Themes

Luna's TUI uses a theme system for consistent visual styling across the chat interface, tool output, markdown rendering, and status bars. Themes are defined as Lua tables with color and attribute specifications.

Built-in Themes

Luna ships with 4 built-in themes:

Theme	Description
default	Classic dark theme with colored roles
onedark	Subdued palette inspired by One Dark
high-contrast	Light background for accessibility
solarized-dark	Solarized color palette on dark background

Selecting a Theme

In ~/.luna/config.json:

{
  "theme": "onedark"
}

Or at startup:

luajit main.lua --theme solarized-dark

Theme Structure

A theme is a Lua table with the following sections:

{
  name = "my-theme",
  background = "black",
  menubar_title = "cyan onblack bold",
  scrollbar_bg = "black",
  scrollbar = "white onblack",
  roles = {
    user         = "green onblack bold",
    assistant    = "blue onblack bold",
    system       = "yellow onblack bold",
    error        = "red onblack bold",
    tool         = "magenta onblack",
    tool_start   = "cyan onblack bold",
    tool_result  = "white onblack dim",
    dim          = "white onblack dim",
    thinking     = "cyan onblack dim",
    thinking_summary = "darkgrey onblack dim",
    compact      = "yellow onblack dim",
  },
  markdown = {
    heading       = "\27[1m\27[36m",
    bold          = "\27[1m\27[33m",
    italic        = "\27[3m\27[35m",
    inline_code   = "\27[32m",
    code_block    = "\27[90m",
    code_border   = "\27[90m",
    code_bg       = "\27[48;5;236m",
    link          = "\27[4m\27[34m",
    strikethrough = "\27[2m",
    quote_prefix  = "\27[90m",
    hr            = "\27[90m",
    table_header  = "\27[1m\27[36m",
    table_sep     = "\27[90m",
  },
  spinner = { "blue" },
}

Color Specification

Role Colors

Role colors use a descriptive string format:

<foreground> [on<background>] [<attribute>]

Examples:

green onblack bold
cyan onblack dim
white onblack
red onwhite bold

Supported Colors

Color	ANSI Code
black	30
red	31
green	32
yellow	33
blue	34
magenta	35
cyan	36
white	37
darkgrey	90

Supported Attributes

Attribute	ANSI Code
bold	1
dim	2
italic	3
underline	4
reverse	7

Markdown Colors

Markdown styling uses raw ANSI escape sequences for full control:

heading = "\27[1m\27[36m"       -- bold cyan
bold = "\27[1m\27[33m"          -- bold yellow
link = "\27[4m\27[34m"          -- underline blue

The M.ANSI table provides named constants:

local theme = require("ui.theme")
theme.ANSI.bold        -- "\27[1m"
theme.ANSI.red         -- "\27[31m"
theme.ANSI.bg_darkgrey -- "\27[48;5;236m"

Custom Theme

To create a custom theme, register it before the TUI initializes:

local theme = require("ui.theme")

theme.themes["my-custom"] = {
  name = "my-custom",
  background = "black",
  menubar_title = "yellow onblack bold",
  scrollbar_bg = "black",
  scrollbar = "darkgrey onblack",
  roles = {
    user         = "green onblack bold",
    assistant    = "cyan onblack",
    system       = "yellow onblack bold",
    error        = "red onblack bold",
    tool         = "magenta onblack",
    tool_start   = "cyan onblack bold",
    tool_result  = "darkgrey onblack",
    dim          = "darkgrey onblack",
    thinking     = "blue onblack dim",
    thinking_summary = "darkgrey onblack dim",
    compact      = "yellow onblack dim",
  },
  markdown = {
    heading       = theme.ANSI.bold .. theme.ANSI.green,
    bold          = theme.ANSI.bold .. theme.ANSI.yellow,
    italic        = theme.ANSI.italic .. theme.ANSI.magenta,
    inline_code   = theme.ANSI.cyan,
    code_block    = theme.ANSI.darkgrey,
    code_border   = theme.ANSI.darkgrey,
    code_bg       = theme.ANSI.bg_darkgrey,
    link          = theme.ANSI.underline .. theme.ANSI.cyan,
    strikethrough = theme.ANSI.dim,
    quote_prefix  = theme.ANSI.darkgrey,
    hr            = theme.ANSI.darkgrey,
    table_header  = theme.ANSI.bold .. theme.ANSI.green,
    table_sep     = theme.ANSI.darkgrey,
  },
  spinner = { "green" },
}

theme.set_theme("my-custom")

LTUI Rendering Engine

Luna uses LTUI (Lua TUI) built on ncurses for terminal rendering:

• 256-color support with automatic quantization via quantize_256()
• Color pair allocation managed by alloc_pair() starting at pair 100
• Image pair caching for sixel/kitty image rendering (pairs 200+)
• Wide character support with proper wcwidth for CJK and emoji
• Dirty-region rendering using CSI 2026 for efficient screen updates

ANSI Helpers

The theme module provides text formatting utilities:

local theme = require("ui.theme")

theme.color("error", "Something went wrong")
theme.color("heading", "Title")

theme.strip_ansi(text)
theme.visible_width(text)
theme.wrap(text, 80)
theme.pad(text, 40)

Listing Available Themes

local theme = require("ui.theme")
local names = theme.list_themes()
for _, name in ipairs(names) do
  print(name)
end