Function supportsTruecolor

cli/src/utils/theme-system.ts:24–74

(env: CliEnv = getCliEnv())

let _truecolorSupport: boolean | null = null

export function supportsTruecolor(env: CliEnv = getCliEnv()): boolean {
  if (_truecolorSupport !== null) {
    return _truecolorSupport
  }
  
  const termProgram = env.TERM_PROGRAM?.toLowerCase() ?? ''
  
  // Terminal.app (Apple_Terminal) does NOT support truecolor - only 256 colors
  if (termProgram === 'apple_terminal') {
    _truecolorSupport = false
    return false
  }
  
  const colorterm = env.COLORTERM?.toLowerCase()
  if (colorterm === 'truecolor' || colorterm === '24bit') {
    _truecolorSupport = true
    return true
  }
  
  // Some terminals that are known to support truecolor
  const truecolorTerminals = [
    'iterm.app',
    'hyper',
    'wezterm',
    'alacritty',
    'kitty',
    'ghostty',
    'vscode',
  ]
  
  if (truecolorTerminals.some(t => termProgram.includes(t))) {
    _truecolorSupport = true
    return true
  }
  
  // Check TERM for known truecolor-capable values
  const term = env.TERM?.toLowerCase() ?? ''
  if (term.includes('truecolor') || term.includes('24bit')) {
    _truecolorSupport = true
    return true
  }
  
  // xterm-kitty, alacritty, etc.
  if (term === 'xterm-kitty' || term === 'alacritty' || term.includes('ghostty')) {
    _truecolorSupport = true
    return true
  }
  
  _truecolorSupport = false
  return false
}