground color (OSC 110)	✓	✓	✓	✓	✓	✓
Reset background color (OSC 111)	✓	✓	✓	✓	✓	✓
Reset cursor color (OSC 112)	✓	✓	✓	✓	✓	✓
Reset pointer fg color (OSC 113)	✓	✓	✓	✓	✓	✓
Reset pointer bg color (OSC 114)	✓	✓	✓	✓	✓	✓
Reset highlight background (OSC 117)	✓	✓	✓	✓	✓	✓
Reset highlight foreground (OSC 119)	✓	✓	✓	✓	✓	✓
Cursor color (OSC 12)	✓	✓	✓	✓	✓	✓
OSC 133;A prompt start (FTCS_PROMPT)	✓	✓	✓	✓	✓	✓
OSC 133;B command start (FTCS_COMMAND_START)	✓	✓	✓	✓	✓	✓
OSC 133;C command executed (FTCS_COMMAND_EXECUTED)	✓	✓	✓	✓	✓	✓
OSC 133;D command finished (FTCS_COMMAND_FINISHED)	✓	✓	✓	✓	✓	✓
OSC 133;P properties	✓	✓	✓	✓	✓	✓
iTerm2 Capability Reporting (OSC 1337)	✗	✗	✗	✗	✗	✗
iTerm2 Cell Size Reporting (OSC 1337)	✗	✗	✗	✗	✗	✗
Highlight background (OSC 17)	✓	✗	✗	✗	✗	✓
Set Wayland app-id (OSC 176)	✓	✓	✓	✓	✓	✓
Highlight foreground (OSC 19)	✓	✗	✗	✗	✗	✓
Window title (OSC 2)	✓	✓	✓	✓	✓	✓
Kitty color protocol (OSC 21)	✓	✓	✓	✓	✓	✓
Pointer shape (OSC 22)	✓	✓	✓	✓	✓	✓
Kitty color stack push (OSC 30001)	✓	✓	✓	✓	✓	✓
Systemd context (OSC 3008)	✓	✓	✓	✓	✓	✓
Kitty color stack pop (OSC 30101)	✓	✓	✓	✓	✓	✓
Color palette (OSC 4)	✓	✓	✓	✗	✓	✓
Audio sound (OSC 440)	✓	✓	✓	✓	✓	✓
Special color (OSC 5)	✗	✗	✗	✗	✗	✓
Clipboard access (OSC 52)	✓	✓	✓	✓	✓	✓
OSC 52 clipboard read	✓	✗	✓	✗	✓	✗
OSC 52 clipboard write	✓	✓	✓	✓	✓	✓
OSC 5522 advanced clipboard	✗	✗	✗	✗	✗	✗
Screen flash (OSC 555)	✓	✓	✓	✓	✓	✓
OSC 633;A prompt start	✓	✓	✓	✓	✓	✓
OSC 633;B prompt end	✓	✓	✓	✓	✓	✓
OSC 633;C pre-execution	✓	✓	✓	✓	✓	✓
OSC 633;D command finished	✓	✓	✓	✓	✓	✓
OSC 633;E set commandline	✓	✓	✓	✓	✓	✓
OSC 633;P properties	✓	✓	✓	✓	✓	✓
OSC 66 text sizing	✓	✓	✓	✓	✓	✓
VTE termprop (OSC 666)	✓	✓	✓	✓	✓	✓
Current directory (OSC 7)	✓	✓	✓	✓	✓	✓
Locale query/set (OSC 701)	✓	✓	✓	✓	✓	✓
Version query (OSC 702)	✓	✓	✓	✓	✓	✓
Set normal font (OSC 710)	✓	✓	✓	✓	✓	✓
Scroll view up (OSC 720)	✓	✓	✓	✓	✓	✓
Cell size report (OSC 776)	✓	✓	✓	✓	✓	✓
Notifications (OSC 777)	✓	✓	✓	✓	✓	✓
Font size query/set (OSC 7770)	✓	✓	✓	✓	✓	✓
Font + window size (OSC 7777)	✓	✓	✓	✓	✓	✓
Hyperlinks (OSC 8)	✓	✓	✓	✓	✓	✓
OSC 9;4 progress bar	✓	✓	✓	✓	✓	✓
Desktop notifications (OSC 99)	✓	✓	✓	✓	✓	✓
Text reflow on resize	✓	✓	✓	✓	✓	✓
Semantic prompts (OSC 133)	✓	✓	✓	✓	✓	✓
Sixel graphics	✗	✗	✗	✗	✗	✓
Sixel support in DA1	✓	✗	✗	✗	✗	✗
Sixel geometry report (CSI ? Pi;Pa;Pv S)	?	?	✗	✗	✗	✗
24-bit truecolor	✓	✓	✓	✓	✓	✓

Headless Backends

Parser correctness tested via Termless. A ✓ means the parser accepts the sequence, not that it renders correctly.

Feature	vterm	xterm.js	Kitty	Alacritty	WezTerm	vt100.js
System clipboard paste	?	?	?	?	?	?
Font ligatures	?	?	?	?	?	?
iTerm2 Inline Images (OSC 1337)	✓	✗	✗	✗	✗	✗
Kitty graphics protocol	✓	✗	✓	✗	✗	✗
Kitty graphics: animation	✓	✗	✓	✗	✗	✗
Kitty graphics: display	✓	✗	✓	✗	✗	✗
Kitty graphics: transmit	✓	✗	✓	✗	✗	✗
Kitty graphics: Unicode placeholders	✓	✗	✓	✗	✗	✗
Kitty keyboard protocol	✓	✗	✓	✓	✓	✗
Kitty keyboard: DISAMBIGUATE (flag 1)	✓	✗	✓	✓	✓	✗
Kitty keyboard: REPORT_ALL_KEYS (flag 8)	✓	✗	✓	✓	✓	✗
Kitty keyboard: REPORT_ALTERNATE (flag 4)	✓	✗	✓	✓	✓	✗
Kitty keyboard: REPORT_EVENTS (flag 2)	✓	✗	✓	✓	✓	✗
Kitty keyboard: REPORT_TEXT (flag 16)	✓	✗	✓	✓	✓	✗
Desktop Notifications (OSC 9/777)	✓	✗	~	~	~	✗
VS Code Shell Integration (OSC 633)	✓	✗	~	✗	✓	✗
Icon and title (OSC 0)	✓	✓	✓	✓	✓	✓
Icon name (OSC 1)	✓	✓	✓	✓	✓	✓
Foreground color query (OSC 10)	✓	✗	~	~	~	✗
Reset color palette (OSC 104)	✗	✗	✗	✗	✗	✗
Background color query (OSC 11)	✓	✗	~	~	~	✗
Reset foreground color (OSC 110)	✓	✗	✗	✗	✗	✗
Reset background color (OSC 111)	✓	✗	✗	✗	✗	✗
Reset cursor color (OSC 112)	✗	✗	✗	✗	✗	✗
Reset pointer fg color (OSC 113)	?	?	?	?	?	?
Reset pointer bg color (OSC 114)	?	?	?	?	?	?
Reset highlight background (OSC 117)	✓	✓	✓	✓	✓	✓
Reset highlight foreground (OSC 119)	✓	✓	✓	✓	✓	✓
Cursor color (OSC 12)	✗	✗	✗	✗	✗	✗
OSC 133;A prompt start (FTCS_PROMPT)	✓	✓	✓	✓	✓	✓
OSC 133;B command start (FTCS_COMMAND_START)	✓	✓	✓	✓	✓	✓
OSC 133;C command executed (FTCS_COMMAND_EXECUTED)	✓	✓	✓	✓	✓	✓
OSC 133;D command finished (FTCS_COMMAND_FINISHED)	✓	✓	✓	✓	✓	✓
OSC 133;P properties	✓	✓	✓	✓	✓	✓
iTerm2 Capability Reporting (OSC 1337)	✓	✗	✗	✗	✗	✗
iTerm2 Cell Size Reporting (OSC 1337)	✓	✗	✗	✗	✗	✗
Highlight background (OSC 17)	✗	✗	✗	✗	✗	✗
Set Wayland app-id (OSC 176)	?	?	?	?	?	?
Highlight foreground (OSC 19)	✗	✗	✗	✗	✗	✗
Window title (OSC 2)	✓	✓	✓	✓	✗	✓
Kitty color protocol (OSC 21)	✗	✗	~	✗	✗	✗
Pointer shape (OSC 22)	?	?	?	?	?	?
Kitty color stack push (OSC 30001)	?	?	?	?	?	?
Systemd context (OSC 3008)	?	?	?	?	?	?
Kitty color stack pop (OSC 30101)	?	?	?	?	?	?
Color palette (OSC 4)	✗	✗	✗	✗	✗	✗
Audio sound (OSC 440)	?	?	?	?	?	?
Special color (OSC 5)	✗	✗	✗	✗	✗	✗
Clipboard access (OSC 52)	✓	✗	~	~	~	✗
OSC 52 clipboard read	✓	✗	~	~	~	✗
OSC 52 clipboard write	✓	✓	✓	✓	✓	✓
OSC 5522 advanced clipboard	✓	✗	~	✗	✗	✗
Screen flash (OSC 555)	?	?	?	?	?	?
OSC 633;A prompt start	✓	✓	✓	✓	✓	✓
OSC 633;B prompt end	✓	✓	✓	✓	✓	✓
OSC 633;C pre-execution	✓	✓	✓	✓	✓	✓
OSC 633;D command finished	✓	✓	✓	✓	✓	✓
OSC 633;E set commandline	✓	✓	✓	✓	✓	✓
OSC 633;P properties	✓	✓	✓	✓	✓	✓
OSC 66 text sizing	✓	✗	~	✗	✗	✗
VTE termprop (OSC 666)	?	?	?	?	?	?
Current directory (OSC 7)	✓	✗	~	~	~	✗
Locale query/set (OSC 701)	?	?	?	?	?	?
Version query (OSC 702)	?	?	?	?	?	?
Set normal font (OSC 710)	?	?	?	?	?	?
Scroll view up (OSC 720)	?	?	?	?	?	?
Cell size report (OSC 776)	?	?	?	?	?	?
Notifications (OSC 777)	?	?	?	?	?	?
Font size query/set (OSC 7770)	?	?	?	?	?	?
Font + window size (OSC 7777)	?	?	?	?	?	?
Hyperlinks (OSC 8)	✓	✓	✓	✓	✓	✗
OSC 9;4 progress bar	?	?	?	?	?	?
Desktop notifications (OSC 99)	?	?	?	?	?	?
Text reflow on resize	✓	✓	✓	✓	✓	✗
Semantic prompts (OSC 133)	✓	✗	~	✗	✓	✗
Sixel graphics	✓	✗	✗	✗	✓	✗
Sixel support in DA1	✓	✗	✗	✗	~	✗
Sixel geometry report (CSI ? Pi;Pa;Pv S)	✓	✓	✗	✗	✗	✓
24-bit truecolor	✓	✓	✓	✓	✓	✗

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