Function parse_feed_line 

fn parse_feed_line(
    line: &str,
    worker_map: &BiHashMap<u32, String>,
    origins: &FeedOrigins,
    is_trace: bool,
    is_sessions: bool,
) -> Option<LiveTarget>

Parse a single feed line into a live target: an NDJSON object (e.g., {"dst":"1.1.1.1","worker":"ams01","origin":2}) or a bare address (e.g., 1.1.1.1).

Returns None when the line was invalid or matched no worker.