fix(cli): drive single-target runs with ManagedClient

Replace the manual single-target ClientSession loops in the stream and TUI adapters with ManagedClient::start_with_subscription so the existing worker owns opening, deadline-aware pacing, receive handling, timeout polling, draining, and close.

Use bounded subscription waits for interruption and input polling, drain queued events before and after join, and report per-subscription drops without changing output, statistics, labels, summaries, warning, or peer-close policy. Add process and unit regressions for 10 ms cadence, interruption, final-event draining, TUI terminal state, and overflow visibility.

crates/irtt-cli/src/cmd/client/run.rs

@@ -9,9 +9,10 @@ use std::{
 };
 
 use irtt_client::{
-    ClientEvent, EventSubscriptionError, ManagedClientGroup, ManagedClientGroupConfig,
-    ManagedGroupCompletionPolicy, ManagedGroupEndReason, ManagedGroupEvent, ManagedTargetOutcome,
-    SubscriberConfig, SubscriberOverflow, TargetEvent,
+    ClientEvent, EventSubscriptionError, ManagedClient, ManagedClientGroup,
+    ManagedClientGroupConfig, ManagedGroupCompletionPolicy, ManagedGroupEndReason,
+    ManagedGroupEvent, ManagedTargetOutcome, SessionEndReason, SubscriberConfig,
+    SubscriberOverflow, TargetEvent,
 };
 #[cfg(all(test, feature = "stats"))]
 use irtt_client::{ClientTimestamp, PacketMeta, RttSample, SignedDuration};
@@ -28,7 +29,6 @@ use crate::shared::client::{
         peer_close_run_error, request_group_stop_once, should_print_final_summary,
         should_stop_group_on_peer_close,
     },
-    ClientSession,
 };
 
 #[cfg(feature = "stats")]
@@ -49,6 +49,8 @@ const FINITE_STATS_MEMORY_VERY_STRONG_WARNING_BYTES: u64 = GIB;
 
 const GROUP_IDLE_SLEEP: Duration = Duration::from_millis(5);
 const GROUP_COMPLETION_GRACE: Duration = Duration::from_secs(1);
+const MANAGED_EVENT_WAIT_SLICE: Duration = Duration::from_millis(20);
+const MANAGED_EVENT_CAPACITY: usize = 16_384;
 
 pub fn run_stream(
     args: ClientArgs,
@@ -103,66 +105,71 @@ pub fn run_stream(
         return Ok(());
     }
 
-    let mut session = ClientSession::connect(args.to_client_config(), continuous)?;
-
-    if is_shutdown_requested(shutdown_requested) {
-        return Ok(());
-    }
-
-    let events = session.open()?;
-    #[cfg(feature = "stats")]
-    print_events_with_stats(&mut stream_output, &events, Some(target_label), &mut stats)?;
-    #[cfg(not(feature = "stats"))]
-    print_events_with_stats(&mut stream_output, &events, Some(target_label))?;
-
+    let (session, events) = ManagedClient::start_with_subscription(
+        args.to_client_config(),
+        managed_event_subscriber_config(),
+    )?;
     let mut interrupted = false;
-    while session.should_continue(shutdown_requested) {
-        let events = session.step(shutdown_requested)?;
-        #[cfg(feature = "stats")]
-        print_events_with_stats(&mut stream_output, &events, Some(target_label), &mut stats)?;
-        #[cfg(not(feature = "stats"))]
-        print_events_with_stats(&mut stream_output, &events, Some(target_label))?;
-
+    loop {
         if is_shutdown_requested(shutdown_requested) {
             interrupted = true;
+            session.stop();
             break;
         }
 
-        session.sleep_until_next_send();
+        match events.recv_timeout(MANAGED_EVENT_WAIT_SLICE) {
+            Ok(Some(event)) => {
+                #[cfg(feature = "stats")]
+                print_events_with_stats(
+                    &mut stream_output,
+                    std::slice::from_ref(&event),
+                    Some(target_label),
+                    &mut stats,
+                )?;
+                #[cfg(not(feature = "stats"))]
+                print_events_with_stats(
+                    &mut stream_output,
+                    std::slice::from_ref(&event),
+                    Some(target_label),
+                )?;
+            }
+            Ok(None) => {}
+            Err(EventSubscriptionError::Disconnected) => break,
+        }
     }
     interrupted |= is_shutdown_requested(shutdown_requested);
 
     if interrupted {
         eprintln!("interrupted, closing session...");
-    }
-
-    if session.should_drain_final(interrupted) {
-        session.drain_final(|events| {
+        drain_single_client_events(
+            &events,
+            &mut stream_output,
+            target_label,
             #[cfg(feature = "stats")]
-            let _ =
-                print_events_with_stats(&mut stream_output, events, Some(target_label), &mut stats);
-            #[cfg(not(feature = "stats"))]
-            let _ = print_events_with_stats(&mut stream_output, events, Some(target_label));
-        })?;
+            &mut stats,
+        )?;
     }
 
-    let events = session.poll_timeouts()?;
-    #[cfg(feature = "stats")]
-    print_events_with_stats(&mut stream_output, &events, Some(target_label), &mut stats)?;
-    #[cfg(not(feature = "stats"))]
-    print_events_with_stats(&mut stream_output, &events, Some(target_label))?;
+    let outcome = session.join();
+    drain_single_client_events(
+        &events,
+        &mut stream_output,
+        target_label,
+        #[cfg(feature = "stats")]
+        &mut stats,
+    )?;
+    if let Some(warning) = dropped_event_warning(events.dropped_events(), "managed client") {
+        eprintln!("{warning}");
+    }
 
-    let events = session.close()?;
-    #[cfg(feature = "stats")]
-    print_events_with_stats(&mut stream_output, &events, Some(target_label), &mut stats)?;
-    #[cfg(not(feature = "stats"))]
-    print_events_with_stats(&mut stream_output, &events, Some(target_label))?;
     interrupted |= is_shutdown_requested(shutdown_requested);
-    let peer_close_error = peer_close_run_error(
-        continuous,
-        interrupted,
-        if session.is_peer_closed() { 1 } else { 0 },
-    );
+    let peer_close_error = outcome.as_ref().ok().and_then(|outcome| {
+        peer_close_run_error(
+            continuous,
+            interrupted,
+            u64::from(outcome.end_reason == SessionEndReason::PeerClosed),
+        )
+    });
     let print_final_summary = should_print_final_summary(continuous, interrupted);
     stream_output.print_final_summary = print_final_summary;
     stream_output.show_running_only_summary_note = continuous && interrupted && print_final_summary;
@@ -171,12 +178,59 @@ pub fn run_stream(
     #[cfg(not(feature = "stats"))]
     stream_output.print_summary()?;
     stream_output.out.flush()?;
+    if let Err(error) = outcome {
+        return Err(error.into());
+    }
     if let Some(error) = peer_close_error {
         return Err(error.into());
     }
     Ok(())
 }
 
+fn managed_event_subscriber_config() -> SubscriberConfig {
+    SubscriberConfig {
+        capacity: MANAGED_EVENT_CAPACITY,
+        // CLI output is best-effort under sustained backpressure. Dropping
+        // stale rows keeps the managed worker independent from output speed,
+        // while dropped_events() makes incomplete output visible.
+        overflow: SubscriberOverflow::DropOldest,
+    }
+}
+
+#[cfg(feature = "stats")]
+fn drain_single_client_events<W: Write>(
+    events: &irtt_client::EventSubscription,
+    stream_output: &mut StreamOutput<'_, W>,
+    target_label: &str,
+    stats: &mut StatsCollector,
+) -> io::Result<()> {
+    while let Ok(Some(event)) = events.try_recv() {
+        print_events_with_stats(
+            stream_output,
+            std::slice::from_ref(&event),
+            Some(target_label),
+            stats,
+        )?;
+    }
+    Ok(())
+}
+
+#[cfg(not(feature = "stats"))]
+fn drain_single_client_events<W: Write>(
+    events: &irtt_client::EventSubscription,
+    stream_output: &mut StreamOutput<'_, W>,
+    target_label: &str,
+) -> io::Result<()> {
+    while let Ok(Some(event)) = events.try_recv() {
+        print_events_with_stats(
+            stream_output,
+            std::slice::from_ref(&event),
+            Some(target_label),
+        )?;
+    }
+    Ok(())
+}
+
 struct StreamOutput<'a, W: Write> {
     config: OutputConfig,
     header_printed: bool,
@@ -300,7 +354,7 @@ fn run_group_stream(
         group_config,
         managed_targets,
         SubscriberConfig {
-            capacity: 16_384,
+            capacity: MANAGED_EVENT_CAPACITY,
             // CLI output is best-effort under sustained backpressure. Dropping
             // stale rows keeps continuous runs attached to the running group
             // instead of turning a full output queue into a disconnected
@@ -427,7 +481,7 @@ fn run_group_stream(
             }
         }
     }
-    if let Some(warning) = dropped_event_warning(events.dropped_events()) {
+    if let Some(warning) = dropped_event_warning(events.dropped_events(), "managed group") {
         eprintln!("{warning}");
     }
 
@@ -492,10 +546,15 @@ fn report_target_failure(target: &ManagedTargetOutcome) {
     }
 }
 
-fn dropped_event_warning(dropped_events: u64) -> Option<String> {
+fn dropped_event_warning(dropped_events: u64, source: &str) -> Option<String> {
     (dropped_events > 0).then(|| {
+        let event_word = if dropped_events == 1 {
+            "event"
+        } else {
+            "events"
+        };
         format!(
-            "irtt-rs: warning: dropped {dropped_events} managed group events; output and statistics may be incomplete"
+            "irtt-rs: warning: dropped {dropped_events} {source} {event_word}; output and statistics may be incomplete"
         )
     })
 }
@@ -654,12 +713,57 @@ mod tests {
 
     #[test]
     fn dropped_event_warning_marks_statistics_incomplete() {
-        assert_eq!(dropped_event_warning(0), None);
-        let warning = dropped_event_warning(7).unwrap();
+        assert_eq!(dropped_event_warning(0, "managed client"), None);
+        let warning = dropped_event_warning(7, "managed group").unwrap();
         assert!(warning.contains("dropped 7 managed group events"));
         assert!(warning.contains("statistics may be incomplete"));
     }
 
+    #[test]
+    fn single_client_drain_preserves_final_queue_and_surfaces_overflow() {
+        let hub = irtt_client::EventHub::new();
+        let events = hub
+            .subscribe(SubscriberConfig {
+                capacity: 1,
+                overflow: SubscriberOverflow::DropOldest,
+            })
+            .unwrap();
+        hub.publish(reply_event(1, 1_000));
+        hub.publish(reply_event(2, 2_000));
+        hub.disconnect_all();
+
+        let mut stats = StatsCollector::new(StatsConfig::finite());
+        let mut out = Vec::new();
+        {
+            let mut stream_output = StreamOutput {
+                config: output_config(
+                    crate::cmd::client::OutputFormat::Csv,
+                    Some("event,seq"),
+                    crate::cmd::client::HeaderMode::Never,
+                    false,
+                ),
+                header_printed: false,
+                print_final_summary: false,
+                show_running_only_summary_note: false,
+                out: &mut out,
+            };
+            drain_single_client_events(&events, &mut stream_output, "target", &mut stats).unwrap();
+        }
+
+        let rendered = String::from_utf8(out).unwrap();
+        assert_eq!(rendered.trim(), "echo_reply,2");
+        assert_eq!(events.dropped_events(), 1);
+        assert!(
+            dropped_event_warning(events.dropped_events(), "managed client")
+                .unwrap()
+                .contains("dropped 1 managed client event")
+        );
+        assert_eq!(
+            events.try_recv().unwrap_err(),
+            EventSubscriptionError::Disconnected
+        );
+    }
+
     #[test]
     fn output_helper_streams_and_collects_events() {
         let sent_at = test_timestamp(Duration::from_secs(1));

crates/irtt-cli/src/cmd/tui/run.rs

@@ -7,9 +7,9 @@ use std::{
 
 use crossterm::event::{self, Event, KeyCode, KeyEventKind, KeyModifiers};
 use irtt_client::{
-    EventSubscriptionError, ManagedClientGroup, ManagedClientGroupConfig,
-    ManagedGroupCompletionPolicy, ManagedGroupEndReason, ManagedGroupEvent, SubscriberConfig,
-    SubscriberOverflow,
+    EventSubscription, EventSubscriptionError, ManagedClient, ManagedClientGroup,
+    ManagedClientGroupConfig, ManagedGroupCompletionPolicy, ManagedGroupEndReason,
+    ManagedGroupEvent, SessionEndReason, SubscriberConfig, SubscriberOverflow,
 };
 
 use crate::{
@@ -17,7 +17,6 @@ use crate::{
     shared::client::{
         is_shutdown_requested,
         session::{peer_close_run_error, request_group_stop_once, should_stop_group_on_peer_close},
-        ClientSession,
     },
 };
 
@@ -27,6 +26,7 @@ const RENDER_INTERVAL: Duration = Duration::from_millis(250);
 const TUI_WAIT_SLICE: Duration = Duration::from_millis(20);
 const IDLE_SLEEP: Duration = Duration::from_millis(5);
 const GROUP_COMPLETION_GRACE: Duration = Duration::from_secs(1);
+const MANAGED_EVENT_CAPACITY: usize = 16_384;
 
 pub fn run_tui(
     args: TuiArgs,
@@ -61,7 +61,10 @@ pub fn run_tui(
         );
     }
 
-    let mut session = match ClientSession::connect(args.to_client_config(), continuous) {
+    let (session, events) = match ManagedClient::start_with_subscription(
+        args.to_client_config(),
+        managed_event_subscriber_config(),
+    ) {
         Ok(session) => session,
         Err(err) => {
             state.set_error(err.to_string());
@@ -70,43 +73,33 @@ pub fn run_tui(
         }
     };
 
-    if is_shutdown_requested(shutdown_requested) {
-        return Ok(());
-    }
-
-    let events = session.open()?;
-    state.process_events(&events);
-    render_if_due(&mut terminal, &state, &mut next_render, true)?;
-
     let mut interrupted = false;
-    // Keep this in lockstep with run_stream: send due probes, drain available
-    // replies, poll timeouts, sleep toward the next absolute send deadline,
-    // then perform the same final drain, timeout poll, and close sequence.
-    while session.should_continue(shutdown_requested) {
+    loop {
+        if is_shutdown_requested(shutdown_requested) {
+            interrupted = true;
+            session.stop();
+            break;
+        }
+
         if handle_input(&mut state, shutdown_requested)? {
             render_if_due(&mut terminal, &state, &mut next_render, true)?;
         }
         if state.quit_requested {
             interrupted = true;
+            session.stop();
             break;
         }
 
-        let events = session.step(shutdown_requested)?;
-        state.process_events(&events);
-
-        if is_shutdown_requested(shutdown_requested) {
-            interrupted = true;
-            break;
+        match events.recv_timeout(managed_tui_wait_duration(&next_render, state.paused)) {
+            Ok(Some(event)) => {
+                state.process_event(&event);
+                render_if_due(&mut terminal, &state, &mut next_render, false)?;
+            }
+            Ok(None) => {
+                render_if_due(&mut terminal, &state, &mut next_render, false)?;
+            }
+            Err(EventSubscriptionError::Disconnected) => break,
         }
-
-        render_if_due(&mut terminal, &state, &mut next_render, false)?;
-        wait_for_tui_activity(
-            session.next_send_deadline(),
-            &mut next_render,
-            &mut state,
-            &mut terminal,
-            shutdown_requested,
-        )?;
     }
     interrupted |= is_shutdown_requested(shutdown_requested);
 
@@ -115,29 +108,32 @@ pub fn run_tui(
         render_if_due(&mut terminal, &state, &mut next_render, true)?;
     }
 
-    if session.should_drain_final(interrupted) {
+    if interrupted {
         state.set_status(TuiStatus::Draining);
-        let mut drain_render = Instant::now();
-        session.drain_final(|events| {
-            state.process_events(events);
-            let _ = render_if_due(&mut terminal, &state, &mut drain_render, false);
-        })?;
+        drain_single_tui_events(&events, &mut state);
         render_if_due(&mut terminal, &state, &mut next_render, true)?;
     }
 
-    let events = session.poll_timeouts()?;
-    state.process_events(&events);
-
     state.set_status(TuiStatus::Closing);
     render_if_due(&mut terminal, &state, &mut next_render, true)?;
 
-    let events = session.close()?;
-    state.process_events(&events);
+    let outcome = session.join();
+    drain_single_tui_events(&events, &mut state);
+    state.mark_dropped_client_events(events.dropped_events());
+    let outcome = match outcome {
+        Ok(outcome) => outcome,
+        Err(err) => {
+            state.set_error(err.to_string());
+            render_if_due(&mut terminal, &state, &mut next_render, true)?;
+            return Err(Box::new(err));
+        }
+    };
+
     interrupted |= is_shutdown_requested(shutdown_requested);
     if let Some(error) = peer_close_run_error(
         continuous,
         interrupted,
-        if session.is_peer_closed() { 1 } else { 0 },
+        u64::from(outcome.end_reason == SessionEndReason::PeerClosed),
     ) {
         state.set_run_error(error.clone());
         render_if_due(&mut terminal, &state, &mut next_render, true)?;
@@ -175,7 +171,7 @@ fn run_group_tui(
         group_config,
         managed_targets,
         SubscriberConfig {
-            capacity: 16_384,
+            capacity: MANAGED_EVENT_CAPACITY,
             overflow: SubscriberOverflow::DropOldest,
         },
     )?;
@@ -272,7 +268,7 @@ fn run_group_tui(
             }
         }
     }
-    state.mark_dropped_events(events.dropped_events());
+    state.mark_dropped_group_events(events.dropped_events());
     for target in &outcome.targets {
         if terminal_targets.insert(target.id.as_str().to_owned()) {
             state.process_target_outcome(target);
@@ -451,6 +447,28 @@ fn render_if_due(
     Ok(())
 }
 
+fn managed_event_subscriber_config() -> SubscriberConfig {
+    SubscriberConfig {
+        capacity: MANAGED_EVENT_CAPACITY,
+        overflow: SubscriberOverflow::DropOldest,
+    }
+}
+
+fn drain_single_tui_events(events: &EventSubscription, state: &mut TuiState) {
+    while let Ok(Some(event)) = events.try_recv() {
+        state.process_event(&event);
+    }
+}
+
+fn managed_tui_wait_duration(next_render: &Instant, paused: bool) -> Duration {
+    let render_wait = if paused {
+        TUI_WAIT_SLICE
+    } else {
+        next_render.saturating_duration_since(Instant::now())
+    };
+    render_wait.min(TUI_WAIT_SLICE)
+}
+
 fn wait_for_tui_activity(
     next_send_deadline: Option<Instant>,
     next_render: &mut Instant,
@@ -552,4 +570,30 @@ mod tests {
             &irtt_client::ManagedTargetEndReason::PeerClosed
         ));
     }
+
+    #[test]
+    fn single_target_managed_drain_consumes_queued_terminal_event() {
+        let hub = irtt_client::EventHub::new();
+        let events = hub
+            .subscribe(SubscriberConfig {
+                capacity: 4,
+                overflow: SubscriberOverflow::DropOldest,
+            })
+            .unwrap();
+        hub.publish(irtt_client::ClientEvent::SessionClosed {
+            remote: "127.0.0.1:2112".parse().unwrap(),
+            token: 7,
+            at: irtt_client::ClientTimestamp::now(),
+        });
+        hub.disconnect_all();
+        let mut state = TuiState::new(TuiConfig::default());
+
+        drain_single_tui_events(&events, &mut state);
+
+        assert_eq!(state.status(), TuiStatus::Complete);
+        assert_eq!(
+            events.try_recv().unwrap_err(),
+            EventSubscriptionError::Disconnected
+        );
+    }
 }

crates/irtt-cli/src/cmd/tui/ui.rs

@@ -140,12 +140,6 @@ impl TuiState {
         }
     }
 
-    pub(super) fn process_events(&mut self, events: &[ClientEvent]) {
-        for event in events {
-            self.process_event(event);
-        }
-    }
-
     pub(super) fn process_event(&mut self, event: &ClientEvent) {
         self.process_event_for_target(0, event);
     }
@@ -388,13 +382,31 @@ impl TuiState {
         self.status = status;
     }
 
-    pub(super) fn mark_dropped_events(&mut self, dropped_events: u64) {
+    #[cfg(test)]
+    pub(super) fn status(&self) -> TuiStatus {
+        self.status
+    }
+
+    pub(super) fn mark_dropped_client_events(&mut self, dropped_events: u64) {
+        self.mark_dropped_events(dropped_events, "managed client");
+    }
+
+    pub(super) fn mark_dropped_group_events(&mut self, dropped_events: u64) {
+        self.mark_dropped_events(dropped_events, "managed group");
+    }
+
+    fn mark_dropped_events(&mut self, dropped_events: u64, source: &str) {
         if dropped_events == 0 {
             return;
         }
         self.dropped_events = dropped_events;
+        let event_word = if dropped_events == 1 {
+            "event"
+        } else {
+            "events"
+        };
         let warning =
-            format!("dropped {dropped_events} managed group events; statistics may be incomplete");
+            format!("dropped {dropped_events} {source} {event_word}; statistics may be incomplete");
         self.last_warning = Some(warning.clone());
         self.push_event(format!("warning {warning}"));
     }
@@ -2497,7 +2509,7 @@ mod tests {
     fn dropped_events_mark_tui_statistics_incomplete() {
         let mut state = TuiState::default();
 
-        state.mark_dropped_events(9);
+        state.mark_dropped_group_events(9);
 
         assert_eq!(state.dropped_events, 9);
         assert!(state
@@ -2510,6 +2522,19 @@ mod tests {
             .is_some_and(|event| event.contains("dropped 9 managed group events")));
     }
 
+    #[test]
+    fn dropped_single_client_events_are_visible() {
+        let mut state = TuiState::default();
+
+        state.mark_dropped_client_events(3);
+
+        assert_eq!(state.dropped_events, 3);
+        assert!(state
+            .recent_events
+            .back()
+            .is_some_and(|event| event.contains("dropped 3 managed client events")));
+    }
+
     #[test]
     fn recent_event_buffer_stays_bounded() {
         let mut state = TuiState::default();

crates/irtt-cli/src/shared/client/mod.rs

@@ -8,7 +8,7 @@ pub use args::{
     ClockArg, CommonClientArgs, ReceivedStatsArg, TimestampArg,
 };
 pub use config::{expected_probe_count, DEFAULT_RECV_TIMEOUT};
-pub use session::{final_drain_duration, is_shutdown_requested, ClientSession, RECV_BUDGET};
+pub use session::is_shutdown_requested;
 pub use targets::{
     parse_labelled_target, resolved_managed_targets, target_specs, GroupPacingArg,
     LabelledTargetArg, ResolvedTarget, TargetSpec,

crates/irtt-cli/src/shared/client/session.rs

@@ -1,146 +1,11 @@
-use std::{
-    sync::atomic::{AtomicBool, Ordering},
-    thread,
-    time::{Duration, Instant},
-};
+use std::sync::atomic::{AtomicBool, Ordering};
 
-use irtt_client::{
-    Client, ClientConfig, ClientEvent, ManagedTargetEndReason, OpenOutcome, RecvBudget,
-};
-
-pub const RECV_BUDGET: RecvBudget = RecvBudget { max_packets: 16 };
-const MAX_FINAL_DRAIN: Duration = Duration::from_secs(30);
-const IDLE_SLEEP: Duration = Duration::from_millis(5);
-const MAX_SLEEP: Duration = Duration::from_millis(20);
-
-pub struct ClientSession {
-    client: Client,
-    continuous: bool,
-}
-
-impl ClientSession {
-    pub fn connect(
-        config: ClientConfig,
-        continuous: bool,
-    ) -> Result<Self, irtt_client::ClientError> {
-        Ok(Self {
-            client: Client::connect(config)?,
-            continuous,
-        })
-    }
-
-    pub fn open(&mut self) -> Result<Vec<ClientEvent>, irtt_client::ClientError> {
-        Ok(vec![open_event(&self.client.open()?).clone()])
-    }
-
-    pub fn step(
-        &mut self,
-        shutdown_requested: &AtomicBool,
-    ) -> Result<Vec<ClientEvent>, irtt_client::ClientError> {
-        let mut events = Vec::new();
-        if should_send_probe(self.client.next_send_deadline(), shutdown_requested) {
-            events.extend(self.client.send_probe()?);
-        }
-        events.extend(self.client.recv_available(RECV_BUDGET)?);
-        if self.client.is_peer_closed() {
-            return Ok(events);
-        }
-        events.extend(self.client.poll_timeouts()?);
-        Ok(events)
-    }
-
-    pub fn should_continue(&self, shutdown_requested: &AtomicBool) -> bool {
-        !is_shutdown_requested(shutdown_requested)
-            && !self.client.is_peer_closed()
-            && (self.continuous || self.client.next_send_deadline().is_some())
-    }
-
-    pub fn should_drain_final(&self, interrupted: bool) -> bool {
-        should_drain_final(self.continuous, interrupted)
-    }
-
-    pub fn drain_final<F>(&mut self, mut on_events: F) -> Result<(), irtt_client::ClientError>
-    where
-        F: FnMut(&[ClientEvent]),
-    {
-        let deadline = Instant::now() + final_drain_duration(self.client.probe_timeout());
-        loop {
-            if self.client.is_peer_closed() {
-                break;
-            }
-
-            let mut received = false;
-
-            let events = self.client.recv_available(RECV_BUDGET)?;
-            received |= !events.is_empty();
-            on_events(&events);
-
-            if self.client.is_peer_closed() {
-                break;
-            }
-
-            let events = self.client.poll_timeouts()?;
-            received |= !events.is_empty();
-            on_events(&events);
-
-            if self.client.is_run_complete() || Instant::now() >= deadline {
-                break;
-            }
-
-            if !received {
-                thread::sleep(IDLE_SLEEP);
-            }
-        }
-        Ok(())
-    }
-
-    pub fn poll_timeouts(&mut self) -> Result<Vec<ClientEvent>, irtt_client::ClientError> {
-        if self.client.is_peer_closed() {
-            return Ok(vec![]);
-        }
-        self.client.poll_timeouts()
-    }
-
-    pub fn close(&mut self) -> Result<Vec<ClientEvent>, irtt_client::ClientError> {
-        if self.client.is_peer_closed() {
-            return Ok(vec![]);
-        }
-        self.client.close()
-    }
-
-    pub fn is_peer_closed(&self) -> bool {
-        self.client.is_peer_closed()
-    }
-
-    pub fn next_send_deadline(&self) -> Option<Instant> {
-        self.client.next_send_deadline()
-    }
-
-    pub fn probe_timeout(&self) -> Duration {
-        self.client.probe_timeout()
-    }
-
-    pub fn sleep_until_next_send(&self) {
-        let sleep_for = match self.next_send_deadline() {
-            Some(deadline) => deadline
-                .saturating_duration_since(Instant::now())
-                .min(MAX_SLEEP),
-            None => Duration::from_millis(1),
-        };
-        if !sleep_for.is_zero() {
-            thread::sleep(sleep_for);
-        }
-    }
-}
+use irtt_client::ManagedTargetEndReason;
 
 pub fn is_shutdown_requested(shutdown_requested: &AtomicBool) -> bool {
     shutdown_requested.load(Ordering::Relaxed)
 }
 
-pub fn should_drain_final(continuous: bool, interrupted: bool) -> bool {
-    !continuous || interrupted
-}
-
 pub fn should_print_final_summary(continuous: bool, interrupted: bool) -> bool {
     !continuous || interrupted
 }
@@ -180,67 +45,9 @@ pub fn request_group_stop_once(stop_requested: &mut bool) -> bool {
     true
 }
 
-pub fn final_drain_duration(probe_timeout: Duration) -> Duration {
-    probe_timeout.min(MAX_FINAL_DRAIN)
-}
-
-fn should_send_probe(next_send_deadline: Option<Instant>, shutdown_requested: &AtomicBool) -> bool {
-    !is_shutdown_requested(shutdown_requested)
-        && next_send_deadline.is_some_and(|deadline| deadline <= Instant::now())
-}
-
-fn open_event(outcome: &OpenOutcome) -> &ClientEvent {
-    match outcome {
-        OpenOutcome::Started { event, .. } | OpenOutcome::NoTestCompleted { event, .. } => event,
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
-    use irtt_proto::{
-        echo_packet_len,
-        flags::{self, FLAG_OPEN, FLAG_REPLY},
-        layout::PacketLayout,
-        Clock, Params, ReceivedStats, StampAt, TimestampFields, MAGIC, PROTOCOL_VERSION,
-    };
-    use std::{
-        net::{SocketAddr, UdpSocket},
-        thread::JoinHandle,
-    };
-
-    const TOKEN: u64 = 0x1234_5678_90ab_cdef;
-
-    struct FakeServer {
-        addr: SocketAddr,
-        done: JoinHandle<()>,
-    }
-
-    impl FakeServer {
-        fn join(self) {
-            self.done.join().unwrap();
-        }
-    }
-
-    #[test]
-    fn final_drain_uses_capped_probe_timeout() {
-        assert_eq!(
-            final_drain_duration(Duration::from_secs(4)),
-            Duration::from_secs(4)
-        );
-        assert_eq!(
-            final_drain_duration(Duration::from_secs(60)),
-            Duration::from_secs(30)
-        );
-    }
-
-    #[test]
-    fn should_drain_final_for_finite_or_interrupted_runs() {
-        assert!(should_drain_final(false, false));
-        assert!(should_drain_final(false, true));
-        assert!(should_drain_final(true, true));
-        assert!(!should_drain_final(true, false));
-    }
 
     #[test]
     fn peer_close_run_error_is_run_mode_and_interruption_aware() {
@@ -284,172 +91,4 @@ mod tests {
         assert!(request_group_stop_once(&mut stop_requested));
         assert!(!request_group_stop_once(&mut stop_requested));
     }
-
-    #[test]
-    fn peer_close_followed_by_session_cleanup_is_successful() {
-        let params = test_params(None, Duration::from_millis(10));
-        let server = start_peer_close_server(params);
-        let mut session = ClientSession::connect(config(server.addr, None), true).unwrap();
-        let shutdown_requested = AtomicBool::new(false);
-
-        assert!(matches!(
-            session.open().unwrap().as_slice(),
-            [ClientEvent::SessionStarted { .. }]
-        ));
-
-        let events = session.step(&shutdown_requested).unwrap();
-        assert!(events
-            .iter()
-            .any(|event| matches!(event, ClientEvent::EchoReply { .. })));
-        assert!(events
-            .iter()
-            .any(|event| matches!(event, ClientEvent::SessionClosed { .. })));
-        assert!(!session.should_continue(&shutdown_requested));
-        assert!(session.is_peer_closed());
-
-        session.drain_final(|_| {}).unwrap();
-        assert!(session.poll_timeouts().unwrap().is_empty());
-        assert!(session.close().unwrap().is_empty());
-        server.join();
-    }
-
-    fn config(addr: SocketAddr, duration: Option<Duration>) -> ClientConfig {
-        ClientConfig {
-            server_addr: addr.to_string(),
-            duration,
-            interval: Duration::from_millis(10),
-            open_timeouts: vec![Duration::from_millis(200)],
-            probe_timeout: Duration::from_millis(20),
-            socket_config: irtt_client::SocketConfig {
-                recv_timeout: Some(Duration::from_millis(200)),
-                ..Default::default()
-            },
-            ..ClientConfig::default()
-        }
-    }
-
-    fn test_params(duration: Option<Duration>, interval: Duration) -> Params {
-        Params {
-            protocol_version: PROTOCOL_VERSION,
-            duration_ns: duration.map_or(0, test_duration_ns_i64),
-            interval_ns: test_duration_ns_i64(interval),
-            length: 0,
-            received_stats: ReceivedStats::Both,
-            stamp_at: StampAt::Both,
-            clock: Clock::Both,
-            dscp: 0,
-            server_fill: None,
-        }
-    }
-
-    fn test_duration_ns_i64(duration: Duration) -> i64 {
-        i64::try_from(duration.as_nanos()).expect("test duration fits i64 nanoseconds")
-    }
-
-    fn start_peer_close_server(params: Params) -> FakeServer {
-        let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
-        let addr = socket.local_addr().unwrap();
-        let done = thread::spawn(move || {
-            let (_, peer) = recv_request(&socket);
-            socket
-                .send_to(&open_reply(FLAG_OPEN | FLAG_REPLY, TOKEN, &params), peer)
-                .unwrap();
-
-            let (packet, peer) = recv_request(&socket);
-            let seq = u32::from_le_bytes(packet[12..16].try_into().unwrap());
-            socket
-                .send_to(
-                    &echo_reply_packet(
-                        TOKEN,
-                        seq,
-                        &params,
-                        &TimestampFields::default(),
-                        FLAG_REPLY | flags::FLAG_CLOSE,
-                    ),
-                    peer,
-                )
-                .unwrap();
-
-            socket
-                .set_read_timeout(Some(Duration::from_millis(250)))
-                .unwrap();
-            if let Some((packet, _)) = recv_request_timeout(&socket) {
-                panic!(
-                    "session cleanup must not send any packet after peer close; flags={:?} len={}",
-                    packet.get(3).copied(),
-                    packet.len()
-                );
-            }
-        });
-        FakeServer { addr, done }
-    }
-
-    fn recv_request(socket: &UdpSocket) -> (Vec<u8>, SocketAddr) {
-        let mut buf = [0_u8; 2048];
-        let (size, peer) = socket.recv_from(&mut buf).unwrap();
-        (buf[..size].to_vec(), peer)
-    }
-
-    fn recv_request_timeout(socket: &UdpSocket) -> Option<(Vec<u8>, SocketAddr)> {
-        let mut buf = [0_u8; 2048];
-        socket
-            .recv_from(&mut buf)
-            .ok()
-            .map(|(size, peer)| (buf[..size].to_vec(), peer))
-    }
-
-    fn open_reply(flags: u8, token: u64, params: &Params) -> Vec<u8> {
-        let mut packet = Vec::new();
-        packet.extend_from_slice(&MAGIC);
-        packet.push(flags);
-        packet.extend_from_slice(&token.to_le_bytes());
-        packet.extend_from_slice(&params.encode());
-        packet
-    }
-
-    fn echo_reply_packet(
-        token: u64,
-        seq: u32,
-        params: &Params,
-        timestamps: &TimestampFields,
-        flags: u8,
-    ) -> Vec<u8> {
-        let layout = PacketLayout::echo(false, params);
-        let packet_len = echo_packet_len(false, params)
-            .expect("session test params must have a non-negative packet length");
-        let mut packet = Vec::with_capacity(packet_len);
-
-        packet.extend_from_slice(&MAGIC);
-        packet.push(flags);
-        packet.extend_from_slice(&token.to_le_bytes());
-        packet.extend_from_slice(&seq.to_le_bytes());
-
-        if layout.recv_count {
-            packet.extend_from_slice(&42_u32.to_le_bytes());
-        }
-        if layout.recv_window {
-            packet.extend_from_slice(&0_u64.to_le_bytes());
-        }
-        if layout.recv_wall {
-            packet.extend_from_slice(&timestamps.recv_wall.unwrap_or(0).to_le_bytes());
-        }
-        if layout.recv_mono {
-            packet.extend_from_slice(&timestamps.recv_mono.unwrap_or(0).to_le_bytes());
-        }
-        if layout.midpoint_wall {
-            packet.extend_from_slice(&timestamps.midpoint_wall.unwrap_or(0).to_le_bytes());
-        }
-        if layout.midpoint_mono {
-            packet.extend_from_slice(&timestamps.midpoint_mono.unwrap_or(0).to_le_bytes());
-        }
-        if layout.send_wall {
-            packet.extend_from_slice(&timestamps.send_wall.unwrap_or(0).to_le_bytes());
-        }
-        if layout.send_mono {
-            packet.extend_from_slice(&timestamps.send_mono.unwrap_or(0).to_le_bytes());
-        }
-
-        packet.resize(packet_len, 0);
-        packet
-    }
 }

crates/irtt-cli/tests/client_multi_target.rs

@@ -48,6 +48,19 @@ impl InterruptibleFakeServer {
     }
 }
 
+struct ObservedFakeServer {
+    addr: SocketAddr,
+    probes: mpsc::Receiver<Instant>,
+    done: JoinHandle<()>,
+}
+
+impl ObservedFakeServer {
+    fn join(self) -> Vec<Instant> {
+        self.done.join().unwrap();
+        self.probes.try_iter().collect()
+    }
+}
+
 #[test]
 fn list_columns_succeeds_without_target() {
     let output = Command::new(env!("CARGO_BIN_EXE_irtt-cli"))
@@ -143,6 +156,56 @@ fn single_target_custom_target_column_renders_positional_label() {
     );
 }
 
+#[test]
+fn single_target_ten_millisecond_cadence_uses_managed_deadlines() {
+    let duration = Duration::from_millis(90);
+    let interval = Duration::from_millis(10);
+    let server = start_observed_echo_server(test_params(Some(duration), interval));
+    let mut command = Command::new(env!("CARGO_BIN_EXE_irtt-cli"));
+    command.args([
+        "--duration",
+        "90ms",
+        "--interval",
+        "10ms",
+        "--format",
+        "csv",
+        "--columns",
+        "event,seq",
+        "--header",
+        "never",
+        &server.addr.to_string(),
+    ]);
+
+    let output = run_with_timeout(command, Duration::from_secs(3));
+    let probe_times = server.join();
+
+    assert!(
+        output.status.success(),
+        "status={:?}\nstderr={}",
+        output.status.code(),
+        String::from_utf8_lossy(&output.stderr)
+    );
+    let stdout = String::from_utf8(output.stdout).unwrap();
+    let sent_rows = stdout
+        .lines()
+        .filter(|line| line.starts_with("echo_sent,"))
+        .count();
+    assert!(
+        (7..=11).contains(&sent_rows),
+        "expected about 9 probes at 10 ms cadence, got {sent_rows}\n{stdout}"
+    );
+    assert_eq!(sent_rows, probe_times.len(), "{stdout}");
+    assert!(
+        !probe_times
+            .windows(3)
+            .any(|window| window[2].duration_since(window[0]) < Duration::from_millis(5)),
+        "managed pacing emitted a catch-up burst: {probe_times:?}"
+    );
+    assert!(stdout
+        .lines()
+        .any(|line| line.starts_with("session_closed,")));
+}
+
 #[test]
 fn finite_single_target_peer_close_exits_successfully() {
     let server = start_peer_close_server(test_params(
@@ -213,6 +276,57 @@ fn continuous_single_target_peer_close_exits_nonzero() {
     assert!(stderr.contains("peer closure"), "{stderr}");
 }
 
+#[cfg(unix)]
+#[test]
+fn continuous_single_target_interruption_drains_final_events_and_succeeds() {
+    let params = test_params(None, Duration::from_millis(10));
+    let server = start_interruptible_echo_server(params);
+    let mut command = Command::new(env!("CARGO_BIN_EXE_irtt-cli"));
+    command.args([
+        "--duration",
+        "0s",
+        "--interval",
+        "10ms",
+        "--format",
+        "csv",
+        "--columns",
+        "event,seq",
+        "--header",
+        "never",
+        &server.addr.to_string(),
+    ]);
+
+    let child = command
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    server.wait_until_opened();
+    thread::sleep(Duration::from_millis(50));
+    let signal_status = Command::new("kill")
+        .args(["-INT", &child.id().to_string()])
+        .status()
+        .unwrap();
+    assert!(signal_status.success());
+    let output = wait_with_timeout(child, Duration::from_secs(2));
+    server.join();
+
+    assert!(
+        output.status.success(),
+        "status={:?}\nstderr={}",
+        output.status.code(),
+        String::from_utf8_lossy(&output.stderr)
+    );
+    let stdout = String::from_utf8(output.stdout).unwrap();
+    let stderr = String::from_utf8(output.stderr).unwrap();
+    assert!(stdout.lines().any(|line| line.starts_with("echo_reply,")));
+    assert!(stdout
+        .lines()
+        .any(|line| line.starts_with("session_closed,")));
+    assert!(stderr.contains("interrupted, closing session"), "{stderr}");
+    assert!(!stderr.contains("peer closure"), "{stderr}");
+}
+
 #[test]
 fn multi_target_csv_emits_rows_for_both_labels() {
     let params = test_params(Some(Duration::from_millis(40)), Duration::from_millis(10));
@@ -658,6 +772,44 @@ fn start_echo_server_inner(
     FakeServer { addr, done }
 }
 
+fn start_observed_echo_server(params: Params) -> ObservedFakeServer {
+    let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
+    socket
+        .set_read_timeout(Some(Duration::from_secs(2)))
+        .unwrap();
+    let addr = socket.local_addr().unwrap();
+    let (probe_tx, probes) = mpsc::channel();
+    let done = thread::spawn(move || {
+        let (_, peer) = recv_request(&socket);
+        socket
+            .send_to(&open_reply(FLAG_OPEN | FLAG_REPLY, TOKEN, &params), peer)
+            .unwrap();
+
+        loop {
+            let (packet, peer) = recv_request(&socket);
+            let flags = packet[3];
+            if flags & FLAG_CLOSE != 0 {
+                break;
+            }
+            probe_tx.send(Instant::now()).unwrap();
+            let seq = u32::from_le_bytes(packet[12..16].try_into().unwrap());
+            socket
+                .send_to(
+                    &echo_reply_packet(
+                        TOKEN,
+                        seq,
+                        &params,
+                        &TimestampFields::default(),
+                        FLAG_REPLY,
+                    ),
+                    peer,
+                )
+                .unwrap();
+        }
+    });
+    ObservedFakeServer { addr, probes, done }
+}
+
 fn start_interruptible_echo_server(params: Params) -> InterruptibleFakeServer {
     let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
     socket