feat(client): add --timeouts option for session-opening retry schedule

crates/irtt-app/src/shared/client/args.rs

@@ -22,6 +22,10 @@ pub struct CommonClientArgs {
     #[arg(short = 'i', long, default_value = "1s", value_parser = parse_duration)]
     pub interval: Duration,
 
+    /// Comma-separated session-opening timeouts, one per attempt (each >= 200ms).
+    #[arg(long, value_name = "DURATIONS", value_delimiter = ',', value_parser = parse_duration, long_help = "Comma-separated session-opening receive timeouts, one per attempt (each at least 200ms), e.g. 1s,2s,4s,8s. Omit to use the library default retry schedule.")]
+    pub timeouts: Vec<Duration>,
+
     /// UDP payload length.
     #[arg(short = 'l', long, default_value_t = 0, value_parser = parse_length)]
     pub length: u32,
@@ -116,6 +120,7 @@ impl fmt::Debug for CommonClientArgs {
             .field("ipv6", &self.ipv6)
             .field("dual_stack", &self.dual_stack)
             .field("interval", &self.interval)
+            .field("timeouts", &self.timeouts)
             .field("length", &self.length)
             .field("hmac", &self.hmac.as_ref().map(|_| "[REDACTED]"))
             .field("clock", &self.clock)

crates/irtt-app/src/shared/client/config.rs

@@ -22,16 +22,21 @@ impl CommonClientArgs {
     ///
     /// The config is endpoint-independent; managed targets own their addresses.
     pub fn to_client_config(&self, duration: Duration) -> Result<ClientConfig, String> {
+        let mut open = OpenPolicy {
+            negotiation: if self.loose {
+                NegotiationPolicy::Loose
+            } else {
+                NegotiationPolicy::Strict
+            },
+            ..Default::default()
+        };
+        if !self.timeouts.is_empty() {
+            open.timeouts.clone_from(&self.timeouts);
+        }
+
         Ok(ClientConfig {
             address_family: self.address_family(),
-            open: OpenPolicy {
-                negotiation: if self.loose {
-                    NegotiationPolicy::Loose
-                } else {
-                    NegotiationPolicy::Strict
-                },
-                ..Default::default()
-            },
+            open,
             request: SessionRequest {
                 duration: (!duration.is_zero()).then_some(duration),
                 interval: self.interval,