wingfoil 6.0.5

//! Typed-parser Aeron subscriber nodes.
//!
//! Backs [`aeron_sub_fragment`](super::aeron_sub_fragment). The typed-parser
//! surface exposes Aeron's per-fragment header (`position`, `session_id`,
//! `stream_id`) and lets parsers signal recoverable errors via
//! [`TransportError`] instead of collapsing "valid but skip" and "malformed"
//! into a single `None`.
//!
//! # Two structs, not one enum
//!
//! Spin and threaded modes live as two distinct types
//! ([`AeronSpinSubFragmentNode`] and the `build_threaded` factory). The split
//! keeps `cycle()` bodies linear (the spin variant polls inline; the threaded
//! variant delegates to
//! [`ReceiverStream`](crate::nodes::receiver::ReceiverStream)). The
//! status-aware threaded variant ([`build_threaded_with_status`]) multiplexes
//! data and lifecycle status over the single receiver channel via
//! [`AeronItem`], so the two shapes diverge further — abstraction over them is
//! an explicit non-goal.

use crate::adapters::aeron::buffer::FragmentBuffer;
use crate::adapters::aeron::error::TransportError;
use crate::adapters::aeron::status::AeronStatus;
use crate::adapters::aeron::status_stream::AeronStatusStream;
use crate::adapters::aeron::transport::AeronSubscriberBackend;
use crate::channel::{ChannelSender, Message};
use crate::nodes::receiver::ReceiverStream;
use crate::{
    Burst, Element, GraphState, IntoStream, MutableNode, Stream, StreamPeekRef, UpStreams,
};
use std::cell::RefCell;
use std::rc::Rc;
use std::sync::{
    Arc, Mutex,
    atomic::{AtomicBool, Ordering},
};
use std::time::Duration;
use tinyvec::TinyVec;

// ---------------------------------------------------------------------------
// AeronSpinSubFragmentNode<T, F, B>
// ---------------------------------------------------------------------------

/// Busy-spin typed-parser Aeron subscriber node.
///
/// Polls Aeron via [`AeronSubscriberBackend::poll_fragments`] inside
/// `cycle()` on the graph thread. Parser errors are logged and dropped — a
/// malformed fragment never aborts the cycle (NFR5 zero-stopping rule).
pub(crate) struct AeronSpinSubFragmentNode<T, F, B>
where
    T: Element,
    F: FnMut(&FragmentBuffer<'_>) -> Result<Option<T>, TransportError>,
    B: AeronSubscriberBackend,
{
    backend: B,
    parser: F,
    value: Burst<T>,
    status: Option<Rc<RefCell<AeronStatusStream>>>,
}

impl<T, F, B> AeronSpinSubFragmentNode<T, F, B>
where
    T: Element,
    F: FnMut(&FragmentBuffer<'_>) -> Result<Option<T>, TransportError>,
    B: AeronSubscriberBackend,
{
    #[must_use]
    pub(crate) fn new(backend: B, parser: F) -> Self {
        Self {
            backend,
            parser,
            value: Burst::new(),
            status: None,
        }
    }

    /// Construct a spin subscriber node that records lifecycle transitions
    /// onto the supplied reactive [`AeronStatusStream`].
    ///
    /// The status is derived after each successful poll from the backend's
    /// `is_closed` / `is_connected` flags. `Closed` is checked first
    /// (terminal); otherwise `Connected` iff the subscription has at least
    /// one publication, else `Disconnected`. A poll error short-circuits the
    /// cycle before the status is recorded.
    #[must_use]
    pub(crate) fn with_status(
        backend: B,
        parser: F,
        status: Rc<RefCell<AeronStatusStream>>,
    ) -> Self {
        Self {
            backend,
            parser,
            value: Burst::new(),
            status: Some(status),
        }
    }
}

impl<T, F, B> MutableNode for AeronSpinSubFragmentNode<T, F, B>
where
    T: Element,
    F: FnMut(&FragmentBuffer<'_>) -> Result<Option<T>, TransportError> + 'static,
    B: AeronSubscriberBackend,
{
    fn cycle(&mut self, _state: &mut GraphState) -> anyhow::Result<bool> {
        self.value.clear();
        if let Some(status) = &self.status {
            status.borrow_mut().clear();
        }
        let parser = &mut self.parser;
        let value = &mut self.value;
        self.backend
            .poll_fragments(&mut |frag| match parser(frag) {
                Ok(Some(v)) => value.push(v),
                Ok(None) => {}
                Err(e) => log::warn!(
                    "aeron sub: parser dropped fragment at position {}: {e}",
                    frag.position()
                ),
            })?;
        let transition = if let Some(status) = &self.status {
            let new_status = if self.backend.is_closed() {
                AeronStatus::Closed
            } else if self.backend.is_connected() {
                AeronStatus::Connected
            } else {
                AeronStatus::Disconnected
            };
            status.borrow_mut().record(new_status)
        } else {
            false
        };
        // Tick when fragments arrived OR a status transition was recorded, so
        // the status node (our active downstream) is scheduled to forward it.
        Ok(!self.value.is_empty() || transition)
    }

    fn start(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        // Always poll every graph cycle regardless of upstream activity.
        state.always_callback();
        Ok(())
    }

    fn upstreams(&self) -> UpStreams {
        UpStreams::none()
    }
}

impl<T, F, B> StreamPeekRef<Burst<T>> for AeronSpinSubFragmentNode<T, F, B>
where
    T: Element,
    F: FnMut(&FragmentBuffer<'_>) -> Result<Option<T>, TransportError> + 'static,
    B: AeronSubscriberBackend,
{
    fn peek_ref(&self) -> &Burst<T> {
        &self.value
    }
}

// ---------------------------------------------------------------------------
// Threaded burst node
// ---------------------------------------------------------------------------

/// Wraps [`ReceiverStream`] to add a cooperative stop signal for the
/// background polling thread (parallel to `sub_threaded::ThreadedAeronNode`).
struct ThreadedAeronFragmentNode<T: Element + Send> {
    inner: ReceiverStream<T>,
    stop_flag: Arc<AtomicBool>,
}

impl<T: Element + Send> MutableNode for ThreadedAeronFragmentNode<T> {
    fn cycle(&mut self, state: &mut GraphState) -> anyhow::Result<bool> {
        self.inner.cycle(state)
    }

    fn upstreams(&self) -> UpStreams {
        self.inner.upstreams()
    }

    fn setup(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.inner.setup(state)
    }

    fn start(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.inner.start(state)
    }

    fn stop(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.stop_flag.store(true, Ordering::Relaxed);
        self.inner.stop(state).ok();
        Ok(())
    }

    fn teardown(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.inner.teardown(state)
    }
}

impl<T: Element + Send> StreamPeekRef<TinyVec<[T; 1]>> for ThreadedAeronFragmentNode<T> {
    fn peek_ref(&self) -> &TinyVec<[T; 1]> {
        self.inner.peek_ref()
    }
}

/// Build a threaded typed-parser Aeron subscriber stream.
///
/// Mirrors [`super::sub_threaded::build`] but uses the typed-parser /
/// typed-header [`AeronSubscriberBackend::poll_fragments`] surface and the
/// `Result<Option<T>, TransportError>` parser signature.
pub(crate) fn build_threaded<T, F, B>(backend: B, parser: F) -> Rc<dyn Stream<Burst<T>>>
where
    T: Element + Send,
    F: FnMut(&FragmentBuffer<'_>) -> Result<Option<T>, TransportError> + Send + 'static,
    B: AeronSubscriberBackend,
{
    let stop_flag = Arc::new(AtomicBool::new(false));
    let stop_thread = stop_flag.clone();

    let state = Mutex::new(Some((backend, parser)));
    let inner = ReceiverStream::new(
        move |sender: ChannelSender<T>, _stop: Arc<AtomicBool>| {
            let mut state_guard = state.lock().expect("state lock poisoned");
            let (mut backend, mut parser) = state_guard
                .take()
                .expect("threaded aeron burst closure called more than once");
            drop(state_guard);

            let mut idle_count = 0u32;
            loop {
                if stop_thread.load(Ordering::Relaxed) {
                    return Ok(());
                }
                let count = backend.poll_fragments(&mut |frag| match parser(frag) {
                    Ok(Some(v)) => {
                        let _ = sender.send_message(Message::RealtimeValue(v));
                    }
                    Ok(None) => {}
                    Err(e) => log::warn!(
                        "aeron sub: parser dropped fragment at position {}: {e}",
                        frag.position()
                    ),
                })?;

                if count == 0 {
                    idle_count = (idle_count + 1).min(20);
                    let micros = 1u64 << idle_count.min(10);
                    std::thread::sleep(Duration::from_micros(micros));
                } else {
                    idle_count = 0;
                }
            }
        },
        true,
    );

    ThreadedAeronFragmentNode { inner, stop_flag }.into_stream()
}

// ---------------------------------------------------------------------------
// Threaded status-aware burst node
// ---------------------------------------------------------------------------

/// Channel payload for the status-aware threaded subscriber.
///
/// The background poll thread multiplexes two kinds of event over the single
/// [`ReceiverStream`] channel: decoded data values and lifecycle-status
/// transitions. Carrying both in one enum keeps status **ordered in-band** with
/// the data that surrounds it (a `Connected` transition is delivered before the
/// fragments that followed it) and reuses the existing channel/notifier machinery
/// rather than adding a second channel.
#[derive(Debug, Clone)]
enum AeronItem<T> {
    /// A decoded data fragment.
    Data(T),
    /// A lifecycle-status transition derived from the backend after a poll.
    Status(AeronStatus),
}

// `Element` requires `Default`; the value is never observed (it only satisfies
// the `TinyVec` backing-array bound), so a default `Data` is fine.
impl<T: Default> Default for AeronItem<T> {
    fn default() -> Self {
        AeronItem::Data(T::default())
    }
}

/// Status-aware threaded subscriber node.
///
/// Wraps a [`ReceiverStream<AeronItem<T>>`] whose background thread sends both
/// data and status over one channel. Each `cycle()` drains the channel, routes
/// [`AeronItem::Data`] into the node's `Burst<T>` output and replays each
/// [`AeronItem::Status`] transition into the shared [`AeronStatusStream`] — the
/// exact `clear()` / `record()` contract the spin node uses, so the status node
/// (wired as our active downstream) forwards transitions identically.
struct ThreadedAeronStatusFragmentNode<T: Element + Send> {
    inner: ReceiverStream<AeronItem<T>>,
    value: Burst<T>,
    status: Rc<RefCell<AeronStatusStream>>,
    stop_flag: Arc<AtomicBool>,
}

impl<T: Element + Send> MutableNode for ThreadedAeronStatusFragmentNode<T> {
    fn cycle(&mut self, state: &mut GraphState) -> anyhow::Result<bool> {
        self.value.clear();
        self.status.borrow_mut().clear();
        // Drain the channel into the inner receiver's burst, then demux it.
        self.inner.cycle(state)?;
        let mut transition = false;
        for item in self.inner.peek_ref().iter() {
            match item {
                AeronItem::Data(v) => self.value.push(v.clone()),
                AeronItem::Status(s) => {
                    transition |= self.status.borrow_mut().record(*s);
                }
            }
        }
        // Tick when data arrived OR a status transition was recorded, so the
        // status node (our active downstream) is scheduled to forward it.
        Ok(!self.value.is_empty() || transition)
    }

    fn upstreams(&self) -> UpStreams {
        self.inner.upstreams()
    }

    fn setup(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.inner.setup(state)
    }

    fn start(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.inner.start(state)
    }

    fn stop(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.stop_flag.store(true, Ordering::Relaxed);
        self.inner.stop(state).ok();
        Ok(())
    }

    fn teardown(&mut self, state: &mut GraphState) -> anyhow::Result<()> {
        self.inner.teardown(state)
    }
}

impl<T: Element + Send> StreamPeekRef<Burst<T>> for ThreadedAeronStatusFragmentNode<T> {
    fn peek_ref(&self) -> &Burst<T> {
        &self.value
    }
}

/// Build a threaded typed-parser Aeron subscriber that also propagates
/// lifecycle status onto the supplied reactive [`AeronStatusStream`].
///
/// Mirrors [`build_threaded`] but multiplexes status transitions over the
/// receiver channel via [`AeronItem`]. The background thread derives the status
/// after each poll (`is_closed` → [`AeronStatus::Closed`] first, then
/// `is_connected` → [`AeronStatus::Connected`], else
/// [`AeronStatus::Disconnected`]) and sends an [`AeronItem::Status`] **only on
/// transition** — matching the spin node's derivation order and dedup. Returns
/// the data stream; the caller wires the status node's producer to it (exactly
/// as the spin path does) so transitions are forwarded once per tick.
pub(crate) fn build_threaded_with_status<T, F, B>(
    backend: B,
    parser: F,
    status: Rc<RefCell<AeronStatusStream>>,
) -> Rc<dyn Stream<Burst<T>>>
where
    T: Element + Send,
    F: FnMut(&FragmentBuffer<'_>) -> Result<Option<T>, TransportError> + Send + 'static,
    B: AeronSubscriberBackend,
{
    let stop_flag = Arc::new(AtomicBool::new(false));
    let stop_thread = stop_flag.clone();

    let state = Mutex::new(Some((backend, parser)));
    let inner = ReceiverStream::new(
        move |sender: ChannelSender<AeronItem<T>>, _stop: Arc<AtomicBool>| {
            let mut state_guard = state.lock().expect("state lock poisoned");
            let (mut backend, mut parser) = state_guard
                .take()
                .expect("threaded aeron status closure called more than once");
            drop(state_guard);

            let mut idle_count = 0u32;
            // Mirror `AeronStatusStream`'s default so the first observed state
            // (e.g. Connected) registers as a transition.
            let mut last_status = AeronStatus::Disconnected;
            loop {
                if stop_thread.load(Ordering::Relaxed) {
                    return Ok(());
                }
                let count = backend.poll_fragments(&mut |frag| match parser(frag) {
                    Ok(Some(v)) => {
                        let _ = sender.send_message(Message::RealtimeValue(AeronItem::Data(v)));
                    }
                    Ok(None) => {}
                    Err(e) => log::warn!(
                        "aeron sub: parser dropped fragment at position {}: {e}",
                        frag.position()
                    ),
                })?;

                // Derive the lifecycle status and propagate it in-band on change.
                let new_status = if backend.is_closed() {
                    AeronStatus::Closed
                } else if backend.is_connected() {
                    AeronStatus::Connected
                } else {
                    AeronStatus::Disconnected
                };
                if new_status != last_status {
                    last_status = new_status;
                    let _ =
                        sender.send_message(Message::RealtimeValue(AeronItem::Status(new_status)));
                }

                if count == 0 {
                    idle_count = (idle_count + 1).min(20);
                    let micros = 1u64 << idle_count.min(10);
                    std::thread::sleep(Duration::from_micros(micros));
                } else {
                    idle_count = 0;
                }
            }
        },
        true,
    );

    ThreadedAeronStatusFragmentNode {
        inner,
        value: Burst::new(),
        status,
        stop_flag,
    }
    .into_stream()
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

#[cfg(test)]
mod tests {
    use super::*;
    use crate::adapters::aeron::transport::MockSubscriber;
    use crate::{IntoStream, NanoTime, NodeOperators, RunFor, RunMode, StreamOperators};
    use std::cell::RefCell;

    /// Typed little-endian i64 parser for the burst surface.
    fn i64_parser_typed(f: &FragmentBuffer<'_>) -> Result<Option<i64>, TransportError> {
        Ok(f.as_ref().try_into().ok().map(i64::from_le_bytes))
    }

    /// Test helper subscriber with controllable `is_connected` / `is_closed`
    /// flags. Mirrors aerofoil's `ConnectedMockSubscriber`.
    struct ConnectedMockSubscriber {
        batches: std::collections::VecDeque<Vec<Vec<u8>>>,
        connected: bool,
        closed: bool,
    }

    impl ConnectedMockSubscriber {
        fn new(messages: Vec<Vec<u8>>, connected: bool) -> Self {
            Self {
                batches: std::collections::VecDeque::from(vec![messages]),
                connected,
                closed: false,
            }
        }

        fn with_batches(batches: Vec<Vec<Vec<u8>>>, connected: bool) -> Self {
            Self {
                batches: batches.into(),
                connected,
                closed: false,
            }
        }
    }

    impl AeronSubscriberBackend for ConnectedMockSubscriber {
        fn poll(&mut self, handler: &mut dyn FnMut(&[u8])) -> anyhow::Result<usize> {
            let batch = self.batches.pop_front().unwrap_or_default();
            let count = batch.len();
            for msg in &batch {
                handler(msg);
            }
            Ok(count)
        }

        fn is_connected(&self) -> bool {
            self.connected
        }

        fn is_closed(&self) -> bool {
            self.closed
        }
    }

    #[test]
    fn given_burst_spin_node_when_no_fragments_then_empty_burst_and_returns_false_active() {
        let backend = MockSubscriber::new(vec![vec![]]);
        let node = AeronSpinSubFragmentNode::new(backend, i64_parser_typed);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(1))
            .unwrap();
        assert!(stream.peek_value().is_empty());
    }

    #[test]
    fn given_burst_spin_node_when_single_fragment_then_one_element_burst() {
        let msg = 42i64.to_le_bytes().to_vec();
        let backend = MockSubscriber::from_messages(vec![msg]);
        let node = AeronSpinSubFragmentNode::new(backend, i64_parser_typed);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(1))
            .unwrap();
        assert_eq!(stream.peek_value().as_slice(), &[42i64]);
    }

    #[test]
    fn given_burst_spin_node_when_three_fragments_one_poll_then_three_element_burst() {
        let batch = vec![
            1i64.to_le_bytes().to_vec(),
            2i64.to_le_bytes().to_vec(),
            3i64.to_le_bytes().to_vec(),
        ];
        let backend = MockSubscriber::new(vec![batch]);
        let node = AeronSpinSubFragmentNode::new(backend, i64_parser_typed);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(1))
            .unwrap();
        assert_eq!(stream.peek_value().as_slice(), &[1i64, 2, 3]);
    }

    #[test]
    fn given_burst_spin_node_when_parser_returns_none_then_fragment_dropped() {
        // Wrong-length first fragment → `try_into` fails → `Ok(None)`.
        let batch = vec![
            vec![0u8; 4],                 // 4 bytes — i64 try_into is None
            42i64.to_le_bytes().to_vec(), // valid
        ];
        let backend = MockSubscriber::new(vec![batch]);
        let node = AeronSpinSubFragmentNode::new(backend, i64_parser_typed);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(1))
            .unwrap();
        assert_eq!(stream.peek_value().as_slice(), &[42i64]);
    }

    #[test]
    fn given_burst_spin_node_when_parser_returns_err_then_fragment_dropped_and_cycle_continues() {
        // Middle fragment yields TransportError::Invalid; valid fragments
        // either side MUST still be collected.  Parser detects the "poison"
        // marker by length rather than content.
        let batch = vec![
            1i64.to_le_bytes().to_vec(),
            vec![0xDE, 0xAD, 0xBE, 0xEF, 0xDE, 0xAD], // 6 bytes — neither 8 nor 4
            3i64.to_le_bytes().to_vec(),
        ];
        let backend = MockSubscriber::new(vec![batch]);
        let parser = |f: &FragmentBuffer<'_>| -> Result<Option<i64>, TransportError> {
            match f.as_ref().len() {
                8 => Ok(Some(i64::from_le_bytes(f.as_ref().try_into().unwrap()))),
                6 => Err(TransportError::Invalid("bad".into())),
                _ => Ok(None),
            }
        };
        let node = AeronSpinSubFragmentNode::new(backend, parser);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(1))
            .unwrap();
        assert_eq!(stream.peek_value().as_slice(), &[1i64, 3]);
    }

    #[test]
    fn given_burst_spin_node_when_burst_completes_then_clears_before_next_cycle() {
        let backend = MockSubscriber::new(vec![vec![1i64.to_le_bytes().to_vec()], vec![]]);
        let node = AeronSpinSubFragmentNode::new(backend, i64_parser_typed);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(2))
            .unwrap();
        assert!(stream.peek_value().is_empty());
    }

    #[test]
    fn given_burst_spin_node_when_parser_inspects_fragment_header_then_default_header_is_zero() {
        let backend = MockSubscriber::from_messages(vec![7i64.to_le_bytes().to_vec()]);
        // Parser asserts the synthesised-default-header values inline so a
        // failure surfaces as a panic during the graph run.
        let parser = |f: &FragmentBuffer<'_>| -> Result<Option<i64>, TransportError> {
            assert_eq!(f.position(), 0);
            assert_eq!(f.header().session_id, 0);
            assert_eq!(f.header().stream_id, 0);
            Ok(f.as_ref().try_into().ok().map(i64::from_le_bytes))
        };
        let node = AeronSpinSubFragmentNode::new(backend, parser);
        let stream = node.into_stream();
        stream
            .clone()
            .as_node()
            .run(RunMode::HistoricalFrom(NanoTime::ZERO), RunFor::Cycles(1))
            .unwrap();
        assert_eq!(stream.peek_value().as_slice(), &[7i64]);
    }

    // ---------------------------------------------------------------------
    // Status-stream wiring tests.
    // ---------------------------------------------------------------------

    fn make_graph_state() -> GraphState {
        GraphState::new(
            RunMode::HistoricalFrom(NanoTime::ZERO),
            RunFor::Cycles(1),
            NanoTime::ZERO,
        )
    }

    #[test]
    fn given_burst_spin_node_with_status_when_connected_subscriber_polled_then_status_transitions_to_connected()
     {
        let backend = ConnectedMockSubscriber::new(vec![], true);
        let status = Rc::new(RefCell::new(AeronStatusStream::default()));
        let mut node =
            AeronSpinSubFragmentNode::with_status(backend, i64_parser_typed, Rc::clone(&status));
        let mut state = make_graph_state();
        node.cycle(&mut state).unwrap();
        assert_eq!(status.borrow().current(), AeronStatus::Connected);
        assert_eq!(status.borrow().peek_ref().len(), 1);
    }

    #[test]
    fn given_burst_spin_node_with_status_when_disconnected_subscriber_polled_then_status_stays_disconnected()
     {
        let backend = ConnectedMockSubscriber::new(vec![], false);
        let status = Rc::new(RefCell::new(AeronStatusStream::default()));
        let mut node =
            AeronSpinSubFragmentNode::with_status(backend, i64_parser_typed, Rc::clone(&status));
        let mut state = make_graph_state();
        node.cycle(&mut state).unwrap();
        assert_eq!(status.borrow().current(), AeronStatus::Disconnected);
        // No transition recorded — default `last` is already Disconnected.
        assert!(status.borrow().peek_ref().is_empty());
    }

    #[test]
    fn given_burst_spin_node_with_status_when_subscriber_closes_then_status_transitions_to_closed()
    {
        let backend = ConnectedMockSubscriber::with_batches(vec![vec![], vec![]], true);
        let status = Rc::new(RefCell::new(AeronStatusStream::default()));
        let mut node =
            AeronSpinSubFragmentNode::with_status(backend, i64_parser_typed, Rc::clone(&status));
        let mut state = make_graph_state();
        node.cycle(&mut state).unwrap();
        assert_eq!(status.borrow().current(), AeronStatus::Connected);
        // Flip the subscriber state between cycles.
        node.backend.closed = true;
        node.cycle(&mut state).unwrap();
        assert_eq!(status.borrow().current(), AeronStatus::Closed);
    }

    #[test]
    fn given_burst_spin_node_with_status_when_steady_then_no_re_emission() {
        let backend = ConnectedMockSubscriber::with_batches(vec![vec![], vec![]], true);
        let status = Rc::new(RefCell::new(AeronStatusStream::default()));
        let mut node =
            AeronSpinSubFragmentNode::with_status(backend, i64_parser_typed, Rc::clone(&status));
        let mut state = make_graph_state();
        node.cycle(&mut state).unwrap();
        assert_eq!(status.borrow().peek_ref().len(), 1);
        node.cycle(&mut state).unwrap();
        assert!(
            status.borrow().peek_ref().is_empty(),
            "steady state must not re-emit the same status"
        );
        assert_eq!(status.borrow().current(), AeronStatus::Connected);
    }

    #[test]
    fn given_burst_spin_node_with_status_when_burst_clears_then_status_burst_also_clears() {
        let backend = ConnectedMockSubscriber::new(vec![], true);
        let status = Rc::new(RefCell::new(AeronStatusStream::default()));
        let mut node =
            AeronSpinSubFragmentNode::with_status(backend, i64_parser_typed, Rc::clone(&status));
        let mut state = make_graph_state();
        node.cycle(&mut state).unwrap();
        assert_eq!(status.borrow().peek_ref().len(), 1);
        node.cycle(&mut state).unwrap();
        // The per-cycle clear at the start of cycle() resets the burst; the
        // re-recorded Connected is suppressed by record's transition check.
        assert!(status.borrow().peek_ref().is_empty());
    }

    #[test]
    fn given_burst_spin_node_new_constructor_when_polled_then_no_status_observed() {
        // Regression guard: the no-status `new()` constructor leaves `status`
        // as None, so no clear / record side-effect runs at all.
        let backend = MockSubscriber::from_messages(vec![]);
        let mut node = AeronSpinSubFragmentNode::new(backend, i64_parser_typed);
        let mut state = make_graph_state();
        node.cycle(&mut state).unwrap();
        assert!(node.status.is_none());
    }

    // ---------------------------------------------------------------------
    // Threaded status propagation (build_threaded_with_status).
    // ---------------------------------------------------------------------

    #[test]
    fn given_threaded_status_when_connected_backend_then_connected_transition_propagates() {
        // A connected backend: the poll thread derives `Connected`, which
        // differs from the default `Disconnected`, and multiplexes it onto the
        // channel as `AeronItem::Status`. The data node replays it into the
        // shared status stream; a brief real run must surface the transition.
        let backend = ConnectedMockSubscriber::new(vec![7i64.to_le_bytes().to_vec()], true);
        let status = Rc::new(RefCell::new(AeronStatusStream::default()));
        let data = build_threaded_with_status(backend, i64_parser_typed, Rc::clone(&status));
        let status_stream: Rc<dyn Stream<Burst<AeronStatus>>> = status.clone();
        status
            .borrow_mut()
            .set_producer(Rc::downgrade(&data.clone().as_node()));

        let collected = status_stream.collect();
        collected
            .clone()
            .run(
                RunMode::RealTime,
                RunFor::Duration(std::time::Duration::from_millis(400)),
            )
            .unwrap();

        let statuses: Vec<AeronStatus> = collected
            .peek_value()
            .into_iter()
            .flat_map(|burst| burst.value)
            .collect();
        assert!(
            statuses.contains(&AeronStatus::Connected),
            "expected a Connected transition, got {statuses:?}"
        );
    }
}