nautilus_network/websocket/

client.rs

// -------------------------------------------------------------------------------------------------
//  Copyright (C) 2015-2026 Nautech Systems Pty Ltd. All rights reserved.
//  https://nautechsystems.io
//
//  Licensed under the GNU Lesser General Public License Version 3.0 (the "License");
//  You may not use this file except in compliance with the License.
//  You may obtain a copy of the License at https://www.gnu.org/licenses/lgpl-3.0.en.html
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
// -------------------------------------------------------------------------------------------------

//! Connection lifecycle and task coordination for [`WebSocketClient`].
//!
//! # Execution model
//!
//! Handler mode runs a controller, reader, and writer task, plus an optional heartbeat task. The
//! reader dispatches frames, the writer serializes all sink access, and the controller drives
//! reconnect and shutdown from the shared [`ConnectionMode`]. Stream mode omits the managed
//! reader task and automatic reconnect.
//!
//! A read failure ends the reader and wakes the controller; a write failure requests reconnect and
//! also wakes it. The controller establishes a replacement transport with exponential backoff,
//! hands its sink to the writer, replaces the reader, then publishes the reconnect notification.
//! Terminal disconnect and close states stop all tasks instead of starting another reconnect.
//!
//! # Send semantics
//!
//! Ordinary sends return after entering the writer channel. Failed ordinary writes and ordinary
//! messages encountered during reconnect enter a FIFO buffer for replay on an active replacement
//! connection. Registered authentication state can hold or discard that replay before it reaches
//! the replacement sink.
//!
//! Ownership‑bound sends wait for the writer result, require the expected connection epoch, and
//! never enter the reconnect buffer. The writer advances the epoch only when it installs a
//! replacement sink, so inbound attribution and bound sends share one transport ownership boundary.

use std::{
    collections::VecDeque,
    fmt::Debug,
    pin::pin,
    sync::{
        Arc, OnceLock, RwLock,
        atomic::{AtomicBool, AtomicU8, AtomicU64, Ordering},
    },
    time::Duration,
};

use futures_util::{SinkExt, StreamExt};
use http::HeaderName;
use nautilus_core::CleanDrop;
use nautilus_cryptography::providers::install_cryptographic_provider;
#[cfg(any(feature = "turmoil", feature = "transport-sockudo"))]
use rustls::ClientConfig;
#[cfg(feature = "transport-sockudo")]
use sockudo_ws::{
    Config as SockudoConfig, Http1, Role, Stream as SockudoStream,
    WebSocketStream as SockudoWebSocketStream,
};
#[cfg(feature = "transport-sockudo")]
use tokio::io::{AsyncRead, AsyncWrite};
#[cfg(any(feature = "turmoil", feature = "transport-sockudo"))]
use tokio_rustls::TlsConnector;
#[cfg(feature = "turmoil")]
use tokio_tungstenite::MaybeTlsStream;
#[cfg(feature = "turmoil")]
use tokio_tungstenite::client_async;
#[cfg(not(feature = "turmoil"))]
use tokio_tungstenite::connect_async_with_config;
use tokio_tungstenite::tungstenite::{client::IntoClientRequest, http::HeaderValue};
use ustr::Ustr;

#[cfg(not(feature = "turmoil"))]
use super::proxy::{ProxiedStream, ProxyKind, WsTarget, tunnel_via_proxy};
use super::{
    auth::{AuthState, AuthTracker},
    config::{TransportBackend, WebSocketConfig},
    consts::{
        CONNECTION_STATE_CHECK_INTERVAL_MS, GRACEFUL_SHUTDOWN_DELAY_MS,
        GRACEFUL_SHUTDOWN_TIMEOUT_SECS,
    },
    types::{
        EpochMessageHandler, MessageHandler, MessageReader, MessageWriter, PingHandler,
        WriterCommand,
    },
};
#[cfg(feature = "turmoil")]
use crate::net::TcpConnector;
#[cfg(feature = "transport-sockudo")]
use crate::net::TcpStream;
#[cfg(feature = "transport-sockudo")]
use crate::transport::sockudo::{
    PrefixedIo, SockudoTransport, client_handshake_with_headers, validate_extra_headers,
};
use crate::{
    RECONNECTED,
    backoff::{ExponentialBackoff, RECONNECT_STABILITY_THRESHOLD, wait_reconnect_delay},
    dst,
    error::{SendError, is_connection_drop_io_error},
    logging::{log_task_aborted, log_task_started, log_task_stopped},
    mode::{ConnectionMode, ReadSessionFence},
    ratelimiter::{RateLimiter, clock::MonotonicClock, quota::Quota},
    transport::{BoxedWsTransport, Message, TransportError, tungstenite::TungsteniteTransport},
};

const WRITE_TIMEOUT_SECS: u64 = 5;

/// Shared headers used by future automatic WebSocket reconnects.
///
/// Updating these headers does not affect the active connection or trigger a reconnect.
#[derive(Clone)]
pub struct ReconnectHeaders {
    inner: Arc<RwLock<Vec<(String, String)>>>,
}

impl ReconnectHeaders {
    fn new(headers: Vec<(String, String)>) -> Self {
        Self {
            inner: Arc::new(RwLock::new(headers)),
        }
    }

    /// Replaces a header used by future automatic reconnect attempts.
    ///
    /// # Errors
    ///
    /// Returns an error if the header name or value is invalid, or if the shared state is poisoned.
    pub fn update(&self, name: &str, value: &str) -> Result<(), TransportError> {
        let name = HeaderName::from_bytes(name.as_bytes()).map_err(|e| {
            TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                format!("Invalid WebSocket reconnect header name: {e}"),
            ))
        })?;
        HeaderValue::from_str(value).map_err(|e| {
            TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                format!("Invalid WebSocket reconnect header value: {e}"),
            ))
        })?;

        let name = name.as_str();
        let mut headers = self.inner.write().map_err(|_| {
            TransportError::Io(std::io::Error::other(
                "WebSocket reconnect headers lock poisoned",
            ))
        })?;
        headers.retain(|(existing, _)| !existing.eq_ignore_ascii_case(name));
        headers.push((name.to_string(), value.to_string()));
        Ok(())
    }

    fn snapshot(&self) -> Result<Vec<(String, String)>, TransportError> {
        self.inner
            .read()
            .map(|headers| headers.clone())
            .map_err(|_| {
                TransportError::Io(std::io::Error::other(
                    "WebSocket reconnect headers lock poisoned",
                ))
            })
    }
}

impl Debug for ReconnectHeaders {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct(stringify!(ReconnectHeaders))
            .finish_non_exhaustive()
    }
}

/// `WebSocketClient` connects to a websocket server to read and send messages.
///
/// The client is opinionated about how messages are read and written. It
/// assumes that data can only have one reader but multiple writers.
///
/// The client splits the connection into read and write halves. It moves
/// the read half into a tokio task which keeps receiving messages from the
/// server and calls a handler - a Python function that takes the data
/// as its parameter. It stores the write half in the struct wrapped
/// with an Arc Mutex. This way the client struct can be used to write
/// data to the server from multiple scopes/tasks.
///
/// The client also maintains a heartbeat if given a duration in seconds.
/// It's preferable to set the duration slightly lower - heartbeat more
/// frequently - than the required amount.
pub struct WebSocketClientInner {
    config: WebSocketConfig,
    reconnect_headers: ReconnectHeaders,
    /// The function to handle incoming messages (stored separately from config).
    message_handler: Option<MessageHandler>,
    epoch_handler: Option<EpochMessageHandler>,
    /// The handler for incoming pings (stored separately from config).
    ping_handler: Option<PingHandler>,
    read_task: Option<tokio::task::JoinHandle<()>>,
    read_fence: Option<ReadSessionFence>,
    write_task: tokio::task::JoinHandle<()>,
    writer_tx: tokio::sync::mpsc::UnboundedSender<WriterCommand>,
    heartbeat_task: Option<tokio::task::JoinHandle<()>>,
    connection_mode: Arc<AtomicU8>,
    connection_epoch: Arc<AtomicU64>,
    state_notify: Arc<tokio::sync::Notify>,
    reconnect_timeout: Duration,
    backoff: ExponentialBackoff,
    /// True if this is a stream-based client (created via `connect_stream`).
    /// Stream-based clients disable auto-reconnect because the reader is
    /// owned by the caller and cannot be replaced during reconnection.
    is_stream_mode: bool,
    /// Maximum number of reconnection attempts before giving up (None = unlimited).
    reconnect_max_attempts: Option<u32>,
    /// Current count of consecutive reconnection attempts.
    reconnection_attempt_count: u32,
    /// Shared auth tracker invalidated on connection drops.
    auth_tracker: Arc<OnceLock<AuthTracker>>,
    /// Controls whether buffered replay waits for the next authenticated session.
    reconnect_buffer_waits_for_auth: Arc<AtomicBool>,
}

enum ReconnectBufferAction {
    Drain,
    Wait,
    Discard,
}

impl WebSocketClientInner {
    /// Create an inner websocket client with an existing writer.
    ///
    /// This is used for stream mode where the reader is owned by the caller.
    ///
    /// # Errors
    ///
    /// Returns an error if the exponential backoff configuration is invalid.
    #[allow(unknown_lints, reason = "Clippy lint is unavailable on Rust 1.97")]
    #[expect(
        clippy::unused_async,
        clippy::unused_async_trait_impl,
        reason = "async signature for consistency with connect-based constructors"
    )]
    pub async fn new_with_writer(
        mut config: WebSocketConfig,
        writer: MessageWriter,
    ) -> Result<Self, TransportError> {
        install_cryptographic_provider();

        if config.heartbeat == Some(0) {
            return Err(TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Heartbeat interval cannot be zero",
            )));
        }

        let connection_mode = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let connection_epoch = Arc::new(AtomicU64::new(0));
        let state_notify = Arc::new(tokio::sync::Notify::new());

        // Note: We don't spawn a read task here since the reader is handled externally
        let read_task = None;
        let read_fence = None;

        // Stream mode ignores reconnect settings, use harmless defaults
        let backoff = ExponentialBackoff::new(
            Duration::from_secs(2),
            Duration::from_secs(30),
            1.5,
            100,
            true,
        )
        .map_err(|e| {
            TransportError::Io(std::io::Error::new(std::io::ErrorKind::InvalidInput, e))
        })?;

        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(false));

        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel::<WriterCommand>();
        let write_task = Self::spawn_write_task(
            connection_mode.clone(),
            state_notify.clone(),
            writer,
            writer_rx,
            Arc::clone(&connection_epoch),
            Arc::clone(&auth_tracker),
            Arc::clone(&reconnect_buffer_waits_for_auth),
        );

        let heartbeat_task = if let Some(heartbeat_interval) = config.heartbeat {
            Some(Self::spawn_heartbeat_task(
                connection_mode.clone(),
                heartbeat_interval,
                config.heartbeat_msg.clone(),
                writer_tx.clone(),
            ))
        } else {
            None
        };

        let reconnect_max_attempts = None; // Stream mode does not reconnect
        let reconnect_timeout = Duration::from_secs(10);

        let reconnect_headers = ReconnectHeaders::new(std::mem::take(&mut config.headers));

        Ok(Self {
            config,
            reconnect_headers,
            message_handler: None, // Stream mode has no handler
            epoch_handler: None,
            ping_handler: None,
            writer_tx,
            connection_mode,
            connection_epoch,
            state_notify,
            reconnect_timeout,
            heartbeat_task,
            read_task,
            read_fence,
            write_task,
            backoff,
            is_stream_mode: true,
            reconnect_max_attempts,
            reconnection_attempt_count: 0,
            auth_tracker,
            reconnect_buffer_waits_for_auth,
        })
    }

    /// Create an inner websocket client.
    ///
    /// # Errors
    ///
    /// Returns an error if:
    /// - The connection to the server fails.
    /// - The exponential backoff configuration is invalid.
    pub async fn connect_url(
        config: WebSocketConfig,
        message_handler: Option<MessageHandler>,
        ping_handler: Option<PingHandler>,
    ) -> Result<Self, TransportError> {
        Self::connect_url_with_handlers(config, message_handler, None, ping_handler).await
    }

    async fn connect_url_with_handlers(
        config: WebSocketConfig,
        message_handler: Option<MessageHandler>,
        epoch_handler: Option<EpochMessageHandler>,
        ping_handler: Option<PingHandler>,
    ) -> Result<Self, TransportError> {
        install_cryptographic_provider();

        if config.heartbeat == Some(0) {
            return Err(TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Heartbeat interval cannot be zero",
            )));
        }

        if config.idle_timeout_ms == Some(0) {
            return Err(TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Idle timeout cannot be zero",
            )));
        }

        // Capture whether we're in stream mode before moving config
        let is_stream_mode = message_handler.is_none() && epoch_handler.is_none();
        let reconnect_max_attempts = config.reconnect_max_attempts;

        if !is_stream_mode && config.reconnect_timeout_ms == Some(0) {
            return Err(TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Reconnect timeout cannot be zero",
            )));
        }

        // Stream mode documents reconnect_* fields as ignored (callers may pass Some(0))
        let reconnect_timeout = if is_stream_mode {
            Duration::from_secs(10)
        } else {
            Duration::from_millis(config.reconnect_timeout_ms.unwrap_or(10_000))
        };
        let backoff = ExponentialBackoff::new(
            Duration::from_millis(config.reconnect_delay_initial_ms.unwrap_or(2_000)),
            Duration::from_millis(config.reconnect_delay_max_ms.unwrap_or(30_000)),
            config.reconnect_backoff_factor.unwrap_or(1.5),
            config.reconnect_jitter_ms.unwrap_or(100),
            true, // immediate-first
        )
        .map_err(|e| {
            TransportError::Io(std::io::Error::new(std::io::ErrorKind::InvalidInput, e))
        })?;

        let reconnect_headers = ReconnectHeaders::new(config.headers.clone());

        // Bound the dial: a server that accepts TCP but never upgrades must not hang the caller
        let (writer, reader) = dst::time::timeout(
            reconnect_timeout,
            Box::pin(Self::connect_with_server(
                &config.url,
                config.headers.clone(),
                config.backend,
                config.proxy_url.as_deref(),
            )),
        )
        .await
        .map_err(|_| {
            TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::TimedOut,
                format!(
                    "connection timed out after {}s",
                    reconnect_timeout.as_secs_f64()
                ),
            ))
        })??;

        let connection_mode = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let connection_epoch = Arc::new(AtomicU64::new(0));
        let state_notify = Arc::new(tokio::sync::Notify::new());

        let (read_task, read_fence) = if is_stream_mode {
            (None, None)
        } else {
            let read_fence = ReadSessionFence::new();
            let read_task = Self::spawn_message_handler_task(
                connection_mode.clone(),
                state_notify.clone(),
                read_fence.clone(),
                reader,
                0,
                message_handler.as_ref(),
                epoch_handler.as_ref(),
                ping_handler.as_ref(),
                config.idle_timeout_ms,
            );
            (Some(read_task), Some(read_fence))
        };

        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(false));

        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel::<WriterCommand>();
        let write_task = Self::spawn_write_task(
            connection_mode.clone(),
            state_notify.clone(),
            writer,
            writer_rx,
            Arc::clone(&connection_epoch),
            Arc::clone(&auth_tracker),
            Arc::clone(&reconnect_buffer_waits_for_auth),
        );

        // Optionally spawn a heartbeat task to periodically ping server
        let heartbeat_task = config.heartbeat.map(|heartbeat_secs| {
            Self::spawn_heartbeat_task(
                connection_mode.clone(),
                heartbeat_secs,
                config.heartbeat_msg.clone(),
                writer_tx.clone(),
            )
        });

        let mut config = config;
        config.headers.clear();

        Ok(Self {
            config,
            reconnect_headers,
            message_handler,
            epoch_handler,
            ping_handler,
            read_task,
            read_fence,
            write_task,
            writer_tx,
            heartbeat_task,
            connection_mode,
            connection_epoch,
            state_notify,
            reconnect_timeout,
            backoff,
            // Set stream mode when no message handler (reader not managed by client)
            is_stream_mode,
            reconnect_max_attempts,
            reconnection_attempt_count: 0,
            auth_tracker,
            reconnect_buffer_waits_for_auth,
        })
    }

    /// Connect to the server and return the split halves of the active transport.
    ///
    /// Dispatches on `backend` to the matching backend helper. The
    /// [`TransportBackend::Tungstenite`] backend is always available; the
    /// [`TransportBackend::Sockudo`] backend requires the `transport-sockudo`
    /// Cargo feature (enabled by default) and uses a custom HTTP/1.1 handshake
    /// path for upgrade headers.
    ///
    /// When `proxy_url` is `Some`, the Tungstenite backend establishes an HTTP
    /// `CONNECT` tunnel through the proxy before performing the WebSocket
    /// handshake. The Sockudo backend does not yet support proxying; when it
    /// is selected together with a proxy URL, this method logs a warning and
    /// transparently falls back to Tungstenite so omitted-backend Python
    /// configurations keep working.
    ///
    /// # Errors
    ///
    /// Returns a [`TransportError`] if the URL is invalid, headers fail to
    /// parse, the TCP / TLS layer cannot be established, the proxy refuses
    /// the tunnel, or the WebSocket handshake is rejected by the peer. When
    /// the Sockudo backend is selected without the `transport-sockudo`
    /// feature, returns [`TransportError::Other`].
    #[inline]
    pub async fn connect_with_server(
        url: &str,
        headers: Vec<(String, String)>,
        backend: TransportBackend,
        proxy_url: Option<&str>,
    ) -> Result<(MessageWriter, MessageReader), TransportError> {
        // Sockudo does not yet support proxy tunnels. When a proxy URL is supplied,
        // route through Tungstenite so configurations that rely on the runtime
        // default keep working (notably the Python `WebSocketConfig` binding,
        // which exposes `proxy_url` but no `backend` selector).
        if matches!(backend, TransportBackend::Sockudo)
            && let Some(proxy) = proxy_url
        {
            log::warn!("Sockudo backend does not support proxy_url; falling back to Tungstenite");
            return Box::pin(Self::connect_tungstenite_via_proxy(url, headers, proxy)).await;
        }

        match backend {
            TransportBackend::Tungstenite => match proxy_url {
                Some(proxy) => {
                    Box::pin(Self::connect_tungstenite_via_proxy(url, headers, proxy)).await
                }
                None => Self::connect_tungstenite(url, headers).await,
            },
            TransportBackend::Sockudo => {
                #[cfg(feature = "transport-sockudo")]
                {
                    Self::connect_sockudo(url, headers).await
                }
                #[cfg(not(feature = "transport-sockudo"))]
                {
                    Err(TransportError::Other(
                        "sockudo backend selected but the transport-sockudo \
                         Cargo feature is not enabled"
                            .to_string(),
                    ))
                }
            }
        }
    }

    /// Connects with the server creating a tokio-tungstenite websocket stream.
    /// Production version that uses `connect_async_with_config` convenience helper.
    #[inline]
    #[cfg(not(feature = "turmoil"))]
    async fn connect_tungstenite(
        url: &str,
        headers: Vec<(String, String)>,
    ) -> Result<(MessageWriter, MessageReader), TransportError> {
        let mut request = url.into_client_request().map_err(TransportError::from)?;
        let req_headers = request.headers_mut();

        for (key, val) in headers {
            let header_value = HeaderValue::from_str(&val)
                .map_err(|e| TransportError::Handshake(format!("invalid header value: {e}")))?;
            let header_name: HeaderName = key
                .parse()
                .map_err(|e| TransportError::Handshake(format!("invalid header name: {e}")))?;
            req_headers.insert(header_name, header_value);
        }

        let (stream, _resp) = connect_async_with_config(request, None, true)
            .await
            .map_err(TransportError::from)?;
        let transport: BoxedWsTransport = Box::pin(TungsteniteTransport::new(stream));
        Ok(transport.split())
    }

    /// Connects via an HTTP `CONNECT` proxy and performs the WebSocket
    /// handshake over the resulting tunnel.
    ///
    /// Recognised but unsupported proxy schemes (currently SOCKS) log a
    /// warning and fall back to a direct connection so existing REST proxy
    /// configs remain usable. Only available in production builds; the
    /// turmoil simulator does not model arbitrary outbound TCP via a proxy.
    #[inline]
    #[cfg(not(feature = "turmoil"))]
    async fn connect_tungstenite_via_proxy(
        url: &str,
        headers: Vec<(String, String)>,
        proxy_url: &str,
    ) -> Result<(MessageWriter, MessageReader), TransportError> {
        let proxy = match ProxyKind::parse(proxy_url)? {
            ProxyKind::Http(target) => target,
            ProxyKind::Unsupported { scheme } => {
                log::warn!(
                    "WebSocket proxy_url scheme '{scheme}' is not yet supported; \
                     connecting without a WebSocket proxy"
                );
                return Self::connect_tungstenite(url, headers).await;
            }
        };

        let mut request = url.into_client_request().map_err(TransportError::from)?;
        let req_headers = request.headers_mut();

        for (key, val) in headers {
            let header_value = HeaderValue::from_str(&val)
                .map_err(|e| TransportError::Handshake(format!("invalid header value: {e}")))?;
            let header_name: HeaderName = key
                .parse()
                .map_err(|e| TransportError::Handshake(format!("invalid header name: {e}")))?;
            req_headers.insert(header_name, header_value);
        }

        let target = WsTarget::parse(url)?;
        let stream = tunnel_via_proxy(&target, &proxy).await?;

        // Each ProxiedStream variant carries a distinct concrete stream type,
        // so we monomorphize the handshake through `proxied_ws_handshake`
        // rather than duplicating the body four times. The futures are boxed
        // because `client_async` produces a large state machine.
        let transport: BoxedWsTransport = match stream {
            ProxiedStream::Plain(tcp) => Box::pin(proxied_ws_handshake(request, tcp)).await?,
            ProxiedStream::PlainOverTlsProxy(s) => {
                Box::pin(proxied_ws_handshake(request, *s)).await?
            }
            ProxiedStream::Tls(s) => Box::pin(proxied_ws_handshake(request, *s)).await?,
            ProxiedStream::TlsOverTlsProxy(s) => {
                Box::pin(proxied_ws_handshake(request, *s)).await?
            }
        };

        Ok(transport.split())
    }

    /// Turmoil simulator variant: HTTP `CONNECT` tunneling is not supported
    /// under the simulator so any proxy URL is rejected up front.
    #[inline]
    #[cfg(feature = "turmoil")]
    #[allow(unknown_lints, reason = "Clippy lint is unavailable on Rust 1.97")]
    #[expect(
        clippy::unused_async,
        clippy::unused_async_trait_impl,
        reason = "signature mirrors the production variant; both are awaited in the dispatcher"
    )]
    async fn connect_tungstenite_via_proxy(
        _url: &str,
        _headers: Vec<(String, String)>,
        _proxy_url: &str,
    ) -> Result<(MessageWriter, MessageReader), TransportError> {
        Err(TransportError::Other(
            "proxy_url is not supported under the turmoil simulator".to_string(),
        ))
    }

    /// Connects with the server creating a tokio-tungstenite websocket stream.
    /// Turmoil version that uses the lower-level `client_async` API with injected stream.
    #[inline]
    #[cfg(feature = "turmoil")]
    async fn connect_tungstenite(
        url: &str,
        headers: Vec<(String, String)>,
    ) -> Result<(MessageWriter, MessageReader), TransportError> {
        let mut request = url.into_client_request().map_err(TransportError::from)?;
        let req_headers = request.headers_mut();

        for (key, val) in headers {
            let header_value = HeaderValue::from_str(&val)
                .map_err(|e| TransportError::Handshake(format!("invalid header value: {e}")))?;
            let header_name: HeaderName = key
                .parse()
                .map_err(|e| TransportError::Handshake(format!("invalid header name: {e}")))?;
            req_headers.insert(header_name, header_value);
        }

        let uri = request.uri();
        let scheme = uri.scheme_str().unwrap_or("ws");
        let host = uri
            .host()
            .ok_or_else(|| TransportError::InvalidUrl("missing hostname".to_string()))?;

        // Determine port: use explicit port if specified, otherwise default based on scheme
        let port = uri
            .port_u16()
            .unwrap_or_else(|| if scheme == "wss" { 443 } else { 80 });

        let addr = format!("{host}:{port}");

        // Use the connector to get a turmoil-compatible stream
        let connector = crate::net::RealTcpConnector;
        let tcp_stream = connector.connect(&addr).await?;
        if let Err(e) = tcp_stream.set_nodelay(true) {
            log::warn!("Failed to enable TCP_NODELAY for socket client: {e:?}");
        }

        // Wrap stream appropriately based on scheme
        let maybe_tls_stream = if scheme == "wss" {
            // Build TLS config with webpki roots
            let mut root_store = rustls::RootCertStore::empty();
            root_store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());

            let config = ClientConfig::builder()
                .with_root_certificates(root_store)
                .with_no_client_auth();

            let tls_connector = TlsConnector::from(std::sync::Arc::new(config));
            let domain = rustls::pki_types::ServerName::try_from(host.to_string())
                .map_err(|e| TransportError::Tls(format!("Invalid DNS name: {e}")))?;

            let tls_stream = tls_connector
                .connect(domain, tcp_stream)
                .await
                .map_err(TransportError::Io)?;
            MaybeTlsStream::Rustls(tls_stream)
        } else {
            MaybeTlsStream::Plain(tcp_stream)
        };

        // Use client_async with the stream (plain or TLS)
        let (stream, _resp) = client_async(request, maybe_tls_stream)
            .await
            .map_err(TransportError::from)?;
        let transport: BoxedWsTransport = Box::pin(TungsteniteTransport::new(stream));
        Ok(transport.split())
    }

    /// Connects with the server using the sockudo-ws backend.
    ///
    /// Uses a local HTTP/1.1 handshake helper so error logging and stream
    /// construction stay in our hands regardless of header count.
    ///
    /// Under the turmoil simulator, only plaintext `ws://` is supported (the
    /// simulator does not model TLS), so a `wss://` URL returns
    /// [`TransportError::Tls`] up front.
    #[inline]
    #[cfg(feature = "transport-sockudo")]
    async fn connect_sockudo(
        url: &str,
        headers: Vec<(String, String)>,
    ) -> Result<(MessageWriter, MessageReader), TransportError> {
        let target = SockudoTarget::parse(url)?;
        validate_extra_headers(&headers).map_err(TransportError::from)?;

        #[cfg(feature = "turmoil")]
        if target.is_tls {
            return Err(TransportError::Tls(
                "wss:// is not supported under the turmoil simulator; use ws://".to_string(),
            ));
        }

        let tcp_stream = TcpStream::connect((target.host.as_str(), target.port))
            .await
            .map_err(TransportError::Io)?;

        if let Err(e) = tcp_stream.set_nodelay(true) {
            log::warn!("Failed to enable TCP_NODELAY for sockudo client: {e:?}");
        }

        #[cfg(not(feature = "turmoil"))]
        if target.is_tls {
            let mut root_store = rustls::RootCertStore::empty();
            root_store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
            let config = ClientConfig::builder()
                .with_root_certificates(root_store)
                .with_no_client_auth();
            let connector = TlsConnector::from(std::sync::Arc::new(config));
            let domain = rustls::pki_types::ServerName::try_from(target.host.clone())
                .map_err(|e| TransportError::Tls(format!("Invalid DNS name: {e}")))?;
            let tls_stream = connector
                .connect(domain, tcp_stream)
                .await
                .map_err(TransportError::Io)?;
            return Self::finish_sockudo_handshake(tls_stream, &target, &headers).await;
        }

        Self::finish_sockudo_handshake(tcp_stream, &target, &headers).await
    }

    #[cfg(feature = "transport-sockudo")]
    async fn finish_sockudo_handshake<S>(
        mut stream: S,
        target: &SockudoTarget,
        headers: &[(String, String)],
    ) -> Result<(MessageWriter, MessageReader), TransportError>
    where
        S: AsyncRead + AsyncWrite + Unpin + Send + 'static,
    {
        // Use our helper for both paths: uniform error logging, and we own
        // stream construction since sockudo's high-level client drops the
        // handshake leftover.
        let handshake = client_handshake_with_headers(
            &mut stream,
            &target.host_header,
            &target.path,
            None,
            headers,
        )
        .await
        .map_err(TransportError::from)?;

        // Reading the HTTP 101 may also read the first WebSocket frame prefix;
        // replay it only when present so the ordinary path stays unwrapped.
        let stream = match handshake.leftover {
            Some(prefix) => SockudoStream::<Http1>::new(PrefixedIo::new(stream, prefix)),
            None => SockudoStream::<Http1>::new(stream),
        };
        let ws = SockudoWebSocketStream::from_raw(stream, Role::Client, SockudoConfig::default());
        let transport: BoxedWsTransport = Box::pin(SockudoTransport::new(ws));
        Ok(transport.split())
    }
}

fn is_connection_drop_transport_error(err: &TransportError) -> bool {
    err.is_closed() || matches!(err, TransportError::Io(e) if is_connection_drop_io_error(e))
}

// Debug when we asked to disconnect (Disconnect/Closed), else Warn for a peer close
fn read_termination_log_level(connection_state: &AtomicU8) -> log::Level {
    let mode = ConnectionMode::from_atomic(connection_state);
    if mode.is_disconnect() || mode.is_closed() {
        log::Level::Debug
    } else {
        log::Level::Warn
    }
}

#[cfg(test)]
mod connection_error_tests {
    use std::io;

    use rstest::rstest;

    use super::*;
    use crate::transport::CloseFrame;

    #[rstest]
    #[case(TransportError::ConnectionClosed, true)]
    #[case(TransportError::ConnectionReset, true)]
    #[case(TransportError::ClosedByPeer(Some(CloseFrame::new(1000, "bye"))), true)]
    #[case(TransportError::ClosedByPeer(None), true)]
    #[case(TransportError::Io(io::Error::from(io::ErrorKind::BrokenPipe)), true)]
    #[case(
        TransportError::Io(io::Error::from(io::ErrorKind::ConnectionReset)),
        true
    )]
    #[case(TransportError::Io(io::Error::from(io::ErrorKind::TimedOut)), true)]
    #[case(
        TransportError::Io(io::Error::from(io::ErrorKind::UnexpectedEof)),
        true
    )]
    #[case(
        TransportError::Io(io::Error::from(io::ErrorKind::InvalidInput)),
        false
    )]
    #[case(TransportError::InvalidUrl("http://example.com".into()), false)]
    #[case(TransportError::Handshake("bad".into()), false)]
    #[case(TransportError::Protocol("bad opcode".into()), false)]
    #[case(TransportError::Tls("bad certificate".into()), false)]
    #[case(TransportError::MessageTooLarge, false)]
    #[case(TransportError::FrameTooLarge, false)]
    #[case(TransportError::InvalidUtf8, false)]
    #[case(TransportError::Other("backend protocol mismatch".into()), false)]
    fn connection_drop_transport_error_classification(
        #[case] err: TransportError,
        #[case] expected: bool,
    ) {
        assert_eq!(is_connection_drop_transport_error(&err), expected);
    }
}

/// Complete the WebSocket handshake over a stream that has already been
/// tunneled through an HTTP `CONNECT` proxy. Generic over the concrete
/// stream type so the four [`super::proxy::ProxiedStream`] variants share
/// a single body.
#[cfg(not(feature = "turmoil"))]
async fn proxied_ws_handshake<S>(
    request: tokio_tungstenite::tungstenite::handshake::client::Request,
    stream: S,
) -> Result<BoxedWsTransport, TransportError>
where
    S: tokio::io::AsyncRead + tokio::io::AsyncWrite + Unpin + Send + 'static,
{
    let (ws, _resp) = tokio_tungstenite::client_async(request, stream)
        .await
        .map_err(TransportError::from)?;
    Ok(Box::pin(TungsteniteTransport::new(ws)))
}

/// Parsed components of a `ws://` / `wss://` URL needed by the sockudo backend.
///
/// Sockudo's HTTP/1.1 client passes the `host` argument verbatim as the
/// HTTP `Host:` header, so it must include the explicit port when one is
/// present in the URL (RFC 7230 section 5.4). The DNS / SNI lookup uses the bare
/// host without the port.
#[cfg(feature = "transport-sockudo")]
#[derive(Debug, PartialEq, Eq)]
struct SockudoTarget {
    host: String,
    /// Value to send as the HTTP `Host:` header. Includes `:port` only when
    /// the URL specifies a non-default port explicitly.
    host_header: String,
    port: u16,
    path: String,
    is_tls: bool,
}

#[cfg(feature = "transport-sockudo")]
impl SockudoTarget {
    fn parse(url: &str) -> Result<Self, TransportError> {
        let parsed =
            url::Url::parse(url).map_err(|e| TransportError::InvalidUrl(format!("{url}: {e}")))?;

        let scheme = parsed.scheme();
        let is_tls = match scheme {
            "ws" => false,
            "wss" => true,
            other => {
                return Err(TransportError::InvalidUrl(format!(
                    "expected ws:// or wss:// scheme, was {other}"
                )));
            }
        };

        let raw_host = parsed
            .host_str()
            .ok_or_else(|| TransportError::InvalidUrl("missing hostname".to_string()))?;

        // url::Url stores IPv6 hosts in their bracketed form (e.g. `[::1]`).
        // Brackets are correct for the HTTP `Host:` header but invalid for
        // DNS/TCP and TLS SNI, so we keep two representations: a bracketed
        // `host_header` for the upgrade, and a bare `host` for socket dialing.
        let is_bracketed = raw_host.starts_with('[') && raw_host.ends_with(']');
        let host = if is_bracketed {
            raw_host[1..raw_host.len() - 1].to_string()
        } else {
            raw_host.to_string()
        };

        let explicit_port = parsed.port();
        let port = explicit_port.unwrap_or(if is_tls { 443 } else { 80 });
        let host_header = match explicit_port {
            Some(p) => format!("{raw_host}:{p}"),
            None => raw_host.to_string(),
        };

        let path = if parsed.path().is_empty() {
            "/".to_string()
        } else {
            let mut p = parsed.path().to_string();
            if let Some(query) = parsed.query() {
                p.push('?');
                p.push_str(query);
            }
            p
        };

        Ok(Self {
            host,
            host_header,
            port,
            path,
            is_tls,
        })
    }
}

impl WebSocketClientInner {
    /// Reconnect with server.
    ///
    /// Make a new connection with server. Use the new read and write halves
    /// to update self writer and read and heartbeat tasks.
    ///
    /// For stream-based clients (created via `connect_stream`), reconnection is disabled
    /// because the reader is owned by the caller and cannot be replaced. Stream users
    /// should handle disconnections by creating a new connection.
    ///
    /// The reconnect timeout bounds only connection establishment. Once the
    /// new writer is handed to the writer task the swap runs to completion,
    /// so buffered messages can never drain into a connection that lost its
    /// reader to a timeout; the post-connect steps are individually bounded
    /// by the writer task's graceful-shutdown timeout.
    ///
    /// # Errors
    ///
    /// Returns an error if:
    /// - The reconnection attempt times out.
    /// - The connection to the server fails.
    pub async fn reconnect(&mut self) -> Result<(), TransportError> {
        log::debug!("Reconnecting");

        if self.is_stream_mode {
            log::warn!(
                "Auto-reconnect disabled for stream-based WebSocket client; \
                stream users must manually reconnect by creating a new connection"
            );
            // Transition to CLOSED state to stop reconnection attempts
            self.connection_mode
                .store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
            fail_registered_auth(
                self.auth_tracker.as_ref(),
                "WebSocket stream mode cannot reconnect",
            );
            return Ok(());
        }

        if ConnectionMode::from_atomic(&self.connection_mode).is_disconnect() {
            log::debug!("Reconnect aborted due to disconnect state");
            return Ok(());
        }

        // Bound only connection establishment; the swap below must run to completion
        let (new_writer, reader) = dst::time::timeout(
            self.reconnect_timeout,
            Self::connect_with_server(
                &self.config.url,
                self.reconnect_headers.snapshot()?,
                self.config.backend,
                self.config.proxy_url.as_deref(),
            ),
        )
        .await
        .map_err(|_| {
            TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::TimedOut,
                format!(
                    "reconnection timed out after {}s",
                    self.reconnect_timeout.as_secs_f64()
                ),
            ))
        })??;

        if ConnectionMode::from_atomic(&self.connection_mode).is_disconnect() {
            log::debug!("Reconnect aborted mid-flight (after connect)");
            return Ok(());
        }

        // Use a oneshot channel to synchronize the writer swap before transitioning
        // back to ACTIVE. Buffered messages stay in the writer task and replay later.
        let (tx, rx) = tokio::sync::oneshot::channel();
        if let Err(e) = self.writer_tx.send(WriterCommand::Update(new_writer, tx)) {
            log::error!("{e}");
            return Err(TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::BrokenPipe,
                format!("Failed to send update command: {e}"),
            )));
        }

        // Wait for writer to confirm it accepted the new socket
        let connection_epoch = match rx.await {
            Ok(connection_epoch) => {
                log::debug!("Writer confirmed socket update: epoch={connection_epoch}");
                connection_epoch
            }
            Err(e) => {
                log::error!("Writer dropped update channel: {e}");
                return Err(TransportError::Io(std::io::Error::new(
                    std::io::ErrorKind::BrokenPipe,
                    "Writer task dropped response channel",
                )));
            }
        };

        // Delay before closing connection
        dst::time::sleep(Duration::from_millis(GRACEFUL_SHUTDOWN_DELAY_MS)).await;

        if ConnectionMode::from_atomic(&self.connection_mode).is_disconnect() {
            log::debug!("Reconnect aborted mid-flight (after delay)");
            return Ok(());
        }

        if let Some(read_fence) = self.read_fence.take() {
            read_fence.invalidate();
        }

        if let Some(ref read_task) = self.read_task.take()
            && !read_task.is_finished()
        {
            read_task.abort();
            log_task_aborted("read");
        }

        // Atomically transition from Reconnect to Active
        // This prevents race condition where disconnect could be requested between check and store
        if self
            .connection_mode
            .compare_exchange(
                ConnectionMode::Reconnect.as_u8(),
                ConnectionMode::Active.as_u8(),
                Ordering::SeqCst,
                Ordering::SeqCst,
            )
            .is_err()
        {
            log::debug!("Reconnect aborted (state changed during reconnect)");
            return Ok(());
        }

        if self.message_handler.is_some() || self.epoch_handler.is_some() {
            let read_fence = ReadSessionFence::new();
            self.read_task = Some(Self::spawn_message_handler_task(
                self.connection_mode.clone(),
                self.state_notify.clone(),
                read_fence.clone(),
                reader,
                connection_epoch,
                self.message_handler.as_ref(),
                self.epoch_handler.as_ref(),
                self.ping_handler.as_ref(),
                self.config.idle_timeout_ms,
            ));
            self.read_fence = Some(read_fence);
        } else {
            self.read_task = None;
            self.read_fence = None;
        }

        log::debug!("Reconnect succeeded");
        Ok(())
    }

    /// Check if the client is still alive.
    ///
    /// Returns `true` if both the read and write tasks are still running.
    /// There may be some delay between the connection closing and the
    /// client detecting it.
    #[inline]
    #[must_use]
    pub fn is_alive(&self) -> bool {
        match &self.read_task {
            Some(read_task) => !read_task.is_finished() && !self.write_task.is_finished(),
            None => !self.write_task.is_finished(),
        }
    }

    #[expect(
        clippy::too_many_arguments,
        reason = "both handler modes share the same reader lifecycle"
    )]
    fn spawn_message_handler_task(
        connection_state: Arc<AtomicU8>,
        state_notify: Arc<tokio::sync::Notify>,
        read_fence: ReadSessionFence,
        mut reader: MessageReader,
        connection_epoch: u64,
        message_handler: Option<&MessageHandler>,
        epoch_handler: Option<&EpochMessageHandler>,
        ping_handler: Option<&PingHandler>,
        idle_timeout_ms: Option<u64>,
    ) -> tokio::task::JoinHandle<()> {
        log::debug!("Started message handler task 'read'");

        let check_interval = Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS);
        let idle_timeout = idle_timeout_ms.map(Duration::from_millis);

        // Clone Arc handlers for the async task
        let message_handler = message_handler.cloned();
        let epoch_handler = epoch_handler.cloned();
        let ping_handler = ping_handler.cloned();

        tokio::task::spawn(async move {
            let mut last_data_time = dst::time::Instant::now();

            loop {
                if !ConnectionMode::from_atomic(&connection_state).is_active()
                    || !read_fence.is_valid()
                {
                    break;
                }

                let read_result = dst::time::timeout(check_interval, reader.next()).await;

                if let Ok(Some(Ok(ref message))) = read_result
                    && (!ConnectionMode::from_atomic(&connection_state).is_active()
                        || !read_fence.is_valid())
                {
                    log::debug!(
                        "Dropping WebSocket message with {} bytes after session ended",
                        message.as_bytes().len()
                    );
                    break;
                }

                match read_result {
                    Ok(Some(Ok(Message::Binary(data)))) => {
                        log::trace!("Received message <binary> {} bytes", data.len());
                        last_data_time = dst::time::Instant::now();

                        if !ConnectionMode::from_atomic(&connection_state).is_active()
                            || !read_fence.is_valid()
                        {
                            log::debug!(
                                "Dropping WebSocket message with {} bytes after session ended",
                                data.len()
                            );
                            break;
                        }

                        if let Some(ref handler) = message_handler {
                            handler(Message::Binary(data.clone()));
                        }

                        if let Some(ref handler) = epoch_handler {
                            handler(connection_epoch, Message::Binary(data));
                        }
                    }
                    Ok(Some(Ok(Message::Text(data)))) => {
                        log::trace!("Received message: {data:?}");
                        last_data_time = dst::time::Instant::now();

                        if !ConnectionMode::from_atomic(&connection_state).is_active()
                            || !read_fence.is_valid()
                        {
                            log::debug!(
                                "Dropping WebSocket message with {} bytes after session ended",
                                data.len()
                            );
                            break;
                        }

                        if let Some(ref handler) = message_handler {
                            handler(Message::Text(data.clone()));
                        }

                        if let Some(ref handler) = epoch_handler {
                            handler(connection_epoch, Message::Text(data));
                        }
                    }
                    Ok(Some(Ok(Message::Ping(ping_data)))) => {
                        log::trace!("Received ping: {ping_data:?}");
                        // Do not reset last_data_time: pings are keep-alive frames, not application
                        // data, so a peer that emits only pings must still trip the idle timeout.
                        // Checked here too: a ping flood faster than the check interval starves the timeout branch

                        if let Some(ref handler) = ping_handler {
                            if !ConnectionMode::from_atomic(&connection_state).is_active()
                                || !read_fence.is_valid()
                            {
                                log::debug!(
                                    "Dropping WebSocket ping with {} bytes after session ended",
                                    ping_data.len()
                                );
                                break;
                            }
                            handler(ping_data.to_vec());
                        }

                        if idle_timeout_exceeded(last_data_time, idle_timeout) {
                            break;
                        }
                    }
                    Ok(Some(Ok(Message::Pong(_)))) => {
                        log::trace!("Received pong");
                        // Do not reset last_data_time: pongs are keep-alive replies (not data)

                        if idle_timeout_exceeded(last_data_time, idle_timeout) {
                            break;
                        }
                    }
                    Ok(Some(Ok(Message::Close(Some(frame))))) => {
                        log::log!(
                            read_termination_log_level(&connection_state),
                            "Received close frame, terminating: code={}, reason='{}'",
                            frame.code,
                            frame.reason
                        );
                        break;
                    }
                    Ok(Some(Ok(Message::Close(None)))) => {
                        log::log!(
                            read_termination_log_level(&connection_state),
                            "Received close frame with no code or reason, terminating"
                        );
                        break;
                    }
                    Ok(Some(Err(e))) => {
                        if is_connection_drop_transport_error(&e) {
                            log::warn!("Received connection error, terminating: {e}");
                        } else {
                            log::error!("Received transport error, terminating: {e}");
                        }
                        break;
                    }
                    Ok(None) => {
                        log::log!(
                            read_termination_log_level(&connection_state),
                            "Connection closed by peer (no close frame), terminating"
                        );
                        break;
                    }
                    Err(_) => {
                        if idle_timeout_exceeded(last_data_time, idle_timeout) {
                            break;
                        }
                    }
                }
            }

            // Wake the controller immediately so it detects the dead read task
            state_notify.notify_one();
        })
    }

    /// Attempts to send all buffered messages after reconnection.
    ///
    /// Returns `true` if a send error occurred (caller should trigger reconnection).
    /// Messages remain in buffer if send fails, preserving them for the next reconnection attempt.
    async fn drain_reconnect_buffer(
        buffer: &mut VecDeque<Message>,
        writer: &mut MessageWriter,
    ) -> bool {
        if buffer.is_empty() {
            return false;
        }

        let initial_buffer_len = buffer.len();
        log::info!("Sending {initial_buffer_len} buffered messages after reconnection");

        let mut send_error_occurred = false;

        while let Some(buffered_msg) = buffer.front() {
            // Clone message before attempting send (to keep in buffer if send fails)
            let msg_to_send = buffered_msg.clone();

            if let Err(e) = writer.send(msg_to_send).await {
                if is_connection_drop_transport_error(&e) {
                    log::warn!(
                        "Failed to send buffered message after reconnection: {e}, {} messages remain in buffer",
                        buffer.len()
                    );
                } else {
                    log::error!(
                        "Failed to send buffered message after reconnection: {e}, {} messages remain in buffer",
                        buffer.len()
                    );
                }
                send_error_occurred = true;
                break; // Stop processing buffer, remaining messages preserved for next reconnection
            }

            // Only remove from buffer after successful send
            buffer.pop_front();
        }

        if buffer.is_empty() {
            log::info!("Successfully sent all {initial_buffer_len} buffered messages");
        }

        send_error_occurred
    }

    fn can_drain_reconnect_buffer(
        reconnect_buffer_waits_for_auth: &AtomicBool,
        auth_tracker: &Arc<OnceLock<AuthTracker>>,
    ) -> ReconnectBufferAction {
        if !reconnect_buffer_waits_for_auth.load(Ordering::Acquire) {
            return ReconnectBufferAction::Drain;
        }

        match auth_tracker.get().map(AuthTracker::auth_state) {
            Some(AuthState::Authenticated) => ReconnectBufferAction::Drain,
            Some(AuthState::Failed) => ReconnectBufferAction::Discard,
            Some(AuthState::Unauthenticated) | None => ReconnectBufferAction::Wait,
        }
    }

    fn spawn_write_task(
        connection_state: Arc<AtomicU8>,
        state_notify: Arc<tokio::sync::Notify>,
        writer: MessageWriter,
        mut writer_rx: tokio::sync::mpsc::UnboundedReceiver<WriterCommand>,
        connection_epoch: Arc<AtomicU64>,
        auth_tracker: Arc<OnceLock<AuthTracker>>,
        reconnect_buffer_waits_for_auth: Arc<AtomicBool>,
    ) -> tokio::task::JoinHandle<()> {
        log_task_started("write");

        // Interval between checking the connection mode
        let check_interval = Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS);

        tokio::task::spawn(async move {
            let mut active_writer = writer;
            // Buffer for messages received during reconnection
            // VecDeque for efficient pop_front() operations
            let mut reconnect_buffer: VecDeque<Message> = VecDeque::new();

            loop {
                let mode = ConnectionMode::from_atomic(&connection_state);

                match mode {
                    ConnectionMode::Disconnect => {
                        // Log any buffered messages that will be lost
                        if !reconnect_buffer.is_empty() {
                            log::warn!(
                                "Discarding {} buffered messages due to disconnect",
                                reconnect_buffer.len()
                            );
                            reconnect_buffer.clear();
                        }

                        // Attempt to close the writer gracefully before exiting,
                        // we ignore any error as the writer may already be closed.
                        _ = dst::time::timeout(
                            Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS),
                            active_writer.close(),
                        )
                        .await;
                        break;
                    }
                    ConnectionMode::Closed => {
                        // Log any buffered messages that will be lost
                        if !reconnect_buffer.is_empty() {
                            log::warn!(
                                "Discarding {} buffered messages due to closed connection",
                                reconnect_buffer.len()
                            );
                            reconnect_buffer.clear();
                        }
                        break;
                    }
                    _ => {}
                }

                if mode.is_active() && !reconnect_buffer.is_empty() {
                    match Self::can_drain_reconnect_buffer(
                        reconnect_buffer_waits_for_auth.as_ref(),
                        &auth_tracker,
                    ) {
                        ReconnectBufferAction::Drain => {
                            let drain_result = dst::time::timeout(
                                Duration::from_secs(WRITE_TIMEOUT_SECS),
                                Self::drain_reconnect_buffer(
                                    &mut reconnect_buffer,
                                    &mut active_writer,
                                ),
                            )
                            .await;
                            let send_error = drain_result.unwrap_or_else(|_| {
                                log::warn!(
                                    "Timed out draining reconnect buffer after {WRITE_TIMEOUT_SECS}s, {} messages remain",
                                    reconnect_buffer.len()
                                );
                                true
                            });

                            // CAS: a disconnect landing mid-drain must not be overwritten
                            if send_error && ConnectionMode::request_reconnect(&connection_state) {
                                if let Some(tracker) = auth_tracker.get() {
                                    tracker.invalidate();
                                }
                                state_notify.notify_one();
                            }

                            continue;
                        }
                        ReconnectBufferAction::Discard => {
                            log::warn!(
                                "Discarding {} buffered messages after authentication failed",
                                reconnect_buffer.len()
                            );
                            reconnect_buffer.clear();
                            continue;
                        }
                        ReconnectBufferAction::Wait => {}
                    }
                }

                match dst::time::timeout(check_interval, writer_rx.recv()).await {
                    Ok(Some(msg)) => {
                        // Re-check connection mode after receiving a message
                        let mode = ConnectionMode::from_atomic(&connection_state);
                        if matches!(mode, ConnectionMode::Disconnect | ConnectionMode::Closed) {
                            break;
                        }

                        match msg {
                            WriterCommand::Update(new_writer, tx) => {
                                log::debug!("Received new writer");

                                // Delay before closing connection
                                dst::time::sleep(Duration::from_millis(100)).await;

                                // Attempt to close the writer gracefully on update,
                                // we ignore any error as the writer may already be closed.
                                _ = dst::time::timeout(
                                    Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS),
                                    active_writer.close(),
                                )
                                .await;

                                active_writer = new_writer;
                                let epoch = connection_epoch.fetch_add(1, Ordering::AcqRel) + 1;
                                log::debug!("Updated writer: epoch={epoch}");

                                if let Err(e) = tx.send(epoch) {
                                    log::error!(
                                        "Failed to report writer update to controller: {e:?}"
                                    );
                                }
                            }
                            WriterCommand::Send(msg) if mode.is_reconnect() => {
                                // Buffer messages during reconnection instead of dropping them
                                log::debug!(
                                    "Buffering message during reconnection (buffer size: {})",
                                    reconnect_buffer.len() + 1
                                );
                                reconnect_buffer.push_back(msg);
                            }
                            WriterCommand::SendOnConnection { response_tx, .. }
                                if mode.is_reconnect() =>
                            {
                                _ = response_tx.send(Err(SendError::ConnectionChanged));
                            }
                            WriterCommand::SendOnConnection {
                                message,
                                connection_epoch: expected_epoch,
                                response_tx,
                            } => {
                                let epoch = connection_epoch.load(Ordering::Acquire);
                                if epoch != expected_epoch {
                                    _ = response_tx.send(Err(SendError::ConnectionChanged));
                                    continue;
                                }

                                let send_result = dst::time::timeout(
                                    Duration::from_secs(WRITE_TIMEOUT_SECS),
                                    active_writer.send(message),
                                )
                                .await;

                                // An ownership-bound message is never replayed, so an expired
                                // deadline reports failure to the caller instead of buffering
                                // the message as the ordinary send path does.
                                let result = match send_result {
                                    Ok(Ok(())) => Ok(()),
                                    Ok(Err(e)) => {
                                        if is_connection_drop_transport_error(&e) {
                                            log::warn!("Failed to send message: {e}");
                                        } else {
                                            log::error!("Failed to send message: {e}");
                                        }

                                        Err(SendError::BrokenPipe(e.to_string()))
                                    }
                                    Err(_) => {
                                        log::warn!(
                                            "Timed out sending message after {WRITE_TIMEOUT_SECS}s"
                                        );

                                        Err(SendError::WriteTimeout)
                                    }
                                };
                                let send_failed = result.is_err();
                                _ = response_tx.send(result);

                                if send_failed
                                    && ConnectionMode::request_reconnect(&connection_state)
                                {
                                    log::warn!("Writer triggering reconnect");

                                    if let Some(tracker) = auth_tracker.get() {
                                        tracker.invalidate();
                                    }
                                    state_notify.notify_one();
                                }
                            }
                            WriterCommand::Send(msg) => {
                                let send_result = dst::time::timeout(
                                    Duration::from_secs(WRITE_TIMEOUT_SECS),
                                    active_writer.send(msg.clone()),
                                )
                                .await;
                                let send_failed = match send_result {
                                    Ok(Ok(())) => false,
                                    Ok(Err(e)) => {
                                        if is_connection_drop_transport_error(&e) {
                                            log::warn!("Failed to send message: {e}");
                                        } else {
                                            log::error!("Failed to send message: {e}");
                                        }
                                        true
                                    }
                                    Err(_) => {
                                        log::warn!(
                                            "Timed out sending message after {WRITE_TIMEOUT_SECS}s"
                                        );
                                        true
                                    }
                                };

                                if send_failed {
                                    reconnect_buffer.push_back(msg);

                                    // CAS: a disconnect landing mid-send must not be overwritten
                                    if ConnectionMode::request_reconnect(&connection_state) {
                                        log::warn!("Writer triggering reconnect");

                                        if let Some(tracker) = auth_tracker.get() {
                                            tracker.invalidate();
                                        }
                                        state_notify.notify_one();
                                    }
                                }
                            }
                        }
                    }
                    Ok(None) => {
                        // Channel closed - writer task should terminate
                        log::debug!("Writer channel closed, terminating writer task");
                        break;
                    }
                    Err(_) => {
                        // Timeout - just continue the loop
                    }
                }
            }

            // Attempt to close the writer gracefully before exiting,
            // we ignore any error as the writer may already be closed.
            _ = dst::time::timeout(
                Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS),
                active_writer.close(),
            )
            .await;

            log_task_stopped("write");
        })
    }

    fn spawn_heartbeat_task(
        connection_state: Arc<AtomicU8>,
        heartbeat_secs: u64,
        message: Option<String>,
        writer_tx: tokio::sync::mpsc::UnboundedSender<WriterCommand>,
    ) -> tokio::task::JoinHandle<()> {
        log_task_started("heartbeat");

        tokio::task::spawn(async move {
            let interval = Duration::from_secs(heartbeat_secs);

            loop {
                dst::time::sleep(interval).await;

                match ConnectionMode::from_u8(connection_state.load(Ordering::SeqCst)) {
                    ConnectionMode::Active => {
                        let msg = match &message {
                            Some(text) => WriterCommand::Send(Message::Text(text.clone().into())),
                            None => WriterCommand::Send(Message::Ping(vec![].into())),
                        };

                        match writer_tx.send(msg) {
                            Ok(()) => log::trace!("Sent heartbeat to writer task"),
                            Err(e) => {
                                log::error!("Failed to send heartbeat to writer task: {e}");
                            }
                        }
                    }
                    ConnectionMode::Reconnect => {}
                    ConnectionMode::Disconnect | ConnectionMode::Closed => break,
                }
            }

            log_task_stopped("heartbeat");
        })
    }
}

fn idle_timeout_exceeded(
    last_data_time: dst::time::Instant,
    idle_timeout: Option<Duration>,
) -> bool {
    if let Some(timeout) = idle_timeout {
        let idle_duration = last_data_time.elapsed();
        if idle_duration >= timeout {
            log::warn!(
                "Read idle timeout: no data received for {:.1}s",
                idle_duration.as_secs_f64()
            );
            return true;
        }
    }
    false
}

impl Drop for WebSocketClientInner {
    fn drop(&mut self) {
        // Delegate to explicit cleanup handler
        self.clean_drop();
    }
}

/// Cleanup on drop: aborts background tasks and clears handlers to break reference cycles.
impl CleanDrop for WebSocketClientInner {
    fn clean_drop(&mut self) {
        if let Some(read_fence) = self.read_fence.take() {
            read_fence.invalidate();
        }

        if let Some(ref read_task) = self.read_task.take()
            && !read_task.is_finished()
        {
            read_task.abort();
            log_task_aborted("read");
        }

        if !self.write_task.is_finished() {
            self.write_task.abort();
            log_task_aborted("write");
        }

        if let Some(ref handle) = self.heartbeat_task.take()
            && !handle.is_finished()
        {
            handle.abort();
            log_task_aborted("heartbeat");
        }

        // Clear handlers to break potential reference cycles
        self.message_handler = None;
        self.epoch_handler = None;
        self.ping_handler = None;
    }
}

#[expect(
    clippy::missing_fields_in_debug,
    reason = "handler closures and internal task handles are intentionally omitted"
)]
impl Debug for WebSocketClientInner {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct(stringify!(WebSocketClientInner))
            .field("config", &self.config)
            .field(
                "connection_mode",
                &ConnectionMode::from_atomic(&self.connection_mode),
            )
            .field("reconnect_timeout", &self.reconnect_timeout)
            .field("is_stream_mode", &self.is_stream_mode)
            .finish()
    }
}

/// WebSocket client with automatic reconnection.
///
/// Handles connection state, callbacks, and rate limiting.
/// See module docs for architecture details.
#[cfg_attr(
    feature = "python",
    pyo3::pyclass(module = "nautilus_trader.core.nautilus_pyo3.network")
)]
#[cfg_attr(
    feature = "python",
    pyo3_stub_gen::derive::gen_stub_pyclass(module = "nautilus_trader.network")
)]
pub struct WebSocketClient {
    pub(crate) controller_task: tokio::task::JoinHandle<()>,
    pub(crate) connection_mode: Arc<AtomicU8>,
    pub(crate) connection_epoch: Arc<AtomicU64>,
    pub(crate) state_notify: Arc<tokio::sync::Notify>,
    pub(crate) reconnect_timeout: Duration,
    pub(crate) rate_limiter: Arc<RateLimiter<Ustr, MonotonicClock>>,
    pub(crate) writer_tx: tokio::sync::mpsc::UnboundedSender<WriterCommand>,
    auth_tracker: Arc<OnceLock<AuthTracker>>,
    reconnect_buffer_waits_for_auth: Arc<AtomicBool>,
    reconnect_headers: ReconnectHeaders,
}

impl Debug for WebSocketClient {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct(stringify!(WebSocketClient)).finish()
    }
}

impl WebSocketClient {
    /// Creates a websocket client in **stream mode** that returns a [`MessageReader`].
    ///
    /// Returns a stream that the caller owns and reads from directly. Automatic reconnection
    /// is **disabled** because the reader cannot be replaced internally. On disconnection, the
    /// client transitions to CLOSED state and the caller must manually reconnect by calling
    /// `connect_stream` again.
    ///
    /// Use stream mode when you need custom reconnection logic, direct control over message
    /// reading, or fine-grained backpressure handling.
    ///
    /// See [`WebSocketConfig`] documentation for comparison with handler mode.
    ///
    /// # Errors
    ///
    /// Returns an error if the connection cannot be established.
    pub async fn connect_stream(
        config: WebSocketConfig,
        keyed_quotas: Vec<(String, Quota)>,
        default_quota: Option<Quota>,
        post_reconnect: Option<Arc<dyn Fn() + Send + Sync>>,
    ) -> Result<(MessageReader, Self), TransportError> {
        install_cryptographic_provider();

        // Create a single connection and split it, respecting configured headers.
        // The dial bound is a fixed default: stream mode documents reconnect_* fields as ignored
        let connect_timeout = Duration::from_secs(10);
        let (writer, reader) = dst::time::timeout(
            connect_timeout,
            WebSocketClientInner::connect_with_server(
                &config.url,
                config.headers.clone(),
                config.backend,
                config.proxy_url.as_deref(),
            ),
        )
        .await
        .map_err(|_| {
            TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::TimedOut,
                format!(
                    "connection timed out after {}s",
                    connect_timeout.as_secs_f64()
                ),
            ))
        })??;

        // Create inner without connecting (we'll provide the writer)
        let inner = WebSocketClientInner::new_with_writer(config, writer).await?;

        let connection_mode = inner.connection_mode.clone();
        let connection_epoch = Arc::clone(&inner.connection_epoch);
        let state_notify = inner.state_notify.clone();
        let reconnect_timeout = inner.reconnect_timeout;
        let auth_tracker = Arc::clone(&inner.auth_tracker);
        let reconnect_buffer_waits_for_auth = Arc::clone(&inner.reconnect_buffer_waits_for_auth);
        let reconnect_headers = inner.reconnect_headers.clone();
        let keyed_quotas = keyed_quotas
            .into_iter()
            .map(|(key, quota)| (Ustr::from(&key), quota))
            .collect();
        let rate_limiter = Arc::new(RateLimiter::new_with_quota(default_quota, keyed_quotas));
        let writer_tx = inner.writer_tx.clone();

        let controller_task = Self::spawn_controller_task(
            inner,
            connection_mode.clone(),
            state_notify.clone(),
            post_reconnect,
            Arc::clone(&auth_tracker),
        );

        Ok((
            reader,
            Self {
                controller_task,
                connection_mode,
                connection_epoch,
                state_notify,
                reconnect_timeout,
                rate_limiter,
                writer_tx,
                auth_tracker,
                reconnect_buffer_waits_for_auth,
                reconnect_headers,
            },
        ))
    }

    /// Creates a websocket client in **handler mode** with automatic reconnection.
    ///
    /// The handler is called for each incoming message on an internal task.
    /// Automatic reconnection is **enabled** with exponential backoff. On disconnection,
    /// the client automatically attempts to reconnect and replaces the internal reader
    /// (the handler continues working seamlessly).
    ///
    /// Use handler mode for simplified connection management, automatic reconnection, Python
    /// bindings, or callback-based message handling.
    ///
    /// See [`WebSocketConfig`] documentation for comparison with stream mode.
    ///
    /// # Errors
    ///
    /// Returns an error if:
    /// - The connection cannot be established.
    /// - `message_handler` is `None` (use `connect_stream` instead).
    pub async fn connect(
        config: WebSocketConfig,
        message_handler: Option<MessageHandler>,
        ping_handler: Option<PingHandler>,
        post_reconnection: Option<Arc<dyn Fn() + Send + Sync>>,
        keyed_quotas: Vec<(String, Quota)>,
        default_quota: Option<Quota>,
    ) -> Result<Self, TransportError> {
        let keyed_quotas = keyed_quotas
            .into_iter()
            .map(|(key, quota)| (Ustr::from(&key), quota))
            .collect();
        let rate_limiter = Arc::new(RateLimiter::new_with_quota(default_quota, keyed_quotas));
        Self::connect_with_rate_limiter(
            config,
            message_handler,
            ping_handler,
            post_reconnection,
            rate_limiter,
        )
        .await
    }

    /// Creates a websocket client in **handler mode** sharing an externally-owned rate limiter.
    ///
    /// Use this constructor to share a single [`RateLimiter`] across multiple
    /// [`WebSocketClient`] instances (for example, the WebSocket clients owned
    /// by an exchange adapter's data and execution clients). All quota state
    /// lives inside the limiter, so passing the same `Arc` produces a single
    /// shared bucket - the only way to honour a venue's per-IP / per-account
    /// WS message cap when more than one connection is opened in-process.
    ///
    /// Behavior otherwise matches [`Self::connect`].
    ///
    /// # Errors
    ///
    /// Returns an error if:
    /// - The connection cannot be established.
    /// - `message_handler` is `None` (use `connect_stream` instead).
    pub async fn connect_with_rate_limiter(
        config: WebSocketConfig,
        message_handler: Option<MessageHandler>,
        ping_handler: Option<PingHandler>,
        post_reconnection: Option<Arc<dyn Fn() + Send + Sync>>,
        rate_limiter: Arc<RateLimiter<Ustr, MonotonicClock>>,
    ) -> Result<Self, TransportError> {
        Self::connect_with_handlers(
            config,
            message_handler,
            None,
            ping_handler,
            post_reconnection,
            rate_limiter,
        )
        .await
    }

    /// Creates a handler-mode client whose incoming messages carry connection ownership.
    ///
    /// The initial connection has epoch `0`. Each replacement connection increments the epoch,
    /// and both its incoming messages and `RECONNECTED` notification carry that new value. Use
    /// [`Self::send_text_on_connection`] to bind an outgoing message to one of those epochs.
    ///
    /// # Errors
    ///
    /// Returns an error if the connection cannot be established.
    pub async fn connect_with_rate_limiter_and_epoch_handler(
        config: WebSocketConfig,
        epoch_handler: EpochMessageHandler,
        ping_handler: Option<PingHandler>,
        post_reconnection: Option<Arc<dyn Fn() + Send + Sync>>,
        rate_limiter: Arc<RateLimiter<Ustr, MonotonicClock>>,
    ) -> Result<Self, TransportError> {
        Self::connect_with_handlers(
            config,
            None,
            Some(epoch_handler),
            ping_handler,
            post_reconnection,
            rate_limiter,
        )
        .await
    }

    async fn connect_with_handlers(
        config: WebSocketConfig,
        message_handler: Option<MessageHandler>,
        epoch_handler: Option<EpochMessageHandler>,
        ping_handler: Option<PingHandler>,
        post_reconnection: Option<Arc<dyn Fn() + Send + Sync>>,
        rate_limiter: Arc<RateLimiter<Ustr, MonotonicClock>>,
    ) -> Result<Self, TransportError> {
        if message_handler.is_none() && epoch_handler.is_none() {
            return Err(TransportError::Io(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Handler mode requires message_handler to be set. Use connect_stream() for stream mode without a handler.",
            )));
        }

        log::debug!("Connecting");
        let inner = WebSocketClientInner::connect_url_with_handlers(
            config,
            message_handler,
            epoch_handler,
            ping_handler,
        )
        .await?;
        let connection_mode = inner.connection_mode.clone();
        let connection_epoch = Arc::clone(&inner.connection_epoch);
        let state_notify = inner.state_notify.clone();
        let writer_tx = inner.writer_tx.clone();
        let reconnect_timeout = inner.reconnect_timeout;
        let auth_tracker = Arc::clone(&inner.auth_tracker);
        let reconnect_buffer_waits_for_auth = Arc::clone(&inner.reconnect_buffer_waits_for_auth);
        let reconnect_headers = inner.reconnect_headers.clone();

        let controller_task = Self::spawn_controller_task(
            inner,
            connection_mode.clone(),
            state_notify.clone(),
            post_reconnection,
            Arc::clone(&auth_tracker),
        );

        Ok(Self {
            controller_task,
            connection_mode,
            connection_epoch,
            state_notify,
            reconnect_timeout,
            rate_limiter,
            writer_tx,
            auth_tracker,
            reconnect_buffer_waits_for_auth,
            reconnect_headers,
        })
    }

    /// Returns shared headers used by future automatic reconnect attempts.
    #[must_use]
    pub fn reconnect_headers(&self) -> ReconnectHeaders {
        self.reconnect_headers.clone()
    }

    /// Returns the current connection mode.
    #[must_use]
    pub fn connection_mode(&self) -> ConnectionMode {
        ConnectionMode::from_atomic(&self.connection_mode)
    }

    /// Returns the ownership epoch of the current connection.
    ///
    /// A connection keeps one epoch for its lifetime. The value increments when the writer swaps
    /// to a replacement connection.
    #[must_use]
    pub fn connection_epoch(&self) -> u64 {
        self.connection_epoch.load(Ordering::Acquire)
    }

    /// Returns a clone of the connection mode atomic for external state tracking.
    ///
    /// This allows adapter clients to track connection state across reconnections
    /// without message-passing delays.
    #[must_use]
    pub fn connection_mode_atomic(&self) -> Arc<AtomicU8> {
        Arc::clone(&self.connection_mode)
    }

    /// Returns shared read access to the current connection epoch.
    ///
    /// Callers must treat the returned atomic as read-only. The WebSocket writer task exclusively
    /// advances it when installing a replacement connection.
    #[must_use]
    pub fn connection_epoch_atomic(&self) -> Arc<AtomicU64> {
        Arc::clone(&self.connection_epoch)
    }

    /// Check if the client connection is active.
    ///
    /// Returns `true` if the client is connected and has not been signalled to disconnect.
    /// The client will automatically retry connection based on its configuration.
    #[inline]
    #[must_use]
    pub fn is_active(&self) -> bool {
        self.connection_mode().is_active()
    }

    /// Check if the client is disconnected.
    #[must_use]
    pub fn is_disconnected(&self) -> bool {
        self.controller_task.is_finished()
    }

    /// Check if the client is reconnecting.
    ///
    /// Returns `true` if the client lost connection and is attempting to reestablish it.
    /// The client will automatically retry connection based on its configuration.
    #[inline]
    #[must_use]
    pub fn is_reconnecting(&self) -> bool {
        self.connection_mode().is_reconnect()
    }

    /// Registers an [`AuthTracker`] with the client.
    ///
    /// When the controller detects a dead connection and transitions to
    /// `Reconnect`, it calls `invalidate()` on the tracker so that any
    /// pending authenticated sends see the state change immediately. Terminal
    /// transitions fail the tracker so pending auth waits can terminate.
    /// Set `reconnect_buffer_waits_for_auth` for clients that must not replay
    /// buffered messages until the next session authenticates.
    ///
    /// Call this once after construction, before any authenticated sends.
    pub fn set_auth_tracker(&self, tracker: AuthTracker, reconnect_buffer_waits_for_auth: bool) {
        let _ = self.auth_tracker.set(tracker);
        self.reconnect_buffer_waits_for_auth
            .store(reconnect_buffer_waits_for_auth, Ordering::Release);
    }

    /// Check if the client is disconnecting.
    ///
    /// Returns `true` if the client is in disconnect mode.
    #[inline]
    #[must_use]
    pub fn is_disconnecting(&self) -> bool {
        self.connection_mode().is_disconnect()
    }

    /// Check if the client is closed.
    ///
    /// Returns `true` if the client has been explicitly disconnected or reached
    /// maximum reconnection attempts. In this state, the client cannot be reused
    /// and a new client must be created for further connections.
    #[inline]
    #[must_use]
    pub fn is_closed(&self) -> bool {
        self.connection_mode().is_closed()
    }

    /// Checks whether the connection is in a terminal state (disconnecting or closed).
    ///
    /// Single atomic load to fail fast before rate limiting or waiting.
    #[inline]
    fn check_not_terminal(&self) -> Result<(), SendError> {
        match self.connection_mode() {
            ConnectionMode::Disconnect | ConnectionMode::Closed => Err(SendError::Closed),
            _ => Ok(()),
        }
    }

    /// Waits for rate limiter quota, aborting early if connection enters a terminal state.
    async fn await_rate_limit_or_closed(&self, keys: Option<&[Ustr]>) -> Result<(), SendError> {
        const CHECK_INTERVAL_MS: u64 = 100;

        tokio::select! {
            biased;
            () = self.rate_limiter.await_keys_ready(keys) => Ok(()),
            () = async {
                loop {
                    // Enable before the state check: an unpolled Notified is unregistered and misses notifies
                    let mut notified = pin!(self.state_notify.notified());
                    notified.as_mut().enable();

                    if matches!(self.connection_mode(), ConnectionMode::Disconnect | ConnectionMode::Closed) {
                        break;
                    }
                    tokio::select! {
                        biased;
                        () = notified => {}
                        () = dst::time::sleep(Duration::from_millis(CHECK_INTERVAL_MS)) => {}
                    }
                }
            } => Err(SendError::Closed),
        }
    }

    /// Waits for the client to become active before sending.
    ///
    /// Uses `state_notify` for event-driven wakeup so sends resume immediately
    /// after reconnection completes. A fallback interval guards against missed
    /// notifications.
    async fn wait_for_active(&self) -> Result<(), SendError> {
        const FALLBACK_INTERVAL_MS: u64 = 100;

        let mode = self.connection_mode();
        if mode.is_active() {
            return Ok(());
        }

        if matches!(mode, ConnectionMode::Disconnect | ConnectionMode::Closed) {
            return Err(SendError::Closed);
        }

        log::debug!("Waiting for client to become ACTIVE before sending...");

        let fallback_interval = Duration::from_millis(FALLBACK_INTERVAL_MS);

        dst::time::timeout(self.reconnect_timeout, async {
            loop {
                // Enable before the state check: an unpolled Notified is unregistered and misses notifies
                let mut notified = pin!(self.state_notify.notified());
                notified.as_mut().enable();

                let mode = self.connection_mode();
                if mode.is_active() {
                    return Ok(());
                }

                if matches!(mode, ConnectionMode::Disconnect | ConnectionMode::Closed) {
                    return Err(());
                }

                tokio::select! {
                    biased;
                    () = notified => {}
                    () = dst::time::sleep(fallback_interval) => {}
                }
            }
        })
        .await
        .map_err(|_| SendError::Timeout)?
        .map_err(|()| SendError::Closed)
    }

    /// Signals that the caller's reader has observed EOF or a fatal error.
    ///
    /// In stream mode the controller has no visibility into the caller-owned reader.
    /// Call this method when `reader.next().await` returns `None` or an unrecoverable
    /// error so the controller transitions to `Closed` and dependent tasks shut down.
    ///
    /// For peer-initiated close frames (`Message::Close`), use [`disconnect`](Self::disconnect)
    /// instead so the writer can send the close reply before shutting down.
    ///
    /// If an [`AuthTracker`] is registered, this fails pending auth waits.
    ///
    /// This is a no-op if the connection is already closed or disconnecting.
    pub fn notify_closed(&self) {
        let mode = self.connection_mode();
        if mode.is_disconnect() || mode.is_closed() {
            return;
        }

        log::debug!("Stream reader signalled EOF, transitioning to CLOSED");

        self.connection_mode
            .store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        fail_registered_auth(self.auth_tracker.as_ref(), "WebSocket client closed");
        self.state_notify.notify_waiters();
    }

    /// Set disconnect mode to true.
    ///
    /// Controller task will periodically check the disconnect mode
    /// and shutdown the client if it is alive
    ///
    /// If an [`AuthTracker`] is registered, this fails pending auth waits.
    pub async fn disconnect(&self) {
        log::debug!("Disconnecting");

        // A CLOSED client keeps its terminal state; its tracker is already failed
        if ConnectionMode::request_disconnect(&self.connection_mode)
            && let Some(tracker) = self.auth_tracker.get()
        {
            tracker.fail("WebSocket client disconnected");
        }
        self.state_notify.notify_waiters();

        if dst::time::timeout(Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS), async {
            while !self.is_disconnected() {
                dst::time::sleep(Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS)).await;
            }

            if !self.controller_task.is_finished() {
                self.controller_task.abort();
                log_task_aborted("controller");
            }
        })
        .await
            == Ok(())
        {
            log::debug!("Controller task finished");
        } else {
            log::warn!("Timeout waiting for controller task to finish");

            if !self.controller_task.is_finished() {
                self.controller_task.abort();
                log_task_aborted("controller");
            }
            self.connection_mode
                .store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        }
    }

    /// Sends the given text `data` to the server.
    ///
    /// Returns `Ok(())` when the message is enqueued to the writer channel. This does NOT
    /// guarantee delivery: if a disconnect occurs concurrently, the writer task may drop the
    /// message. During reconnection, messages are buffered and replayed on the new connection.
    ///
    /// # Errors
    ///
    /// Returns a websocket error if unable to send.
    #[allow(unused_variables)]
    pub async fn send_text(&self, data: String, keys: Option<&[Ustr]>) -> Result<(), SendError> {
        self.check_not_terminal()?;

        self.await_rate_limit_or_closed(keys).await?;
        self.wait_for_active().await?;

        log::trace!("Sending text: {data:?}");

        let msg = Message::Text(data.into());
        self.writer_tx
            .send(WriterCommand::Send(msg))
            .map_err(|e| SendError::BrokenPipe(e.to_string()))
    }

    /// Sends text once if the active connection matches `connection_epoch`.
    ///
    /// The writer rejects the send if reconnection changes ownership before the write. The
    /// message is never replayed on another connection.
    ///
    /// # Errors
    ///
    /// Returns:
    /// - [`SendError::Closed`] if the client closes.
    /// - [`SendError::Timeout`] if the active wait times out before the write starts.
    /// - [`SendError::ConnectionChanged`] if the expected connection no longer owns the writer.
    /// - [`SendError::BrokenPipe`] if the command or transport write fails.
    /// - [`SendError::WriteTimeout`] if the write starts but does not complete within the write
    ///   deadline. Delivery is undetermined in that case: the message is not replayed, and it
    ///   must not be resent blindly.
    pub async fn send_text_on_connection(
        &self,
        data: String,
        keys: Option<&[Ustr]>,
        connection_epoch: u64,
    ) -> Result<(), SendError> {
        self.check_not_terminal()?;
        self.await_rate_limit_or_closed(keys).await?;
        self.wait_for_active().await?;

        log::trace!("Sending text once: {data:?}");

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        self.writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::Text(data.into()),
                connection_epoch,
                response_tx,
            })
            .map_err(|e| SendError::BrokenPipe(e.to_string()))?;
        response_rx
            .await
            .map_err(|e| SendError::BrokenPipe(e.to_string()))?
    }

    /// Sends a pong frame back to the server.
    ///
    /// # Errors
    ///
    /// Returns a websocket error if unable to send.
    pub async fn send_pong(&self, data: Vec<u8>) -> Result<(), SendError> {
        self.wait_for_active().await?;

        log::trace!("Sending pong frame ({} bytes)", data.len());

        let msg = Message::Pong(data.into());
        self.writer_tx
            .send(WriterCommand::Send(msg))
            .map_err(|e| SendError::BrokenPipe(e.to_string()))
    }

    /// Sends the given bytes `data` to the server.
    ///
    /// Returns `Ok(())` when the message is enqueued to the writer channel. This does NOT
    /// guarantee delivery: if a disconnect occurs concurrently, the writer task may drop the
    /// message. During reconnection, messages are buffered and replayed on the new connection.
    ///
    /// # Errors
    ///
    /// Returns a websocket error if unable to send.
    #[allow(unused_variables)]
    pub async fn send_bytes(&self, data: Vec<u8>, keys: Option<&[Ustr]>) -> Result<(), SendError> {
        self.check_not_terminal()?;

        self.await_rate_limit_or_closed(keys).await?;
        self.wait_for_active().await?;

        log::trace!("Sending bytes: {data:?}");

        let msg = Message::Binary(data.into());
        self.writer_tx
            .send(WriterCommand::Send(msg))
            .map_err(|e| SendError::BrokenPipe(e.to_string()))
    }

    /// Sends a close message to the server.
    ///
    /// # Errors
    ///
    /// Returns a websocket error if unable to send.
    pub async fn send_close_message(&self) -> Result<(), SendError> {
        self.wait_for_active().await?;

        let msg = Message::Close(None);
        self.writer_tx
            .send(WriterCommand::Send(msg))
            .map_err(|e| SendError::BrokenPipe(e.to_string()))
    }

    fn spawn_controller_task(
        mut inner: WebSocketClientInner,
        connection_mode: Arc<AtomicU8>,
        state_notify: Arc<tokio::sync::Notify>,
        post_reconnection: Option<Arc<dyn Fn() + Send + Sync>>,
        auth_tracker: Arc<OnceLock<AuthTracker>>,
    ) -> tokio::task::JoinHandle<()> {
        const CONTROLLER_FALLBACK_INTERVAL_MS: u64 = 100;

        tokio::task::spawn(async move {
            log_task_started("controller");

            let fallback_interval = Duration::from_millis(CONTROLLER_FALLBACK_INTERVAL_MS);
            let mut reconnected_at = None;

            loop {
                tokio::select! {
                    biased;
                    () = state_notify.notified() => {}
                    () = dst::time::sleep(fallback_interval) => {}
                }

                let mut mode = ConnectionMode::from_atomic(&connection_mode);

                if mode.is_disconnect() {
                    log::debug!("Disconnecting");

                    let timeout = Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS);
                    if dst::time::timeout(timeout, async {
                        // Delay awaiting graceful shutdown
                        dst::time::sleep(Duration::from_millis(GRACEFUL_SHUTDOWN_DELAY_MS)).await;

                        if let Some(read_fence) = inner.read_fence.take() {
                            read_fence.invalidate();
                        }

                        if let Some(task) = &inner.read_task
                            && !task.is_finished()
                        {
                            task.abort();
                            log_task_aborted("read");
                        }

                        if let Some(task) = &inner.heartbeat_task
                            && !task.is_finished()
                        {
                            task.abort();
                            log_task_aborted("heartbeat");
                        }
                    })
                    .await
                    .is_err()
                    {
                        log::warn!("Shutdown timed out after {}s", timeout.as_secs());
                    }

                    log::debug!("Closed");
                    break; // Controller finished
                }

                if mode.is_closed() {
                    log::debug!("Connection closed");
                    break;
                }

                if mode.is_active() && !inner.is_alive() {
                    let target = if inner.is_stream_mode {
                        ConnectionMode::Closed
                    } else {
                        ConnectionMode::Reconnect
                    };

                    if connection_mode
                        .compare_exchange(
                            ConnectionMode::Active.as_u8(),
                            target.as_u8(),
                            Ordering::SeqCst,
                            Ordering::SeqCst,
                        )
                        .is_ok()
                    {
                        if target.is_closed() {
                            fail_registered_auth(auth_tracker.as_ref(), "WebSocket client closed");
                        } else if let Some(tracker) = auth_tracker.get() {
                            tracker.invalidate();
                        }
                        log::debug!("Detected dead connection, transitioning to {target:?}");
                    }
                    mode = ConnectionMode::from_atomic(&connection_mode);
                }

                if mode.is_reconnect() {
                    let reconnect_uptime = reconnected_at
                        .take()
                        .map(|started: dst::time::Instant| started.elapsed());
                    let previous_reconnect_stable = reconnect_uptime
                        .is_some_and(|uptime| uptime >= RECONNECT_STABILITY_THRESHOLD);

                    if previous_reconnect_stable {
                        inner.backoff.reset();
                        inner.reconnection_attempt_count = 0;
                        log::debug!(
                            "WebSocket remained active for at least {}s, resetting reconnect cycle",
                            RECONNECT_STABILITY_THRESHOLD.as_secs()
                        );
                    }

                    // Check if max reconnection attempts exceeded
                    if let Some(max_attempts) = inner.reconnect_max_attempts
                        && inner.reconnection_attempt_count >= max_attempts
                    {
                        log::error!(
                            "Max reconnection attempts ({max_attempts}) exceeded, transitioning to CLOSED"
                        );
                        connection_mode.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
                        fail_registered_auth(
                            auth_tracker.as_ref(),
                            "WebSocket reconnect attempts exhausted",
                        );
                        state_notify.notify_waiters();
                        break;
                    }

                    if reconnect_uptime.is_some() && !previous_reconnect_stable {
                        let duration = inner.backoff.next_duration();
                        if !duration.is_zero() {
                            log::warn!("Backing off for {}s...", duration.as_secs_f64());
                        }

                        if !wait_reconnect_delay(
                            duration,
                            connection_mode.as_ref(),
                            state_notify.as_ref(),
                        )
                        .await
                        {
                            log::debug!("Backoff interrupted by terminal state");
                            continue;
                        }
                    }

                    inner.reconnection_attempt_count += 1;
                    log::debug!(
                        "Reconnection attempt {} of {}",
                        inner.reconnection_attempt_count,
                        inner
                            .reconnect_max_attempts
                            .map_or_else(|| "unlimited".to_string(), |m| m.to_string())
                    );

                    // Race reconnect against disconnect notification
                    let reconnect_result = tokio::select! {
                        biased;
                        result = inner.reconnect() => Some(result),
                        () = async {
                            loop {
                                // Enable before the check so a disconnect notify between iterations is not missed
                                let mut notified = pin!(state_notify.notified());
                                notified.as_mut().enable();

                                if ConnectionMode::from_atomic(&connection_mode).is_disconnect() {
                                    break;
                                }
                                notified.await;
                            }
                        } => None,
                    };

                    match reconnect_result {
                        None => {
                            log::debug!("Reconnect interrupted by disconnect");
                        }
                        Some(Ok(())) => {
                            reconnected_at = Some(dst::time::Instant::now());

                            state_notify.notify_waiters();

                            if ConnectionMode::from_atomic(&connection_mode).is_active() {
                                if let Some(ref handler) = inner.message_handler {
                                    let reconnected_msg =
                                        Message::Text(RECONNECTED.to_string().into());
                                    handler(reconnected_msg);
                                    log::debug!("Sent reconnected message to handler");
                                }

                                if let Some(ref handler) = inner.epoch_handler {
                                    let connection_epoch =
                                        inner.connection_epoch.load(Ordering::Acquire);
                                    let reconnected_msg =
                                        Message::Text(RECONNECTED.to_string().into());
                                    handler(connection_epoch, reconnected_msg);
                                    log::debug!(
                                        "Sent reconnected message to epoch handler: \
                                         epoch={connection_epoch}",
                                    );
                                }

                                // TODO: Retain this legacy callback for use from Python
                                if let Some(ref callback) = post_reconnection {
                                    callback();
                                    log::debug!("Called `post_reconnection` handler");
                                }

                                log::debug!("Reconnected successfully");
                            } else {
                                log::debug!(
                                    "Skipping post_reconnection handlers due to disconnect state"
                                );
                            }
                        }
                        Some(Err(e)) => {
                            let duration = inner.backoff.next_duration();
                            log::warn!(
                                "Reconnect attempt {} failed: {e}",
                                inner.reconnection_attempt_count
                            );

                            if !duration.is_zero() {
                                log::warn!("Backing off for {}s...", duration.as_secs_f64());
                                if !wait_reconnect_delay(
                                    duration,
                                    connection_mode.as_ref(),
                                    state_notify.as_ref(),
                                )
                                .await
                                {
                                    log::debug!("Backoff interrupted by terminal state");
                                }
                            }
                        }
                    }
                }
            }
            inner
                .connection_mode
                .store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);

            log_task_stopped("controller");
        })
    }
}

fn fail_registered_auth(auth_tracker: &OnceLock<AuthTracker>, reason: &str) {
    if let Some(tracker) = auth_tracker.get() {
        tracker.fail(reason);
    }
}

impl Drop for WebSocketClient {
    fn drop(&mut self) {
        self.connection_mode
            .store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);

        if !self.controller_task.is_finished() {
            self.controller_task.abort();
            log_task_aborted("controller");
        }
    }
}

#[cfg(test)]
#[cfg(not(feature = "turmoil"))]
#[cfg(not(all(feature = "simulation", madsim)))] // transport-layer I/O not simulated
#[cfg(target_os = "linux")] // Only run network tests on Linux (CI stability)
mod tests {
    use std::{num::NonZeroU32, sync::Arc, time::Duration};

    use futures_util::{SinkExt, StreamExt};
    use rstest::rstest;
    use tokio::{
        net::TcpListener,
        task::{self, JoinHandle},
    };
    use tokio_tungstenite::{
        accept_hdr_async,
        tungstenite::{
            Message as WsMessage,
            handshake::server::{self, Callback},
            http::HeaderValue,
        },
    };

    use crate::{
        mode::ConnectionMode,
        ratelimiter::quota::Quota,
        websocket::{TransportBackend, WebSocketClient, WebSocketConfig},
    };

    struct TestServer {
        task: JoinHandle<()>,
        port: u16,
    }

    #[derive(Debug, Clone)]
    struct TestCallback {
        key: String,
        value: HeaderValue,
    }

    impl Callback for TestCallback {
        #[expect(clippy::panic_in_result_fn)]
        fn on_request(
            self,
            request: &server::Request,
            response: server::Response,
        ) -> Result<server::Response, server::ErrorResponse> {
            let _ = response;
            let value = request.headers().get(&self.key);
            assert!(value.is_some());

            if let Some(value) = request.headers().get(&self.key) {
                assert_eq!(value, self.value);
            }

            Ok(response)
        }
    }

    impl TestServer {
        async fn setup() -> Self {
            let server = TcpListener::bind("127.0.0.1:0").await.unwrap();
            let port = TcpListener::local_addr(&server).unwrap().port();

            let header_key = "test".to_string();
            let header_value = "test".to_string();

            let test_call_back = TestCallback {
                key: header_key,
                value: HeaderValue::from_str(&header_value).unwrap(),
            };

            let task = task::spawn(async move {
                // Keep accepting connections
                loop {
                    let (conn, _) = server.accept().await.unwrap();
                    let mut websocket = accept_hdr_async(conn, test_call_back.clone())
                        .await
                        .unwrap();

                    task::spawn(async move {
                        while let Some(Ok(msg)) = websocket.next().await {
                            match msg {
                                WsMessage::Text(txt) if txt == "close-now" => {
                                    log::debug!("Forcibly closing from server side");
                                    // This sends a close frame, then stops reading
                                    let _ = websocket.close(None).await;
                                    break;
                                }
                                // Echo text/binary frames
                                WsMessage::Text(_) | WsMessage::Binary(_) => {
                                    if websocket.send(msg).await.is_err() {
                                        break;
                                    }
                                }
                                // If the client closes, we also break
                                WsMessage::Close(_frame) => {
                                    let _ = websocket.close(None).await;
                                    break;
                                }
                                // Ignore pings/pongs
                                _ => {}
                            }
                        }
                    });
                }
            });

            Self { task, port }
        }
    }

    impl Drop for TestServer {
        fn drop(&mut self) {
            self.task.abort();
        }
    }

    async fn setup_test_client(port: u16) -> WebSocketClient {
        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![("test".into(), "test".into())],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: None,
            reconnect_delay_initial_ms: None,
            reconnect_backoff_factor: None,
            reconnect_delay_max_ms: None,
            reconnect_jitter_ms: None,
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };
        WebSocketClient::connect(config, Some(Arc::new(|_| {})), None, None, vec![], None)
            .await
            .expect("Failed to connect")
    }

    #[tokio::test]
    async fn test_websocket_basic() {
        let server = TestServer::setup().await;
        let client = setup_test_client(server.port).await;

        assert!(!client.is_disconnected());

        client.disconnect().await;
        assert!(client.is_disconnected());
    }

    #[rstest]
    #[tokio::test]
    async fn test_drop_sets_shared_connection_mode_closed() {
        let server = TestServer::setup().await;
        let client = setup_test_client(server.port).await;
        let connection_mode = client.connection_mode_atomic();

        drop(client);

        assert_eq!(
            ConnectionMode::from_atomic(&connection_mode),
            ConnectionMode::Closed
        );
    }

    #[tokio::test]
    async fn test_websocket_heartbeat() {
        let server = TestServer::setup().await;
        let client = setup_test_client(server.port).await;

        // Wait ~3s => server should see multiple "ping"
        tokio::time::sleep(std::time::Duration::from_secs(3)).await;

        // Cleanup
        client.disconnect().await;
        assert!(client.is_disconnected());
    }

    #[tokio::test]
    async fn test_websocket_reconnect_exhausted() {
        let config = WebSocketConfig {
            url: "ws://127.0.0.1:9997".into(), // <-- No server
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: None,
            reconnect_delay_initial_ms: None,
            reconnect_backoff_factor: None,
            reconnect_delay_max_ms: None,
            reconnect_jitter_ms: None,
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };
        let res =
            WebSocketClient::connect(config, Some(Arc::new(|_| {})), None, None, vec![], None)
                .await;
        assert!(res.is_err(), "Should fail quickly with no server");
    }

    #[tokio::test]
    async fn test_websocket_forced_close_reconnect() {
        let server = TestServer::setup().await;
        let client = setup_test_client(server.port).await;

        // 1) Send normal message
        client.send_text("Hello".into(), None).await.unwrap();

        // 2) Trigger forced close from server
        client.send_text("close-now".into(), None).await.unwrap();

        // 3) Wait a bit => read loop sees close => reconnect
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;

        // Confirm not disconnected
        assert!(!client.is_disconnected());

        // Cleanup
        client.disconnect().await;
        assert!(client.is_disconnected());
    }

    #[tokio::test]
    #[allow(clippy::result_large_err)]
    async fn test_reconnect_uses_updated_headers_without_interrupting_active_connection() {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();
        let (header_tx, mut header_rx) = tokio::sync::mpsc::unbounded_channel();

        let server_task = task::spawn(async move {
            loop {
                let (conn, _) = listener.accept().await.unwrap();
                let header_tx = header_tx.clone();
                let mut websocket = accept_hdr_async(
                    conn,
                    move |request: &server::Request, response: server::Response| {
                        let values = request
                            .headers()
                            .get_all("authorization")
                            .iter()
                            .map(|value| value.to_str().unwrap().to_string())
                            .collect::<Vec<_>>();
                        header_tx.send(values).unwrap();
                        Ok(response)
                    },
                )
                .await
                .unwrap();

                task::spawn(async move {
                    while let Some(Ok(msg)) = websocket.next().await {
                        if matches!(&msg, WsMessage::Text(text) if text.as_str() == "close-now") {
                            let _ = websocket.close(None).await;
                            break;
                        }
                    }
                });
            }
        });

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![("Authorization".into(), "Bearer initial".into())],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(50),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };
        let client =
            WebSocketClient::connect(config, Some(Arc::new(|_| {})), None, None, vec![], None)
                .await
                .unwrap();

        let initial = header_rx.recv().await.unwrap();
        let reconnect_headers = client.reconnect_headers();
        reconnect_headers
            .update("authorization", "Bearer refreshed")
            .unwrap();

        tokio::time::sleep(Duration::from_millis(100)).await;
        assert_eq!(initial, vec!["Bearer initial"]);
        assert!(client.is_active());
        assert!(header_rx.try_recv().is_err());
        assert!(!format!("{reconnect_headers:?}").contains("refreshed"));

        client.send_text("close-now".into(), None).await.unwrap();
        let refreshed = tokio::time::timeout(Duration::from_secs(3), header_rx.recv())
            .await
            .unwrap()
            .unwrap();

        assert_eq!(refreshed, vec!["Bearer refreshed"]);

        client.disconnect().await;
        server_task.abort();
    }

    #[tokio::test]
    async fn test_rate_limiter() {
        let server = TestServer::setup().await;
        let quota = Quota::per_second(NonZeroU32::new(2).unwrap()).unwrap();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{}", server.port),
            headers: vec![("test".into(), "test".into())],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: None,
            reconnect_delay_initial_ms: None,
            reconnect_backoff_factor: None,
            reconnect_delay_max_ms: None,
            reconnect_jitter_ms: None,
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(
            config,
            Some(Arc::new(|_| {})),
            None,
            None,
            vec![("default".into(), quota)],
            None,
        )
        .await
        .unwrap();

        // Burst of 2 passes immediately; the third send must wait for the
        // ~500ms replenish interval (keys=None would bypass the limiter)
        let keys: [ustr::Ustr; 1] = [ustr::Ustr::from("default")];
        let start = std::time::Instant::now();
        client
            .send_text("test1".into(), Some(keys.as_slice()))
            .await
            .unwrap();
        client
            .send_text("test2".into(), Some(keys.as_slice()))
            .await
            .unwrap();
        let after_burst = start.elapsed();
        client
            .send_text("test3".into(), Some(keys.as_slice()))
            .await
            .unwrap();
        let after_third = start.elapsed();

        assert!(
            after_burst < std::time::Duration::from_millis(300),
            "Burst sends should not be rate limited, took {after_burst:?}"
        );
        assert!(
            after_third >= std::time::Duration::from_millis(400),
            "Third send should wait for quota replenishment, took {after_third:?}"
        );

        // Cleanup
        client.disconnect().await;
        assert!(client.is_disconnected());
    }

    #[tokio::test]
    async fn test_concurrent_writers() {
        let server = TestServer::setup().await;
        let client = Arc::new(setup_test_client(server.port).await);

        let mut handles = vec![];

        for i in 0..10 {
            let client = client.clone();
            handles.push(task::spawn(async move {
                client.send_text(format!("test{i}"), None).await.unwrap();
            }));
        }

        for handle in handles {
            handle.await.unwrap();
        }

        // Cleanup
        client.disconnect().await;
        assert!(client.is_disconnected());
    }
}

#[cfg(test)]
#[cfg(not(feature = "turmoil"))]
#[cfg(not(all(feature = "simulation", madsim)))] // transport-layer I/O not simulated
mod rust_tests {
    use std::{
        pin::Pin,
        sync::{
            Arc, Condvar, Mutex as StdMutex, OnceLock,
            atomic::{AtomicBool, AtomicU8, AtomicUsize, Ordering},
        },
        task::{Context, Poll},
    };

    use futures_util::{SinkExt, StreamExt};
    use nautilus_common::testing::wait_until_async;
    use rstest::rstest;
    #[cfg(feature = "transport-sockudo")]
    use sockudo_ws::handshake as sockudo_handshake;
    #[cfg(feature = "transport-sockudo")]
    use tokio::io::{AsyncRead, AsyncReadExt, AsyncWriteExt};
    use tokio::{
        net::TcpListener,
        task::{self, JoinHandle},
        time::{Duration, sleep},
    };
    use tokio_tungstenite::{accept_async, tungstenite::Message as WsMessage};
    #[cfg(feature = "transport-sockudo")]
    use tokio_tungstenite::{
        accept_hdr_async,
        tungstenite::{
            handshake::server::{self, Callback},
            http::HeaderValue,
        },
    };

    use super::*;
    use crate::websocket::types::channel_message_handler;

    const TEST_TIMEOUT: Duration = Duration::from_secs(10);

    struct CondvarReleaseGuard<'a> {
        release: &'a (StdMutex<bool>, Condvar),
    }

    impl<'a> CondvarReleaseGuard<'a> {
        fn new(release: &'a (StdMutex<bool>, Condvar)) -> Self {
            Self { release }
        }

        fn release(&self) {
            let (lock, condvar) = self.release;
            let mut released = lock
                .lock()
                .unwrap_or_else(std::sync::PoisonError::into_inner);
            *released = true;
            condvar.notify_all();
        }
    }

    impl Drop for CondvarReleaseGuard<'_> {
        fn drop(&mut self) {
            self.release();
        }
    }

    async fn recv_rendezvous<T: Send + 'static>(
        receiver: std::sync::mpsc::Receiver<T>,
        name: &'static str,
    ) -> T {
        let receive_task = tokio::task::spawn_blocking(move || receiver.recv_timeout(TEST_TIMEOUT));

        match tokio::time::timeout(TEST_TIMEOUT * 2, receive_task).await {
            Ok(Ok(Ok(value))) => value,
            Ok(Ok(Err(e))) => {
                panic!("{name} did not arrive within the test timeout: {e}")
            }
            Ok(Err(e)) => panic!("{name} receive task failed: {e}"),
            Err(e) => panic!("{name} receive task did not finish: {e}"),
        }
    }

    async fn await_task_termination(task: tokio::task::JoinHandle<()>, name: &'static str) {
        match tokio::time::timeout(TEST_TIMEOUT, task).await {
            Ok(Ok(())) => {}
            Ok(Err(e)) if e.is_cancelled() => {}
            Ok(Err(e)) => panic!("{name} failed: {e}"),
            Err(e) => panic!("{name} did not terminate within the test timeout: {e}"),
        }
    }

    struct RecordingServer {
        task: JoinHandle<()>,
        port: u16,
        messages: Arc<tokio::sync::Mutex<Vec<String>>>,
    }

    #[cfg(feature = "transport-sockudo")]
    async fn read_http_request<S>(stream: &mut S) -> Vec<u8>
    where
        S: AsyncRead + Unpin,
    {
        let mut buf = Vec::new();
        let mut chunk = [0u8; 256];

        loop {
            let n = stream.read(&mut chunk).await.unwrap();
            assert!(n > 0, "HTTP request closed before headers completed");
            buf.extend_from_slice(&chunk[..n]);
            if buf.windows(4).any(|window| window == b"\r\n\r\n") {
                return buf;
            }
        }
    }

    #[cfg(feature = "transport-sockudo")]
    fn extract_header<'a>(request: &'a str, name: &str) -> Option<&'a str> {
        request.lines().find_map(|line| {
            let (header_name, header_value) = line.split_once(':')?;
            if header_name.eq_ignore_ascii_case(name) {
                Some(header_value.trim())
            } else {
                None
            }
        })
    }

    #[cfg(feature = "transport-sockudo")]
    #[derive(Debug, Clone)]
    struct HeaderAssertCallback {
        key: String,
        value: HeaderValue,
    }

    #[cfg(feature = "transport-sockudo")]
    impl Callback for HeaderAssertCallback {
        #[expect(
            clippy::panic_in_result_fn,
            reason = "assertion failures should fail the test"
        )]
        fn on_request(
            self,
            request: &server::Request,
            response: server::Response,
        ) -> Result<server::Response, server::ErrorResponse> {
            assert_eq!(request.headers().get(&self.key), Some(&self.value));
            Ok(response)
        }
    }

    impl RecordingServer {
        async fn setup() -> Self {
            let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
            let port = listener.local_addr().unwrap().port();
            let messages = Arc::new(tokio::sync::Mutex::new(Vec::new()));
            let messages_clone = Arc::clone(&messages);

            let task = task::spawn(async move {
                loop {
                    let (stream, _) = listener.accept().await.unwrap();
                    let mut websocket = accept_async(stream).await.unwrap();
                    let messages = Arc::clone(&messages_clone);

                    task::spawn(async move {
                        while let Some(Ok(msg)) = websocket.next().await {
                            match msg {
                                WsMessage::Text(text) => {
                                    messages.lock().await.push(text.to_string());
                                }
                                WsMessage::Close(_) => {
                                    let _ = websocket.close(None).await;
                                    break;
                                }
                                _ => {}
                            }
                        }
                    });
                }
            });

            Self {
                task,
                port,
                messages,
            }
        }

        async fn messages(&self) -> Vec<String> {
            self.messages.lock().await.clone()
        }
    }

    impl Drop for RecordingServer {
        fn drop(&mut self) {
            self.task.abort();
        }
    }

    #[rstest]
    #[tokio::test]
    async fn test_reconnect_then_disconnect() {
        // Bind an ephemeral port
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        // Server task: accept one ws connection then close it
        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            let ws = accept_async(stream).await.unwrap();
            drop(ws);
            // Keep alive briefly
            sleep(Duration::from_secs(1)).await;
        });

        // Build a channel-based message handler for incoming messages (unused here)
        let (handler, _rx) = channel_message_handler();

        // Configure client with short reconnect backoff
        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        // Connect the client
        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Allow server to drop connection and client to detect
        sleep(Duration::from_millis(100)).await;
        // Now immediately disconnect the client
        client.disconnect().await;
        assert!(client.is_disconnected());
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_reconnect_state_flips_when_reader_stops() {
        // Bind an ephemeral port and accept a single websocket connection which we drop.
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }
            sleep(Duration::from_millis(50)).await;
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        tokio::time::timeout(Duration::from_secs(2), async {
            loop {
                if client.is_reconnecting() {
                    break;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await
        .expect("client did not enter RECONNECT state");

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_stream_mode_disables_auto_reconnect() {
        // Test that stream-based clients (created via connect_stream) set is_stream_mode flag
        // and that reconnect() transitions to CLOSED state for stream mode
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(_ws) = accept_async(stream).await
            {
                // Keep connection alive briefly
                sleep(Duration::from_millis(100)).await;
            }
        });

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let (_reader, _client) = WebSocketClient::connect_stream(config, vec![], None, None)
            .await
            .unwrap();

        // Note: We can't easily test the reconnect behavior from the outside since
        // the inner client is private. The key fix is that WebSocketClientInner
        // now has is_stream_mode=true for connect_stream, and reconnect() will
        // transition to CLOSED state instead of creating a new reader that gets dropped.
        // This is tested implicitly by the fact that stream users won't get stuck
        // in an infinite reconnect loop.

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_message_handler_mode_allows_auto_reconnect() {
        // Test that regular clients (with message handler) can auto-reconnect
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept first connection and close it
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }
            sleep(Duration::from_millis(50)).await;
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Wait for the connection to be dropped and reconnection to be attempted
        tokio::time::timeout(Duration::from_secs(2), async {
            loop {
                if client.is_reconnecting() || client.is_closed() {
                    break;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await
        .expect("client should attempt reconnection or close");

        // Should either be reconnecting or closed (depending on timing)
        // The important thing is it's not staying active forever
        assert!(
            client.is_reconnecting() || client.is_closed(),
            "Client with message handler should attempt reconnection"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_handler_mode_reconnect_with_new_connection() {
        // Test that handler mode successfully reconnects and messages continue flowing
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // First connection - accept and immediately close
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }

            // Small delay to let client detect disconnection
            sleep(Duration::from_millis(100)).await;

            // Second connection - accept, send a message, then keep alive
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                use futures_util::SinkExt;
                let _ = ws
                    .send(WsMessage::Text("reconnected".to_string().into()))
                    .await;
                sleep(Duration::from_secs(1)).await;
            }
        });

        let (handler, mut rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(200),
            reconnect_backoff_factor: Some(1.5),
            reconnect_jitter_ms: Some(10),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Wait for reconnection to happen and message to arrive
        let result = tokio::time::timeout(Duration::from_secs(5), async {
            loop {
                if let Ok(msg) = rx.try_recv()
                    && matches!(msg, WsMessage::Text(ref text) if AsRef::<str>::as_ref(text) == "reconnected")
                {
                    return true;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await;

        assert!(
            result.is_ok(),
            "Should receive message after reconnection within timeout"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_stream_mode_no_auto_reconnect() {
        // Test that stream mode does not automatically reconnect when connection is lost
        // The caller owns the reader and is responsible for detecting disconnection
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept connection and send one message, then close
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                use futures_util::SinkExt;
                let _ = ws.send(WsMessage::Text("hello".to_string().into())).await;
                sleep(Duration::from_millis(50)).await;
                // Connection closes when ws is dropped
            }
        });

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let (mut reader, client) = WebSocketClient::connect_stream(config, vec![], None, None)
            .await
            .unwrap();

        // Initially active
        assert!(client.is_active(), "Client should start as active");

        // Read the hello message
        let msg = reader.next().await;
        assert!(
            matches!(&msg, Some(Ok(Message::Text(bytes))) if bytes.as_ref() == b"hello"),
            "Should receive initial message"
        );

        // Read until connection closes (reader will return None or error)
        while let Some(msg) = reader.next().await {
            if msg.is_err() || matches!(msg, Ok(Message::Close(_))) {
                break;
            }
        }

        // Controller cannot detect reader EOF (reader is owned by caller),
        // so the client stays ACTIVE until the caller signals.
        sleep(Duration::from_millis(200)).await;
        assert!(
            client.is_active(),
            "Stream mode client stays ACTIVE before notify_closed()"
        );

        // Caller signals EOF via notify_closed()
        client.notify_closed();

        assert!(
            client.is_closed(),
            "Stream mode client should be CLOSED after notify_closed()"
        );
        assert!(
            !client.is_reconnecting(),
            "Stream mode client should never attempt reconnection"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_send_timeout_uses_configured_reconnect_timeout() {
        // Test that send operations respect the configured reconnect_timeout.
        // When a client is stuck in RECONNECT longer than the timeout, sends should fail with Timeout.
        use nautilus_common::testing::wait_until_async;

        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept first connection and immediately close it
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }
            // Don't accept second connection - client will be stuck in RECONNECT
            sleep(Duration::from_mins(1)).await;
        });

        let (handler, _rx) = channel_message_handler();

        // Configure with SHORT 2s reconnect timeout
        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000), // 2s timeout
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Wait for client to enter RECONNECT state
        wait_until_async(
            || async { client.is_reconnecting() },
            Duration::from_secs(3),
        )
        .await;

        // Attempt send while stuck in RECONNECT - should timeout after 2s (configured timeout)
        let start = std::time::Instant::now();
        let send_result = client.send_text("test".to_string(), None).await;
        let elapsed = start.elapsed();

        assert!(
            send_result.is_err(),
            "Send should fail when client stuck in RECONNECT"
        );
        assert!(
            matches!(send_result, Err(crate::error::SendError::Timeout)),
            "Send should return Timeout error, was: {send_result:?}"
        );
        // Verify timeout respects configured value (2s), but don't check upper bound
        // as CI scheduler jitter can cause legitimate delays beyond the timeout
        assert!(
            elapsed >= Duration::from_millis(1800),
            "Send should timeout after at least 2s (configured timeout), took {elapsed:?}"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_send_waits_during_reconnection() {
        // Test that send operations wait for reconnection to complete (up to timeout)
        use nautilus_common::testing::wait_until_async;

        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // First connection - accept and immediately close
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }

            // Wait a bit before accepting second connection
            sleep(Duration::from_millis(500)).await;

            // Second connection - accept and keep alive
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                // Echo messages
                while let Some(Ok(msg)) = ws.next().await {
                    if ws.send(msg).await.is_err() {
                        break;
                    }
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(5_000), // 5s timeout - enough for reconnect
            reconnect_delay_initial_ms: Some(100),
            reconnect_delay_max_ms: Some(200),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Wait for reconnection to trigger
        wait_until_async(
            || async { client.is_reconnecting() },
            Duration::from_secs(2),
        )
        .await;

        // Try to send while reconnecting - should wait and succeed after reconnect
        let send_result = tokio::time::timeout(
            Duration::from_secs(3),
            client.send_text("test_message".to_string(), None),
        )
        .await;

        assert!(
            send_result.is_ok() && send_result.unwrap().is_ok(),
            "Send should succeed after waiting for reconnection"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_rate_limiter_before_active_wait() {
        // Test that rate limiting happens BEFORE active state check.
        // This prevents race conditions where connection state changes during rate limit wait.
        // We verify this by: (1) exhausting rate limit, (2) ensuring client is RECONNECTING,
        // (3) sending again and confirming it waits for rate limit THEN reconnection.
        use std::{num::NonZeroU32, sync::Arc};

        use nautilus_common::testing::wait_until_async;

        use crate::ratelimiter::quota::Quota;

        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // First connection - accept and close after receiving one message
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                // Receive first message then close
                if let Some(Ok(_)) = ws.next().await {
                    drop(ws);
                }
            }

            // Wait before accepting reconnection
            sleep(Duration::from_millis(500)).await;

            // Second connection - accept and keep alive
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                while let Some(Ok(msg)) = ws.next().await {
                    if ws.send(msg).await.is_err() {
                        break;
                    }
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(5_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        // Very restrictive rate limit: 1 request per second, burst of 1
        let quota = Quota::per_second(NonZeroU32::new(1).unwrap())
            .unwrap()
            .allow_burst(NonZeroU32::new(1).unwrap());

        let client = Arc::new(
            WebSocketClient::connect(
                config,
                Some(handler),
                None,
                None,
                vec![("test_key".to_string(), quota)],
                None,
            )
            .await
            .unwrap(),
        );

        // First send exhausts burst capacity and triggers connection close
        let test_key: [Ustr; 1] = [Ustr::from("test_key")];
        client
            .send_text("msg1".to_string(), Some(test_key.as_slice()))
            .await
            .unwrap();

        // Wait for client to enter RECONNECT state
        wait_until_async(
            || async { client.is_reconnecting() },
            Duration::from_secs(2),
        )
        .await;

        // Second send: will hit rate limit (~1s) THEN wait for reconnection (~0.5s)
        let start = std::time::Instant::now();
        let send_result = client
            .send_text("msg2".to_string(), Some(test_key.as_slice()))
            .await;
        let elapsed = start.elapsed();

        // Should succeed after both rate limit AND reconnection
        assert!(
            send_result.is_ok(),
            "Send should succeed after rate limit + reconnection, was: {send_result:?}"
        );
        // Total wait should be at least rate limit time (~1s)
        // The reconnection completes while rate limiting or after
        // Use 850ms threshold to account for timing jitter in CI
        assert!(
            elapsed >= Duration::from_millis(850),
            "Should wait for rate limit (~1s), waited {elapsed:?}"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_disconnect_during_reconnect_exits_cleanly() {
        // Test CAS race condition: disconnect called during reconnection
        // Should exit cleanly without spawning new tasks
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept first connection and immediately close
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }
            // Don't accept second connection - let reconnect hang
            sleep(Duration::from_mins(1)).await;
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000), // 2s timeout - shorter than disconnect timeout
            reconnect_delay_initial_ms: Some(100),
            reconnect_delay_max_ms: Some(200),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Wait for reconnection to start
        tokio::time::timeout(Duration::from_secs(2), async {
            while !client.is_reconnecting() {
                sleep(Duration::from_millis(10)).await;
            }
        })
        .await
        .expect("Client should enter RECONNECT state");

        // Disconnect while reconnecting
        client.disconnect().await;

        // Should be cleanly closed
        assert!(
            client.is_disconnected(),
            "Client should be cleanly disconnected"
        );

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_send_fails_fast_when_closed_before_rate_limit() {
        // Test that send operations check connection state BEFORE rate limiting,
        // preventing unnecessary delays when the connection is already closed.
        use std::{num::NonZeroU32, sync::Arc};

        use nautilus_common::testing::wait_until_async;

        use crate::ratelimiter::quota::Quota;

        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept connection and immediately close
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }
            sleep(Duration::from_mins(1)).await;
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(5_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        // Very restrictive rate limit: 1 request per 10 seconds
        // This ensures that if we wait for rate limit, the test will timeout
        let quota = Quota::with_period(Duration::from_secs(10))
            .unwrap()
            .allow_burst(NonZeroU32::new(1).unwrap());

        let client = Arc::new(
            WebSocketClient::connect(
                config,
                Some(handler),
                None,
                None,
                vec![("test_key".to_string(), quota)],
                None,
            )
            .await
            .unwrap(),
        );

        // Wait for disconnection
        wait_until_async(
            || async { client.is_reconnecting() || client.is_closed() },
            Duration::from_secs(2),
        )
        .await;

        // Explicitly disconnect to move away from ACTIVE state
        client.disconnect().await;
        assert!(
            !client.is_active(),
            "Client should not be active after disconnect"
        );

        // Attempt send - should fail IMMEDIATELY without waiting for rate limit
        let start = std::time::Instant::now();
        let test_key: [Ustr; 1] = [Ustr::from("test_key")];
        let result = client
            .send_text("test".to_string(), Some(test_key.as_slice()))
            .await;
        let elapsed = start.elapsed();

        // Should fail with Closed error
        assert!(result.is_err(), "Send should fail when client is closed");
        assert!(
            matches!(result, Err(crate::error::SendError::Closed)),
            "Send should return Closed error, was: {result:?}"
        );

        // Should fail FAST (< 100ms) without waiting for rate limit (10s)
        assert!(
            elapsed < Duration::from_millis(100),
            "Send should fail fast without rate limiting, took {elapsed:?}"
        );

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_connect_rejects_none_message_handler() {
        // Test that connect() properly rejects None message_handler
        // to prevent zombie connections that appear alive but never detect disconnections

        let config = WebSocketConfig {
            url: "ws://127.0.0.1:9999".to_string(),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(100),
            reconnect_delay_max_ms: Some(500),
            reconnect_backoff_factor: Some(1.5),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        // Pass None for message_handler - should be rejected
        let result = WebSocketClient::connect(config, None, None, None, vec![], None).await;

        assert!(
            result.is_err(),
            "connect() should reject None message_handler"
        );

        let err = result.unwrap_err();
        let err_msg = err.to_string();
        assert!(
            err_msg.contains("Handler mode requires message_handler"),
            "Error should mention missing message_handler, was: {err_msg}"
        );
    }

    #[rstest]
    #[tokio::test]
    async fn test_connect_url_rejects_invalid_reconnect_timing_before_connect() {
        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: "ws://127.0.0.1:1".to_string(),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(0),
            reconnect_delay_initial_ms: Some(100),
            reconnect_delay_max_ms: Some(500),
            reconnect_backoff_factor: Some(1.5),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let err = WebSocketClientInner::connect_url(config, Some(handler), None)
            .await
            .expect_err("invalid reconnect timing should be rejected");

        match err {
            TransportError::Io(error) => {
                assert_eq!(error.kind(), std::io::ErrorKind::InvalidInput);
                assert!(
                    error
                        .to_string()
                        .contains("Reconnect timeout cannot be zero"),
                    "error should mention zero reconnect timeout, was: {error}"
                );
            }
            other => panic!("expected InvalidInput IO error, was: {other:?}"),
        }
    }

    #[rstest]
    #[tokio::test]
    async fn test_connect_url_rejects_invalid_reconnect_backoff_before_dial() {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();
        let accepted = Arc::new(std::sync::atomic::AtomicBool::new(false));
        let accepted_clone = Arc::clone(&accepted);

        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            accepted_clone.store(true, Ordering::SeqCst);
            accept_async(stream).await.unwrap();
        });
        let (handler, _rx) = channel_message_handler();
        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(100.1),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let error = WebSocketClientInner::connect_url(config, Some(handler), None)
            .await
            .expect_err("invalid reconnect backoff should be rejected");

        match error {
            TransportError::Io(error) => {
                assert_eq!(error.kind(), std::io::ErrorKind::InvalidInput);
                assert!(
                    error.to_string().contains("factor"),
                    "error should mention the invalid factor, was: {error}"
                );
            }
            other => panic!("expected InvalidInput IO error, was: {other:?}"),
        }
        assert!(
            !accepted.load(Ordering::SeqCst),
            "invalid reconnect backoff must be rejected before dialing"
        );
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_client_without_handler_sets_stream_mode() {
        // Test that if a client is created without a handler via connect_url,
        // it properly sets is_stream_mode=true to prevent zombie connections

        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept and immediately close to simulate server disconnect
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws); // Drop connection immediately
            }
        });

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(100),
            reconnect_delay_max_ms: Some(500),
            reconnect_backoff_factor: Some(1.5),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        // Create client directly via connect_url with no handler (stream mode)
        let inner = WebSocketClientInner::connect_url(config, None, None)
            .await
            .unwrap();

        // Verify is_stream_mode is true when no handler
        assert!(
            inner.is_stream_mode,
            "Client without handler should have is_stream_mode=true"
        );

        // Verify that when stream mode is enabled, reconnection is disabled
        // (documented behavior - stream mode clients close instead of reconnecting)

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_idle_timeout_triggers_reconnect() {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        // Server accepts WS connection but sends nothing (simulates silent death)
        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            let _ws = accept_async(stream).await.unwrap();
            // Hold connection open but send nothing
            sleep(Duration::from_secs(5)).await;
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: Some(1),
            idle_timeout_ms: Some(500),
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        assert!(client.is_active());

        // Wait for idle timeout to fire and client to enter reconnect/closed
        wait_until_async(
            || async { client.is_reconnecting() || client.is_disconnected() },
            Duration::from_secs(3),
        )
        .await;

        assert!(
            !client.is_active(),
            "Client should not be active after idle timeout"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_idle_timeout_resets_on_data() {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        // Server sends a message every 200ms (well within 1s idle timeout)
        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            let mut ws = accept_async(stream).await.unwrap();

            for _ in 0..10 {
                sleep(Duration::from_millis(200)).await;

                if ws.send(WsMessage::Text("ping".into())).await.is_err() {
                    break;
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: Some(1),
            idle_timeout_ms: Some(1_000),
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        assert!(client.is_active());

        // Wait 1.5s - data arrives every 200ms so idle timeout (1s) should NOT fire
        sleep(Duration::from_millis(1_500)).await;

        assert!(
            client.is_active(),
            "Client should remain active when data is flowing"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_idle_timeout_fires_when_only_pings_received() {
        // Regression: pings and pongs are keep-alive frames, not application data,
        // so a peer that only emits control frames must still trip the idle timeout.
        // The peer keeps pinging for well past the observation window so the
        // pre-fix behavior (reset-on-ping) would keep the client active; under the
        // fix the idle timer never resets and fires after ~500ms.
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            let mut ws = accept_async(stream).await.unwrap();

            for _ in 0..60 {
                sleep(Duration::from_millis(100)).await;

                if ws.send(WsMessage::Ping(Vec::new().into())).await.is_err() {
                    break;
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: Some(1),
            idle_timeout_ms: Some(500),
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        assert!(client.is_active());

        // Observation window is shorter than the ping stream (6s). If the idle
        // timer mistakenly reset on every ping the client would still be active
        // here; under the fix it goes inactive at ~500ms.
        wait_until_async(
            || async { client.is_reconnecting() || client.is_disconnected() },
            Duration::from_millis(1_500),
        )
        .await;

        assert!(
            !client.is_active(),
            "Client should not be active after idle timeout when only pings/pongs flow"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_idle_timeout_fires_when_only_pongs_received() {
        // Regression for the heartbeat-reply path. When the client heartbeat is
        // enabled, the peer auto-replies with pongs for every outgoing ping. If
        // those pongs refreshed last_data_time the idle timer would never fire on
        // a zombie connection (the motivating Polymarket scenario).
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            let mut ws = accept_async(stream).await.unwrap();

            // Drain incoming frames so tungstenite's internal pong replies are
            // actually flushed to the client. Hold the connection open well past
            // the observation window.
            let deadline = tokio::time::Instant::now() + Duration::from_secs(6);
            while tokio::time::Instant::now() < deadline {
                if let Ok(Some(Err(_)) | None) =
                    tokio::time::timeout(Duration::from_millis(100), ws.next()).await
                {
                    break;
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: Some(1),
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: Some(1),
            idle_timeout_ms: Some(1_500),
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        assert!(client.is_active());

        // Heartbeat cadence is 1s; each ping draws a pong reply. Under the fix
        // the idle timer ignores those pongs and fires at ~1.5s. Under the bug
        // every pong reset the timer and the client would stay active.
        wait_until_async(
            || async { client.is_reconnecting() || client.is_disconnected() },
            Duration::from_millis(2_500),
        )
        .await;

        assert!(
            !client.is_active(),
            "Client should not be active after idle timeout when only pongs flow"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_disconnect_during_backoff_exits_promptly() {
        // Verify that disconnect interrupts backoff sleep (Finding 1).
        // Server accepts then drops, no second listener -> reconnect fails -> enters backoff.
        // We disconnect while backing off and assert the client shuts down quickly.
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept first connection, close immediately
            if let Ok((stream, _)) = listener.accept().await {
                let _ = accept_async(stream).await;
            }
            // Don't accept again so reconnect fails and enters backoff
            sleep(Duration::from_mins(1)).await;
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(10_000), // 10s backoff to ensure we're sleeping
            reconnect_delay_max_ms: Some(10_000),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        // Wait for client to enter reconnect
        wait_until_async(
            || async { client.is_reconnecting() },
            Duration::from_secs(3),
        )
        .await;

        // Wait a bit more for the reconnect attempt to fail and enter backoff sleep
        sleep(Duration::from_millis(1_500)).await;

        // Disconnect while backing off
        let start = std::time::Instant::now();
        client.disconnect().await;
        let elapsed = start.elapsed();

        assert!(client.is_disconnected(), "Client should be disconnected");
        // Should exit well before the 10s backoff sleep completes
        assert!(
            elapsed < Duration::from_secs(2),
            "Disconnect should interrupt backoff sleep, took {elapsed:?}"
        );

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_rate_limit_cancelled_on_disconnect() {
        // Verify that a send blocked on rate limiting returns Closed when
        // the client disconnects (Finding 6).
        use std::{num::NonZeroU32, sync::Arc};

        use crate::ratelimiter::quota::Quota;

        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((stream, _)) = listener.accept().await {
                let mut ws = accept_async(stream).await.unwrap();
                // Keep alive and echo
                while let Some(Ok(msg)) = ws.next().await {
                    if ws.send(msg).await.is_err() {
                        break;
                    }
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(5_000),
            reconnect_delay_initial_ms: Some(100),
            reconnect_delay_max_ms: Some(500),
            reconnect_backoff_factor: Some(1.5),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        // Very restrictive: 1 req per 60 seconds
        let quota = Quota::with_period(Duration::from_mins(1))
            .unwrap()
            .allow_burst(NonZeroU32::new(1).unwrap());

        let client = Arc::new(
            WebSocketClient::connect(
                config,
                Some(handler),
                None,
                None,
                vec![("rate_key".to_string(), quota)],
                None,
            )
            .await
            .unwrap(),
        );

        let test_key: [Ustr; 1] = [Ustr::from("rate_key")];

        // Exhaust the burst quota
        client
            .send_text("exhaust".to_string(), Some(test_key.as_slice()))
            .await
            .unwrap();

        // Spawn a send that will block on rate limiter
        let client_clone = client.clone();
        let send_handle = task::spawn(async move {
            client_clone
                .send_text("blocked".to_string(), Some(&[Ustr::from("rate_key")]))
                .await
        });

        // Let the send block on rate limit
        sleep(Duration::from_millis(200)).await;

        // Disconnect while send is blocked
        let start = std::time::Instant::now();
        client.disconnect().await;
        let elapsed_disconnect = start.elapsed();

        // The blocked send should return Closed
        let result = tokio::time::timeout(Duration::from_secs(2), send_handle)
            .await
            .expect("Send task should complete quickly")
            .expect("Send task should not panic");

        assert!(
            matches!(result, Err(crate::error::SendError::Closed)),
            "Blocked send should return Closed, was: {result:?}"
        );

        // Disconnect should be fast, not waiting for the 60s rate limit
        assert!(
            elapsed_disconnect < Duration::from_secs(3),
            "Disconnect should not wait for rate limiter, took {elapsed_disconnect:?}"
        );

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_stream_mode_transitions_to_closed_on_dead_write_task() {
        // Verify that stream mode transitions to CLOSED (not RECONNECT) when
        // the write task dies (Finding 4). We force write failure by sending
        // after the server closes the connection.
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                // Close immediately to cause write errors
                drop(ws);
            }
        });

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(1_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let (_reader, client) = WebSocketClient::connect_stream(config, vec![], None, None)
            .await
            .unwrap();

        assert!(client.is_active(), "Client should start active");

        // Wait for server to close, then send to trigger write task failure
        sleep(Duration::from_millis(100)).await;

        // Keep sending until the write task detects the broken connection
        for _ in 0..20 {
            let _ = client.send_text("ping".to_string(), None).await;
            sleep(Duration::from_millis(50)).await;

            if !client.is_active() {
                break;
            }
        }

        // Wait for controller to process the state change
        wait_until_async(|| async { !client.is_active() }, Duration::from_secs(5)).await;

        // Stream mode should go to CLOSED, not RECONNECT
        assert!(
            client.is_closed() || client.is_disconnected(),
            "Stream mode should transition to CLOSED, not RECONNECT. \
             is_reconnecting={}, is_closed={}, is_disconnected={}",
            client.is_reconnecting(),
            client.is_closed(),
            client.is_disconnected(),
        );
        assert!(
            !client.is_reconnecting(),
            "Stream mode should never attempt reconnection"
        );

        server.abort();
    }

    #[derive(Default)]
    struct BlockingFailState {
        send_entered: AtomicBool,
        send_entered_notify: tokio::sync::Notify,
        fail: AtomicBool,
        waker: std::sync::Mutex<Option<std::task::Waker>>,
    }

    impl BlockingFailState {
        fn trigger_failure(&self) {
            self.fail.store(true, Ordering::SeqCst);

            if let Some(waker) = self.waker.lock().unwrap().take() {
                waker.wake();
            }
        }
    }

    /// Transport whose sends block until [`BlockingFailState::trigger_failure`],
    /// then fail. Used to interleave a disconnect with an in-flight send.
    struct BlockingFailTransport {
        state: Arc<BlockingFailState>,
    }

    impl futures_util::Stream for BlockingFailTransport {
        type Item = Result<Message, TransportError>;

        fn poll_next(
            self: std::pin::Pin<&mut Self>,
            _cx: &mut std::task::Context<'_>,
        ) -> std::task::Poll<Option<Self::Item>> {
            std::task::Poll::Pending
        }
    }

    impl futures_util::Sink<Message> for BlockingFailTransport {
        type Error = TransportError;

        fn poll_ready(
            self: std::pin::Pin<&mut Self>,
            _cx: &mut std::task::Context<'_>,
        ) -> std::task::Poll<Result<(), Self::Error>> {
            std::task::Poll::Ready(Ok(()))
        }

        fn start_send(self: std::pin::Pin<&mut Self>, _item: Message) -> Result<(), Self::Error> {
            Ok(())
        }

        fn poll_flush(
            self: std::pin::Pin<&mut Self>,
            cx: &mut std::task::Context<'_>,
        ) -> std::task::Poll<Result<(), Self::Error>> {
            // Store the waker before checking the flag so trigger_failure
            // cannot slip between the check and the registration
            *self.state.waker.lock().unwrap() = Some(cx.waker().clone());
            self.state.send_entered.store(true, Ordering::SeqCst);
            self.state.send_entered_notify.notify_one();

            if self.state.fail.load(Ordering::SeqCst) {
                std::task::Poll::Ready(Err(TransportError::ConnectionReset))
            } else {
                std::task::Poll::Pending
            }
        }

        fn poll_close(
            self: std::pin::Pin<&mut Self>,
            _cx: &mut std::task::Context<'_>,
        ) -> std::task::Poll<Result<(), Self::Error>> {
            std::task::Poll::Ready(Ok(()))
        }
    }

    struct BlockingMessageState {
        polled_tx: StdMutex<Option<std::sync::mpsc::Sender<()>>>,
        release: (StdMutex<bool>, std::sync::Condvar),
        message: StdMutex<Option<Message>>,
    }

    struct BlockingMessageTransport {
        state: Arc<BlockingMessageState>,
    }

    impl futures_util::Stream for BlockingMessageTransport {
        type Item = Result<Message, TransportError>;

        fn poll_next(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
            if let Some(polled_tx) = self.state.polled_tx.lock().unwrap().take() {
                polled_tx.send(()).unwrap();
            }
            let (lock, condvar) = &self.state.release;
            let mut released = lock.lock().unwrap();

            while !*released {
                released = condvar.wait(released).unwrap();
            }

            Poll::Ready(self.state.message.lock().unwrap().take().map(Ok))
        }
    }

    impl futures_util::Sink<Message> for BlockingMessageTransport {
        type Error = TransportError;

        fn poll_ready(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
        ) -> Poll<Result<(), Self::Error>> {
            Poll::Ready(Ok(()))
        }

        fn start_send(self: Pin<&mut Self>, _item: Message) -> Result<(), Self::Error> {
            Ok(())
        }

        fn poll_flush(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
        ) -> Poll<Result<(), Self::Error>> {
            Poll::Ready(Ok(()))
        }

        fn poll_close(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
        ) -> Poll<Result<(), Self::Error>> {
            Poll::Ready(Ok(()))
        }
    }

    struct RecordingState {
        messages: Arc<StdMutex<Vec<Message>>>,
        recorded_notify: tokio::sync::Notify,
    }

    struct RecordingTransport {
        state: Arc<RecordingState>,
    }

    impl futures_util::Stream for RecordingTransport {
        type Item = Result<Message, TransportError>;

        fn poll_next(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
            Poll::Pending
        }
    }

    impl futures_util::Sink<Message> for RecordingTransport {
        type Error = TransportError;

        fn poll_ready(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
        ) -> Poll<Result<(), Self::Error>> {
            Poll::Ready(Ok(()))
        }

        fn start_send(self: Pin<&mut Self>, item: Message) -> Result<(), Self::Error> {
            self.state.messages.lock().unwrap().push(item);
            self.state.recorded_notify.notify_one();
            Ok(())
        }

        fn poll_flush(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
        ) -> Poll<Result<(), Self::Error>> {
            Poll::Ready(Ok(()))
        }

        fn poll_close(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
        ) -> Poll<Result<(), Self::Error>> {
            Poll::Ready(Ok(()))
        }
    }

    #[rstest]
    #[case(Message::text("stale"))]
    #[case(Message::Binary(vec![1, 2, 3].into()))]
    #[case(Message::Ping(vec![1, 2, 3].into()))]
    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
    async fn test_message_handler_drops_old_session_message(#[case] message: Message) {
        let (polled_tx, polled_rx) = std::sync::mpsc::channel();
        let state = Arc::new(BlockingMessageState {
            polled_tx: StdMutex::new(Some(polled_tx)),
            release: (StdMutex::new(false), Condvar::new()),
            message: StdMutex::new(Some(message)),
        });
        let release_guard = CondvarReleaseGuard::new(&state.release);
        let transport: BoxedWsTransport = Box::pin(BlockingMessageTransport {
            state: Arc::clone(&state),
        });
        let (_writer, reader) = transport.split();
        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let read_fence = ReadSessionFence::new();
        let message_count = Arc::new(AtomicUsize::new(0));
        let ping_count = Arc::new(AtomicUsize::new(0));
        let message_count_clone = Arc::clone(&message_count);
        let ping_count_clone = Arc::clone(&ping_count);
        let message_handler: MessageHandler =
            Arc::new(move |_| _ = message_count_clone.fetch_add(1, Ordering::SeqCst));
        let ping_handler: PingHandler =
            Arc::new(move |_| _ = ping_count_clone.fetch_add(1, Ordering::SeqCst));

        let read_task = WebSocketClientInner::spawn_message_handler_task(
            Arc::clone(&connection_state),
            state_notify,
            read_fence.clone(),
            reader,
            0,
            Some(&message_handler),
            None,
            Some(&ping_handler),
            None,
        );

        recv_rendezvous(polled_rx, "WebSocket reader poll entry").await;
        connection_state.store(ConnectionMode::Reconnect.as_u8(), Ordering::SeqCst);
        read_fence.invalidate();
        read_task.abort();
        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);
        release_guard.release();
        await_task_termination(read_task, "old WebSocket read task").await;

        assert_eq!(message_count.load(Ordering::SeqCst), 0);
        assert_eq!(ping_count.load(Ordering::SeqCst), 0);
    }

    #[rstest]
    #[tokio::test(start_paused = true)]
    async fn test_stalled_websocket_send_reconnects_and_replays() {
        let state = Arc::new(BlockingFailState::default());
        let transport: BoxedWsTransport = Box::pin(BlockingFailTransport {
            state: Arc::clone(&state),
        });
        let (writer, _reader) = transport.split();
        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(false));
        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::new(AtomicU64::new(0)),
            Arc::clone(&auth_tracker),
            reconnect_buffer_waits_for_auth,
        );

        writer_tx
            .send(WriterCommand::Send(Message::text("complete-message")))
            .unwrap();
        state.send_entered_notify.notified().await;

        let recorded = Arc::new(StdMutex::new(Vec::new()));
        let recording_state = Arc::new(RecordingState {
            messages: Arc::clone(&recorded),
            recorded_notify: tokio::sync::Notify::new(),
        });
        let transport: BoxedWsTransport = Box::pin(RecordingTransport {
            state: Arc::clone(&recording_state),
        });
        let (new_writer, _reader) = transport.split();
        let (update_tx, update_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(new_writer, update_tx))
            .unwrap();

        tokio::time::advance(Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS)).await;
        assert_eq!(
            tokio::time::timeout(Duration::from_secs(1), update_rx)
                .await
                .expect("writer update should not remain queued behind a stalled send")
                .unwrap(),
            1,
            "the replacement sink should install as connection epoch 1"
        );
        assert_eq!(
            ConnectionMode::from_atomic(&connection_state),
            ConnectionMode::Reconnect
        );

        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        tokio::time::advance(Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS)).await;
        recording_state.recorded_notify.notified().await;
        assert_eq!(
            recorded.lock().unwrap().as_slice(),
            &[Message::text("complete-message")]
        );

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.await.unwrap();
    }

    #[rstest]
    #[tokio::test(start_paused = true)]
    async fn test_stalled_ownership_bound_send_times_out_without_replay() {
        let state = Arc::new(BlockingFailState::default());
        let transport: BoxedWsTransport = Box::pin(BlockingFailTransport {
            state: Arc::clone(&state),
        });
        let (writer, _reader) = transport.split();
        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(false));
        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::new(AtomicU64::new(0)),
            Arc::clone(&auth_tracker),
            reconnect_buffer_waits_for_auth,
        );

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("ownership-bound"),
                connection_epoch: 0,
                response_tx,
            })
            .unwrap();
        state.send_entered_notify.notified().await;

        tokio::time::advance(Duration::from_secs(WRITE_TIMEOUT_SECS)).await;
        let outcome = tokio::time::timeout(Duration::from_secs(1), response_rx)
            .await
            .expect("a stalled ownership-bound send must not wedge the writer task")
            .unwrap();
        assert!(
            matches!(outcome, Err(SendError::WriteTimeout)),
            "expected the write deadline to be reported, was {outcome:?}"
        );
        assert_eq!(
            ConnectionMode::from_atomic(&connection_state),
            ConnectionMode::Reconnect
        );

        // The timed-out message is ownership-bound, so unlike an ordinary send it must
        // NOT be buffered for replay onto the replacement sink.
        let recorded = Arc::new(StdMutex::new(Vec::new()));
        let recording_state = Arc::new(RecordingState {
            messages: Arc::clone(&recorded),
            recorded_notify: tokio::sync::Notify::new(),
        });
        let transport: BoxedWsTransport = Box::pin(RecordingTransport {
            state: Arc::clone(&recording_state),
        });
        let (new_writer, _reader) = transport.split();
        let (update_tx, update_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(new_writer, update_tx))
            .unwrap();

        tokio::time::advance(Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS)).await;
        assert_eq!(
            tokio::time::timeout(Duration::from_secs(1), update_rx)
                .await
                .expect("writer update should not remain queued behind a stalled send")
                .unwrap(),
            1
        );

        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        tokio::time::advance(Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS)).await;

        // Barrier: two sentinels bound to the NEW epoch, the second sent only after the first
        // is acknowledged. The writer can accept the first from a `recv()` that was already
        // pending when the mode flipped, so only the second is necessarily processed after the
        // intervening loop-top drain - which is where a mistakenly buffered message would be
        // replayed. One sentinel alone would leave the ordering to chance.
        for name in ["sentinel-1", "sentinel-2"] {
            let (sentinel_tx, sentinel_rx) = tokio::sync::oneshot::channel();
            writer_tx
                .send(WriterCommand::SendOnConnection {
                    message: Message::text(name),
                    connection_epoch: 1,
                    response_tx: sentinel_tx,
                })
                .unwrap();
            recording_state.recorded_notify.notified().await;
            sentinel_rx
                .await
                .unwrap()
                .expect("the sentinel should send on the replacement connection");
        }

        assert_eq!(
            recorded.lock().unwrap().as_slice(),
            &[Message::text("sentinel-1"), Message::text("sentinel-2")],
            "an ownership-bound message must never be replayed after its deadline expires"
        );

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.await.unwrap();
    }

    #[rstest]
    #[tokio::test(start_paused = true)]
    async fn test_stalled_websocket_replay_reconnects_and_retries_buffer() {
        let initial_messages = Arc::new(StdMutex::new(Vec::new()));
        let initial_recording_state = Arc::new(RecordingState {
            messages: initial_messages,
            recorded_notify: tokio::sync::Notify::new(),
        });
        let transport: BoxedWsTransport = Box::pin(RecordingTransport {
            state: initial_recording_state,
        });
        let (writer, _reader) = transport.split();
        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Reconnect.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(false));
        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::new(AtomicU64::new(0)),
            Arc::clone(&auth_tracker),
            reconnect_buffer_waits_for_auth,
        );

        writer_tx
            .send(WriterCommand::Send(Message::text("buffered-message")))
            .unwrap();

        let blocking_state = Arc::new(BlockingFailState::default());
        let transport: BoxedWsTransport = Box::pin(BlockingFailTransport {
            state: Arc::clone(&blocking_state),
        });
        let (blocking_writer, _reader) = transport.split();
        let (blocking_tx, blocking_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(blocking_writer, blocking_tx))
            .unwrap();
        assert_eq!(blocking_rx.await.unwrap(), 1);

        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        tokio::time::advance(Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS)).await;
        blocking_state.send_entered_notify.notified().await;

        let recorded = Arc::new(StdMutex::new(Vec::new()));
        let recording_state = Arc::new(RecordingState {
            messages: Arc::clone(&recorded),
            recorded_notify: tokio::sync::Notify::new(),
        });
        let transport: BoxedWsTransport = Box::pin(RecordingTransport {
            state: Arc::clone(&recording_state),
        });
        let (new_writer, _reader) = transport.split();
        let (update_tx, update_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(new_writer, update_tx))
            .unwrap();

        tokio::time::advance(Duration::from_secs(GRACEFUL_SHUTDOWN_TIMEOUT_SECS)).await;
        assert_eq!(
            tokio::time::timeout(Duration::from_secs(1), update_rx)
                .await
                .expect("writer update should not remain queued behind stalled replay")
                .unwrap(),
            2,
            "the second replacement sink should install as connection epoch 2"
        );
        assert_eq!(
            ConnectionMode::from_atomic(&connection_state),
            ConnectionMode::Reconnect
        );

        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        tokio::time::advance(Duration::from_millis(CONNECTION_STATE_CHECK_INTERVAL_MS)).await;
        recording_state.recorded_notify.notified().await;
        assert_eq!(
            recorded.lock().unwrap().as_slice(),
            &[Message::text("buffered-message")]
        );

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.await.unwrap();
    }

    #[rstest]
    #[tokio::test]
    async fn test_new_with_writer_rejects_zero_heartbeat() {
        // Stream mode shares connect_url's validation: a zero heartbeat would
        // spawn a busy-loop ping flood
        let transport: BoxedWsTransport = Box::pin(BlockingFailTransport {
            state: Arc::new(BlockingFailState::default()),
        });
        let (writer, _reader) = transport.split();

        let config = WebSocketConfig {
            url: "ws://127.0.0.1:1".to_string(),
            headers: vec![],
            heartbeat: Some(0),
            heartbeat_msg: None,
            reconnect_timeout_ms: None,
            reconnect_delay_initial_ms: None,
            reconnect_delay_max_ms: None,
            reconnect_backoff_factor: None,
            reconnect_jitter_ms: None,
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let err = WebSocketClientInner::new_with_writer(config, writer)
            .await
            .expect_err("zero heartbeat should be rejected in stream mode");
        assert!(
            err.to_string()
                .contains("Heartbeat interval cannot be zero"),
            "error should mention zero heartbeat, was: {err}"
        );
    }

    #[rstest]
    #[tokio::test]
    async fn test_connect_times_out_on_silent_server() {
        // A server that accepts TCP but never completes the WebSocket upgrade
        // must not hang connect() indefinitely
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // Accept and hold the socket open without responding
            if let Ok((_stream, _)) = listener.accept().await {
                sleep(Duration::from_secs(30)).await;
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(500),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let result = tokio::time::timeout(
            Duration::from_secs(5),
            WebSocketClient::connect(config, Some(handler), None, None, vec![], None),
        )
        .await
        .expect("connect should not hang on a silent server");

        assert!(result.is_err(), "connect should fail with a timeout error");
        let err_msg = result.unwrap_err().to_string();
        assert!(
            err_msg.contains("timed out"),
            "error should mention the timeout, was: {err_msg}"
        );

        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_reconnect_succeeds_with_timeout_shorter_than_swap_ceremony() {
        // Regression: the reconnect timeout used to cover the writer swap and
        // graceful-shutdown delays (~200ms minimum), so a short timeout caused
        // every otherwise-successful reconnect to be discarded mid-swap and the
        // already-swapped writer to be orphaned. The timeout now bounds only
        // connection establishment.
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            // First connection: accept and immediately drop
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(ws) = accept_async(stream).await
            {
                drop(ws);
            }

            // Second connection: announce and keep alive
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                let _ = ws
                    .send(WsMessage::Text("reconnected-msg".to_string().into()))
                    .await;
                sleep(Duration::from_secs(5)).await;
            }
        });

        let (handler, mut rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(150), // Shorter than the ~200ms swap ceremony
            reconnect_delay_initial_ms: Some(25),
            reconnect_delay_max_ms: Some(50),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        let received = tokio::time::timeout(Duration::from_secs(5), async {
            loop {
                if let Ok(WsMessage::Text(text)) = rx.try_recv()
                    && text.as_str() == "reconnected-msg"
                {
                    return true;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await;

        assert!(
            received.is_ok(),
            "Reconnect should complete despite a timeout shorter than the swap ceremony"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_idle_timeout_fires_under_ping_flood() {
        // Regression: the idle check used to run only when nothing arrived for a
        // full check interval (10ms), so pings flooding faster than that starved
        // it and a ping-only zombie connection never tripped the timeout
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            let (stream, _) = listener.accept().await.unwrap();
            let mut ws = accept_async(stream).await.unwrap();

            for _ in 0..600 {
                sleep(Duration::from_millis(5)).await;

                if ws.send(WsMessage::Ping(Vec::new().into())).await.is_err() {
                    break;
                }
            }
        });

        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: Some(1),
            idle_timeout_ms: Some(500),
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .unwrap();

        assert!(client.is_active());

        wait_until_async(
            || async { client.is_reconnecting() || client.is_disconnected() },
            Duration::from_millis(1_500),
        )
        .await;

        assert!(
            !client.is_active(),
            "Client should not be active after idle timeout under a ping flood"
        );

        client.disconnect().await;
        server.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_send_failure_does_not_overwrite_disconnect() {
        let state = Arc::new(BlockingFailState::default());
        let transport: BoxedWsTransport = Box::pin(BlockingFailTransport {
            state: Arc::clone(&state),
        });
        let (writer, _reader) = transport.split();

        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(false));
        let connection_epoch = Arc::new(AtomicU64::new(0));

        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            connection_epoch,
            Arc::clone(&auth_tracker),
            Arc::clone(&reconnect_buffer_waits_for_auth),
        );

        writer_tx
            .send(WriterCommand::Send(Message::text("doomed")))
            .unwrap();

        // Wait until the writer task is blocked inside the transport send
        wait_until_async(
            || {
                let state = Arc::clone(&state);
                async move { state.send_entered.load(Ordering::SeqCst) }
            },
            Duration::from_secs(2),
        )
        .await;

        // Disconnect lands while the send is in flight, then the send fails;
        // the writer error path must not overwrite DISCONNECT with RECONNECT
        connection_state.store(ConnectionMode::Disconnect.as_u8(), Ordering::SeqCst);
        state.trigger_failure();

        tokio::time::timeout(Duration::from_secs(2), write_task)
            .await
            .expect("write task should exit after disconnect")
            .unwrap();

        assert_eq!(
            ConnectionMode::from_atomic(&connection_state),
            ConnectionMode::Disconnect,
            "Send failure must not resurrect a disconnecting client into RECONNECT"
        );
    }

    #[tokio::test]
    async fn send_on_connection_write_failure_reports_broken_pipe_and_reconnects() {
        let state = Arc::new(BlockingFailState::default());
        let transport: BoxedWsTransport = Box::pin(BlockingFailTransport {
            state: Arc::clone(&state),
        });
        let (writer, _reader) = transport.split();
        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let connection_epoch = Arc::new(AtomicU64::new(0));
        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::clone(&connection_epoch),
            Arc::new(OnceLock::new()),
            Arc::new(AtomicBool::new(false)),
        );

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("doomed"),
                connection_epoch: 0,
                response_tx,
            })
            .unwrap();
        wait_until_async(
            || {
                let state = Arc::clone(&state);
                async move { state.send_entered.load(Ordering::SeqCst) }
            },
            Duration::from_secs(2),
        )
        .await;

        state.trigger_failure();

        match response_rx.await.unwrap().unwrap_err() {
            SendError::BrokenPipe(message) => assert_eq!(message, "connection reset"),
            other => panic!("expected broken-pipe send error, was {other:?}"),
        }
        wait_until_async(
            || async {
                ConnectionMode::from_atomic(&connection_state) == ConnectionMode::Reconnect
            },
            Duration::from_secs(2),
        )
        .await;
        assert_eq!(
            ConnectionMode::from_atomic(&connection_state),
            ConnectionMode::Reconnect,
        );
        assert_eq!(connection_epoch.load(Ordering::Acquire), 0);

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.await.unwrap();
    }

    #[tokio::test]
    async fn send_on_connection_rejects_stale_epoch_without_replay() {
        let server = RecordingServer::setup().await;
        let url = format!("ws://127.0.0.1:{}", server.port);
        let (writer, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();
        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Active.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let connection_epoch = Arc::new(AtomicU64::new(0));
        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::clone(&connection_epoch),
            auth_tracker,
            Arc::new(AtomicBool::new(false)),
        );

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("epoch-0"),
                connection_epoch: 0,
                response_tx,
            })
            .unwrap();
        response_rx.await.unwrap().unwrap();

        connection_state.store(ConnectionMode::Reconnect.as_u8(), Ordering::SeqCst);
        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("during-reconnect"),
                connection_epoch: 0,
                response_tx,
            })
            .unwrap();
        assert!(matches!(
            response_rx.await.unwrap(),
            Err(SendError::ConnectionChanged),
        ));

        let (replacement, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();
        let (update_tx, update_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(replacement, update_tx))
            .unwrap();
        assert_eq!(update_rx.await.unwrap(), 1);
        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("stale"),
                connection_epoch: 0,
                response_tx,
            })
            .unwrap();
        assert!(matches!(
            response_rx.await.unwrap(),
            Err(SendError::ConnectionChanged),
        ));

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("epoch-1"),
                connection_epoch: 1,
                response_tx,
            })
            .unwrap();
        response_rx.await.unwrap().unwrap();

        connection_state.store(ConnectionMode::Reconnect.as_u8(), Ordering::SeqCst);
        let (second_replacement, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();
        let (update_tx, update_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(second_replacement, update_tx))
            .unwrap();
        assert_eq!(update_rx.await.unwrap(), 2);
        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("stale-after-second-reconnect"),
                connection_epoch: 1,
                response_tx,
            })
            .unwrap();
        assert!(matches!(
            response_rx.await.unwrap(),
            Err(SendError::ConnectionChanged),
        ));

        let (response_tx, response_rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::SendOnConnection {
                message: Message::text("epoch-2"),
                connection_epoch: 2,
                response_tx,
            })
            .unwrap();
        response_rx.await.unwrap().unwrap();

        wait_until_async(
            || {
                let messages = Arc::clone(&server.messages);
                async move { messages.lock().await.len() == 3 }
            },
            Duration::from_secs(2),
        )
        .await;
        assert_eq!(connection_epoch.load(Ordering::Acquire), 2);
        assert_eq!(
            server.messages().await,
            vec![
                "epoch-0".to_string(),
                "epoch-1".to_string(),
                "epoch-2".to_string(),
            ],
        );

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.abort();
    }

    #[tokio::test]
    async fn test_write_task_waits_for_auth_before_replaying_buffer() {
        use nautilus_common::testing::wait_until_async;

        let server = RecordingServer::setup().await;
        let url = format!("ws://127.0.0.1:{}", server.port);
        let (writer, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();

        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Reconnect.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(true));
        let connection_epoch = Arc::new(AtomicU64::new(0));
        let tracker = AuthTracker::new();
        auth_tracker.set(tracker.clone()).unwrap();

        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::clone(&connection_epoch),
            Arc::clone(&auth_tracker),
            Arc::clone(&reconnect_buffer_waits_for_auth),
        );

        writer_tx
            .send(WriterCommand::Send(Message::Text("stale".into())))
            .unwrap();

        let (new_writer, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();
        let (tx, rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(new_writer, tx))
            .unwrap();
        assert_eq!(rx.await.unwrap(), 1);

        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);

        tokio::time::sleep(Duration::from_millis(300)).await;
        assert!(
            server.messages().await.is_empty(),
            "buffered messages should wait for re-authentication"
        );

        tracker.succeed();

        wait_until_async(
            || {
                let messages = Arc::clone(&server.messages);
                async move { !messages.lock().await.is_empty() }
            },
            Duration::from_secs(3),
        )
        .await;

        assert_eq!(server.messages().await, vec!["stale".to_string()]);

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.abort();
    }

    #[tokio::test]
    async fn test_write_task_discards_buffer_after_auth_failure() {
        let server = RecordingServer::setup().await;
        let url = format!("ws://127.0.0.1:{}", server.port);
        let (writer, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();

        let connection_state = Arc::new(AtomicU8::new(ConnectionMode::Reconnect.as_u8()));
        let state_notify = Arc::new(tokio::sync::Notify::new());
        let auth_tracker = Arc::new(OnceLock::new());
        let reconnect_buffer_waits_for_auth = Arc::new(AtomicBool::new(true));
        let connection_epoch = Arc::new(AtomicU64::new(0));
        let tracker = AuthTracker::new();
        auth_tracker.set(tracker.clone()).unwrap();

        let (writer_tx, writer_rx) = tokio::sync::mpsc::unbounded_channel();
        let write_task = WebSocketClientInner::spawn_write_task(
            Arc::clone(&connection_state),
            Arc::clone(&state_notify),
            writer,
            writer_rx,
            Arc::clone(&connection_epoch),
            Arc::clone(&auth_tracker),
            Arc::clone(&reconnect_buffer_waits_for_auth),
        );

        writer_tx
            .send(WriterCommand::Send(Message::Text("stale".into())))
            .unwrap();

        let (new_writer, _reader) = WebSocketClientInner::connect_with_server(
            &url,
            vec![],
            TransportBackend::Tungstenite,
            None,
        )
        .await
        .unwrap();
        let (tx, rx) = tokio::sync::oneshot::channel();
        writer_tx
            .send(WriterCommand::Update(new_writer, tx))
            .unwrap();
        assert_eq!(rx.await.unwrap(), 1);

        connection_state.store(ConnectionMode::Active.as_u8(), Ordering::SeqCst);
        tracker.fail("rejected");
        tokio::time::sleep(Duration::from_millis(300)).await;
        assert!(
            server.messages().await.is_empty(),
            "buffered messages should be discarded after authentication failure"
        );

        let _auth_receiver = tracker.begin();
        tracker.succeed();
        tokio::time::sleep(Duration::from_millis(300)).await;
        assert!(
            server.messages().await.is_empty(),
            "discarded buffered messages should not replay on a later auth success"
        );

        connection_state.store(ConnectionMode::Closed.as_u8(), Ordering::SeqCst);
        state_notify.notify_waiters();
        drop(writer_tx);
        write_task.abort();
    }

    #[rstest]
    #[tokio::test]
    async fn test_zero_idle_timeout_rejected() {
        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: "ws://127.0.0.1:9999".to_string(),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: None,
            reconnect_delay_initial_ms: None,
            reconnect_delay_max_ms: None,
            reconnect_backoff_factor: None,
            reconnect_jitter_ms: None,
            reconnect_max_attempts: None,
            idle_timeout_ms: Some(0),
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        };

        let result =
            WebSocketClient::connect(config, Some(handler), None, None, vec![], None).await;

        assert!(result.is_err(), "Zero idle timeout should be rejected");
        let err_msg = result.unwrap_err().to_string();
        assert!(
            err_msg.contains("Idle timeout cannot be zero"),
            "Error should mention zero idle timeout, was: {err_msg}"
        );
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    #[tokio::test]
    async fn test_sockudo_backend_rejects_reserved_headers_before_connect() {
        let (handler, _rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: "ws://127.0.0.1:1".to_string(),
            headers: vec![("Host".to_string(), "example.com".to_string())],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: None,
            reconnect_delay_initial_ms: None,
            reconnect_delay_max_ms: None,
            reconnect_backoff_factor: None,
            reconnect_jitter_ms: None,
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Sockudo,
            proxy_url: None,
        };

        let err = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .expect_err("reserved header should fail before TCP connect");

        assert!(
            err.to_string()
                .contains("reserved upgrade header not allowed in extra_headers"),
            "expected reserved-header failure, was: {err}"
        );
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    #[tokio::test]
    async fn test_sockudo_backend_replays_leftover_without_custom_headers() {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((mut stream, _)) = listener.accept().await {
                let request = read_http_request(&mut stream).await;
                let request = String::from_utf8(request).unwrap();
                let sec_websocket_key = extract_header(&request, "Sec-WebSocket-Key").unwrap();
                let accept = sockudo_handshake::generate_accept_key(sec_websocket_key);
                let mut response = format!(
                    concat!(
                        "HTTP/1.1 101 Switching Protocols\r\n",
                        "Upgrade: websocket\r\n",
                        "Connection: Upgrade\r\n",
                        "Sec-WebSocket-Accept: {}\r\n",
                        "\r\n",
                    ),
                    accept
                )
                .into_bytes();
                response.extend_from_slice(b"\x81\x05hello");
                stream.write_all(&response).await.unwrap();
            }
        });

        let (handler, mut rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}/ws"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Sockudo,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .expect("sockudo connect without custom headers");

        let received = tokio::time::timeout(Duration::from_secs(3), async {
            loop {
                if let Ok(msg) = rx.try_recv() {
                    return msg;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await
        .expect("did not receive leftover frame before timeout");

        match received {
            WsMessage::Text(t) => assert_eq!(t.as_str(), "hello"),
            other => panic!("expected text, was {other:?}"),
        }

        client.disconnect().await;
        tokio::time::timeout(Duration::from_secs(3), server)
            .await
            .expect("server did not close before timeout")
            .unwrap();
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    #[tokio::test]
    async fn test_sockudo_backend_sends_custom_headers() {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((stream, _)) = listener.accept().await {
                let callback = HeaderAssertCallback {
                    key: "X-Test".to_string(),
                    value: HeaderValue::from_static("value"),
                };

                if let Ok(mut ws) = accept_hdr_async(stream, callback).await {
                    while let Some(Ok(msg)) = ws.next().await {
                        if msg.is_text() || msg.is_binary() {
                            if ws.send(msg).await.is_err() {
                                break;
                            }

                            continue;
                        }

                        if msg.is_close() {
                            let _ = ws.close(None).await;
                            break;
                        }
                    }
                }
            }
        });

        let (handler, mut rx) = channel_message_handler();

        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![("X-Test".to_string(), "value".to_string())],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Sockudo,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .expect("sockudo connect with custom headers");

        client.send_text("ping".to_string(), None).await.unwrap();

        let received = tokio::time::timeout(Duration::from_secs(3), async {
            loop {
                if let Ok(msg) = rx.try_recv() {
                    return msg;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await
        .expect("did not receive echo before timeout");

        match received {
            WsMessage::Text(t) => assert_eq!(t.as_str(), "ping"),
            other => panic!("expected text, was {other:?}"),
        }

        client.disconnect().await;
        tokio::time::timeout(Duration::from_secs(3), server)
            .await
            .expect("server did not close before timeout")
            .unwrap();
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    #[tokio::test]
    async fn test_sockudo_backend_round_trip_text() {
        // tokio-tungstenite test peer paired with a sockudo client.
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let port = listener.local_addr().unwrap().port();

        let server = task::spawn(async move {
            if let Ok((stream, _)) = listener.accept().await
                && let Ok(mut ws) = accept_async(stream).await
            {
                while let Some(Ok(msg)) = ws.next().await {
                    match msg {
                        WsMessage::Text(_) | WsMessage::Binary(_) => {
                            if ws.send(msg).await.is_err() {
                                break;
                            }
                        }
                        WsMessage::Close(_) => {
                            let _ = ws.close(None).await;
                            break;
                        }
                        _ => {}
                    }
                }
            }
        });

        let (handler, mut rx) = channel_message_handler();
        let config = WebSocketConfig {
            url: format!("ws://127.0.0.1:{port}"),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(2_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(100),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Sockudo,
            proxy_url: None,
        };

        let client = WebSocketClient::connect(config, Some(handler), None, None, vec![], None)
            .await
            .expect("sockudo connect");

        client.send_text("ping".to_string(), None).await.unwrap();

        let received = tokio::time::timeout(Duration::from_secs(3), async {
            loop {
                if let Ok(msg) = rx.try_recv() {
                    return msg;
                }
                tokio::time::sleep(Duration::from_millis(10)).await;
            }
        })
        .await
        .expect("did not receive echo before timeout");

        match received {
            WsMessage::Text(t) => assert_eq!(t.as_str(), "ping"),
            other => panic!("expected text, was {other:?}"),
        }

        client.disconnect().await;
        server.abort();
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    #[case::ws_default_port("ws://example.com/ws", "example.com", "example.com", 80, "/ws", false)]
    #[case::wss_default_port(
        "wss://example.com/ws",
        "example.com",
        "example.com",
        443,
        "/ws",
        true
    )]
    // url::Url normalises explicit default ports (`:80` for ws, `:443` for wss)
    // away, so `parsed.port()` reports `None` here and Host stays unqualified.
    #[case::ws_explicit_default(
        "ws://example.com:80/ws",
        "example.com",
        "example.com",
        80,
        "/ws",
        false
    )]
    #[case::ws_non_default(
        "ws://example.com:8443/feed",
        "example.com",
        "example.com:8443",
        8443,
        "/feed",
        false
    )]
    #[case::wss_non_default(
        "wss://example.com:9443/feed",
        "example.com",
        "example.com:9443",
        9443,
        "/feed",
        true
    )]
    #[case::root_path(
        "ws://example.com:9000/",
        "example.com",
        "example.com:9000",
        9000,
        "/",
        false
    )]
    #[case::query_string(
        "ws://example.com/feed?token=abc&channel=trades",
        "example.com",
        "example.com",
        80,
        "/feed?token=abc&channel=trades",
        false
    )]
    // IPv6: bare host strips brackets for DNS/TCP/SNI; Host header keeps them.
    #[case::ipv6_default("ws://[::1]/feed", "::1", "[::1]", 80, "/feed", false)]
    #[case::ipv6_explicit_port("ws://[::1]:9000/feed", "::1", "[::1]:9000", 9000, "/feed", false)]
    #[case::ipv6_wss(
        "wss://[2001:db8::1]:8443/",
        "2001:db8::1",
        "[2001:db8::1]:8443",
        8443,
        "/",
        true
    )]
    fn sockudo_target_parses_url(
        #[case] url: &str,
        #[case] host: &str,
        #[case] host_header: &str,
        #[case] port: u16,
        #[case] path: &str,
        #[case] is_tls: bool,
    ) {
        let target = super::SockudoTarget::parse(url).expect("parse should succeed");
        assert_eq!(target.host, host);
        assert_eq!(target.host_header, host_header);
        assert_eq!(target.port, port);
        assert_eq!(target.path, path);
        assert_eq!(target.is_tls, is_tls);
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    fn sockudo_target_rejects_unsupported_scheme() {
        let err = super::SockudoTarget::parse("http://example.com/feed").expect_err("not a ws URL");
        let msg = err.to_string();
        assert!(
            msg.contains("expected ws:// or wss://"),
            "unexpected error: {msg}"
        );
    }

    #[cfg(all(feature = "transport-sockudo", not(feature = "turmoil")))]
    #[rstest]
    fn sockudo_target_rejects_malformed_url() {
        let err = super::SockudoTarget::parse("not a url").expect_err("malformed URL");
        assert!(
            matches!(err, super::TransportError::InvalidUrl(_)),
            "expected InvalidUrl, was: {err:?}"
        );
    }
}

#[cfg(test)]
mod property_tests {
    use std::{
        collections::{HashSet, VecDeque},
        sync::{Arc, OnceLock, atomic::AtomicBool},
    };

    use proptest::prelude::*;
    use rstest::rstest;

    use super::{super::auth::AuthResultReceiver, *};

    const AUTH_FAILED: &str = "model auth failed";

    #[derive(Debug, Clone)]
    enum ReconnectBufferTraceOp {
        BeginAuth,
        AuthSucceeds,
        AuthFails,
        AuthInvalidates,
        ReconnectStarts,
        ReconnectCompletes,
        BufferedMessage(u8),
    }

    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
    enum ModelConnectionMode {
        Active,
        Reconnect,
    }

    #[derive(Debug, Clone, Copy)]
    enum ExpectedReconnectBufferAction {
        Drain,
        Wait,
        Discard,
    }

    #[derive(Debug)]
    struct ReconnectBufferModel {
        mode: ModelConnectionMode,
        auth_state: AuthState,
        buffer: VecDeque<String>,
        released: Vec<String>,
        discarded: Vec<String>,
        live_sent: Vec<String>,
        handler_controls: Vec<&'static str>,
        next_message_index: usize,
    }

    impl ReconnectBufferModel {
        fn new() -> Self {
            Self {
                mode: ModelConnectionMode::Active,
                auth_state: AuthState::Unauthenticated,
                buffer: VecDeque::new(),
                released: Vec::new(),
                discarded: Vec::new(),
                live_sent: Vec::new(),
                handler_controls: Vec::new(),
                next_message_index: 0,
            }
        }

        fn next_payload(&mut self, raw: u8) -> String {
            let payload = format!("message-{}-{raw}", self.next_message_index);
            self.next_message_index += 1;
            payload
        }

        fn expected_action(&self, waits_for_auth: bool) -> ExpectedReconnectBufferAction {
            if !waits_for_auth {
                return ExpectedReconnectBufferAction::Drain;
            }

            match self.auth_state {
                AuthState::Authenticated => ExpectedReconnectBufferAction::Drain,
                AuthState::Failed => ExpectedReconnectBufferAction::Discard,
                AuthState::Unauthenticated => ExpectedReconnectBufferAction::Wait,
            }
        }
    }

    fn reconnect_buffer_trace_op_strategy() -> impl Strategy<Value = ReconnectBufferTraceOp> {
        prop_oneof![
            Just(ReconnectBufferTraceOp::BeginAuth),
            Just(ReconnectBufferTraceOp::AuthSucceeds),
            Just(ReconnectBufferTraceOp::AuthFails),
            Just(ReconnectBufferTraceOp::AuthInvalidates),
            Just(ReconnectBufferTraceOp::ReconnectStarts),
            Just(ReconnectBufferTraceOp::ReconnectCompletes),
            any::<u8>().prop_map(ReconnectBufferTraceOp::BufferedMessage),
        ]
    }

    fn reconnect_buffer_actions_match(
        actual: ReconnectBufferAction,
        expected: ExpectedReconnectBufferAction,
    ) -> bool {
        matches!(
            (actual, expected),
            (
                ReconnectBufferAction::Drain,
                ExpectedReconnectBufferAction::Drain
            ) | (
                ReconnectBufferAction::Wait,
                ExpectedReconnectBufferAction::Wait
            ) | (
                ReconnectBufferAction::Discard,
                ExpectedReconnectBufferAction::Discard
            )
        )
    }

    fn apply_ready_reconnect_buffer_action(
        model: &mut ReconnectBufferModel,
        reconnect_buffer_waits_for_auth: &AtomicBool,
        auth_tracker: &Arc<OnceLock<AuthTracker>>,
        waits_for_auth: bool,
        step: usize,
        op: &ReconnectBufferTraceOp,
    ) -> Result<(), TestCaseError> {
        if model.mode != ModelConnectionMode::Active || model.buffer.is_empty() {
            return Ok(());
        }

        let expected = model.expected_action(waits_for_auth);
        let actual = WebSocketClientInner::can_drain_reconnect_buffer(
            reconnect_buffer_waits_for_auth,
            auth_tracker,
        );

        prop_assert!(
            reconnect_buffer_actions_match(actual, expected),
            "reconnect buffer action mismatch at step {}, op {:?}, waits_for_auth={}, auth_state={:?}",
            step,
            op,
            waits_for_auth,
            model.auth_state
        );

        match expected {
            ExpectedReconnectBufferAction::Drain => {
                model.released.extend(model.buffer.drain(..));
            }
            ExpectedReconnectBufferAction::Wait => {}
            ExpectedReconnectBufferAction::Discard => {
                model.discarded.extend(model.buffer.drain(..));
            }
        }

        Ok(())
    }

    fn assert_reconnected_control_stays_separate(
        model: &ReconnectBufferModel,
        step: usize,
    ) -> Result<(), TestCaseError> {
        prop_assert!(
            model
                .handler_controls
                .iter()
                .all(|message| *message == RECONNECTED),
            "handler control stream contained a non-RECONNECTED message at step {}",
            step
        );
        prop_assert!(
            !model.buffer.iter().any(|message| message == RECONNECTED),
            "RECONNECTED control message entered reconnect buffer at step {}",
            step
        );
        prop_assert!(
            !model.released.iter().any(|message| message == RECONNECTED),
            "RECONNECTED control message entered replayed messages at step {}",
            step
        );
        prop_assert!(
            !model.discarded.iter().any(|message| message == RECONNECTED),
            "RECONNECTED control message entered discarded messages at step {}",
            step
        );
        prop_assert!(
            !model.live_sent.iter().any(|message| message == RECONNECTED),
            "RECONNECTED control message entered application sends at step {}",
            step
        );

        Ok(())
    }

    fn assert_messages_accounted_once(
        model: &ReconnectBufferModel,
        step: usize,
    ) -> Result<(), TestCaseError> {
        let mut seen = HashSet::new();

        for message in model
            .released
            .iter()
            .chain(model.discarded.iter())
            .chain(model.buffer.iter())
            .chain(model.live_sent.iter())
        {
            prop_assert!(
                seen.insert(message.as_str()),
                "message {} appeared more than once at step {}",
                message,
                step
            );
        }

        Ok(())
    }

    fn apply_reconnect_buffer_trace_op(
        model: &mut ReconnectBufferModel,
        tracker: &AuthTracker,
        auth_receivers: &mut Vec<AuthResultReceiver>,
        op: &ReconnectBufferTraceOp,
    ) -> Result<(), TestCaseError> {
        match op {
            ReconnectBufferTraceOp::BeginAuth => {
                auth_receivers.push(tracker.begin());
                model.auth_state = AuthState::Unauthenticated;
            }
            ReconnectBufferTraceOp::AuthSucceeds => {
                tracker.succeed();
                model.auth_state = AuthState::Authenticated;
            }
            ReconnectBufferTraceOp::AuthFails => {
                tracker.fail(AUTH_FAILED);
                model.auth_state = AuthState::Failed;
            }
            ReconnectBufferTraceOp::AuthInvalidates => {
                tracker.invalidate();
                model.auth_state = AuthState::Unauthenticated;
            }
            ReconnectBufferTraceOp::ReconnectStarts => {
                tracker.invalidate();
                model.auth_state = AuthState::Unauthenticated;
                model.mode = ModelConnectionMode::Reconnect;
            }
            ReconnectBufferTraceOp::ReconnectCompletes => {
                model.mode = ModelConnectionMode::Active;
                model.handler_controls.push(RECONNECTED);
            }
            ReconnectBufferTraceOp::BufferedMessage(raw) => {
                let payload = model.next_payload(*raw);
                prop_assert_ne!(payload.as_str(), RECONNECTED);

                if model.mode == ModelConnectionMode::Reconnect {
                    model.buffer.push_back(payload);
                } else {
                    model.live_sent.push(payload);
                }
            }
        }

        Ok(())
    }

    proptest! {
        #![proptest_config(ProptestConfig::with_cases(256))]

        /// Property: reconnect-buffer traces match the auth-gated release and
        /// discard model, and `RECONNECTED` remains a separate control signal.
        #[rstest]
        fn test_reconnect_buffer_trace_matches_auth_gate_model(
            waits_for_auth in any::<bool>(),
            ops in proptest::collection::vec(reconnect_buffer_trace_op_strategy(), 1..100)
        ) {
            let auth_tracker = Arc::new(OnceLock::new());
            let reconnect_buffer_waits_for_auth = AtomicBool::new(waits_for_auth);
            let tracker = AuthTracker::new();
            auth_tracker.set(tracker.clone()).unwrap();
            let mut auth_receivers = Vec::new();
            let mut model = ReconnectBufferModel::new();

            for (step, op) in ops.iter().enumerate() {
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    op,
                )?;

                prop_assert_eq!(
                    tracker.auth_state(),
                    model.auth_state,
                    "auth state mismatch at step {}, op {:?}",
                    step,
                    op
                );

                apply_ready_reconnect_buffer_action(
                    &mut model,
                    &reconnect_buffer_waits_for_auth,
                    &auth_tracker,
                    waits_for_auth,
                    step,
                    op,
                )?;
                assert_reconnected_control_stays_separate(&model, step)?;
                prop_assert_eq!(
                    model.handler_controls.len(),
                    ops[..=step]
                        .iter()
                        .filter(|op| matches!(op, ReconnectBufferTraceOp::ReconnectCompletes))
                        .count(),
                    "handler control count mismatch at step {}",
                    step
                );
                assert_messages_accounted_once(&model, step)?;
            }
        }

        /// Property: successful re-authentication releases buffered messages
        /// exactly once when replay is configured to wait for auth.
        #[rstest]
        fn test_reconnect_buffer_releases_after_auth_success_once(
            payloads in proptest::collection::vec(any::<u8>(), 1..32),
            extra_success_ticks in 0usize..16
        ) {
            let auth_tracker = Arc::new(OnceLock::new());
            let reconnect_buffer_waits_for_auth = AtomicBool::new(true);
            let tracker = AuthTracker::new();
            auth_tracker.set(tracker.clone()).unwrap();
            let mut auth_receivers = Vec::new();
            let mut model = ReconnectBufferModel::new();

            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::ReconnectStarts,
            )?;
            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::BeginAuth,
            )?;

            for payload in payloads {
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    &ReconnectBufferTraceOp::BufferedMessage(payload),
                )?;
            }

            let buffered_len = model.buffer.len();
            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::ReconnectCompletes,
            )?;
            apply_ready_reconnect_buffer_action(
                &mut model,
                &reconnect_buffer_waits_for_auth,
                &auth_tracker,
                true,
                0,
                &ReconnectBufferTraceOp::ReconnectCompletes,
            )?;

            prop_assert_eq!(model.released.len(), 0);
            prop_assert_eq!(model.buffer.len(), buffered_len);

            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::AuthSucceeds,
            )?;
            apply_ready_reconnect_buffer_action(
                &mut model,
                &reconnect_buffer_waits_for_auth,
                &auth_tracker,
                true,
                1,
                &ReconnectBufferTraceOp::AuthSucceeds,
            )?;

            prop_assert_eq!(model.released.len(), buffered_len);
            prop_assert!(model.buffer.is_empty());
            assert_messages_accounted_once(&model, 1)?;

            for tick in 0..extra_success_ticks {
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    &ReconnectBufferTraceOp::AuthSucceeds,
                )?;
                apply_ready_reconnect_buffer_action(
                    &mut model,
                    &reconnect_buffer_waits_for_auth,
                    &auth_tracker,
                    true,
                    tick + 2,
                    &ReconnectBufferTraceOp::AuthSucceeds,
                )?;
                prop_assert_eq!(
                    model.released.len(),
                    buffered_len,
                    "buffered messages replayed more than once at tick {}",
                    tick
                );
            }
        }

        /// Property: auth failure discards messages buffered before or after
        /// that failure, and later auth success does not replay discarded data.
        #[rstest]
        fn test_reconnect_buffer_discards_after_auth_failure(
            before_failure_payloads in proptest::collection::vec(any::<u8>(), 0..16),
            after_failure_payloads in proptest::collection::vec(any::<u8>(), 1..16),
            later_success_ticks in 0usize..16
        ) {
            let auth_tracker = Arc::new(OnceLock::new());
            let reconnect_buffer_waits_for_auth = AtomicBool::new(true);
            let tracker = AuthTracker::new();
            auth_tracker.set(tracker.clone()).unwrap();
            let mut auth_receivers = Vec::new();
            let mut model = ReconnectBufferModel::new();

            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::ReconnectStarts,
            )?;
            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::BeginAuth,
            )?;

            for payload in before_failure_payloads {
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    &ReconnectBufferTraceOp::BufferedMessage(payload),
                )?;
            }

            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::AuthFails,
            )?;

            for payload in after_failure_payloads {
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    &ReconnectBufferTraceOp::BufferedMessage(payload),
                )?;
            }

            let buffered_len = model.buffer.len();
            apply_reconnect_buffer_trace_op(
                &mut model,
                &tracker,
                &mut auth_receivers,
                &ReconnectBufferTraceOp::ReconnectCompletes,
            )?;
            apply_ready_reconnect_buffer_action(
                &mut model,
                &reconnect_buffer_waits_for_auth,
                &auth_tracker,
                true,
                0,
                &ReconnectBufferTraceOp::ReconnectCompletes,
            )?;

            prop_assert_eq!(model.discarded.len(), buffered_len);
            prop_assert!(model.released.is_empty());
            prop_assert!(model.buffer.is_empty());
            assert_messages_accounted_once(&model, 0)?;

            for tick in 0..later_success_ticks {
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    &ReconnectBufferTraceOp::BeginAuth,
                )?;
                apply_reconnect_buffer_trace_op(
                    &mut model,
                    &tracker,
                    &mut auth_receivers,
                    &ReconnectBufferTraceOp::AuthSucceeds,
                )?;
                apply_ready_reconnect_buffer_action(
                    &mut model,
                    &reconnect_buffer_waits_for_auth,
                    &auth_tracker,
                    true,
                    tick + 1,
                    &ReconnectBufferTraceOp::AuthSucceeds,
                )?;
                prop_assert!(
                    model.released.is_empty(),
                    "discarded messages replayed after later auth success at tick {}",
                    tick
                );
            }
        }
    }
}

#[cfg(test)]
#[cfg(feature = "turmoil")]
mod turmoil_tests {
    use std::{sync::Arc, time::Duration};

    use futures_util::{SinkExt, StreamExt};
    use nautilus_common::testing::wait_until_async;
    use rstest::rstest;
    use tokio_tungstenite::{accept_async, tungstenite::Message as WsMessage};
    use turmoil::{Builder, net};

    use super::*;
    use crate::websocket::types::channel_message_handler;

    const AUTH_BUFFER_WAIT_SEED: u64 = 0xA17B_0001;
    const AUTH_BUFFER_DISCARD_SEED: u64 = 0xA17B_0002;

    fn seeded_turmoil_builder(seed: u64) -> Builder {
        let mut builder = Builder::new();
        builder.rng_seed(seed);
        builder
    }

    #[rstest]
    fn test_turmoil_reconnect_buffer_waits_for_auth() {
        let mut sim = seeded_turmoil_builder(AUTH_BUFFER_WAIT_SEED).build();
        let messages = Arc::new(tokio::sync::Mutex::new(Vec::new()));
        let server_messages = Arc::clone(&messages);

        sim.host("server", move || {
            let messages = Arc::clone(&server_messages);
            auth_buffer_server(messages)
        });

        sim.client("client", async move {
            let tracker = AuthTracker::new();
            let (handler, _rx) = channel_message_handler();
            let client = WebSocketClient::connect(
                turmoil_websocket_config(),
                Some(handler),
                None,
                None,
                vec![],
                None,
            )
            .await
            .expect("Should connect");

            client.set_auth_tracker(tracker.clone(), true);
            assert!(client.is_active(), "Client should start active");

            wait_until_async(
                || async { client.is_reconnecting() },
                Duration::from_secs(3),
            )
            .await;

            client
                .writer_tx
                .send(WriterCommand::Send(Message::Text("stale".into())))
                .unwrap();

            wait_until_async(|| async { client.is_active() }, Duration::from_secs(3)).await;

            let _auth_receiver = tracker.begin();

            tokio::time::sleep(Duration::from_millis(300)).await;
            assert!(
                messages.lock().await.is_empty(),
                "buffered messages should wait for auth after reconnect"
            );

            tracker.succeed();

            wait_until_async(
                || {
                    let messages = Arc::clone(&messages);
                    async move { messages.lock().await.as_slice() == ["stale"] }
                },
                Duration::from_secs(3),
            )
            .await;

            assert_eq!(messages.lock().await.as_slice(), ["stale"]);

            client.disconnect().await;
            assert!(client.is_disconnected());

            Ok(())
        });

        sim.run().unwrap();
    }

    #[rstest]
    fn test_turmoil_reconnect_buffer_discards_after_auth_failure() {
        let mut sim = seeded_turmoil_builder(AUTH_BUFFER_DISCARD_SEED).build();
        let messages = Arc::new(tokio::sync::Mutex::new(Vec::new()));
        let server_messages = Arc::clone(&messages);

        sim.host("server", move || {
            let messages = Arc::clone(&server_messages);
            auth_buffer_server(messages)
        });

        sim.client("client", async move {
            let tracker = AuthTracker::new();
            let (handler, _rx) = channel_message_handler();
            let client = WebSocketClient::connect(
                turmoil_websocket_config(),
                Some(handler),
                None,
                None,
                vec![],
                None,
            )
            .await
            .expect("Should connect");

            client.set_auth_tracker(tracker.clone(), true);
            assert!(client.is_active(), "Client should start active");

            wait_until_async(
                || async { client.is_reconnecting() },
                Duration::from_secs(3),
            )
            .await;

            client
                .writer_tx
                .send(WriterCommand::Send(Message::Text("stale".into())))
                .unwrap();

            wait_until_async(|| async { client.is_active() }, Duration::from_secs(3)).await;

            let _auth_receiver = tracker.begin();
            tracker.fail("rejected");

            tokio::time::sleep(Duration::from_millis(300)).await;
            assert!(
                messages.lock().await.is_empty(),
                "buffered messages should be discarded after auth failure"
            );

            let _retry_auth_receiver = tracker.begin();
            tracker.succeed();

            tokio::time::sleep(Duration::from_millis(300)).await;
            assert!(
                messages.lock().await.is_empty(),
                "discarded messages should not replay on a later auth success"
            );

            client.disconnect().await;
            assert!(client.is_disconnected());

            Ok(())
        });

        sim.run().unwrap();
    }

    fn turmoil_websocket_config() -> WebSocketConfig {
        WebSocketConfig {
            url: "ws://server:8080".to_string(),
            headers: vec![],
            heartbeat: None,
            heartbeat_msg: None,
            reconnect_timeout_ms: Some(5_000),
            reconnect_delay_initial_ms: Some(50),
            reconnect_delay_max_ms: Some(200),
            reconnect_backoff_factor: Some(1.0),
            reconnect_jitter_ms: Some(0),
            reconnect_max_attempts: None,
            idle_timeout_ms: None,
            backend: TransportBackend::Tungstenite,
            proxy_url: None,
        }
    }

    async fn auth_buffer_server(
        messages: Arc<tokio::sync::Mutex<Vec<String>>>,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let listener = net::TcpListener::bind("0.0.0.0:8080").await?;

        let (stream, _) = listener.accept().await?;
        let mut websocket = accept_async(stream).await?;
        let _ = websocket.send(WsMessage::Text("first".into())).await;
        drop(websocket);

        tokio::time::sleep(Duration::from_millis(200)).await;

        let (stream, _) = listener.accept().await?;
        let mut websocket = accept_async(stream).await?;

        while let Some(msg) = websocket.next().await {
            match msg {
                Ok(WsMessage::Text(text)) => {
                    messages.lock().await.push(text.to_string());
                }
                Ok(WsMessage::Close(_)) => {
                    let _ = websocket.close(None).await;
                    break;
                }
                Ok(_) => {}
                Err(_) => break,
            }
        }

        Ok(())
    }
}