Function sendOscQuery

cli/src/utils/terminal-color-detection.ts:108–237

* Query the terminal for OSC color information. * * IMPORTANT: This function reads from stdin because OSC responses come through * the PTY which appears on stdin. This means it MUST be run BEFORE any other * stdin listeners (like OpenTUI) are attached. OSC detection runs at the very * start of

(
  ttyPath: string,
  query: string,
)

 * @returns The raw response string or null if query failed
 */
async function sendOscQuery(
  ttyPath: string,
  query: string,
): Promise<string | null> {
  return new Promise((resolve) => {
    // Guard: Must have TTY for both reading and writing
    if (!process.stdin.isTTY) {
      resolve(null)
      return
    }

    let ttyWriteFd: number | null = null
    let timeoutId: NodeJS.Timeout | null = null
    let resolved = false
    let response = ''
    let wasRawMode = false
    let dataHandler: ((data: Buffer) => void) | null = null

    const cleanup = () => {
      if (resolved) return
      resolved = true

      if (timeoutId) {
        clearTimeout(timeoutId)
        timeoutId = null
      }

      // Remove data handler from stdin
      if (dataHandler) {
        process.stdin.removeListener('data', dataHandler)
        dataHandler = null
      }

      // Restore raw mode state
      if (process.stdin.isTTY && process.stdin.setRawMode) {
        try {
          process.stdin.setRawMode(wasRawMode)
        } catch {
          // Ignore errors restoring raw mode
        }
      }

      // Pause stdin so we leave it non-flowing before other listeners attach
      try {
        process.stdin.pause()
      } catch {
        // Ignore pause errors
      }

      // Close TTY write fd
      if (ttyWriteFd !== null) {
        try {
          closeSync(ttyWriteFd)
        } catch {
          // Ignore close errors
        }
        ttyWriteFd = null
      }