Function detectTerminalThemeModeFromBackground

src/core/themeDetection.ts:81–122

({
  input,
  output,
  timeoutMs = 150,
}: DetectTerminalThemeOptions)

 * This avoids treating piped diff stdin as terminal input while leaving renderer stdout unchanged.
 */
export async function detectTerminalThemeModeFromBackground({
  input,
  output,
  timeoutMs = 150,
}: DetectTerminalThemeOptions): Promise<TerminalThemeMode | null> {
  const wasRaw = input.isRaw;
  let settled = false;
  let buffer = "";

  return await new Promise<TerminalThemeMode | null>((resolve) => {
    const cleanup = () => {
      if (settled) {
        return;
      }
      settled = true;
      clearTimeout(timer);
      input.removeListener("data", onData);
      if (wasRaw !== undefined) {
        input.setRawMode?.(wasRaw);
      }
    };

    const finish = (mode: TerminalThemeMode | null) => {
      cleanup();
      resolve(mode);
    };

    const timer = setTimeout(() => finish(null), timeoutMs);
    const onData = (chunk: Buffer | string) => {
      buffer += Buffer.isBuffer(chunk) ? chunk.toString("utf8") : chunk;
      const color = parseOsc11BackgroundColor(buffer);
      if (color) {
        finish(themeModeForBackgroundColor(color));
      }
    };

    input.setRawMode?.(true);
    input.resume?.();
    input.on("data", onData);
    output.write(OSC_11_BACKGROUND_QUERY);
  });
}