Function is_interrupt_marker 

pub fn is_interrupt_marker(text: &str) -> bool

Whether text is the CLI’s interrupt marker: the row it writes when the reader’s own interrupt ends a turn.

A user row, and not one that opens a turn (#1323): it arrives INSIDE the turn it ended - the in-flight call, then this, then the failing Result - so a turn opened for it separates the call from the report and failure line that answer it. Both folds read it as a plain row of the open turn (the client mirror is isInterruptMarker in its conversation.ts).