Constant IROH_IDLE_TIMEOUT 

pub const IROH_IDLE_TIMEOUT: Duration;

QUIC idle timeout for every iroh endpoint.

With IROH_KEEP_ALIVE_INTERVAL underneath it, a dead connection surfaces within ~5s instead of the 30s QUIC default. The negotiated idle timeout is the minimum of both sides’, so a guardian setting this caps detection latency for clients whose endpoints keep iroh’s defaults. The path-level settings stay untouched — iroh tunes those for hole punching.