pub fn parse_traceparent(
headers: &HeaderMap,
) -> Result<Option<String>, CoolError>Expand description
Extract a W3C traceparent header, returning the trace-id portion when
the header is present and well-formed. Returns Ok(None) when absent —
callers should mint their own request id in that case so every audit row
carries something. The trace-id is the second hyphen-delimited segment
per W3C Trace Context; this implementation does not validate the
flags/version segments since banks usually rebuild traceparent at the
edge anyway.