Function fail_closed_marker_path 

pub fn fail_closed_marker_path() -> PathBuf

Path to the fail-closed marker (alongside the default event log). Its mere existence is the signal — the content is irrelevant. The interception layer (shim/hook/MCP) reads it without the daemon, so that killing the daemon can’t be used to open the gate: with the marker present, an unreachable daemon means block, not run unguarded.