Terminal Font Capability Matrix (Tessera V1)

This matrix covers whether a TUI app can change terminal font family/size through output sequences. Scope is runtime behavior from app output, not manual user settings.

Matrix

Terminal	Family from TUI output	Size from TUI output	Mechanism	Notes
xterm	Partial	Partial	OSC 50 ("Set Font to Pt"), subject to allowFontOps	Legacy/xterm-specific; may be disabled by terminal policy.
iTerm2	Indirect	Indirect	OSC 1337;SetProfile=... (switch profile)	Font changes come from selected profile settings; iTerm2 docs note legacy OSC 50 moved to 1337.
Kitty	Not first-class	Yes	kitty remote control kitten @ set-font-size	Kitty-specific control path; requires kitty protocol/remote-control usage.
WezTerm	No (via generic VT output)	No (via generic VT output)	Config/Lua (font, font_size, window:set_config_overrides)	Use config/runtime API, not portable OSC font control.
Ghostty	No	No (via generic VT output)	Config (font-family, font-size) and local keybind actions	VT reference does not define OSC font-family/font-size control for app output.
Windows Terminal	No (VT)	No (VT)	settings.json profile (font.face, font.size)	Profile/config driven; not exposed as VT font sequence.
Windows Console (conhost)	No (VT)	No (VT)	Host settings / Win32 APIs	Console VT sequence docs do not define font-family/font-size OSC control.

Tessera Recommendations

• Keep ScreenOptions.FontSpec explicitly best-effort and optional.
• Do not treat font requests as cross-terminal contract; treat them as advisory.
• Emit font request only on change/startup, never per frame.
• Keep sanitization and no forced restore behavior (current Tessera policy).
• For predictable typography, recommend profile/config setup in app docs instead of runtime font mutation.

Official Sources

• xterm control sequences: https://invisible-island.net/xterm/ctlseqs/ctlseqs.html
• iTerm2 proprietary escape codes: https://iterm2.com/documentation-escape-codes.html
• Kitty remote control (set-font-size): https://sw.kovidgoyal.net/kitty/remote-control/
• Kitty font config (font_family, font_size): https://sw.kovidgoyal.net/kitty/conf/
• WezTerm escape sequences: https://wezterm.org/escape-sequences.html
• WezTerm font_size: https://wezterm.org/config/lua/config/font_size.html
• WezTerm runtime overrides: https://wezterm.org/config/lua/window/set_config_overrides.html
• Ghostty VT reference: https://ghostty.org/docs/vt/reference
• Ghostty config reference: https://ghostty.org/docs/config/reference
• Ghostty keybind actions: https://ghostty.org/docs/config/keybind/reference
• Windows Console VT sequences: https://learn.microsoft.com/windows/console/console-virtual-terminal-sequences
• Windows Terminal profile appearance (font.face, font.size): https://learn.microsoft.com/windows/terminal/customize-settings/profile-appearance