Function format_trace_line 

pub fn format_trace_line(record: &PluginTraceRecord) -> String

Format one record into a single line (no trailing newline — the drain joins with \n).

A logging record (Layer 2, the guest’s own narrative) has no meaningful timing/outcome — the message is the point — so it renders {level} [plugin:{id}] logging {context}: {message}, with context in call and message in detail. Every other record is a boundary call: {level} [plugin:{id}] {seam} {»/«}{call} → {outcome}.