How to distinguish which process the output stream line comes from

I have a output stream looking like this, however it doesn't work reliably because some lines simply do not have a prefix.

const outputStream = {
  write: (data) => {
    if (['[SDK]', '[bundle]', '[dts]'].some((str) => data.includes(str))) {
      sdkStream.write(data);
    } else if (data.includes('[Demo App]')) {
      demoStream.write(data);
    }
  },
};

May I know if there's any way I can tell reliably which process a line is coming form? Many thanks!

The issue mentions only an outputStream.write handler and no repository file or test. Start by locating the output-stream handling and process-prefixing entry points, then check whether each process's identity is preserved for every emitted line. Done means a documented or tested reliable way to associate each line with its originating process.