mkdir -p ~/.config/opencode/themes
cp /path/to/karasu/platforms/opencode/themes/karasu.json ~/.config/opencode/themes/~/.config/opencode/tui.json:
{
"$schema": "https://opencode.ai/tui.json",
"theme": "karasu"
}karasu matches OpenCode's built-in theme convention: Night colors in dark mode and Snow colors in light mode.
OpenCode theme selection belongs in tui.json, not opencode.json.
Custom themes are resolved from ~/.config/opencode/themes, <project>/.opencode/themes, and ./.opencode/themes, with later locations overriding earlier ones.
Karasu OpenCode themes use explicit hex values for stable, deterministic rendering. Matching your terminal ANSI palette to Karasu (Ghostty/iTerm2) is optional, but improves cross-tool consistency. For best results, run OpenCode in a truecolor terminal.