Function happy_dial 

pub async fn happy_dial(
    host: &str,
    port: u16,
    delay: Option<Duration>,
) -> Result<TcpStream>

Resolve one endpoint authority and dial it with the RFC 8305 racing (DW-030). IP-literal authorities skip DNS entirely (the resolver’s short-circuit, the same path getaddrinfo takes); a multi-address resolution races per delay. One dial, one outcome: the caller’s health/breaker accounting sees exactly this Result, never the losing arms’ failures. Shared by the pooled connector and the active health probes (one dialing discipline per upstream).