Themes

CoStrict ships with several built-in themes and supports custom themes. The default theme is opencode.

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Terminal Requirements

Themes require true color (24-bit) terminal support for accurate color rendering:

• Check support: Run echo $COLORTERM — output should be truecolor or 24bit
• Enable true color: Set export COLORTERM=truecolor in your shell profile
• Compatible terminals: iTerm2, Alacritty, Kitty, Windows Terminal, GNOME Terminal (recent versions)

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Built-in Themes

Name	Description
opencode	CoStrict default theme
system	Automatically adapts to the terminal's color scheme
tokyonight	Based on Tokyonight
everforest	Based on Everforest
ayu	Based on Ayu dark theme
catppuccin	Based on Catppuccin
catppuccin-macchiato	Based on Catppuccin Macchiato
gruvbox	Based on Gruvbox
kanagawa	Based on Kanagawa
nord	Based on Nord
matrix	Hacker-style black and green
one-dark	Based on Atom One Dark

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Switching Themes

Type /theme in the TUI to open the theme picker, or set it in the config file:

costrict.json

{
  "$schema": "https://opencode.ai/config.json",
  "theme": "tokyonight"
}

Shortcut: ctrl+x t

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System Theme

The system theme adapts automatically to your terminal's color scheme:

• Generates a grayscale ramp based on the terminal background for optimal contrast
• Uses standard ANSI colors (0–15) for syntax highlighting
• Sets text and background to none to preserve the terminal's native appearance

Best for users who want CoStrict to blend in with their terminal's color scheme.

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Custom Themes

Theme File Locations

Themes are loaded in the following priority order (later sources override earlier ones):

1. Built-in themes
2. User config directory: ~/.config/costrict/themes/*.json
3. Project root: .costrict/themes/*.json
4. Current working directory: ./.costrict/themes/*.json

Create a user-level theme:

mkdir -p ~/.config/costrict/themes
vim ~/.config/costrict/themes/my-theme.json

Create a project-level theme:

mkdir -p .costrict/themes
vim .costrict/themes/my-theme.json

JSON Format

Themes use JSON with the following color value formats:

• Hex: "#ffffff"
• ANSI color: 3 (0–255)
• Color reference: a name defined in defs
• Dark/light variant: {"dark": "#000", "light": "#fff"}
• No color: "none" — uses the terminal's default

Example

.costrict/themes/my-theme.json

{
  "$schema": "https://opencode.ai/theme.json",
  "defs": {
    "nord0": "#2E3440",
    "nord1": "#3B4252",
    "nord4": "#D8DEE9",
    "nord8": "#88C0D0",
    "nord9": "#81A1C1",
    "nord11": "#BF616A",
    "nord14": "#A3BE8C"
  },
  "theme": {
    "primary": { "dark": "nord8", "light": "nord9" },
    "secondary": { "dark": "nord9", "light": "nord9" },
    "error": { "dark": "nord11", "light": "nord11" },
    "success": { "dark": "nord14", "light": "nord14" },
    "text": { "dark": "nord4", "light": "nord0" },
    "background": { "dark": "nord0", "light": "#ECEFF4" },
    "backgroundPanel": { "dark": "nord1", "light": "#E5E9F0" },
    "border": { "dark": "#434C5E", "light": "#4C566A" },
    "diffAdded": { "dark": "nord14", "light": "nord14" },
    "diffRemoved": { "dark": "nord11", "light": "nord11" }
  }
}