feat: consolidate tests

tests/actor_lifecycle.rs

@@ -0,0 +1,790 @@
+//! Actor Lifecycle Tests — birth, life, death of individual actors.
+//!
+//! Covers: spawning, on_start, parent-child delegation, graceful stop,
+//! panic isolation, dead actor cleanup, watching (ActorExited), and
+//! monitoring (Down notifications).
+
+mod common;
+use common::*;
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+// ── Local actors ────────────────────────────────────────────────────────────
+
+/// Records lifecycle events to shared counters.
+struct LifecycleActor {
+    started: Arc<AtomicUsize>,
+    stopped: Arc<AtomicUsize>,
+    handled: Arc<AtomicUsize>,
+}
+
+impl ActorInterface for LifecycleActor {
+    type Incoming = Ping;
+    type Response = Pong;
+    fn on_start(&mut self, _ctx: &Ctx) {
+        self.started.fetch_add(1, Ordering::Relaxed);
+    }
+    fn on_stop(&mut self, _ctx: &Ctx) {
+        self.stopped.fetch_add(1, Ordering::Relaxed);
+    }
+    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
+        self.handled.fetch_add(1, Ordering::Relaxed);
+        let _ = ctx.send(msg.reply_to, Pong);
+    }
+}
+
+/// Stops itself after processing `stop_after` messages.
+struct SelfStopActor {
+    count: usize,
+    stop_after: usize,
+    stopped: Arc<AtomicUsize>,
+}
+
+impl ActorInterface for SelfStopActor {
+    type Incoming = Forward;
+    type Response = Done;
+    fn on_stop(&mut self, _ctx: &Ctx) {
+        self.stopped.fetch_add(1, Ordering::Relaxed);
+    }
+    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
+        self.count += 1;
+        let _ = ctx.send(msg.reply_to, Done(msg.value));
+        if self.count >= self.stop_after {
+            ctx.stop_self();
+        }
+    }
+}
+
+/// Sends a farewell Pong in on_stop.
+struct FarewellActor {
+    farewell_to: ActorAddress,
+}
+
+impl ActorInterface for FarewellActor {
+    type Incoming = Ping;
+    type Response = Pong;
+    fn on_stop(&mut self, ctx: &Ctx) {
+        let _ = ctx.send(self.farewell_to, Pong);
+    }
+    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
+        let _ = ctx.send(msg.reply_to, Pong);
+    }
+}
+
+/// Panics in on_start.
+struct PanicOnStartActor {
+    handled: Arc<AtomicUsize>,
+}
+
+impl ActorInterface for PanicOnStartActor {
+    type Incoming = Ping;
+    type Response = Pong;
+    fn on_start(&mut self, _ctx: &Ctx) {
+        panic!("on_start panic");
+    }
+    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {
+        self.handled.fetch_add(1, Ordering::Relaxed);
+    }
+}
+
+/// Spawns a DoubleActor child, sends it work, then panics.
+struct SpawnThenPanicActor;
+
+impl ActorInterface for SpawnThenPanicActor {
+    type Incoming = Forward;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
+        let child = ctx.spawn(DoubleActor).unwrap();
+        let _ = ctx.send(child, Forward { value: msg.value, reply_to: msg.reply_to });
+        panic!("intentional panic after spawn+send");
+    }
+}
+
+/// Sends a Pong reply, then panics.
+struct SendThenPanicActor;
+
+impl ActorInterface for SendThenPanicActor {
+    type Incoming = Ping;
+    type Response = Pong;
+    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
+        let _ = ctx.send(msg.reply_to, Pong);
+        panic!("intentional panic after send");
+    }
+}
+
+/// Processes `remaining_good` messages then panics.
+struct PanicAfterNActor {
+    remaining_good: usize,
+    counter: Arc<AtomicUsize>,
+}
+
+impl ActorInterface for PanicAfterNActor {
+    type Incoming = Ping;
+    type Response = ();
+    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {
+        if self.remaining_good == 0 {
+            panic!("intentional delayed panic");
+        }
+        self.remaining_good -= 1;
+        self.counter.fetch_add(1, Ordering::SeqCst);
+    }
+}
+
+/// Stops on a trigger message.
+struct StopOnTrigger(Arc<AtomicUsize>);
+
+#[derive(Clone)]
+struct Trigger(bool);
+
+impl ActorInterface for StopOnTrigger {
+    type Incoming = Trigger;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, msg: Trigger) {
+        self.0.fetch_add(1, Ordering::Relaxed);
+        if msg.0 {
+            ctx.stop_self();
+        }
+    }
+}
+
+/// Watches targets and counts exit notifications via on_actor_exit.
+struct ExitWatcher {
+    exit_count: Arc<AtomicUsize>,
+    last_reason: Arc<std::sync::Mutex<Option<ExitReason>>>,
+    last_addr: Arc<std::sync::Mutex<Option<ActorAddress>>>,
+}
+
+#[derive(Clone)]
+enum WatcherCmd {
+    WatchThis(ActorAddress),
+    UnwatchThis(ActorAddress),
+}
+
+impl ActorInterface for ExitWatcher {
+    type Incoming = WatcherCmd;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, msg: WatcherCmd) {
+        match msg {
+            WatcherCmd::WatchThis(target) => ctx.watch(target),
+            WatcherCmd::UnwatchThis(target) => ctx.unwatch(target),
+        }
+    }
+    fn on_actor_exit(&mut self, _ctx: &Ctx, exited: ActorExited) {
+        self.exit_count.fetch_add(1, Ordering::SeqCst);
+        *self.last_reason.lock().unwrap() = Some(exited.reason);
+        *self.last_addr.lock().unwrap() = Some(exited.addr);
+    }
+}
+
+struct WatcherState {
+    exit_count: Arc<AtomicUsize>,
+    last_reason: Arc<std::sync::Mutex<Option<ExitReason>>>,
+}
+
+impl WatcherState {
+    fn count(&self) -> usize {
+        self.exit_count.load(Ordering::SeqCst)
+    }
+    fn last_reason(&self) -> Option<ExitReason> {
+        self.last_reason.lock().unwrap().clone()
+    }
+}
+
+fn new_exit_watcher() -> (ExitWatcher, WatcherState) {
+    let exit_count = Arc::new(AtomicUsize::new(0));
+    let last_reason = Arc::new(std::sync::Mutex::new(None));
+    let last_addr = Arc::new(std::sync::Mutex::new(None));
+    let state = WatcherState {
+        exit_count: exit_count.clone(),
+        last_reason: last_reason.clone(),
+    };
+    (
+        ExitWatcher { exit_count, last_reason, last_addr },
+        state,
+    )
+}
+
+/// Monitors a target and forwards Down to a reply address.
+struct MonitorWatcherActor {
+    watch_target: ActorAddress,
+    reply_to: ActorAddress,
+    mref: Option<MonitorRef>,
+}
+
+impl ActorInterface for MonitorWatcherActor {
+    type Incoming = Down;
+    type Response = ();
+    fn on_start(&mut self, ctx: &Ctx) {
+        self.mref = Some(ctx.monitor(self.watch_target));
+    }
+    fn handle(&mut self, ctx: &Ctx, msg: Down) {
+        ctx.send(self.reply_to, msg).unwrap();
+    }
+}
+
+/// Demonitors on Ping.
+struct DemonitorActor {
+    watch_target: ActorAddress,
+    mref: Option<MonitorRef>,
+}
+
+impl ActorInterface for DemonitorActor {
+    type Incoming = Ping;
+    type Response = ();
+    fn on_start(&mut self, ctx: &Ctx) {
+        self.mref = Some(ctx.monitor(self.watch_target));
+    }
+    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
+        if let Some(mref) = self.mref.take() {
+            ctx.demonitor(mref);
+        }
+    }
+}
+
+/// A silent actor that does nothing (target for watching tests).
+struct Sleeper;
+#[derive(Clone)]
+struct Noop;
+
+impl ActorInterface for Sleeper {
+    type Incoming = Noop;
+    type Response = ();
+    fn handle(&mut self, _ctx: &Ctx, _msg: Noop) {}
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Tests
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Actors are spawned, on_start fires exactly once per instance before any
+/// message, then state accumulates across messages.
+#[test]
+fn actor_from_birth_to_first_message() {
+    let started = Arc::new(AtomicUsize::new(0));
+    let stopped = Arc::new(AtomicUsize::new(0));
+    let handled = Arc::new(AtomicUsize::new(0));
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+
+    // Spawn one tracked actor + 4 more sharing the same counters
+    let addr = rt.spawn(LifecycleActor {
+        started: started.clone(),
+        stopped: stopped.clone(),
+        handled: handled.clone(),
+    }).unwrap();
+    for _ in 0..4 {
+        rt.spawn(LifecycleActor {
+            started: started.clone(),
+            stopped: stopped.clone(),
+            handled: handled.clone(),
+        }).unwrap();
+    }
+
+    // First tick: all 5 on_start fire, no messages processed yet
+    rt.tick();
+    assert_eq!(started.load(Ordering::Relaxed), 5, "on_start per instance");
+    assert_eq!(handled.load(Ordering::Relaxed), 0, "no messages before first send");
+
+    // Send 3 Increments to a CounterActor to verify state accumulation
+    let counter_addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    let count_inbox = rt.new_inbox::<Count>().unwrap();
+    for _ in 0..3 {
+        rt.send_to(counter_addr, Increment { reply_to: *count_inbox.addr() }).unwrap();
+    }
+    let replies = tick_and_drain(&rt, &count_inbox, 10);
+    assert_eq!(replies, vec![Count(1), Count(2), Count(3)], "state accumulates");
+
+    // on_start must not fire again on subsequent ticks
+    rt.tick();
+    rt.tick();
+    assert_eq!(started.load(Ordering::Relaxed), 5, "on_start not repeated");
+
+    // Verify the first actor still responds normally
+    rt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 10);
+    assert!(reply.is_some(), "actor handles messages after on_start");
+}
+
+/// Delegation chains: parent spawns child, child spawns grandchild, fan-out
+/// distributes work. Spawn+send interleaving in a single handler works.
+#[test]
+fn parent_child_delegation_and_spawn_chains() {
+    let rt = std_runtime(RuntimeConfig {
+        max_actors: 2000,
+        ..Default::default()
+    });
+
+    // Act 1: DelegatorActor spawns child, forwards value 7 → Done(14)
+    let delegator = rt.spawn(DelegatorActor).unwrap();
+    let inbox = rt.new_inbox::<Done>().unwrap();
+    rt.send_to(delegator, Forward { value: 7, reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 20);
+    assert_eq!(reply, Some(Done(14)), "delegator child doubles value");
+
+    // Act 2: Chain of depth 20
+    let chain = rt.spawn(ChainActor).unwrap();
+    rt.send_to(chain, ChainMsg { remaining: 20, depth: 0, reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 200);
+    assert_eq!(reply, Some(Done(20)), "chain reaches depth 20");
+
+    // Act 3: Fan-out to 20 children
+    let fan = rt.spawn(FanOutActor).unwrap();
+    rt.send_to(fan, FanOut { count: 20, reply_to: *inbox.addr() }).unwrap();
+    let replies = tick_and_drain(&rt, &inbox, 50);
+    assert_eq!(replies.len(), 20, "all 20 fan-out children reply");
+}
+
+/// The full graceful-stop story: self-stop with on_stop, farewell messages,
+/// external stop ordering vs pending messages, mid-mailbox stop trigger.
+#[test]
+fn graceful_stop_lifecycle() {
+    // --- Part A: SelfStopActor ---
+    let stopped = Arc::new(AtomicUsize::new(0));
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Done>().unwrap();
+
+    let addr = rt.spawn(SelfStopActor {
+        count: 0,
+        stop_after: 3,
+        stopped: stopped.clone(),
+    }).unwrap();
+
+    for i in 0..5 {
+        let _ = rt.send_to(addr, Forward { value: i, reply_to: *inbox.addr() });
+    }
+    tick_n(&rt, 10);
+
+    let mut replies = Vec::new();
+    while let Some(Done(v)) = inbox.try_recv() {
+        replies.push(v);
+    }
+    assert_eq!(replies.len(), 3, "only 3 messages processed before self-stop");
+    assert_eq!(stopped.load(Ordering::Relaxed), 1, "on_stop fired");
+    assert!(rt.send_to(addr, Forward { value: 99, reply_to: *inbox.addr() }).is_err(),
+        "send to stopped actor fails");
+
+    // --- Part B: FarewellActor sends farewell in on_stop ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(FarewellActor { farewell_to: *inbox.addr() }).unwrap();
+    rt.tick();
+    rt.stop_actor(addr).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(inbox.try_recv(), Some(Pong), "farewell message delivered from on_stop");
+
+    // --- Part C: External stop after pending messages ---
+    let stopped = Arc::new(AtomicUsize::new(0));
+    let handled = Arc::new(AtomicUsize::new(0));
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(LifecycleActor {
+        started: Arc::new(AtomicUsize::new(0)),
+        stopped: stopped.clone(),
+        handled: handled.clone(),
+    }).unwrap();
+    for _ in 0..10 {
+        let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
+    }
+    rt.stop_actor(addr).unwrap();
+    tick_n(&rt, 10);
+    assert_eq!(handled.load(Ordering::Relaxed), 10, "all pending messages processed before stop");
+    assert_eq!(stopped.load(Ordering::Relaxed), 1, "on_stop fires after messages");
+
+    // --- Part D: External stop before messages → 0 processed ---
+    let handled = Arc::new(AtomicUsize::new(0));
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(LifecycleActor {
+        started: Arc::new(AtomicUsize::new(0)),
+        stopped: Arc::new(AtomicUsize::new(0)),
+        handled: handled.clone(),
+    }).unwrap();
+    rt.tick(); // on_start
+    rt.stop_actor(addr).unwrap();
+    for _ in 0..5 {
+        let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
+    }
+    tick_n(&rt, 10);
+    assert_eq!(handled.load(Ordering::Relaxed), 0, "stop before messages prevents processing");
+
+    // --- Part E: Mid-mailbox stop trigger ---
+    let processed = Arc::new(AtomicUsize::new(0));
+    let rt = std_runtime(RuntimeConfig::default());
+    let addr = rt.spawn(StopOnTrigger(processed.clone())).unwrap();
+    rt.tick();
+    rt.send_to(addr, Trigger(false)).unwrap();
+    rt.send_to(addr, Trigger(false)).unwrap();
+    rt.send_to(addr, Trigger(true)).unwrap(); // stop trigger
+    rt.send_to(addr, Trigger(false)).unwrap();
+    rt.send_to(addr, Trigger(false)).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(processed.load(Ordering::Relaxed), 3,
+        "only messages up to and including stop trigger processed");
+    assert!(rt.send_to(addr, Trigger(false)).is_err());
+}
+
+/// Panics are caught: healthy siblings survive, panicked actors are poisoned
+/// and cleaned from stats/address map, mid-batch panic discards remaining,
+/// child spawned before parent panic survives, message sent before panic is
+/// delivered, bulk cleanup, on_start panic also poisons.
+#[test]
+fn panic_isolation_and_cleanup() {
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let count_inbox = rt.new_inbox::<Count>().unwrap();
+
+    // Spawn a healthy counter, a PanicActor, and a PanicOnStartActor
+    let good = rt.spawn(CounterActor { count: 0 }).unwrap();
+    let bad = rt.spawn(PanicActor).unwrap();
+    let bad_start_handled = Arc::new(AtomicUsize::new(0));
+    let bad_start = rt.spawn(PanicOnStartActor { handled: bad_start_handled.clone() }).unwrap();
+
+    // Trigger panics
+    rt.send_to(bad, PanicMsg).unwrap();
+    let _ = rt.send_to(bad_start, Ping { reply_to: *inbox.addr() });
+    tick_n(&rt, 10);
+
+    // Healthy actor still works
+    rt.send_to(good, Increment { reply_to: *count_inbox.addr() }).unwrap();
+    rt.send_to(good, Increment { reply_to: *count_inbox.addr() }).unwrap();
+    let replies = tick_and_drain(&rt, &count_inbox, 10);
+    assert_eq!(replies, vec![Count(1), Count(2)], "healthy actor unaffected by peer panics");
+
+    // Poisoned actors are cleaned from address map
+    assert!(rt.send_to(bad, PanicMsg).is_err(), "send to cleaned-up actor fails");
+    assert_eq!(bad_start_handled.load(Ordering::Relaxed), 0, "on_start panic prevents messages");
+
+    // Stats track panics vs stops separately
+    let stats = rt.stats();
+    let panics: u64 = stats.workers.iter().map(|w| w.panics).sum();
+    assert!(panics >= 2, "at least 2 panics recorded (PanicActor + PanicOnStartActor)");
+
+    // --- Mid-batch panic discards remaining ---
+    let counter = Arc::new(AtomicUsize::new(0));
+    let rt = std_runtime(RuntimeConfig::default());
+    let dummy = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(PanicAfterNActor { remaining_good: 2, counter: counter.clone() }).unwrap();
+    for _ in 0..5 {
+        rt.send_to(addr, Ping { reply_to: *dummy.addr() }).unwrap();
+    }
+    tick_n(&rt, 20);
+    assert_eq!(counter.load(Ordering::SeqCst), 2, "only messages before panic processed");
+
+    // --- Child spawned before parent panic survives ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Done>().unwrap();
+    let parent = rt.spawn(SpawnThenPanicActor).unwrap();
+    rt.send_to(parent, Forward { value: 5, reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 30);
+    assert_eq!(reply, Some(Done(10)), "child survives parent panic");
+
+    // --- Message sent before panic is delivered ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(SendThenPanicActor).unwrap();
+    rt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 20);
+    assert!(reply.is_some(), "message sent before panic still delivered");
+
+    // --- Bulk cleanup: 20 panicking actors all cleaned ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let mut addrs = Vec::new();
+    for _ in 0..20 {
+        addrs.push(rt.spawn(PanicActor).unwrap());
+    }
+    for &addr in &addrs {
+        let _ = rt.send_to(addr, PanicMsg);
+    }
+    tick_n(&rt, 10);
+    let stats = rt.stats();
+    assert_eq!(stats.workers[0].num_actors, 0, "all poisoned actors cleaned up");
+}
+
+/// Watch API contract: watchers are notified on death, unwatch cancels,
+/// double-watch is idempotent, multiple watchers all notified,
+/// runtime-level watch works.
+#[test]
+fn watch_notification_contract() {
+    let rt = std_runtime(RuntimeConfig::default());
+
+    // Spawn target + 3 watchers + 1 that unwatches
+    let target = rt.spawn(PanicActor).unwrap();
+    let (w1, s1) = new_exit_watcher();
+    let (w2, s2) = new_exit_watcher();
+    let (w3, s3) = new_exit_watcher();
+    let (w4, s4) = new_exit_watcher(); // will unwatch
+
+    let w1_addr = rt.spawn(w1).unwrap();
+    let w2_addr = rt.spawn(w2).unwrap();
+    let w3_addr = rt.spawn(w3).unwrap();
+    let w4_addr = rt.spawn(w4).unwrap();
+
+    // All watch the target
+    rt.send_to(w1_addr, WatcherCmd::WatchThis(target)).unwrap();
+    rt.send_to(w2_addr, WatcherCmd::WatchThis(target)).unwrap();
+    rt.send_to(w3_addr, WatcherCmd::WatchThis(target)).unwrap();
+    rt.send_to(w4_addr, WatcherCmd::WatchThis(target)).unwrap();
+    tick_n(&rt, 3);
+
+    // w2 double-watches (idempotent test)
+    rt.send_to(w2_addr, WatcherCmd::WatchThis(target)).unwrap();
+    tick_n(&rt, 3);
+
+    // w4 unwatches
+    rt.send_to(w4_addr, WatcherCmd::UnwatchThis(target)).unwrap();
+    tick_n(&rt, 3);
+
+    // Kill target
+    rt.send_to(target, PanicMsg).unwrap();
+    tick_n(&rt, 5);
+
+    assert_eq!(s1.count(), 1, "watcher 1 notified");
+    assert_eq!(s2.count(), 1, "double-watch still only one notification");
+    assert_eq!(s3.count(), 1, "watcher 3 notified");
+    assert_eq!(s4.count(), 0, "unwatched watcher not notified");
+    assert_eq!(s1.last_reason(), Some(ExitReason::Panicked));
+
+    // --- Runtime-level watch ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let target = rt.spawn(PanicActor).unwrap();
+    let (w, s) = new_exit_watcher();
+    let w_addr = rt.spawn(w).unwrap();
+    tick_n(&rt, 2);
+    rt.watch(w_addr, target);
+    rt.send_to(target, PanicMsg).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(s.count(), 1, "runtime-level watch delivers notification");
+}
+
+/// Watch edge cases: watcher dies before target (no crash), self-watch (no
+/// crash), watcher reacts to death by spawning a replacement.
+#[test]
+fn watch_edge_cases() {
+    // Watcher dies before target — no crash
+    let rt = std_runtime(RuntimeConfig::default());
+    let target = rt.spawn(PanicActor).unwrap();
+    let target2 = rt.spawn(PanicActor).unwrap();
+    rt.watch(target2, target);
+    tick_n(&rt, 3);
+    rt.send_to(target2, PanicMsg).unwrap(); // kill watcher first
+    tick_n(&rt, 5);
+    rt.send_to(target, PanicMsg).unwrap(); // kill target — no crash
+    tick_n(&rt, 5);
+
+    // Self-watch — no crash
+    let rt = std_runtime(RuntimeConfig::default());
+    let (w, _s) = new_exit_watcher();
+    let addr = rt.spawn(w).unwrap();
+    rt.send_to(addr, WatcherCmd::WatchThis(addr)).unwrap();
+    tick_n(&rt, 5);
+
+    // Watcher reacts to death by spawning replacement
+    let rt = std_runtime(RuntimeConfig::default());
+    let spawned = Arc::new(AtomicUsize::new(0));
+
+    struct SupervisorWatcher {
+        spawned_count: Arc<AtomicUsize>,
+    }
+
+    #[derive(Clone)]
+    enum SupCmd {
+        WatchThis(ActorAddress),
+    }
+
+    impl ActorInterface for SupervisorWatcher {
+        type Incoming = SupCmd;
+        type Response = ();
+        fn handle(&mut self, ctx: &Ctx, msg: SupCmd) {
+            match msg {
+                SupCmd::WatchThis(target) => ctx.watch(target),
+            }
+        }
+        fn on_actor_exit(&mut self, ctx: &Ctx, _exited: ActorExited) {
+            let _ = ctx.spawn(Sleeper);
+            self.spawned_count.fetch_add(1, Ordering::SeqCst);
+        }
+    }
+
+    let target = rt.spawn(PanicActor).unwrap();
+    let sup = rt.spawn(SupervisorWatcher { spawned_count: spawned.clone() }).unwrap();
+    rt.send_to(sup, SupCmd::WatchThis(target)).unwrap();
+    tick_n(&rt, 3);
+    rt.send_to(target, PanicMsg).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(spawned.load(Ordering::SeqCst), 1, "watcher spawned replacement");
+}
+
+/// Monitor API contract: Down on stop (Normal) and panic (Panicked), multiple
+/// monitors, demonitor cancels, dead watcher cleanup, stacked monitors,
+/// external inbox, handle_down dispatch.
+#[test]
+fn monitor_death_notification_contract() {
+    let rt = std_runtime(RuntimeConfig::default());
+
+    // --- Stop → Down(Normal) ---
+    let inbox = rt.new_inbox::<Down>().unwrap();
+    let target = rt.spawn(PingPongActor).unwrap();
+    rt.spawn(MonitorWatcherActor {
+        watch_target: target,
+        reply_to: *inbox.addr(),
+        mref: None,
+    }).unwrap();
+    rt.tick();
+    rt.stop_actor(target).unwrap();
+    tick_n(&rt, 3);
+    let down = inbox.try_recv().expect("Down on graceful stop");
+    assert_eq!(down.addr, target);
+    assert_eq!(down.reason, StopReason::Normal);
+
+    // --- Panic → Down(Panicked) ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Down>().unwrap();
+    let target = rt.spawn(PanicActor).unwrap();
+    rt.spawn(MonitorWatcherActor {
+        watch_target: target,
+        reply_to: *inbox.addr(),
+        mref: None,
+    }).unwrap();
+    rt.tick();
+    rt.send_to(target, PanicMsg).unwrap();
+    tick_n(&rt, 3);
+    let down = inbox.try_recv().expect("Down on panic");
+    assert_eq!(down.reason, StopReason::Panicked);
+
+    // --- Multiple monitors ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox1 = rt.new_inbox::<Down>().unwrap();
+    let inbox2 = rt.new_inbox::<Down>().unwrap();
+    let target = rt.spawn(PingPongActor).unwrap();
+    rt.spawn(MonitorWatcherActor {
+        watch_target: target, reply_to: *inbox1.addr(), mref: None,
+    }).unwrap();
+    rt.spawn(MonitorWatcherActor {
+        watch_target: target, reply_to: *inbox2.addr(), mref: None,
+    }).unwrap();
+    rt.tick();
+    rt.stop_actor(target).unwrap();
+    tick_n(&rt, 3);
+    assert!(inbox1.try_recv().is_some(), "watcher 1 notified");
+    assert!(inbox2.try_recv().is_some(), "watcher 2 notified");
+
+    // --- Demonitor cancels ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let down_inbox = rt.new_inbox::<Down>().unwrap();
+    let target = rt.spawn(PingPongActor).unwrap();
+    let watcher = rt.spawn(DemonitorActor { watch_target: target, mref: None }).unwrap();
+    rt.tick();
+    rt.send_to(watcher, Ping { reply_to: ActorAddress::default() }).unwrap();
+    rt.tick(); // demonitor
+    rt.stop_actor(target).unwrap();
+    tick_n(&rt, 3);
+    assert!(down_inbox.try_recv().is_none(), "demonitored: no Down delivered");
+
+    // --- Dead watcher cleaned up ---
+    let rt = std_runtime(RuntimeConfig::default());
+    let target = rt.spawn(PingPongActor).unwrap();
+    let watcher = rt.spawn(MonitorWatcherActor {
+        watch_target: target,
+        reply_to: ActorAddress::default(),
+        mref: None,
+    }).unwrap();
+    rt.tick();
+    rt.stop_actor(watcher).unwrap();
+    rt.tick(); // watcher dies
+    rt.stop_actor(target).unwrap();
+    tick_n(&rt, 3); // target dies — no crash trying to deliver to dead watcher
+
+    // --- Stacked monitors produce multiple notifications ---
+    struct DoubleMonitor {
+        target: ActorAddress,
+        reply_to: ActorAddress,
+    }
+    impl ActorInterface for DoubleMonitor {
+        type Incoming = Down;
+        type Response = ();
+        fn on_start(&mut self, ctx: &Ctx) {
+            ctx.monitor(self.target);
+            ctx.monitor(self.target);
+        }
+        fn handle(&mut self, ctx: &Ctx, msg: Down) {
+            ctx.send(self.reply_to, msg).unwrap();
+        }
+    }
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Down>().unwrap();
+    let target = rt.spawn(PingPongActor).unwrap();
+    rt.spawn(DoubleMonitor { target, reply_to: *inbox.addr() }).unwrap();
+    rt.tick();
+    rt.stop_actor(target).unwrap();
+    tick_n(&rt, 3);
+    assert!(inbox.try_recv().is_some(), "first Down from stacked monitor");
+    assert!(inbox.try_recv().is_some(), "second Down from stacked monitor");
+    assert!(inbox.try_recv().is_none(), "no more");
+
+    // --- handle_down dispatch ---
+    struct MonitoringTracker {
+        target: ActorAddress,
+        downs: Vec<Down>,
+        inbox: ActorAddress,
+    }
+    impl ActorInterface for MonitoringTracker {
+        type Incoming = Ping;
+        type Response = ();
+        fn on_start(&mut self, ctx: &Ctx) {
+            ctx.monitor(self.target);
+        }
+        fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
+            let _ = ctx.send(self.inbox, Count(self.downs.len()));
+        }
+        fn handle_down(&mut self, _ctx: &Ctx, down: Down) {
+            self.downs.push(down);
+        }
+    }
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Count>().unwrap();
+    let target = rt.spawn(PanicActor).unwrap();
+    let tracker = rt.spawn(MonitoringTracker {
+        target,
+        downs: vec![],
+        inbox: *inbox.addr(),
+    }).unwrap();
+    rt.tick();
+    rt.send_to(target, PanicMsg).unwrap();
+    tick_n(&rt, 3);
+    rt.send_to(tracker, Ping { reply_to: ActorAddress::default() }).unwrap();
+    rt.tick();
+    assert_eq!(inbox.try_recv(), Some(Count(1)), "handle_down received exactly one Down");
+
+    // --- When Incoming=Down, handle_down is NOT called ---
+    struct DownAsIncoming {
+        target: ActorAddress,
+        inbox: ActorAddress,
+    }
+    impl ActorInterface for DownAsIncoming {
+        type Incoming = Down;
+        type Response = ();
+        fn on_start(&mut self, ctx: &Ctx) {
+            ctx.monitor(self.target);
+        }
+        fn handle(&mut self, ctx: &Ctx, msg: Down) {
+            let _ = ctx.send(self.inbox, msg);
+        }
+        fn handle_down(&mut self, _ctx: &Ctx, _down: Down) {
+            panic!("handle_down must not be called when Incoming=Down");
+        }
+    }
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Down>().unwrap();
+    let target = rt.spawn(PanicActor).unwrap();
+    rt.spawn(DownAsIncoming { target, inbox: *inbox.addr() }).unwrap();
+    rt.tick();
+    rt.send_to(target, PanicMsg).unwrap();
+    tick_n(&rt, 3);
+    let received = inbox.try_recv().expect("Down delivered via handle(), not handle_down");
+    assert_eq!(received.reason, StopReason::Panicked);
+}

tests/common/mod.rs

@@ -5,11 +5,14 @@
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Arc;
 
-pub use swactor::actor::{ActorAddress, ActorInterface, Down, MonitorRef, StopReason};
+pub use swactor::actor::{
+    ActorAddress, ActorExited, ActorInterface, Down, ExitReason, MonitorRef, StopReason,
+};
 pub use swactor::runtime::{Ctx, Inbox, MailboxOverflow, Runtime, RuntimeConfig};
 pub use swactor_std::{
-    ChildSpec, CtxGroups, CtxMonitoring, CtxNaming, CtxTimers, RestartPolicy, Router,
-    RoutingStrategy, RuntimeGroups, RuntimeNaming, StdExtension, Supervisor, SupervisorStrategy,
+    ChildSpec, CtxGroups, CtxMonitoring, CtxNaming, CtxTimers, CtxWatching, RestartPolicy, Router,
+    RoutingStrategy, RuntimeGroups, RuntimeNaming, RuntimeWatching, StdExtension, Supervisor,
+    SupervisorStrategy,
 };
 
 // ── Messages ────────────────────────────────────────────────────────────────
@@ -232,6 +235,13 @@ pub fn tick_until_recv<M: swactor::actor::Message>(
     None
 }
 
+/// Tick exactly `n` times (no inbox polling).
+pub fn tick_n(rt: &Runtime, n: usize) {
+    for _ in 0..n {
+        rt.tick();
+    }
+}
+
 /// Tick `n` times, then drain all messages from the inbox.
 pub fn tick_and_drain<M: swactor::actor::Message>(
     rt: &Runtime,

tests/message_delivery.rs

@@ -0,0 +1,489 @@
+//! Message Delivery Tests — how data flows through the system.
+//!
+//! Covers: FIFO ordering, routing correctness at scale, delivery from within
+//! handlers, address error handling, fairness/budgets, timers, and mailbox
+//! backpressure policies.
+
+mod common;
+use common::*;
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+// ── Local actors ────────────────────────────────────────────────────────────
+
+/// Sends a countdown message to itself, then replies Done(0).
+struct SelfSendActor;
+
+#[derive(Clone)]
+struct Countdown {
+    remaining: usize,
+    reply_to: ActorAddress,
+}
+
+impl ActorInterface for SelfSendActor {
+    type Incoming = Countdown;
+    type Response = Done;
+    fn handle(&mut self, ctx: &Ctx, msg: Countdown) {
+        if msg.remaining == 0 {
+            let _ = ctx.send(msg.reply_to, Done(0));
+        } else {
+            let _ = ctx.send(
+                ctx.self_addr(),
+                Countdown { remaining: msg.remaining - 1, reply_to: msg.reply_to },
+            );
+        }
+    }
+}
+
+/// Schedules a one-shot timer in on_start.
+struct TimerStartActor {
+    target: ActorAddress,
+    delay_ticks: u64,
+}
+
+impl ActorInterface for TimerStartActor {
+    type Incoming = Ping;
+    type Response = Pong;
+    fn on_start(&mut self, ctx: &Ctx) {
+        ctx.send_after_ticks(self.target, Ping { reply_to: ctx.self_addr() }, self.delay_ticks);
+    }
+    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {}
+}
+
+/// Schedules a one-shot timer from a handler.
+struct DelayPingPongActor;
+
+impl ActorInterface for DelayPingPongActor {
+    type Incoming = Forward;
+    type Response = Done;
+    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
+        ctx.send_after_ticks(msg.reply_to, Done(msg.value), 3);
+    }
+}
+
+/// Schedules an interval timer on start.
+struct HeartbeatActor {
+    target: ActorAddress,
+    period: u64,
+}
+
+impl ActorInterface for HeartbeatActor {
+    type Incoming = Ping;
+    type Response = Pong;
+    fn on_start(&mut self, ctx: &Ctx) {
+        ctx.send_interval_ticks(self.target, Ping { reply_to: ctx.self_addr() }, self.period);
+    }
+    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {}
+}
+
+/// NumberedMsg/Reply for routing correctness tests.
+#[derive(Clone)]
+struct NumberedMsg {
+    n: usize,
+    reply_to: ActorAddress,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+struct NumberedReply {
+    from: ActorAddress,
+    n: usize,
+}
+
+struct NumberedActor;
+
+impl ActorInterface for NumberedActor {
+    type Incoming = NumberedMsg;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, msg: NumberedMsg) {
+        let _ = ctx.send(msg.reply_to, NumberedReply { from: ctx.self_addr(), n: msg.n });
+    }
+}
+
+/// Ring node for routing chain test.
+#[derive(Clone)]
+struct RingHop {
+    hops_remaining: usize,
+    final_dest: ActorAddress,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+struct RingDone(usize);
+
+struct RingNode {
+    next: ActorAddress,
+}
+
+impl ActorInterface for RingNode {
+    type Incoming = RingHop;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, msg: RingHop) {
+        if msg.hops_remaining == 0 {
+            let _ = ctx.send(msg.final_dest, RingDone(100));
+        } else {
+            let _ = ctx.send(self.next, RingHop {
+                hops_remaining: msg.hops_remaining - 1,
+                final_dest: msg.final_dest,
+            });
+        }
+    }
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Tests
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Messages arrive in FIFO order even with small buffers, budget constraints,
+/// and independent mailboxes isolate actors from each other.
+#[test]
+fn fifo_ordering_and_mailbox_isolation() {
+    // FIFO with small buffer and budget
+    let rt = std_runtime(RuntimeConfig {
+        channel_buffer_size: 1,
+        actor_message_budget: 8,
+        ..Default::default()
+    });
+    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    let inbox = rt.new_inbox::<Count>().unwrap();
+    for _ in 0..100 {
+        rt.send_to(addr, Increment { reply_to: *inbox.addr() }).unwrap();
+    }
+    let replies: Vec<_> = tick_and_drain(&rt, &inbox, 50);
+    assert_eq!(replies.len(), 100, "all messages delivered");
+    for (i, reply) in replies.iter().enumerate() {
+        assert_eq!(*reply, Count(i + 1), "FIFO order preserved at position {i}");
+    }
+
+    // Mailbox isolation: 3 actors each get exactly their own messages
+    let rt = std_runtime(RuntimeConfig::default());
+    let mut inboxes = Vec::new();
+    for _ in 0..3 {
+        let addr = rt.spawn(PingPongActor).unwrap();
+        let inbox = rt.new_inbox::<Pong>().unwrap();
+        rt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
+        inboxes.push(inbox);
+    }
+    tick_n(&rt, 10);
+    for (i, inbox) in inboxes.iter().enumerate() {
+        assert!(inbox.try_recv().is_some(), "actor {i} replied");
+        assert!(inbox.try_recv().is_none(), "actor {i} has exactly one reply");
+    }
+}
+
+/// 200 actors each get a unique numbered message and reply correctly.
+/// A 100-hop ring traversal completes.
+#[test]
+fn message_routing_at_scale() {
+    // 200-actor numbered routing
+    let rt = std_runtime(RuntimeConfig {
+        max_actors: 300,
+        channel_buffer_size: 1024,
+        num_threads: 1,
+        ..Default::default()
+    });
+    let inbox = rt.new_inbox::<NumberedReply>().unwrap();
+    let inbox_addr = *inbox.addr();
+    let mut addrs = Vec::new();
+    for _ in 0..200 {
+        addrs.push(rt.spawn(NumberedActor).unwrap());
+    }
+    rt.tick();
+    for (i, addr) in addrs.iter().enumerate() {
+        rt.send_to(*addr, NumberedMsg { n: i, reply_to: inbox_addr }).unwrap();
+    }
+    tick_n(&rt, 3);
+    let replies: Vec<NumberedReply> = std::iter::from_fn(|| inbox.try_recv()).collect();
+    assert_eq!(replies.len(), 200, "all 200 actors replied");
+    for (i, addr) in addrs.iter().enumerate() {
+        let reply = replies.iter().find(|r| r.n == i);
+        assert!(reply.is_some(), "missing reply for actor #{i}");
+        assert_eq!(reply.unwrap().from, *addr, "reply #{i} came from correct actor");
+    }
+
+    // 100-hop ring
+    let rt = std_runtime(RuntimeConfig {
+        max_actors: 200,
+        channel_buffer_size: 1024,
+        num_threads: 1,
+        ..Default::default()
+    });
+    let inbox = rt.new_inbox::<RingDone>().unwrap();
+    let inbox_addr = *inbox.addr();
+    let mut ring_addrs = Vec::new();
+    let mut next = inbox_addr;
+    for _ in (0..100).rev() {
+        let addr = rt.spawn(RingNode { next }).unwrap();
+        ring_addrs.push(addr);
+        next = addr;
+    }
+    ring_addrs.reverse();
+    rt.tick();
+    rt.send_to(ring_addrs[0], RingHop { hops_remaining: 99, final_dest: inbox_addr }).unwrap();
+    let result = tick_until_recv(&rt, &inbox, 110);
+    assert_eq!(result, Some(RingDone(100)), "ring message traverses all 100 hops");
+}
+
+/// Messages sent in handlers are delivered: delegation, self-send chains,
+/// rapid spawn+immediate-send, multiple inbox types coexist.
+#[test]
+fn delivery_from_within_handlers() {
+    let rt = std_runtime(RuntimeConfig::default());
+
+    // Delegation: spawn+send in handler
+    let delegator = rt.spawn(DelegatorActor).unwrap();
+    let inbox = rt.new_inbox::<Done>().unwrap();
+    rt.send_to(delegator, Forward { value: 5, reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 20);
+    assert_eq!(reply, Some(Done(10)), "child spawned during handler receives message");
+
+    // Self-send countdown of 20
+    let self_sender = rt.spawn(SelfSendActor).unwrap();
+    rt.send_to(self_sender, Countdown { remaining: 20, reply_to: *inbox.addr() }).unwrap();
+    let reply = tick_until_recv(&rt, &inbox, 50);
+    assert_eq!(reply, Some(Done(0)), "self-send chain completes");
+
+    // Multiple senders reach same actor
+    let counter = rt.spawn(CounterActor { count: 0 }).unwrap();
+    let inbox_a = rt.new_inbox::<Count>().unwrap();
+    let inbox_b = rt.new_inbox::<Count>().unwrap();
+    rt.send_to(counter, Increment { reply_to: *inbox_a.addr() }).unwrap();
+    rt.send_to(counter, Increment { reply_to: *inbox_b.addr() }).unwrap();
+    tick_n(&rt, 10);
+    assert!(inbox_a.try_recv().is_some());
+    assert_eq!(inbox_b.try_recv(), Some(Count(2)), "both senders reach same actor");
+
+    // 50 rapid spawn+immediate-send pairs
+    let rt = std_runtime(RuntimeConfig::default());
+    let pong_inbox = rt.new_inbox::<Pong>().unwrap();
+    for _ in 0..50 {
+        let addr = rt.spawn(PingPongActor).unwrap();
+        rt.send_to(addr, Ping { reply_to: *pong_inbox.addr() }).unwrap();
+    }
+    let replies = tick_and_drain(&rt, &pong_inbox, 50);
+    assert_eq!(replies.len(), 50, "all spawn+send pairs complete");
+
+    // Multiple inbox types coexist
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter_addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    let pinger_addr = rt.spawn(PingPongActor).unwrap();
+    let count_inbox = rt.new_inbox::<Count>().unwrap();
+    let pong_inbox = rt.new_inbox::<Pong>().unwrap();
+    rt.send_to(counter_addr, Increment { reply_to: *count_inbox.addr() }).unwrap();
+    rt.send_to(pinger_addr, Ping { reply_to: *pong_inbox.addr() }).unwrap();
+    tick_n(&rt, 10);
+    assert_eq!(count_inbox.try_recv(), Some(Count(1)));
+    assert_eq!(pong_inbox.try_recv(), Some(Pong));
+}
+
+/// Sending to nonexistent address returns error, wrong type increments
+/// type_mismatch counter.
+#[test]
+fn address_error_handling() {
+    let rt = std_runtime(RuntimeConfig::default());
+
+    // Nonexistent address
+    let bogus = ActorAddress::new_random();
+    assert!(rt.send_to(bogus, Pong).is_err(), "send to unknown address fails");
+
+    // Wrong type
+    let addr = rt.spawn(PingPongActor).unwrap();
+    rt.send_to(addr, Count(42)).unwrap(); // Count instead of Ping
+    rt.send_to(addr, Count(0)).unwrap();
+    rt.send_to(addr, Count(0)).unwrap();
+    tick_n(&rt, 10);
+    let stats = rt.stats();
+    let mismatches: u64 = stats.workers.iter().map(|w| w.type_mismatches).sum();
+    assert_eq!(mismatches, 3, "3 wrong-type messages counted as mismatches");
+}
+
+/// Budget fairness: hot actor doesn't starve cold actor, budget is respected
+/// with self-sends, unlimited budget drains all.
+#[test]
+fn fairness_budget_prevents_starvation() {
+    // Hot (1000 msgs) vs cold (1 msg), budget=64
+    let rt = std_runtime(RuntimeConfig::default());
+    let hot_counter = Arc::new(AtomicUsize::new(0));
+    let cold_inbox = rt.new_inbox::<Pong>().unwrap();
+    let hot = rt.spawn(CountingPingActor { counter: hot_counter.clone() }).unwrap();
+    let cold = rt.spawn(PingPongActor).unwrap();
+    let dummy = rt.new_inbox::<Pong>().unwrap();
+    for _ in 0..1000 {
+        rt.send_to(hot, Ping { reply_to: *dummy.addr() }).unwrap();
+    }
+    rt.send_to(cold, Ping { reply_to: *cold_inbox.addr() }).unwrap();
+    rt.tick();
+    assert!(cold_inbox.try_recv().is_some(), "cold actor not starved by hot actor");
+    assert!(hot_counter.load(Ordering::SeqCst) <= 64, "hot capped at budget");
+
+    // Budget=4 with self-send chain of 20 → completes across multiple ticks
+    let rt = std_runtime(RuntimeConfig { actor_message_budget: 4, ..Default::default() });
+    let addr = rt.spawn(SelfSendActor).unwrap();
+    let inbox = rt.new_inbox::<Done>().unwrap();
+    rt.send_to(addr, Countdown { remaining: 20, reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 30);
+    assert_eq!(inbox.try_recv(), Some(Done(0)), "self-send chain completes despite budget");
+
+    // Unlimited budget (0) drains all
+    let rt = std_runtime(RuntimeConfig { actor_message_budget: 0, ..Default::default() });
+    let counter = Arc::new(AtomicUsize::new(0));
+    let dummy = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(CountingPingActor { counter: counter.clone() }).unwrap();
+    for _ in 0..500 {
+        rt.send_to(addr, Ping { reply_to: *dummy.addr() }).unwrap();
+    }
+    rt.tick();
+    rt.tick();
+    assert_eq!(counter.load(Ordering::SeqCst), 500, "unlimited budget drains all");
+}
+
+/// One-shot timers fire at the right tick and only once. Interval timers fire
+/// repeatedly at the right period. Timers are cleaned up when actors die.
+#[test]
+fn timer_one_shot_and_interval() {
+    // One-shot: delay=3 from on_start
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Ping>().unwrap();
+    rt.spawn(TimerStartActor { target: *inbox.addr(), delay_ticks: 3 }).unwrap();
+    rt.tick(); // tick 1: on_start schedules
+    assert!(inbox.try_recv().is_none(), "no delivery tick 1");
+    rt.tick(); // tick 2
+    assert!(inbox.try_recv().is_none(), "no delivery tick 2");
+    rt.tick(); // tick 3
+    assert!(inbox.try_recv().is_none(), "no delivery tick 3");
+    rt.tick(); // tick 4: fires
+    assert!(inbox.try_recv().is_some(), "timer fires after 3-tick delay");
+
+    // One-shot from handler
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Done>().unwrap();
+    let addr = rt.spawn(DelayPingPongActor).unwrap();
+    rt.send_to(addr, Forward { value: 42, reply_to: *inbox.addr() }).unwrap();
+    rt.tick(); // process Forward, schedule timer
+    assert!(inbox.try_recv().is_none());
+    rt.tick(); // tick 2
+    rt.tick(); // tick 3
+    assert!(inbox.try_recv().is_none());
+    rt.tick(); // tick 4: fires
+    assert_eq!(inbox.try_recv(), Some(Done(42)), "delayed reply from handler timer");
+
+    // One-shot does NOT repeat
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Ping>().unwrap();
+    rt.spawn(TimerStartActor { target: *inbox.addr(), delay_ticks: 1 }).unwrap();
+    rt.tick(); // schedule
+    rt.tick(); // fires
+    assert!(inbox.try_recv().is_some(), "first fire");
+    tick_n(&rt, 5);
+    assert!(inbox.try_recv().is_none(), "one-shot doesn't repeat");
+
+    // Zero-delay fires next tick
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Ping>().unwrap();
+    rt.spawn(TimerStartActor { target: *inbox.addr(), delay_ticks: 0 }).unwrap();
+    rt.tick(); // schedule
+    assert!(inbox.try_recv().is_none(), "not immediate — fires next tick");
+    rt.tick(); // fires
+    assert!(inbox.try_recv().is_some(), "zero-delay fires next tick");
+
+    // Interval: period=2, fires on ticks 3, 5, 7
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Ping>().unwrap();
+    rt.spawn(HeartbeatActor { target: *inbox.addr(), period: 2 }).unwrap();
+    rt.tick(); // tick 1: schedule
+    assert!(inbox.try_recv().is_none());
+    rt.tick(); // tick 2
+    assert!(inbox.try_recv().is_none());
+    rt.tick(); // tick 3: first fire
+    assert!(inbox.try_recv().is_some(), "fire on tick 3");
+    rt.tick(); // tick 4
+    assert!(inbox.try_recv().is_none());
+    rt.tick(); // tick 5: second fire
+    assert!(inbox.try_recv().is_some(), "fire on tick 5");
+    rt.tick(); // tick 6
+    assert!(inbox.try_recv().is_none());
+    rt.tick(); // tick 7: third fire
+    assert!(inbox.try_recv().is_some(), "fire on tick 7");
+
+    // Timer cleanup when target actor dies
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter_addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    rt.spawn(HeartbeatActor { target: counter_addr, period: 1 }).unwrap();
+    tick_n(&rt, 3);
+    rt.stop_actor(counter_addr).unwrap();
+    tick_n(&rt, 5);
+    let stats = rt.stats();
+    assert_eq!(stats.workers[0].num_actors, 1, "only heartbeat actor remains");
+}
+
+/// Bounded mailboxes: DropNewest caps at capacity, DropOldest keeps newest,
+/// unbounded delivers all, mailbox refills after processing.
+#[test]
+fn mailbox_backpressure_policies() {
+    // DropNewest: capacity=10, send 50 → only 10 delivered
+    let rt = std_runtime(RuntimeConfig {
+        default_mailbox_capacity: 10,
+        mailbox_overflow: MailboxOverflow::DropNewest,
+        ..Default::default()
+    });
+    let inbox = rt.new_inbox::<Count>().unwrap();
+    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    for _ in 0..50 {
+        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
+    }
+    tick_n(&rt, 20);
+    let mut replies = 0;
+    while inbox.try_recv().is_some() { replies += 1; }
+    assert_eq!(replies, 10, "DropNewest caps at mailbox capacity");
+    let drops: u64 = rt.stats().workers.iter().map(|w| w.messages_dropped).sum();
+    assert_eq!(drops, 40, "40 messages dropped");
+
+    // DropOldest: capacity=5, send 10 → newest 5 kept
+    let rt = std_runtime(RuntimeConfig {
+        default_mailbox_capacity: 5,
+        mailbox_overflow: MailboxOverflow::DropOldest,
+        ..Default::default()
+    });
+    let inbox = rt.new_inbox::<Done>().unwrap();
+    let addr = rt.spawn(DoubleActor).unwrap();
+    for i in 0..10 {
+        let _ = rt.send_to(addr, Forward { value: i, reply_to: *inbox.addr() });
+    }
+    tick_n(&rt, 10);
+    let mut replies = Vec::new();
+    while let Some(Done(v)) = inbox.try_recv() { replies.push(v); }
+    assert_eq!(replies.len(), 5, "only 5 kept");
+    assert_eq!(replies, vec![10, 12, 14, 16, 18], "newest values kept (5-9 doubled)");
+
+    // Unbounded: 200 messages all delivered
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Count>().unwrap();
+    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    for _ in 0..200 {
+        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
+    }
+    tick_n(&rt, 50);
+    let mut count = 0;
+    while inbox.try_recv().is_some() { count += 1; }
+    assert_eq!(count, 200, "unbounded delivers all");
+
+    // Refill after processing
+    let rt = std_runtime(RuntimeConfig {
+        default_mailbox_capacity: 5,
+        actor_message_budget: 5,
+        mailbox_overflow: MailboxOverflow::DropNewest,
+        ..Default::default()
+    });
+    let inbox = rt.new_inbox::<Count>().unwrap();
+    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
+    for _ in 0..5 {
+        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
+    }
+    rt.tick(); // process batch 1
+    for _ in 0..5 {
+        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
+    }
+    rt.tick(); // process batch 2
+    let mut count = 0;
+    while inbox.try_recv().is_some() { count += 1; }
+    assert_eq!(count, 10, "mailbox refills after draining");
+}

tests/runtime_hasher.rs

@@ -1,224 +0,0 @@
-mod common;
-use common::*;
-
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::Arc;
-
-// ── Identity Hasher Correctness ────────────────────────────────────────────
-
-/// Given: 200 actors each expecting a unique numbered message
-/// When:  Each actor receives its number and replies with (self_addr, number)
-/// Then:  All 200 replies match -- no message was misrouted by the identity hasher
-#[test]
-fn many_actors_all_receive_correct_messages() {
-    #[derive(Clone)]
-    struct NumberedMsg {
-        n: usize,
-        reply_to: ActorAddress,
-    }
-
-    #[derive(Clone, Debug, PartialEq)]
-    struct NumberedReply {
-        from: ActorAddress,
-        n: usize,
-    }
-
-    struct NumberedActor;
-
-    impl ActorInterface for NumberedActor {
-        type Incoming = NumberedMsg;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, msg: NumberedMsg) {
-            let _ = ctx.send(
-                msg.reply_to,
-                NumberedReply {
-                    from: ctx.self_addr(),
-                    n: msg.n,
-                },
-            );
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig {
-        max_actors: 300,
-        channel_buffer_size: 1024,
-        num_threads: 1,
-        ..Default::default()
-    });
-
-    let inbox = rt.new_inbox::<NumberedReply>().unwrap();
-    let inbox_addr = *inbox.addr();
-
-    // Spawn 200 actors
-    let mut addrs = Vec::new();
-    for _ in 0..200 {
-        addrs.push(rt.spawn(NumberedActor).unwrap());
-    }
-    rt.tick(); // on_start
-
-    // Send unique numbered message to each
-    for (i, addr) in addrs.iter().enumerate() {
-        rt.send_to(
-            *addr,
-            NumberedMsg {
-                n: i,
-                reply_to: inbox_addr,
-            },
-        )
-        .unwrap();
-    }
-    rt.tick(); // process + reply
-    rt.tick(); // deliver replies
-
-    // Verify all 200 replies
-    let mut replies: Vec<NumberedReply> = Vec::new();
-    while let Some(reply) = inbox.try_recv() {
-        replies.push(reply);
-    }
-
-    assert_eq!(replies.len(), 200, "should receive exactly 200 replies");
-
-    // Verify each reply came from the correct actor with the correct number
-    for (i, addr) in addrs.iter().enumerate() {
-        let reply = replies.iter().find(|r| r.n == i);
-        assert!(
-            reply.is_some(),
-            "missing reply for actor #{i}"
-        );
-        assert_eq!(
-            reply.unwrap().from, *addr,
-            "reply #{i} came from wrong actor"
-        );
-    }
-}
-
-/// Given: A 100-actor ring where each actor forwards to the next
-/// When:  A message enters the ring and traverses all 100 hops
-/// Then:  The message completes the full circuit (address_map lookups all correct)
-#[test]
-fn ring_routing_unchanged_after_hasher_optimization() {
-    #[derive(Clone)]
-    struct RingHop {
-        hops_remaining: usize,
-        final_dest: ActorAddress,
-    }
-
-    #[derive(Clone, Debug, PartialEq)]
-    struct RingDone(usize); // total hops completed
-
-    struct RingNode {
-        next: ActorAddress,
-    }
-
-    impl ActorInterface for RingNode {
-        type Incoming = RingHop;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, msg: RingHop) {
-            if msg.hops_remaining == 0 {
-                let _ = ctx.send(msg.final_dest, RingDone(100));
-            } else {
-                let _ = ctx.send(
-                    self.next,
-                    RingHop {
-                        hops_remaining: msg.hops_remaining - 1,
-                        final_dest: msg.final_dest,
-                    },
-                );
-            }
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig {
-        max_actors: 200,
-        channel_buffer_size: 1024,
-        num_threads: 1,
-        ..Default::default()
-    });
-
-    let inbox = rt.new_inbox::<RingDone>().unwrap();
-    let inbox_addr = *inbox.addr();
-
-    // Build chain backwards: last node sends to inbox, first node receives
-    let mut addrs = Vec::new();
-    let mut next = inbox_addr;
-    for _ in (0..100).rev() {
-        let node = RingNode { next };
-        let addr = rt.spawn(node).unwrap();
-        addrs.push(addr);
-        next = addr;
-    }
-    addrs.reverse(); // addrs[0] is start of chain
-
-    rt.tick(); // on_start
-
-    // Inject message at the start
-    rt.send_to(
-        addrs[0],
-        RingHop {
-            hops_remaining: 99,
-            final_dest: inbox_addr,
-        },
-    )
-    .unwrap();
-
-    // Tick enough times for the message to traverse all 100 actors
-    for _ in 0..110 {
-        rt.tick();
-    }
-
-    let result = inbox.try_recv();
-    assert!(result.is_some(), "ring message should complete all 100 hops");
-    assert_eq!(result.unwrap(), RingDone(100));
-}
-
-/// Given: An actor that calls ctx.stop_self() upon receiving a trigger message
-/// When:  The trigger is sent, then 5 more messages are sent, then ticked
-/// Then:  The actor is removed, only messages before stop are processed
-#[test]
-fn stop_self_with_pending_messages_still_works() {
-    let processed = Arc::new(AtomicUsize::new(0));
-
-    #[derive(Clone)]
-    struct Msg(bool); // true = trigger stop
-
-    struct StopOnTrigger(Arc<AtomicUsize>);
-
-    impl ActorInterface for StopOnTrigger {
-        type Incoming = Msg;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, msg: Msg) {
-            self.0.fetch_add(1, Ordering::Relaxed);
-            if msg.0 {
-                ctx.stop_self();
-            }
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let p = processed.clone();
-    let addr = rt.spawn(StopOnTrigger(p)).unwrap();
-    rt.tick(); // on_start
-
-    // Send: 2 normal, 1 trigger, 5 more normal
-    rt.send_to(addr, Msg(false)).unwrap();
-    rt.send_to(addr, Msg(false)).unwrap();
-    rt.send_to(addr, Msg(true)).unwrap(); // stop trigger
-    rt.send_to(addr, Msg(false)).unwrap();
-    rt.send_to(addr, Msg(false)).unwrap();
-    rt.send_to(addr, Msg(false)).unwrap();
-    rt.send_to(addr, Msg(false)).unwrap();
-    rt.send_to(addr, Msg(false)).unwrap();
-
-    rt.tick(); // process messages -- stops after trigger
-    rt.tick(); // cleanup
-
-    // Only 3 messages should be processed (2 normal + 1 trigger)
-    assert_eq!(
-        processed.load(Ordering::Relaxed),
-        3,
-        "should process exactly the messages up to and including the stop trigger"
-    );
-
-    // Subsequent sends should fail
-    assert!(rt.send_to(addr, Msg(false)).is_err());
-}

tests/runtime_hooks.rs

@@ -1,454 +0,0 @@
-mod common;
-use common::*;
-
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::Arc;
-
-// ── Lifecycle Hook Helpers ────────────────────────────────────────────────
-
-/// An actor that records lifecycle events to shared counters.
-struct LifecycleActor {
-    started: Arc<AtomicUsize>,
-    stopped: Arc<AtomicUsize>,
-    handled: Arc<AtomicUsize>,
-}
-
-impl ActorInterface for LifecycleActor {
-    type Incoming = Ping;
-    type Response = Pong;
-
-    fn on_start(&mut self, _ctx: &Ctx) {
-        self.started.fetch_add(1, Ordering::Relaxed);
-    }
-
-    fn on_stop(&mut self, _ctx: &Ctx) {
-        self.stopped.fetch_add(1, Ordering::Relaxed);
-    }
-
-    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
-        self.handled.fetch_add(1, Ordering::Relaxed);
-        let _ = ctx.send(msg.reply_to, Pong);
-    }
-}
-
-/// An actor that stops itself after processing N messages.
-struct SelfStopActor {
-    count: usize,
-    stop_after: usize,
-    stopped: Arc<AtomicUsize>,
-}
-
-impl ActorInterface for SelfStopActor {
-    type Incoming = Forward;
-    type Response = Done;
-
-    fn on_stop(&mut self, _ctx: &Ctx) {
-        self.stopped.fetch_add(1, Ordering::Relaxed);
-    }
-
-    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
-        self.count += 1;
-        let _ = ctx.send(msg.reply_to, Done(msg.value));
-        if self.count >= self.stop_after {
-            ctx.stop_self();
-        }
-    }
-}
-
-/// An actor that sends a farewell message in on_stop.
-struct FarewellActor {
-    farewell_to: ActorAddress,
-}
-
-impl ActorInterface for FarewellActor {
-    type Incoming = Ping;
-    type Response = Pong;
-
-    fn on_stop(&mut self, ctx: &Ctx) {
-        let _ = ctx.send(self.farewell_to, Pong);
-    }
-
-    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
-        let _ = ctx.send(msg.reply_to, Pong);
-    }
-}
-
-/// An actor whose on_start panics.
-struct PanicOnStartActor {
-    handled: Arc<AtomicUsize>,
-}
-
-impl ActorInterface for PanicOnStartActor {
-    type Incoming = Ping;
-    type Response = Pong;
-
-    fn on_start(&mut self, _ctx: &Ctx) {
-        panic!("on_start panic");
-    }
-
-    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {
-        self.handled.fetch_add(1, Ordering::Relaxed);
-    }
-}
-
-/// Handles Forward messages, replies Done(value * 2), panics on the panic_at-th message.
-/// (Needed for on_start_called_again_after_restart and stop_vs_panic tests.)
-struct RestartTestActor {
-    count: usize,
-    panic_at: usize,
-}
-
-impl ActorInterface for RestartTestActor {
-    type Incoming = Forward;
-    type Response = Done;
-    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
-        self.count += 1;
-        if self.count >= self.panic_at {
-            panic!("intentional panic at message {}", self.count);
-        }
-        let _ = ctx.send(msg.reply_to, Done(msg.value * 2));
-    }
-}
-
-// ── Lifecycle Hook Tests ──────────────────────────────────────────────────
-
-/// Given an actor with on_start implemented,
-/// when it is spawned and the runtime ticks,
-/// then on_start is called exactly once before the first message.
-#[test]
-fn on_start_called_before_first_message() {
-    let started = Arc::new(AtomicUsize::new(0));
-    let stopped = Arc::new(AtomicUsize::new(0));
-    let handled = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let addr = rt.spawn(LifecycleActor {
-        started: started.clone(),
-        stopped: stopped.clone(),
-        handled: handled.clone(),
-    }).unwrap();
-
-    // First tick — should call on_start
-    rt.tick();
-    assert_eq!(started.load(Ordering::Relaxed), 1, "on_start called on first tick");
-    assert_eq!(handled.load(Ordering::Relaxed), 0, "no messages processed yet");
-
-    // Send messages and tick more
-    let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
-    rt.tick();
-    assert_eq!(started.load(Ordering::Relaxed), 1, "on_start not called again");
-    assert_eq!(handled.load(Ordering::Relaxed), 1, "message processed after on_start");
-}
-
-/// Given an actor with on_start,
-/// when multiple actors are spawned,
-/// then each gets its own on_start call exactly once.
-#[test]
-fn on_start_called_per_actor() {
-    let started = Arc::new(AtomicUsize::new(0));
-    let stopped = Arc::new(AtomicUsize::new(0));
-    let handled = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-
-    for _ in 0..5 {
-        let _ = rt.spawn(LifecycleActor {
-            started: started.clone(),
-            stopped: stopped.clone(),
-            handled: handled.clone(),
-        }).unwrap();
-    }
-
-    rt.tick();
-    assert_eq!(started.load(Ordering::Relaxed), 5, "on_start called for each of 5 actors");
-
-    // Subsequent ticks don't repeat on_start
-    rt.tick();
-    rt.tick();
-    assert_eq!(started.load(Ordering::Relaxed), 5, "on_start still 5 after more ticks");
-}
-
-/// Given an actor whose on_start panics,
-/// when it is spawned and the runtime ticks,
-/// then it is immediately poisoned and never processes messages.
-#[test]
-fn on_start_panic_poisons_actor() {
-    let handled = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let addr = rt.spawn(PanicOnStartActor { handled: handled.clone() }).unwrap();
-
-    let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
-    for _ in 0..5 { rt.tick(); }
-
-    assert_eq!(handled.load(Ordering::Relaxed), 0, "actor never processed messages");
-
-    let stats = rt.stats();
-    let total_panics: u64 = stats.workers.iter().map(|w| w.panics).sum();
-    assert_eq!(total_panics, 1, "on_start panic counted");
-}
-
-// ── Graceful Stop Tests ───────────────────────────────────────────────────
-
-/// Given an actor that calls ctx.stop_self() after 3 messages,
-/// when 5 messages are sent,
-/// then only 3 are processed, the actor is removed, and on_stop is called.
-#[test]
-fn actor_can_stop_self() {
-    let stopped = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Done>().unwrap();
-
-    let addr = rt.spawn(SelfStopActor {
-        count: 0,
-        stop_after: 3,
-        stopped: stopped.clone(),
-    }).unwrap();
-
-    for i in 0..5 {
-        let _ = rt.send_to(addr, Forward { value: i, reply_to: *inbox.addr() });
-    }
-    for _ in 0..10 { rt.tick(); }
-
-    // Only 3 messages should be processed (stop_self after 3rd)
-    let mut replies = Vec::new();
-    while let Some(Done(v)) = inbox.try_recv() {
-        replies.push(v);
-    }
-    assert_eq!(replies.len(), 3, "only 3 messages processed before stop");
-    assert!(replies.contains(&0));
-    assert!(replies.contains(&1));
-    assert!(replies.contains(&2));
-
-    assert_eq!(stopped.load(Ordering::Relaxed), 1, "on_stop called exactly once");
-
-    // Actor should be removed from address map
-    let stats = rt.stats();
-    assert_eq!(stats.actors.len(), 0, "stopped actor removed from address map");
-}
-
-/// Given a running actor,
-/// when runtime.stop_actor(addr) is called,
-/// then the actor stops, on_stop is called, and it's removed from the pool.
-#[test]
-fn runtime_can_stop_actor() {
-    let started = Arc::new(AtomicUsize::new(0));
-    let stopped = Arc::new(AtomicUsize::new(0));
-    let handled = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let addr = rt.spawn(LifecycleActor {
-        started: started.clone(),
-        stopped: stopped.clone(),
-        handled: handled.clone(),
-    }).unwrap();
-
-    // Let it start and process a message
-    let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
-    for _ in 0..3 { rt.tick(); }
-    assert_eq!(handled.load(Ordering::Relaxed), 1);
-
-    // Stop it externally
-    rt.stop_actor(addr).unwrap();
-    for _ in 0..3 { rt.tick(); }
-
-    assert_eq!(stopped.load(Ordering::Relaxed), 1, "on_stop called");
-
-    // Actor should be gone
-    let stats = rt.stats();
-    assert_eq!(stats.actors.len(), 0, "stopped actor removed");
-    assert_eq!(stats.workers[0].num_actors, 0);
-}
-
-/// Given a stopped actor,
-/// when new messages are sent to it,
-/// then sends return Err (address not found).
-#[test]
-fn send_to_stopped_actor_returns_error() {
-    let stopped = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Done>().unwrap();
-
-    let addr = rt.spawn(SelfStopActor {
-        count: 0,
-        stop_after: 1,
-        stopped: stopped.clone(),
-    }).unwrap();
-
-    // One message triggers stop
-    let _ = rt.send_to(addr, Forward { value: 1, reply_to: *inbox.addr() });
-    for _ in 0..10 { rt.tick(); }
-
-    // Actor is now removed — send should fail
-    let result = rt.send_to(addr, Forward { value: 2, reply_to: *inbox.addr() });
-    assert!(result.is_err(), "send to stopped actor should return Err");
-}
-
-/// Given a gracefully stopped actor and a panicked actor,
-/// then stats.stops and stats.panics track them separately.
-#[test]
-fn stop_vs_panic_tracked_separately_in_stats() {
-    let stopped = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Done>().unwrap();
-
-    // Actor that stops itself after 1 message
-    let _stop_addr = rt.spawn(SelfStopActor {
-        count: 0,
-        stop_after: 1,
-        stopped: stopped.clone(),
-    }).unwrap();
-
-    // Actor that panics on first message
-    let panic_addr = rt.spawn(RestartTestActor { count: 0, panic_at: 1 }).unwrap();
-
-    let _ = rt.send_to(_stop_addr, Forward { value: 1, reply_to: *inbox.addr() });
-    let _ = rt.send_to(panic_addr, Forward { value: 1, reply_to: *inbox.addr() });
-    for _ in 0..10 { rt.tick(); }
-
-    let stats = rt.stats();
-    let total_stops: u64 = stats.workers.iter().map(|w| w.stops).sum();
-    let total_panics: u64 = stats.workers.iter().map(|w| w.panics).sum();
-
-    assert_eq!(total_stops, 1, "one graceful stop");
-    assert_eq!(total_panics, 1, "one panic");
-}
-
-/// Given an actor with on_stop that sends a farewell message,
-/// when the actor is stopped,
-/// then the farewell message is delivered.
-#[test]
-fn on_stop_can_send_messages() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let addr = rt.spawn(FarewellActor {
-        farewell_to: *inbox.addr(),
-    }).unwrap();
-
-    // Let it start
-    rt.tick();
-
-    // Stop it
-    rt.stop_actor(addr).unwrap();
-    for _ in 0..5 { rt.tick(); }
-
-    // Should receive farewell Pong from on_stop
-    let farewell = inbox.try_recv();
-    assert_eq!(farewell, Some(Pong), "farewell message delivered from on_stop");
-}
-
-/// Given a supervisor with a child that panics and is restarted,
-/// when the child is respawned by the supervisor,
-/// then on_start is called again on the fresh instance.
-#[test]
-fn on_start_called_again_after_restart() {
-    let started = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let started_c = started.clone();
-    let _sup_addr = rt.spawn(Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![ChildSpec::new("child", RestartPolicy::Permanent, move |ctx| {
-            ctx.spawn(LifecycleActor {
-                started: started_c.clone(),
-                stopped: Arc::new(AtomicUsize::new(0)),
-                handled: Arc::new(AtomicUsize::new(0)),
-            })
-        })],
-    )).unwrap();
-
-    // First tick: supervisor starts, spawns child, on_start called
-    for _ in 0..3 { rt.tick(); }
-    assert_eq!(started.load(Ordering::Relaxed), 1, "on_start called once");
-}
-
-/// Given an actor stopped via stop_actor() with messages already queued,
-/// when the stop signal arrives after the queued messages (PoisonPill semantics),
-/// then messages ahead of the signal are processed, then the actor stops.
-#[test]
-fn external_stop_is_queued_after_pending_messages() {
-    let stopped = Arc::new(AtomicUsize::new(0));
-    let handled = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let started = Arc::new(AtomicUsize::new(0));
-    let addr = rt.spawn(LifecycleActor {
-        started: started.clone(),
-        stopped: stopped.clone(),
-        handled: handled.clone(),
-    }).unwrap();
-
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    // Queue 10 messages, then stop — StopSignal is queued AFTER the 10
-    for _ in 0..10 {
-        let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
-    }
-    rt.stop_actor(addr).unwrap();
-    for _ in 0..10 { rt.tick(); }
-
-    // All 10 messages processed (they were ahead of StopSignal in the queue)
-    let total_handled = handled.load(Ordering::Relaxed);
-    assert_eq!(total_handled, 10, "all messages processed before stop signal");
-    assert_eq!(stopped.load(Ordering::Relaxed), 1, "on_stop called");
-
-    // Actor is removed
-    let stats = rt.stats();
-    assert_eq!(stats.actors.len(), 0, "stopped actor removed");
-}
-
-/// Given a running actor with no pending messages,
-/// when stop_actor() is called and then new messages are sent,
-/// then the stop takes priority and new messages are not processed.
-#[test]
-fn external_stop_before_new_messages_prevents_processing() {
-    let stopped = Arc::new(AtomicUsize::new(0));
-    let handled = Arc::new(AtomicUsize::new(0));
-    let started = Arc::new(AtomicUsize::new(0));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let addr = rt.spawn(LifecycleActor {
-        started: started.clone(),
-        stopped: stopped.clone(),
-        handled: handled.clone(),
-    }).unwrap();
-
-    // Let actor start
-    rt.tick();
-
-    // Stop first, then send messages
-    rt.stop_actor(addr).unwrap();
-    for _ in 0..5 {
-        let _ = rt.send_to(addr, Ping { reply_to: *inbox.addr() });
-    }
-    for _ in 0..10 { rt.tick(); }
-
-    // Stop signal was first in queue, so no messages processed
-    assert_eq!(handled.load(Ordering::Relaxed), 0, "no messages processed after stop");
-    assert_eq!(stopped.load(Ordering::Relaxed), 1, "on_stop called");
-}
-
-/// Given stop_actor is called on a nonexistent address,
-/// then it returns Err.
-#[test]
-fn stop_nonexistent_actor_returns_error() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let fake_addr = swactor::actor::ActorAddress::default();
-    let result = rt.stop_actor(fake_addr);
-    assert!(result.is_err(), "stop_actor on nonexistent address should return Err");
-}

tests/runtime_mechanics.rs

@@ -1,362 +0,0 @@
-mod common;
-use common::*;
-
-// ── Load-Aware Placement Tests ─────────────────────────────────────────────
-
-/// Given a multi-threaded runtime where one worker has many more actors,
-/// when new actors are spawned after a few ticks (so stats propagate),
-/// then they should be placed on the lighter worker.
-#[test]
-fn load_aware_placement_prefers_lighter_worker() {
-    // 2 threads: intentionally imbalance by spawning many actors first
-    let rt = std_runtime(RuntimeConfig {
-        num_threads: 2,
-        ..Default::default()
-    });
-
-    // Phase 1: Spawn 20 actors. With round-robin, they split ~10/10.
-    let mut addrs = Vec::new();
-    for _ in 0..20 {
-        addrs.push(rt.spawn(CounterActor { count: 0 }).unwrap());
-    }
-
-    // Run so stats propagate, then bombard worker 0's actors with messages
-    // to create mailbox depth imbalance.
-    let handle = rt.run().unwrap();
-    std::thread::sleep(std::time::Duration::from_millis(10));
-
-    // Send 500 messages to the first 10 actors (likely on worker 0).
-    for addr in &addrs[..10] {
-        for _ in 0..50 {
-            let _ = handle.runtime.send_to(*addr, Increment {
-                reply_to: *addr, // self-reply to keep mailbox depth up
-            });
-        }
-    }
-
-    std::thread::sleep(std::time::Duration::from_millis(20));
-
-    // Phase 2: Spawn 10 more actors. With load-aware placement,
-    // they should bias toward the lighter worker.
-    let mut late_addrs = Vec::new();
-    for _ in 0..10 {
-        late_addrs.push(handle.runtime.spawn(CounterActor { count: 0 }).unwrap());
-    }
-
-    std::thread::sleep(std::time::Duration::from_millis(20));
-
-    let stats = handle.runtime.stats();
-    handle.shutdown();
-    handle.join();
-
-    // Verify the system is operational — both workers should have actors
-    let total_actors: usize = stats.workers.iter().map(|w| w.num_actors).sum();
-    assert!(total_actors >= 20, "expected at least 20 actors, got {}", total_actors);
-
-    // The lighter worker should have gotten more of the late actors.
-    assert!(
-        stats.workers.iter().all(|w| w.num_actors > 0),
-        "both workers should have actors, got {:?}",
-        stats.workers.iter().map(|w| w.num_actors).collect::<Vec<_>>()
-    );
-}
-
-/// Given a single-threaded runtime (1 worker),
-/// when many actors are spawned,
-/// then all go to worker 0 regardless of load (no panic, no error).
-#[test]
-fn load_aware_placement_single_worker_degrades_gracefully() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    for _ in 0..50 {
-        rt.spawn(CounterActor { count: 0 }).unwrap();
-    }
-
-    // Tick several times to let stats update
-    for _ in 0..10 {
-        rt.tick();
-    }
-
-    let stats = rt.stats();
-    assert_eq!(stats.workers.len(), 1);
-    assert_eq!(stats.workers[0].num_actors, 50);
-}
-
-/// Given a fresh runtime with no prior ticks,
-/// when actors are spawned in a burst,
-/// then they distribute evenly (round-robin fallback when stats are all zero).
-#[test]
-fn load_aware_placement_falls_back_to_round_robin_on_fresh_runtime() {
-    let rt = std_runtime(RuntimeConfig {
-        num_threads: 4,
-        ..Default::default()
-    });
-
-    // Spawn 100 actors before any ticks (all stats are zero)
-    for _ in 0..100 {
-        rt.spawn(CounterActor { count: 0 }).unwrap();
-    }
-
-    let handle = rt.run().unwrap();
-    std::thread::sleep(std::time::Duration::from_millis(20));
-
-    let stats = handle.runtime.stats();
-    handle.shutdown();
-    handle.join();
-
-    // With 4 workers and 100 actors, each should have ~25 (+-5).
-    for w in &stats.workers {
-        assert!(
-            w.num_actors >= 20 && w.num_actors <= 30,
-            "worker {} has {} actors, expected ~25 (round-robin)",
-            w.id, w.num_actors
-        );
-    }
-}
-
-// ── Mailbox Backpressure Tests ─────────────────────────────────────────────
-
-/// Given a runtime with bounded mailboxes (capacity=10, DropNewest),
-/// when 50 messages are sent to an actor before any ticks,
-/// then only the first 10 are delivered and the rest are dropped.
-#[test]
-fn bounded_mailbox_drop_newest_caps_at_capacity() {
-    let rt = std_runtime(RuntimeConfig {
-        default_mailbox_capacity: 10,
-        mailbox_overflow: MailboxOverflow::DropNewest,
-        ..Default::default()
-    });
-
-    let inbox = rt.new_inbox::<Count>().unwrap();
-    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
-
-    // Send 50 messages — only first 10 should be queued
-    for _ in 0..50 {
-        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
-    }
-
-    // Tick enough times to process all queued messages
-    for _ in 0..20 {
-        rt.tick();
-    }
-
-    // Count replies — should be exactly 10 (the mailbox capacity)
-    let mut replies = 0;
-    while inbox.try_recv().is_some() {
-        replies += 1;
-    }
-    assert_eq!(replies, 10, "should deliver exactly mailbox_capacity messages");
-
-    // Stats should show drops
-    let stats = rt.stats();
-    let total_drops: u64 = stats.workers.iter().map(|w| w.messages_dropped).sum();
-    assert_eq!(total_drops, 40, "40 messages should have been dropped");
-}
-
-/// Given a runtime with bounded mailboxes (capacity=5, DropOldest),
-/// when 10 messages are sent before any tick,
-/// then only the 5 most recent messages are delivered.
-#[test]
-fn bounded_mailbox_drop_oldest_keeps_newest() {
-    let rt = std_runtime(RuntimeConfig {
-        default_mailbox_capacity: 5,
-        mailbox_overflow: MailboxOverflow::DropOldest,
-        ..Default::default()
-    });
-
-    let inbox = rt.new_inbox::<Done>().unwrap();
-    let addr = rt.spawn(DoubleActor).unwrap();
-
-    // Send messages with values 0..10. DoubleActor replies Done(value * 2).
-    for i in 0..10 {
-        let _ = rt.send_to(addr, Forward {
-            value: i,
-            reply_to: *inbox.addr(),
-        });
-    }
-
-    for _ in 0..10 {
-        rt.tick();
-    }
-
-    // Collect all replies
-    let mut replies = Vec::new();
-    while let Some(Done(v)) = inbox.try_recv() {
-        replies.push(v);
-    }
-
-    assert_eq!(replies.len(), 5, "should deliver exactly 5 messages");
-    // The 5 most recent: values 5,6,7,8,9 -> doubled: 10,12,14,16,18
-    assert_eq!(replies, vec![10, 12, 14, 16, 18], "should keep the newest messages");
-}
-
-/// Given a runtime with unbounded mailboxes (capacity=0, the default),
-/// when many messages are sent,
-/// then all are delivered (backward compatibility).
-#[test]
-fn unbounded_mailbox_delivers_all_messages() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let inbox = rt.new_inbox::<Count>().unwrap();
-    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
-
-    for _ in 0..200 {
-        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
-    }
-
-    for _ in 0..50 {
-        rt.tick();
-    }
-
-    let mut replies = 0;
-    while inbox.try_recv().is_some() {
-        replies += 1;
-    }
-    assert_eq!(replies, 200, "all 200 messages should be delivered with unbounded mailbox");
-
-    let stats = rt.stats();
-    let total_drops: u64 = stats.workers.iter().map(|w| w.messages_dropped).sum();
-    assert_eq!(total_drops, 0, "no drops with unbounded mailbox");
-}
-
-/// Given bounded mailboxes with budget, when an actor processes messages
-/// and frees mailbox space, then new messages should be accepted on subsequent ticks.
-#[test]
-fn bounded_mailbox_refills_after_processing() {
-    let rt = std_runtime(RuntimeConfig {
-        default_mailbox_capacity: 5,
-        actor_message_budget: 5,
-        mailbox_overflow: MailboxOverflow::DropNewest,
-        ..Default::default()
-    });
-
-    let inbox = rt.new_inbox::<Count>().unwrap();
-    let addr = rt.spawn(CounterActor { count: 0 }).unwrap();
-
-    // Send first batch of 5 — fills mailbox exactly
-    for _ in 0..5 {
-        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
-    }
-
-    // Tick to process all 5 (budget=5, capacity=5)
-    rt.tick();
-
-    // Send second batch of 5 — mailbox is empty, so all 5 should be accepted
-    for _ in 0..5 {
-        let _ = rt.send_to(addr, Increment { reply_to: *inbox.addr() });
-    }
-
-    rt.tick();
-
-    let mut replies = 0;
-    while inbox.try_recv().is_some() {
-        replies += 1;
-    }
-    assert_eq!(replies, 10, "all 10 messages across 2 batches should be processed");
-
-    let stats = rt.stats();
-    let total_drops: u64 = stats.workers.iter().map(|w| w.messages_dropped).sum();
-    assert_eq!(total_drops, 0, "no drops when mailbox drains between batches");
-}
-
-// ── Dead Actor Cleanup Tests ───────────────────────────────────────────────
-
-/// Given an actor that panics and is poisoned,
-/// when ticks continue,
-/// then the actor is removed from stats and sends to its address fail.
-#[test]
-fn dead_actor_cleaned_up_from_stats_and_address_map() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let good = rt.spawn(PingPongActor).unwrap();
-    let bad = rt.spawn(PanicActor).unwrap();
-
-    // Trigger panic
-    let _ = rt.send_to(bad, PanicMsg);
-    for _ in 0..5 { rt.tick(); }
-
-    let stats = rt.stats();
-    // Good actor still present, bad actor cleaned up
-    assert_eq!(stats.workers[0].num_actors, 1, "only the healthy actor should remain");
-    assert!(
-        stats.actors.iter().any(|(a, _)| *a == good),
-        "good actor should be in address map"
-    );
-    assert!(
-        !stats.actors.iter().any(|(a, _)| *a == bad),
-        "poisoned actor should be removed from address map"
-    );
-
-    // Sends to cleaned-up actor fail
-    let result = rt.send_to(bad, PanicMsg);
-    assert!(result.is_err(), "send to cleaned-up actor should fail");
-}
-
-/// Given many actors that all panic,
-/// when ticks proceed,
-/// then all are cleaned up and stats reflect zero actors.
-#[test]
-fn bulk_dead_actor_cleanup() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let mut addrs = Vec::new();
-    for _ in 0..20 {
-        addrs.push(rt.spawn(PanicActor).unwrap());
-    }
-
-    // Trigger all panics
-    for &addr in &addrs {
-        let _ = rt.send_to(addr, PanicMsg);
-    }
-    for _ in 0..10 { rt.tick(); }
-
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 0, "all poisoned actors should be cleaned up");
-    assert_eq!(
-        stats.actors.len(), 0,
-        "address map should be empty after all actors poisoned"
-    );
-}
-
-// ── Actor Recovery Helpers ──────────────────────────────────────────────────
-
-/// Handles Forward messages, replies Done(value * 2), panics on the panic_at-th message.
-struct RestartTestActor {
-    count: usize,
-    panic_at: usize,
-}
-
-impl ActorInterface for RestartTestActor {
-    type Incoming = Forward;
-    type Response = Done;
-    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
-        self.count += 1;
-        if self.count >= self.panic_at {
-            panic!("intentional panic at message {}", self.count);
-        }
-        let _ = ctx.send(msg.reply_to, Done(msg.value * 2));
-    }
-}
-
-// ── Actor Recovery Tests ───────────────────────────────────────────────────
-
-/// Given an actor that panics,
-/// when it panics,
-/// then it is poisoned and future messages are discarded.
-#[test]
-fn non_restartable_actor_still_poisons_on_panic() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Done>().unwrap();
-
-    // Normal spawn — not restartable
-    let addr = rt.spawn(RestartTestActor { count: 0, panic_at: 1 }).unwrap();
-
-    let _ = rt.send_to(addr, Forward { value: 42, reply_to: *inbox.addr() });
-    for _ in 0..5 { rt.tick(); }
-
-    let stats = rt.stats();
-    let total_panics: u64 = stats.workers.iter().map(|w| w.panics).sum();
-    let total_restarts: u64 = stats.workers.iter().map(|w| w.restarts).sum();
-    assert_eq!(total_panics, 1, "should panic");
-    assert_eq!(total_restarts, 0, "should not restart (not restartable)");
-}

tests/runtime_registry.rs

@@ -1,758 +0,0 @@
-mod common;
-use common::*;
-
-// ── Named Actor Registry ────────────────────────────────────────────────────
-
-/// Given a named actor is spawned,
-/// when I look it up by name,
-/// then I get the same address that spawn returned.
-#[test]
-fn named_actor_lookup_returns_spawn_address() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let addr = rt.spawn_named("greeter", PingPongActor).unwrap();
-    assert_eq!(rt.where_is("greeter"), Some(addr));
-}
-
-/// Given a named actor exists,
-/// when I send a message to the looked-up address,
-/// then the actor receives and processes it.
-#[test]
-fn named_actor_receives_messages_via_lookup() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    let addr = rt.spawn_named("ponger", PingPongActor).unwrap();
-    assert_eq!(rt.where_is("ponger"), Some(addr));
-
-    rt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick();
-    assert!(inbox.try_recv().is_some(), "named actor should process message");
-}
-
-/// Given a name is already registered,
-/// when I try to spawn another actor with the same name,
-/// then I get an error and the original binding is preserved.
-#[test]
-fn duplicate_name_returns_error() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let first_addr = rt.spawn_named("singleton", PingPongActor).unwrap();
-    let result = rt.spawn_named("singleton", PingPongActor);
-    assert!(result.is_err(), "duplicate name should fail");
-    assert_eq!(rt.where_is("singleton"), Some(first_addr), "original binding preserved");
-}
-
-/// Given no actors are registered,
-/// when I look up a nonexistent name,
-/// then I get None.
-#[test]
-fn where_is_returns_none_for_unknown_name() {
-    let rt = std_runtime(RuntimeConfig::default());
-    assert_eq!(rt.where_is("ghost"), None);
-}
-
-/// Given a named actor is stopped,
-/// when the next tick runs cleanup,
-/// then the name is automatically unregistered.
-#[test]
-fn name_auto_unregistered_on_actor_death() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let addr = rt.spawn_named("ephemeral", PingPongActor).unwrap();
-    rt.tick(); // on_start
-
-    rt.stop_actor(addr).unwrap();
-    rt.tick(); // process StopSignal + cleanup
-
-    assert_eq!(rt.where_is("ephemeral"), None, "name should be freed after stop");
-}
-
-/// Given a named actor died and its name was freed,
-/// when I spawn a new actor with the same name,
-/// then registration succeeds with a new address.
-#[test]
-fn name_can_be_reused_after_actor_death() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let first = rt.spawn_named("worker", PingPongActor).unwrap();
-    rt.tick();
-    rt.stop_actor(first).unwrap();
-    rt.tick(); // cleanup frees the name
-
-    let second = rt.spawn_named("worker", PingPongActor).unwrap();
-    assert_ne!(first, second, "new actor should have a different address");
-    assert_eq!(rt.where_is("worker"), Some(second));
-}
-
-/// Given a named actor panics (and is not restartable),
-/// when the next tick runs cleanup,
-/// then the name is freed.
-#[test]
-fn name_auto_unregistered_on_panic() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    let _addr = rt.spawn_named("fragile", PanicActor).unwrap();
-    rt.tick(); // on_start
-
-    rt.send_to(_addr, PanicMsg).unwrap();
-    rt.tick(); // panic -> poison -> cleanup
-
-    assert_eq!(rt.where_is("fragile"), None, "name freed after panic");
-    // Can reuse the name
-    let _new = rt.spawn_named("fragile", PingPongActor).unwrap();
-    assert!(rt.where_is("fragile").is_some());
-    drop(inbox);
-}
-
-/// Given multiple named actors are registered,
-/// when I call registered_names(),
-/// then all names are returned.
-#[test]
-fn registered_names_lists_all() {
-    let rt = std_runtime(RuntimeConfig::default());
-    rt.spawn_named("alpha", PingPongActor).unwrap();
-    rt.spawn_named("beta", PingPongActor).unwrap();
-    rt.spawn_named("gamma", PingPongActor).unwrap();
-
-    let mut names = rt.registered_names();
-    names.sort();
-    assert_eq!(names, vec!["alpha", "beta", "gamma"]);
-}
-
-/// Given a named actor exists,
-/// when I manually unregister the name,
-/// then the name is freed but the actor continues running.
-#[test]
-fn manual_unregister_frees_name_but_actor_lives() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    let addr = rt.spawn_named("temp-name", PingPongActor).unwrap();
-    rt.tick(); // on_start
-
-    let removed = rt.unregister("temp-name");
-    assert_eq!(removed, Some(addr));
-    assert_eq!(rt.where_is("temp-name"), None, "name freed");
-
-    // Actor still alive and can receive messages
-    rt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick();
-    assert!(inbox.try_recv().is_some(), "actor still processes messages");
-}
-
-/// An actor that looks up a peer by name using ctx.where_is().
-struct NameLookupActor {
-    target_name: &'static str,
-    reply_to: ActorAddress,
-}
-
-impl ActorInterface for NameLookupActor {
-    type Incoming = Ping;
-    type Response = ();
-    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
-        if let Some(peer) = ctx.where_is(self.target_name) {
-            ctx.send(self.reply_to, MyAddr(peer)).unwrap();
-        }
-    }
-}
-
-/// Given a named actor exists,
-/// when another actor calls ctx.where_is() from inside a handler,
-/// then it resolves the correct address.
-#[test]
-fn ctx_where_is_resolves_inside_handler() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<MyAddr>().unwrap();
-    let target = rt.spawn_named("target", PingPongActor).unwrap();
-
-    let looker = rt.spawn(NameLookupActor {
-        target_name: "target",
-        reply_to: *inbox.addr(),
-    }).unwrap();
-
-    rt.tick(); // on_start
-    rt.send_to(looker, Ping { reply_to: ActorAddress::default() }).unwrap();
-    rt.tick(); // handle -> where_is -> send
-    rt.tick(); // deliver reply
-
-    let result = inbox.try_recv();
-    assert_eq!(result, Some(MyAddr(target)), "ctx.where_is found the named actor");
-}
-
-/// An actor that spawns a named child using ctx.spawn_named().
-struct NamedSpawnerActor {
-    reply_to: ActorAddress,
-}
-
-impl ActorInterface for NamedSpawnerActor {
-    type Incoming = Ping;
-    type Response = ();
-    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
-        match ctx.spawn_named("child", PingPongActor) {
-            Ok(addr) => { ctx.send(self.reply_to, MyAddr(addr)).unwrap(); }
-            Err(_) => {}
-        }
-    }
-}
-
-/// Given an actor calls ctx.spawn_named("child", ...),
-/// when the child is spawned,
-/// then where_is("child") returns the correct address.
-#[test]
-fn ctx_spawn_named_registers_from_handler() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<MyAddr>().unwrap();
-
-    let spawner = rt.spawn(NamedSpawnerActor {
-        reply_to: *inbox.addr(),
-    }).unwrap();
-
-    rt.tick(); // on_start
-    rt.send_to(spawner, Ping { reply_to: ActorAddress::default() }).unwrap();
-    rt.tick(); // handle -> spawn_named
-    rt.tick(); // deliver reply
-
-    let child_addr = inbox.try_recv().expect("should receive child address");
-    assert_eq!(rt.where_is("child"), Some(child_addr.0), "name registered from handler");
-}
-
-// ── Actor Monitoring / Death Watch ──────────────────────────────────────────
-
-/// An actor that monitors a target and forwards Down notifications to a reply address.
-struct WatcherActor {
-    watch_target: ActorAddress,
-    reply_to: ActorAddress,
-    mref: Option<MonitorRef>,
-}
-
-impl ActorInterface for WatcherActor {
-    type Incoming = Down;
-    type Response = ();
-    fn on_start(&mut self, ctx: &Ctx) {
-        self.mref = Some(ctx.monitor(self.watch_target));
-    }
-    fn handle(&mut self, ctx: &Ctx, msg: Down) {
-        // Forward the Down notification to the test inbox
-        ctx.send(self.reply_to, msg).unwrap();
-    }
-}
-
-/// Given actor A monitors actor B,
-/// when B is gracefully stopped,
-/// then A receives a Down { reason: Normal } message.
-#[test]
-fn monitor_notifies_on_graceful_stop() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Down>().unwrap();
-
-    let target = rt.spawn(PingPongActor).unwrap();
-    let _watcher = rt.spawn(WatcherActor {
-        watch_target: target,
-        reply_to: *inbox.addr(),
-        mref: None,
-    }).unwrap();
-
-    rt.tick(); // on_start -> watcher sets up monitor
-    rt.stop_actor(target).unwrap();
-    rt.tick(); // target receives StopSignal -> cleanup_dead emits Down
-    rt.tick(); // watcher receives Down -> forwards to inbox
-
-    let down = inbox.try_recv().expect("should receive Down notification");
-    assert_eq!(down.addr, target);
-    assert_eq!(down.reason, StopReason::Normal);
-}
-
-/// Given actor A monitors actor B,
-/// when B panics,
-/// then A receives a Down { reason: Panicked } message.
-#[test]
-fn monitor_notifies_on_panic() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Down>().unwrap();
-
-    let target = rt.spawn(PanicActor).unwrap();
-    let _watcher = rt.spawn(WatcherActor {
-        watch_target: target,
-        reply_to: *inbox.addr(),
-        mref: None,
-    }).unwrap();
-
-    rt.tick(); // on_start
-    rt.send_to(target, PanicMsg).unwrap();
-    rt.tick(); // target panics -> cleanup_dead emits Down
-    rt.tick(); // watcher receives Down -> forwards to inbox
-
-    let down = inbox.try_recv().expect("should receive Down on panic");
-    assert_eq!(down.addr, target);
-    assert_eq!(down.reason, StopReason::Panicked);
-}
-
-/// Given two actors both monitor the same target,
-/// when the target dies,
-/// then both watchers receive independent Down notifications.
-#[test]
-fn multiple_watchers_all_notified() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox1 = rt.new_inbox::<Down>().unwrap();
-    let inbox2 = rt.new_inbox::<Down>().unwrap();
-
-    let target = rt.spawn(PingPongActor).unwrap();
-    rt.spawn(WatcherActor {
-        watch_target: target,
-        reply_to: *inbox1.addr(),
-        mref: None,
-    }).unwrap();
-    rt.spawn(WatcherActor {
-        watch_target: target,
-        reply_to: *inbox2.addr(),
-        mref: None,
-    }).unwrap();
-
-    rt.tick(); // on_start for all
-    rt.stop_actor(target).unwrap();
-    rt.tick(); // cleanup -> Down emitted to both watchers
-    rt.tick(); // watchers forward Down to inboxes
-
-    assert!(inbox1.try_recv().is_some(), "watcher 1 should receive Down");
-    assert!(inbox2.try_recv().is_some(), "watcher 2 should receive Down");
-}
-
-/// An actor that demonitors in response to a Ping message.
-struct DemonitorActor {
-    watch_target: ActorAddress,
-    mref: Option<MonitorRef>,
-}
-
-impl ActorInterface for DemonitorActor {
-    type Incoming = Ping;
-    type Response = ();
-    fn on_start(&mut self, ctx: &Ctx) {
-        self.mref = Some(ctx.monitor(self.watch_target));
-    }
-    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
-        // Cancel the monitor
-        if let Some(mref) = self.mref.take() {
-            ctx.demonitor(mref);
-        }
-    }
-}
-
-/// Given actor A monitors actor B then demonitors,
-/// when B dies,
-/// then A does NOT receive a Down notification.
-#[test]
-fn demonitor_cancels_notification() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let down_inbox = rt.new_inbox::<Down>().unwrap();
-
-    let target = rt.spawn(PingPongActor).unwrap();
-    let watcher = rt.spawn(DemonitorActor {
-        watch_target: target,
-        mref: None,
-    }).unwrap();
-
-    rt.tick(); // on_start -> monitor set up
-
-    // Trigger demonitor
-    rt.send_to(watcher, Ping { reply_to: ActorAddress::default() }).unwrap();
-    rt.tick(); // handle -> demonitor
-
-    // Now kill the target
-    rt.stop_actor(target).unwrap();
-    rt.tick(); // cleanup -- no Down should be emitted
-    rt.tick(); // extra tick to be sure
-
-    assert!(down_inbox.try_recv().is_none(), "demonitored -- should NOT receive Down");
-}
-
-/// Given actor A monitors B, and A dies before B,
-/// when B dies,
-/// then no Down is delivered (dead watcher cleaned up).
-#[test]
-fn dead_watcher_does_not_receive_down() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let target = rt.spawn(PingPongActor).unwrap();
-    let watcher = rt.spawn(WatcherActor {
-        watch_target: target,
-        reply_to: ActorAddress::default(), // won't matter, watcher dies first
-        mref: None,
-    }).unwrap();
-
-    rt.tick(); // on_start -> monitor set up
-    rt.stop_actor(watcher).unwrap();
-    rt.tick(); // watcher dies -> its monitors are cleaned up
-
-    // Now kill the target -- the dead watcher's subscription should be gone
-    rt.stop_actor(target).unwrap();
-    rt.tick(); // cleanup -- should not panic or try to deliver to dead watcher
-    // If we get here without panic, the test passes
-}
-
-/// Given an external inbox monitors via the runtime,
-/// when the target dies,
-/// then the inbox receives a Down message.
-#[test]
-fn down_delivered_to_external_inbox() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Down>().unwrap();
-
-    let target = rt.spawn(PingPongActor).unwrap();
-
-    let _watcher = rt.spawn(WatcherActor {
-        watch_target: target,
-        reply_to: *inbox.addr(),
-        mref: None,
-    }).unwrap();
-
-    rt.tick(); // on_start
-    rt.stop_actor(target).unwrap();
-    rt.tick(); // cleanup -> Down to watcher
-    rt.tick(); // watcher forwards to inbox
-
-    let down = inbox.try_recv().expect("inbox should receive forwarded Down");
-    assert_eq!(down.addr, target);
-    assert_eq!(down.reason, StopReason::Normal);
-}
-
-/// Given actor A monitors B with two independent monitors,
-/// when B dies,
-/// then A receives two Down messages (one per monitor).
-#[test]
-fn stacked_monitors_produce_multiple_notifications() {
-    /// An actor that creates two monitors on the same target.
-    struct DoubleWatcherActor {
-        target: ActorAddress,
-        reply_to: ActorAddress,
-    }
-
-    impl ActorInterface for DoubleWatcherActor {
-        type Incoming = Down;
-        type Response = ();
-        fn on_start(&mut self, ctx: &Ctx) {
-            ctx.monitor(self.target);
-            ctx.monitor(self.target);
-        }
-        fn handle(&mut self, ctx: &Ctx, msg: Down) {
-            ctx.send(self.reply_to, msg).unwrap();
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Down>().unwrap();
-
-    let target = rt.spawn(PingPongActor).unwrap();
-    rt.spawn(DoubleWatcherActor {
-        target,
-        reply_to: *inbox.addr(),
-    }).unwrap();
-
-    rt.tick(); // on_start -> 2 monitors
-    rt.stop_actor(target).unwrap();
-    rt.tick(); // cleanup -> 2 Down messages to watcher
-    rt.tick(); // watcher forwards both to inbox
-
-    assert!(inbox.try_recv().is_some(), "first Down");
-    assert!(inbox.try_recv().is_some(), "second Down");
-    assert!(inbox.try_recv().is_none(), "no more");
-}
-
-// ── Actor Groups / Pub-Sub ──────────────────────────────────────────────────
-
-/// Given actors join a group,
-/// when I query group_members,
-/// then all joined actors are listed.
-#[test]
-fn group_members_returns_joined_actors() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let a = rt.spawn(PingPongActor).unwrap();
-    let b = rt.spawn(PingPongActor).unwrap();
-
-    rt.join_group(a, "workers");
-    rt.join_group(b, "workers");
-
-    let mut members = rt.group_members("workers");
-    members.sort_by_key(|addr| addr.0);
-    let mut expected = vec![a, b];
-    expected.sort_by_key(|addr| addr.0);
-    assert_eq!(members, expected);
-}
-
-/// Given no actors have joined a group,
-/// when I query group_members,
-/// then the result is empty.
-#[test]
-fn empty_group_returns_no_members() {
-    let rt = std_runtime(RuntimeConfig::default());
-    assert!(rt.group_members("nonexistent").is_empty());
-}
-
-/// Given actors in a group,
-/// when a message is published to the group,
-/// then all members receive the message.
-#[test]
-fn publish_broadcasts_to_all_members() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox1 = rt.new_inbox::<Pong>().unwrap();
-    let inbox2 = rt.new_inbox::<Pong>().unwrap();
-
-    let a = rt.spawn(PingPongActor).unwrap();
-    let b = rt.spawn(PingPongActor).unwrap();
-    rt.join_group(a, "pongers");
-    rt.join_group(b, "pongers");
-
-    rt.tick(); // on_start
-
-    // Publish a Ping with inbox1's addr as reply_to.
-    let count = rt.publish_to("pongers", Ping { reply_to: *inbox1.addr() });
-    assert_eq!(count, 2, "two members, two messages sent");
-
-    rt.tick(); // actors handle Ping -> send Pong to inbox1
-
-    // Both actors send to inbox1
-    assert!(inbox1.try_recv().is_some(), "first Pong");
-    assert!(inbox1.try_recv().is_some(), "second Pong");
-    assert!(inbox1.try_recv().is_none(), "no more");
-    drop(inbox2);
-}
-
-/// Given an actor leaves a group,
-/// when a message is published,
-/// then the leaver does not receive it.
-#[test]
-fn leave_group_stops_receiving_publishes() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let a = rt.spawn(PingPongActor).unwrap();
-    let b = rt.spawn(PingPongActor).unwrap();
-    rt.join_group(a, "pool");
-    rt.join_group(b, "pool");
-    rt.leave_group(b, "pool");
-
-    rt.tick(); // on_start
-    let count = rt.publish_to("pool", Ping { reply_to: *inbox.addr() });
-    assert_eq!(count, 1, "only one member after leave");
-
-    rt.tick();
-    assert!(inbox.try_recv().is_some(), "one Pong from remaining member");
-    assert!(inbox.try_recv().is_none(), "no second Pong");
-}
-
-/// Given a group member dies,
-/// when a message is published,
-/// then the dead member is not included.
-#[test]
-fn dead_actor_auto_removed_from_group() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    let a = rt.spawn(PingPongActor).unwrap();
-    let b = rt.spawn(PingPongActor).unwrap();
-    rt.join_group(a, "team");
-    rt.join_group(b, "team");
-
-    rt.tick(); // on_start
-    rt.stop_actor(b).unwrap();
-    rt.tick(); // b dies, cleaned up from group
-
-    let count = rt.publish_to("team", Ping { reply_to: *inbox.addr() });
-    assert_eq!(count, 1, "dead actor removed from group");
-
-    rt.tick();
-    assert!(inbox.try_recv().is_some());
-    assert!(inbox.try_recv().is_none());
-}
-
-/// Given an actor is in multiple groups,
-/// when the actor dies,
-/// then it is removed from all groups.
-#[test]
-fn actor_removed_from_all_groups_on_death() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(PingPongActor).unwrap();
-    rt.join_group(actor, "alpha");
-    rt.join_group(actor, "beta");
-    rt.join_group(actor, "gamma");
-
-    rt.tick();
-    rt.stop_actor(actor).unwrap();
-    rt.tick(); // cleanup removes from all groups
-
-    assert!(rt.group_members("alpha").is_empty());
-    assert!(rt.group_members("beta").is_empty());
-    assert!(rt.group_members("gamma").is_empty());
-}
-
-/// Given a group becomes empty after its last member leaves,
-/// then the group name disappears from the active groups list.
-#[test]
-fn empty_group_auto_deleted() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(PingPongActor).unwrap();
-    rt.join_group(actor, "temp");
-    assert!(rt.groups().contains(&"temp".to_string()));
-
-    rt.leave_group(actor, "temp");
-    assert!(!rt.groups().contains(&"temp".to_string()), "empty group should be removed");
-}
-
-/// Given actors join groups from handlers using ctx.join_group(),
-/// when group_members is queried,
-/// then the joining actors are listed.
-#[test]
-fn ctx_join_group_from_handler() {
-    struct GroupJoinerActor;
-
-    impl ActorInterface for GroupJoinerActor {
-        type Incoming = Ping;
-        type Response = ();
-        fn on_start(&mut self, ctx: &Ctx) {
-            ctx.join_group("auto-joined");
-        }
-        fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {}
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let a = rt.spawn(GroupJoinerActor).unwrap();
-    let b = rt.spawn(GroupJoinerActor).unwrap();
-
-    rt.tick(); // on_start -> both join "auto-joined"
-
-    let members = rt.group_members("auto-joined");
-    assert_eq!(members.len(), 2);
-    assert!(members.contains(&a));
-    assert!(members.contains(&b));
-}
-
-/// Given an actor uses ctx.publish() from inside a handler,
-/// when the published message is processed,
-/// then all group members receive it.
-#[test]
-fn ctx_publish_broadcasts_from_handler() {
-    #[derive(Clone)]
-    struct BroadcastCmd {
-        reply_to: ActorAddress,
-    }
-
-    struct BroadcasterActor;
-
-    impl ActorInterface for BroadcasterActor {
-        type Incoming = BroadcastCmd;
-        type Response = ();
-        fn on_start(&mut self, ctx: &Ctx) {
-            ctx.join_group("broadcast-test");
-        }
-        fn handle(&mut self, ctx: &Ctx, msg: BroadcastCmd) {
-            ctx.publish("broadcast-test", Ping { reply_to: msg.reply_to });
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-
-    // Spawn 3 PingPongActors and one Broadcaster, all in the same group
-    let _p1 = rt.spawn(PingPongActor).unwrap();
-    let _p2 = rt.spawn(PingPongActor).unwrap();
-    rt.join_group(_p1, "broadcast-test");
-    rt.join_group(_p2, "broadcast-test");
-
-    let broadcaster = rt.spawn(BroadcasterActor).unwrap();
-
-    rt.tick(); // on_start (broadcaster joins group too)
-
-    // Send BroadcastCmd to broadcaster
-    rt.send_to(broadcaster, BroadcastCmd { reply_to: *inbox.addr() }).unwrap();
-    rt.tick(); // broadcaster handles -> publish Ping to all 3 members (including self)
-    rt.tick(); // PingPong actors handle Ping -> send Pong to inbox
-
-    // At least 2 Pongs from the PingPongActors
-    let mut pong_count = 0;
-    while inbox.try_recv().is_some() {
-        pong_count += 1;
-    }
-    assert!(pong_count >= 2, "at least 2 PingPong members should reply, got {pong_count}");
-}
-
-// ── Ask Pattern ─────────────────────────────────────────────────────────────
-
-/// Given a PingPong actor,
-/// when I ask with recv_ticking,
-/// then I get the Pong response.
-#[test]
-fn ask_recv_ticking_returns_response() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(PingPongActor).unwrap();
-    rt.tick(); // on_start
-
-    let pong: Pong = rt.ask(actor, |reply_to| Ping { reply_to })
-        .unwrap()
-        .recv_ticking(&rt, 10)
-        .unwrap();
-    assert_eq!(pong, Pong);
-}
-
-/// Given a CounterActor,
-/// when I ask multiple times,
-/// then each response reflects the updated state.
-#[test]
-fn ask_multiple_times_tracks_state() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(CounterActor { count: 0 }).unwrap();
-    rt.tick(); // on_start
-
-    let c1: Count = rt.ask(actor, |reply_to| Increment { reply_to })
-        .unwrap().recv_ticking(&rt, 10).unwrap();
-    let c2: Count = rt.ask(actor, |reply_to| Increment { reply_to })
-        .unwrap().recv_ticking(&rt, 10).unwrap();
-    let c3: Count = rt.ask(actor, |reply_to| Increment { reply_to })
-        .unwrap().recv_ticking(&rt, 10).unwrap();
-
-    assert_eq!(c1, Count(1));
-    assert_eq!(c2, Count(2));
-    assert_eq!(c3, Count(3));
-}
-
-/// Given a dead actor,
-/// when I ask and tick,
-/// then recv_ticking returns a timeout error.
-#[test]
-fn ask_timeout_when_no_response() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(PingPongActor).unwrap();
-    rt.tick();
-    rt.stop_actor(actor).unwrap();
-    rt.tick(); // actor dies
-
-    // Ask the dead actor -- message is undeliverable, no response
-    let result = rt.ask::<Ping, Pong>(actor, |reply_to| Ping { reply_to });
-    // send_to may succeed or fail
-    if let Ok(ask) = result {
-        let err = ask.recv_ticking(&rt, 5);
-        assert!(err.is_err(), "should timeout with no response");
-    }
-}
-
-/// Given an ask handle,
-/// when I use try_recv before ticking,
-/// then it returns None (response hasn't arrived yet).
-#[test]
-fn ask_try_recv_returns_none_before_tick() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(PingPongActor).unwrap();
-    rt.tick(); // on_start
-
-    let ask = rt.ask::<Ping, Pong>(actor, |reply_to| Ping { reply_to }).unwrap();
-    assert!(ask.try_recv().is_none(), "no response before ticking");
-
-    rt.tick(); // process message
-    assert_eq!(ask.try_recv(), Some(Pong));
-}
-
-/// Given an ask, the reply_addr() returns the inbox address for manual use.
-#[test]
-fn ask_reply_addr_is_accessible() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let actor = rt.spawn(PingPongActor).unwrap();
-    rt.tick();
-
-    let ask = rt.ask::<Ping, Pong>(actor, |reply_to| Ping { reply_to }).unwrap();
-    let addr = *ask.reply_addr();
-    // The address should be valid (non-zero)
-    assert_ne!(addr, ActorAddress::default());
-}

tests/runtime_stress.rs

@@ -0,0 +1,364 @@
+//! Runtime Stress Tests — multi-threaded execution, parking, placement, and scale.
+//!
+//! Covers: single vs multi-threaded processing, high-volume MT delivery,
+//! panic isolation under load, worker parking/shutdown, sustained throughput,
+//! and load-aware actor placement.
+
+mod common;
+use common::*;
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+// ── Helpers ──────────────────────────────────────────────────────────────────
+
+/// Poll `inbox` until a message arrives or `timeout` elapses.
+fn poll_inbox<M: swactor::actor::Message>(
+    inbox: &Inbox<M>,
+    timeout: Duration,
+) -> Option<M> {
+    let deadline = Instant::now() + timeout;
+    loop {
+        if let Some(msg) = inbox.try_recv() {
+            return Some(msg);
+        }
+        if Instant::now() > deadline {
+            return None;
+        }
+        std::thread::sleep(Duration::from_millis(1));
+    }
+}
+
+/// Wait until `counter` reaches `target` or `timeout` elapses.
+fn wait_for_count(counter: &AtomicUsize, target: usize, timeout: Duration) -> usize {
+    let deadline = Instant::now() + timeout;
+    loop {
+        let n = counter.load(Ordering::SeqCst);
+        if n >= target {
+            return n;
+        }
+        if Instant::now() > deadline {
+            return n;
+        }
+        std::thread::sleep(Duration::from_millis(5));
+    }
+}
+
+// ── Tests ────────────────────────────────────────────────────────────────────
+
+/// Single-threaded vs multi-threaded runtime basics.
+///
+/// Story: We start with a single-threaded runtime driven by tick(), confirm
+/// nothing happens without ticking, then graduate to a multi-threaded runtime
+/// with run() and verify background processing, cross-worker delegation,
+/// custom thread counts, and clean shutdown.
+#[test]
+fn single_vs_multi_threaded_basics() {
+    // ── Part A: Single-threaded requires tick() ──
+    let rt = std_runtime(RuntimeConfig::default());
+    let addr = rt.spawn(PingPongActor).unwrap();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    rt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
+
+    assert!(inbox.try_recv().is_none(), "no processing before tick");
+    tick_n(&rt, 2);
+    assert!(inbox.try_recv().is_some(), "tick() drives single-threaded processing");
+
+    // ── Part B: Multi-threaded processes without ticking ──
+    let rt_mt = std_runtime(RuntimeConfig { num_threads: 4, ..Default::default() });
+    let addr = rt_mt.spawn(PingPongActor).unwrap();
+    let inbox = rt_mt.new_inbox::<Pong>().unwrap();
+    rt_mt.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
+
+    let handle = rt_mt.run().unwrap();
+    let reply = poll_inbox(&inbox, Duration::from_secs(5));
+    assert!(reply.is_some(), "background workers process without manual ticking");
+
+    // ── Part C: Cross-worker delegation (2 threads, spawn child from handler) ──
+    let addr2 = handle.runtime.spawn(DelegatorActor).unwrap();
+    let done_inbox = handle.runtime.new_inbox::<Done>().unwrap();
+    handle.runtime.send_to(addr2, Forward { value: 3, reply_to: *done_inbox.addr() }).unwrap();
+
+    let reply = poll_inbox(&done_inbox, Duration::from_secs(5));
+    assert_eq!(reply, Some(Done(6)), "cross-worker delegation delivers reply");
+
+    // ── Part D: Custom thread count reflected in stats ──
+    let stats = handle.runtime.stats();
+    assert_eq!(stats.num_workers, 4, "runtime respects requested thread count");
+
+    // ── Part E: Clean shutdown ──
+    handle.shutdown();
+    handle.join();
+    // Test passes by not hanging.
+}
+
+/// High-volume multi-threaded delivery.
+///
+/// Story: We throw large workloads at a 4-thread runtime — 50 senders
+/// each firing 100 messages at one receiver, 200 concurrent spawn+send
+/// pairs, and a 50-level chain that must hop across workers.
+#[test]
+fn mt_high_volume_delivery() {
+    let cfg = || RuntimeConfig {
+        num_threads: 4,
+        max_actors: 5_000,
+        channel_buffer_size: 10_000,
+        ..Default::default()
+    };
+
+    // ── Part A: 50 senders × 100 messages → one receiver ──
+    {
+        let rt = std_runtime(cfg());
+        let counter = Arc::new(AtomicUsize::new(0));
+        let dummy = rt.new_inbox::<Pong>().unwrap();
+        let receiver = rt.spawn(CountingPingActor { counter: counter.clone() }).unwrap();
+
+        let total_expected = 50 * 100;
+        for _ in 0..50 {
+            for _ in 0..100 {
+                rt.send_to(receiver, Ping { reply_to: *dummy.addr() }).unwrap();
+            }
+        }
+
+        let handle = rt.run().unwrap();
+        let processed = wait_for_count(&counter, total_expected, Duration::from_secs(5));
+        handle.shutdown();
+        handle.join();
+        assert_eq!(processed, total_expected, "all 5000 messages delivered to single receiver");
+    }
+
+    // ── Part B: 200 concurrent spawn+send pairs ──
+    {
+        let rt = std_runtime(cfg());
+        let counter = Arc::new(AtomicUsize::new(0));
+        let dummy = rt.new_inbox::<Pong>().unwrap();
+        for _ in 0..200 {
+            let a = rt.spawn(CountingPingActor { counter: counter.clone() }).unwrap();
+            rt.send_to(a, Ping { reply_to: *dummy.addr() }).unwrap();
+        }
+
+        let handle = rt.run().unwrap();
+        let received = wait_for_count(&counter, 200, Duration::from_secs(5));
+        handle.shutdown();
+        handle.join();
+        assert_eq!(received, 200, "all 200 spawn+send pairs complete");
+    }
+
+    // ── Part C: 50-level chain across workers ──
+    {
+        let rt = std_runtime(RuntimeConfig { num_threads: 2, max_actors: 5_000, ..Default::default() });
+        let addr = rt.spawn(ChainActor).unwrap();
+        let inbox = rt.new_inbox::<Done>().unwrap();
+        rt.send_to(addr, ChainMsg { remaining: 50, depth: 0, reply_to: *inbox.addr() }).unwrap();
+
+        let handle = rt.run().unwrap();
+        let reply = poll_inbox(&inbox, Duration::from_secs(5));
+        handle.shutdown();
+        handle.join();
+        assert_eq!(reply, Some(Done(50)), "50-level chain completes across workers");
+    }
+}
+
+/// Panic isolation under multi-threaded load.
+///
+/// Story: 10 panicking actors and 10 healthy actors on 4 threads — every
+/// panic is isolated and all 1000 healthy messages are still processed.
+#[test]
+fn mt_panic_isolation_under_load() {
+    let rt = std_runtime(RuntimeConfig {
+        num_threads: 4,
+        max_actors: 5_000,
+        channel_buffer_size: 10_000,
+        ..Default::default()
+    });
+
+    let counter = Arc::new(AtomicUsize::new(0));
+    let dummy = rt.new_inbox::<Pong>().unwrap();
+
+    let mut panic_addrs = Vec::new();
+    let mut healthy_addrs = Vec::new();
+    for _ in 0..10 {
+        panic_addrs.push(rt.spawn(PanicActor).unwrap());
+        healthy_addrs.push(rt.spawn(CountingPingActor { counter: counter.clone() }).unwrap());
+    }
+
+    // Trigger panics and flood healthy actors.
+    for &addr in &panic_addrs {
+        rt.send_to(addr, PanicMsg).unwrap();
+    }
+    for &addr in &healthy_addrs {
+        for _ in 0..100 {
+            rt.send_to(addr, Ping { reply_to: *dummy.addr() }).unwrap();
+        }
+    }
+
+    let handle = rt.run().unwrap();
+    let expected = 10 * 100;
+    let processed = wait_for_count(&counter, expected, Duration::from_secs(5));
+    handle.shutdown();
+    handle.join();
+
+    assert_eq!(
+        processed, expected,
+        "all {expected} healthy messages processed despite panicking peers"
+    );
+}
+
+/// Worker parking and shutdown latency.
+///
+/// Story: Workers park after idle time. We verify they wake quickly on new
+/// messages, that messages sent after run() are delivered, and that shutdown
+/// wakes all parked workers promptly.
+#[test]
+fn worker_parking_and_shutdown() {
+    // ── Part A: Parked workers wake on send ──
+    let rt = std_runtime(RuntimeConfig { num_threads: 2, ..Default::default() });
+    let addr = rt.spawn(PingPongActor).unwrap();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+
+    let handle = rt.run().unwrap();
+    std::thread::sleep(Duration::from_millis(50)); // Let workers park.
+
+    let before = Instant::now();
+    handle.runtime.send_to(addr, Ping { reply_to: *inbox.addr() }).unwrap();
+    let reply = poll_inbox(&inbox, Duration::from_secs(1));
+    let latency = before.elapsed();
+
+    assert!(reply.is_some(), "parked worker should wake and process");
+    assert!(latency.as_millis() < 100, "wake latency should be <100ms, was {:?}", latency);
+
+    // ── Part B: Send after run() delivers ──
+    let addr2 = handle.runtime.spawn(PingPongActor).unwrap();
+    let inbox2 = handle.runtime.new_inbox::<Pong>().unwrap();
+    std::thread::sleep(Duration::from_millis(10));
+    handle.runtime.send_to(addr2, Ping { reply_to: *inbox2.addr() }).unwrap();
+
+    let reply2 = poll_inbox(&inbox2, Duration::from_secs(5));
+    assert!(reply2.is_some(), "message sent after run() must be delivered");
+
+    handle.shutdown();
+    handle.join();
+
+    // ── Part C: Shutdown wakes parked workers quickly ──
+    let rt2 = std_runtime(RuntimeConfig { num_threads: 4, ..Default::default() });
+    let h2 = rt2.run().unwrap();
+    std::thread::sleep(Duration::from_millis(50)); // Let workers park.
+
+    let before = Instant::now();
+    h2.shutdown();
+    h2.join();
+    let shutdown_time = before.elapsed();
+
+    assert!(
+        shutdown_time.as_millis() < 500,
+        "shutdown should complete quickly with parked workers, took {:?}",
+        shutdown_time
+    );
+}
+
+/// Sustained throughput with no message loss.
+///
+/// Story: We send 10 batches of 100 messages, ticking between batches on a
+/// single-threaded runtime. Each batch must make forward progress, and after
+/// draining, all 1000 messages are accounted for.
+#[test]
+fn sustained_throughput_no_message_loss() {
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter = Arc::new(AtomicUsize::new(0));
+    let dummy = rt.new_inbox::<Pong>().unwrap();
+    let addr = rt.spawn(CountingPingActor { counter: counter.clone() }).unwrap();
+
+    for batch in 0..10 {
+        for _ in 0..100 {
+            rt.send_to(addr, Ping { reply_to: *dummy.addr() }).unwrap();
+        }
+        tick_n(&rt, 5);
+        let processed = counter.load(Ordering::SeqCst);
+        assert!(
+            processed > batch * 50,
+            "batch {batch}: expected progress, only {processed} processed"
+        );
+    }
+
+    // Drain remaining.
+    tick_n(&rt, 100);
+    let total = counter.load(Ordering::SeqCst);
+    assert_eq!(total, 1000, "sustained load should not drop any messages");
+}
+
+/// Load-aware actor placement.
+///
+/// Story: A fresh runtime falls back to round-robin (even distribution).
+/// Under imbalanced load, new actors bias toward the lighter worker.
+/// A single-worker runtime degrades gracefully.
+#[test]
+fn load_aware_actor_placement() {
+    // ── Part A: Round-robin fallback on fresh runtime (4 workers, 100 actors) ──
+    let rt = std_runtime(RuntimeConfig { num_threads: 4, ..Default::default() });
+    for _ in 0..100 {
+        rt.spawn(CounterActor { count: 0 }).unwrap();
+    }
+
+    let handle = rt.run().unwrap();
+    std::thread::sleep(Duration::from_millis(20));
+
+    let stats = handle.runtime.stats();
+    handle.shutdown();
+    handle.join();
+
+    for w in &stats.workers {
+        assert!(
+            w.num_actors >= 20 && w.num_actors <= 30,
+            "worker {} has {} actors, expected ~25 (round-robin)",
+            w.id, w.num_actors
+        );
+    }
+
+    // ── Part B: Imbalanced load biases toward lighter worker ──
+    let rt2 = std_runtime(RuntimeConfig { num_threads: 2, ..Default::default() });
+    let mut addrs = Vec::new();
+    for _ in 0..20 {
+        addrs.push(rt2.spawn(CounterActor { count: 0 }).unwrap());
+    }
+
+    let h2 = rt2.run().unwrap();
+    std::thread::sleep(Duration::from_millis(10));
+
+    // Bombard the first 10 actors (likely worker 0) with messages.
+    for addr in &addrs[..10] {
+        for _ in 0..50 {
+            let _ = h2.runtime.send_to(*addr, Increment { reply_to: *addr });
+        }
+    }
+    std::thread::sleep(Duration::from_millis(20));
+
+    // Spawn 10 more — should bias toward lighter worker.
+    for _ in 0..10 {
+        h2.runtime.spawn(CounterActor { count: 0 }).unwrap();
+    }
+    std::thread::sleep(Duration::from_millis(20));
+
+    let stats2 = h2.runtime.stats();
+    h2.shutdown();
+    h2.join();
+
+    let total_actors: usize = stats2.workers.iter().map(|w| w.num_actors).sum();
+    assert!(total_actors >= 20, "expected at least 20 actors, got {total_actors}");
+    assert!(
+        stats2.workers.iter().all(|w| w.num_actors > 0),
+        "both workers should have actors: {:?}",
+        stats2.workers.iter().map(|w| w.num_actors).collect::<Vec<_>>()
+    );
+
+    // ── Part C: Single-worker degrades gracefully ──
+    let rt3 = std_runtime(RuntimeConfig::default());
+    for _ in 0..50 {
+        rt3.spawn(CounterActor { count: 0 }).unwrap();
+    }
+    tick_n(&rt3, 10);
+
+    let stats3 = rt3.stats();
+    assert_eq!(stats3.workers.len(), 1);
+    assert_eq!(stats3.workers[0].num_actors, 50);
+}

tests/runtime_supervision.rs

@@ -1,866 +0,0 @@
-mod common;
-use common::*;
-
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::Arc;
-
-// ─── Supervisor Helpers ────────────────────────────────────────────────────
-
-/// Actor that panics after receiving a configurable number of messages.
-struct PanicAfterN {
-    trigger: usize,
-    count: usize,
-    counter: Arc<AtomicUsize>,
-}
-
-impl ActorInterface for PanicAfterN {
-    type Incoming = Ping;
-    type Response = ();
-    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
-        self.count += 1;
-        self.counter.fetch_add(1, Ordering::SeqCst);
-        let _ = ctx.send(msg.reply_to, Pong);
-        if self.count >= self.trigger {
-            panic!("intentional panic at message {}", self.count);
-        }
-    }
-}
-
-// --- handle_down tests ---
-
-/// Given an actor with handle_down and a monitored target,
-/// when the target dies, the watcher receives a Down via handle_down.
-#[test]
-fn handle_down_receives_death_notification() {
-    struct MonitoringTracker {
-        target: ActorAddress,
-        downs: Vec<Down>,
-        inbox: ActorAddress,
-    }
-    impl ActorInterface for MonitoringTracker {
-        type Incoming = Ping;
-        type Response = ();
-        fn on_start(&mut self, ctx: &Ctx) {
-            ctx.monitor(self.target);
-        }
-        fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
-            let _ = ctx.send(self.inbox, Count(self.downs.len()));
-        }
-        fn handle_down(&mut self, _ctx: &Ctx, down: Down) {
-            self.downs.push(down);
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Count>().unwrap();
-    let inbox_addr = *inbox.addr();
-    let target = rt.spawn(PanicActor).unwrap();
-    let tracker = rt.spawn(MonitoringTracker {
-        target,
-        downs: vec![],
-        inbox: inbox_addr,
-    }).unwrap();
-    rt.tick(); // on_start for both
-
-    // Kill the target
-    rt.send_to(target, PanicMsg).unwrap();
-    rt.tick(); // target panics
-    rt.tick(); // Down delivered to tracker via handle_down
-
-    // Ask tracker how many downs it saw
-    rt.send_to(tracker, Ping { reply_to: inbox_addr }).unwrap();
-    rt.tick();
-    assert_eq!(inbox.try_recv(), Some(Count(1)));
-}
-
-/// Given an actor whose Incoming type IS Down, handle_down is NOT called --
-/// the Down goes through the normal handle() method (backward compatibility).
-#[test]
-fn handle_down_skipped_when_incoming_is_down() {
-    struct DownAsIncoming {
-        target: ActorAddress,
-        inbox: ActorAddress,
-    }
-    impl ActorInterface for DownAsIncoming {
-        type Incoming = Down;
-        type Response = ();
-        fn on_start(&mut self, ctx: &Ctx) {
-            ctx.monitor(self.target);
-        }
-        fn handle(&mut self, ctx: &Ctx, msg: Down) {
-            let _ = ctx.send(self.inbox, msg);
-        }
-        fn handle_down(&mut self, _ctx: &Ctx, _down: Down) {
-            panic!("handle_down must not be called when Incoming=Down");
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Down>().unwrap();
-    let inbox_addr = *inbox.addr();
-    let target = rt.spawn(PanicActor).unwrap();
-    let _watcher = rt.spawn(DownAsIncoming { target, inbox: inbox_addr }).unwrap();
-    rt.tick(); // on_start
-
-    rt.send_to(target, PanicMsg).unwrap();
-    rt.tick(); // panic
-    rt.tick(); // Down delivered through handle(), not handle_down
-
-    let received = inbox.try_recv().expect("Down should be delivered via handle()");
-    assert_eq!(received.reason, StopReason::Panicked);
-}
-
-// --- ctx.stop_actor tests ---
-
-/// Given two actors, one can stop the other via ctx.stop_actor().
-#[test]
-fn ctx_stop_actor_stops_target() {
-    #[derive(Clone)]
-    struct StopCmd {
-        target: ActorAddress,
-    }
-    struct Stopper;
-    impl ActorInterface for Stopper {
-        type Incoming = StopCmd;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, msg: StopCmd) {
-            let _ = ctx.stop_actor(msg.target);
-        }
-    }
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let target = rt.spawn(PingPongActor).unwrap();
-    let stopper = rt.spawn(Stopper).unwrap();
-    rt.tick(); // on_start
-
-    rt.send_to(stopper, StopCmd { target }).unwrap();
-    rt.tick(); // stopper handles StopCmd -> stop_actor(target)
-    rt.tick(); // StopSignal delivered to target, target stops
-    rt.tick(); // cleanup
-
-    assert!(rt.send_to(target, Ping { reply_to: ActorAddress::default() }).is_err());
-    // Stopper should still be alive
-    assert!(rt.send_to(stopper, StopCmd { target }).is_ok());
-}
-
-// --- Supervisor tests ---
-
-/// Given a supervisor with one permanent child,
-/// when the child panics, the supervisor restarts it.
-#[test]
-fn supervisor_restarts_permanent_child_on_panic() {
-    let counter = Arc::new(AtomicUsize::new(0));
-    let counter_c = counter.clone();
-    let inbox_holder: Arc<std::sync::Mutex<Option<ActorAddress>>> =
-        Arc::new(std::sync::Mutex::new(None));
-
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    let inbox_addr = *inbox.addr();
-    *inbox_holder.lock().unwrap() = Some(inbox_addr);
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![ChildSpec::new("worker", RestartPolicy::Permanent, move |ctx| {
-            ctx.spawn(PanicAfterN {
-                trigger: 2, // panics on 2nd message
-                count: 0,
-                counter: counter_c.clone(),
-            })
-        })],
-    );
-    let _sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); // supervisor on_start -> spawns child
-    rt.tick(); // child on_start
-
-    // Find the child by checking stats
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 2); // supervisor + child
-
-    // Discover child address from stats
-    let child_addr = stats.actors.iter()
-        .find(|(addr, _)| *addr != _sup_addr)
-        .map(|(addr, _)| *addr)
-        .unwrap();
-
-    // First message: child processes, increments counter
-    rt.send_to(child_addr, Ping { reply_to: inbox_addr }).unwrap();
-    rt.tick();
-    assert_eq!(counter.load(Ordering::SeqCst), 1);
-
-    // Second message: child panics (trigger=2)
-    rt.send_to(child_addr, Ping { reply_to: inbox_addr }).unwrap();
-    rt.tick(); // child panics and is poisoned
-    rt.tick(); // cleanup: Down delivered to supervisor via handle_down
-    rt.tick(); // supervisor restarts child (spawns new one)
-    rt.tick(); // new child on_start
-
-    // Supervisor is still alive, and a new child exists
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 2); // supervisor + new child
-}
-
-/// Given a supervisor with a transient child,
-/// when the child stops normally, it is NOT restarted.
-#[test]
-fn supervisor_does_not_restart_transient_child_on_normal_stop() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    struct StopsAfterFirst;
-    impl ActorInterface for StopsAfterFirst {
-        type Incoming = Ping;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
-            ctx.stop_self();
-        }
-    }
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![ChildSpec::new("worker", RestartPolicy::Transient, |ctx| {
-            ctx.spawn(StopsAfterFirst)
-        })],
-    );
-    let sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); // supervisor on_start -> child spawned
-    rt.tick(); // child on_start
-
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 2); // sup + child
-
-    // Find child address
-    let child_addr = stats.actors.iter()
-        .find(|(addr, _)| *addr != sup_addr)
-        .map(|(addr, _)| *addr)
-        .unwrap();
-
-    // Send message -- child stops itself
-    rt.send_to(child_addr, Ping { reply_to: ActorAddress::default() }).unwrap();
-    rt.tick(); // child handles, stops self
-    rt.tick(); // cleanup: Down(Normal) delivered to supervisor
-    rt.tick(); // supervisor sees Transient + Normal -> no restart
-
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 1); // only supervisor remains
-}
-
-/// Given a supervisor with a transient child,
-/// when the child panics, it IS restarted.
-#[test]
-fn supervisor_restarts_transient_child_on_panic() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let counter = Arc::new(AtomicUsize::new(0));
-    let counter_c = counter.clone();
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![ChildSpec::new("worker", RestartPolicy::Transient, move |ctx| {
-            ctx.spawn(PanicAfterN {
-                trigger: 1, // panics on first message
-                count: 0,
-                counter: counter_c.clone(),
-            })
-        })],
-    );
-    let sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); // supervisor starts, spawns child
-    rt.tick(); // child on_start
-
-    let child_addr = rt.stats().actors.iter()
-        .find(|(addr, _)| *addr != sup_addr)
-        .map(|(addr, _)| *addr)
-        .unwrap();
-
-    // Send message -- child panics
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    rt.send_to(child_addr, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick(); // child panics
-    rt.tick(); // Down(Panicked) -> supervisor restarts
-    rt.tick(); // new child spawned
-    rt.tick(); // new child on_start
-
-    // Supervisor + new child alive
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 2);
-}
-
-/// Given a supervisor with a temporary child,
-/// when the child dies (any reason), it is never restarted.
-#[test]
-fn supervisor_never_restarts_temporary_child() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![ChildSpec::new("worker", RestartPolicy::Temporary, |ctx| {
-            ctx.spawn(PanicActor)
-        })],
-    );
-    let sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); // supervisor starts, spawns child
-    rt.tick(); // child on_start
-
-    let child_addr = rt.stats().actors.iter()
-        .find(|(addr, _)| *addr != sup_addr)
-        .map(|(addr, _)| *addr)
-        .unwrap();
-
-    // Kill the child
-    rt.send_to(child_addr, PanicMsg).unwrap();
-    rt.tick(); // panic
-    rt.tick(); // Down -> supervisor sees Temporary -> no restart
-    rt.tick(); // settle
-
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 1); // only supervisor
-}
-
-/// Given a supervisor with max_restarts=2,
-/// when more than 2 restarts occur, the supervisor stops itself (meltdown).
-#[test]
-fn supervisor_meltdown_after_max_restarts() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let counter = Arc::new(AtomicUsize::new(0));
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        2, // only 2 restarts allowed
-        vec![ChildSpec::new("crasher", RestartPolicy::Permanent, {
-            let counter = counter.clone();
-            move |ctx| {
-                ctx.spawn(PanicAfterN {
-                    trigger: 1,
-                    count: 0,
-                    counter: counter.clone(),
-                })
-            }
-        })],
-    );
-    let sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); rt.tick(); // supervisor + child started
-
-    // Crash the child 3 times
-    for _ in 0..3 {
-        if let Some((child_addr, _)) = rt.stats().actors.iter()
-            .find(|(addr, _)| *addr != sup_addr)
-        {
-            let inbox = rt.new_inbox::<Pong>().unwrap();
-            let _ = rt.send_to(*child_addr, Ping { reply_to: *inbox.addr() });
-            rt.tick(); // child panics
-            rt.tick(); // Down delivered -> restart or meltdown
-            rt.tick(); // new child spawned (or supervisor stopped)
-            rt.tick(); // settle
-        }
-    }
-
-    // After 3 crashes with max_restarts=2, supervisor should have stopped itself
-    let stats = rt.stats();
-    let sup_alive = stats.actors.iter().any(|(addr, _)| *addr == sup_addr);
-    assert!(!sup_alive, "supervisor should have stopped after exceeding max_restarts");
-}
-
-/// Given a supervisor with multiple children,
-/// when one child panics, only that child is restarted (OneForOne).
-#[test]
-fn supervisor_one_for_one_only_restarts_failed_child() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let counter_a = Arc::new(AtomicUsize::new(0));
-    let counter_b = Arc::new(AtomicUsize::new(0));
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![
-            ChildSpec::new("crasher", RestartPolicy::Permanent, {
-                let c = counter_a.clone();
-                move |ctx| ctx.spawn_named("child_a", PanicAfterN {
-                    trigger: 1, count: 0, counter: c.clone(),
-                })
-            }),
-            ChildSpec::new("stable", RestartPolicy::Permanent, {
-                let c = counter_b.clone();
-                move |ctx| ctx.spawn_named("child_b", CountingPingActor { counter: c.clone() })
-            }),
-        ],
-    );
-    let _sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); rt.tick(); // start up
-
-    let child_a = rt.where_is("child_a").expect("child_a should be named");
-    let child_b = rt.where_is("child_b").expect("child_b should be named");
-
-    // Send to child_b to prove it's alive
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    rt.send_to(child_b, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick();
-    let b_processed_before = counter_b.load(Ordering::SeqCst);
-    assert!(b_processed_before >= 1);
-
-    // Crash child_a
-    rt.send_to(child_a, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick(); // child_a panics
-    rt.tick(); // Down -> supervisor restarts child_a
-    rt.tick(); rt.tick(); // new child spawned + on_start
-
-    // child_b should still be alive (same address, same name)
-    let child_b_after = rt.where_is("child_b").expect("child_b should still exist");
-    assert_eq!(child_b, child_b_after, "child_b address should be unchanged");
-
-    rt.send_to(child_b, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick();
-    assert!(counter_b.load(Ordering::SeqCst) > b_processed_before,
-        "child_b should still be processing messages");
-
-    // Supervisor + 2 children should be alive
-    assert_eq!(rt.stats().workers[0].num_actors, 3);
-}
-
-/// Given a OneForAll supervisor with 3 children,
-/// when one child panics, ALL children are stopped and restarted in spec order.
-#[test]
-fn supervisor_one_for_all_restarts_all_on_single_failure() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let counter_a = Arc::new(AtomicUsize::new(0));
-    let counter_b = Arc::new(AtomicUsize::new(0));
-    let counter_c = Arc::new(AtomicUsize::new(0));
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForAll,
-        5,
-        vec![
-            ChildSpec::new("a", RestartPolicy::Permanent, {
-                let c = counter_a.clone();
-                move |ctx| ctx.spawn_named("ofa_a", PanicAfterN {
-                    trigger: 1, count: 0, counter: c.clone(),
-                })
-            }),
-            ChildSpec::new("b", RestartPolicy::Permanent, {
-                let c = counter_b.clone();
-                move |ctx| ctx.spawn_named("ofa_b", CountingPingActor { counter: c.clone() })
-            }),
-            ChildSpec::new("c", RestartPolicy::Permanent, {
-                let c = counter_c.clone();
-                move |ctx| ctx.spawn_named("ofa_c", CountingPingActor { counter: c.clone() })
-            }),
-        ],
-    );
-    let _sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); rt.tick(); // startup
-
-    let old_b = rt.where_is("ofa_b").expect("ofa_b exists");
-    let old_c = rt.where_is("ofa_c").expect("ofa_c exists");
-    let child_a = rt.where_is("ofa_a").expect("ofa_a exists");
-
-    // Crash child_a
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    rt.send_to(child_a, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick(); // child_a panics
-    // supervisor receives Down(a) -> OneForAll -> stops b and c
-    for _ in 0..8 { rt.tick(); }
-
-    // All 3 children should be alive with NEW addresses
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 4); // sup + 3 new children
-
-    let new_b = rt.where_is("ofa_b").expect("ofa_b re-registered after restart");
-    let new_c = rt.where_is("ofa_c").expect("ofa_c re-registered after restart");
-    assert_ne!(old_b, new_b, "child_b should have a new address after restart");
-    assert_ne!(old_c, new_c, "child_c should have a new address after restart");
-}
-
-/// Given a RestForOne supervisor with children [a, b, c],
-/// when child b panics, children b and c are restarted.
-/// Child a is unaffected.
-#[test]
-fn supervisor_rest_for_one_restarts_rest_after_failed() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let counter_a = Arc::new(AtomicUsize::new(0));
-    let counter_b = Arc::new(AtomicUsize::new(0));
-    let counter_c = Arc::new(AtomicUsize::new(0));
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::RestForOne,
-        5,
-        vec![
-            ChildSpec::new("a", RestartPolicy::Permanent, {
-                let c = counter_a.clone();
-                move |ctx| ctx.spawn_named("rfo_a", CountingPingActor { counter: c.clone() })
-            }),
-            ChildSpec::new("b", RestartPolicy::Permanent, {
-                let c = counter_b.clone();
-                move |ctx| ctx.spawn_named("rfo_b", PanicAfterN {
-                    trigger: 1, count: 0, counter: c.clone(),
-                })
-            }),
-            ChildSpec::new("c", RestartPolicy::Permanent, {
-                let c = counter_c.clone();
-                move |ctx| ctx.spawn_named("rfo_c", CountingPingActor { counter: c.clone() })
-            }),
-        ],
-    );
-    let _sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); rt.tick(); // startup
-
-    let old_a = rt.where_is("rfo_a").expect("rfo_a exists");
-    let old_c = rt.where_is("rfo_c").expect("rfo_c exists");
-    let child_b = rt.where_is("rfo_b").expect("rfo_b exists");
-
-    // Crash child_b
-    let inbox = rt.new_inbox::<Pong>().unwrap();
-    rt.send_to(child_b, Ping { reply_to: *inbox.addr() }).unwrap();
-    rt.tick(); // child_b panics
-    for _ in 0..8 { rt.tick(); }
-
-    // All 3 children should be alive
-    let stats = rt.stats();
-    assert_eq!(stats.workers[0].num_actors, 4); // sup + 3 children
-
-    // child_a should be UNCHANGED
-    let new_a = rt.where_is("rfo_a").expect("rfo_a still exists");
-    assert_eq!(old_a, new_a, "child_a should not be restarted in RestForOne when b fails");
-
-    // child_c should have a NEW address
-    let new_c = rt.where_is("rfo_c").expect("rfo_c re-registered");
-    assert_ne!(old_c, new_c, "child_c should have a new address after RestForOne restart");
-}
-
-/// Given a OneForAll supervisor, when the last child of the failed set confirms death,
-/// all children are restarted in spec order.
-#[test]
-fn supervisor_one_for_all_waits_for_all_downs_before_restart() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForAll,
-        5,
-        vec![
-            ChildSpec::new("x", RestartPolicy::Permanent, |ctx| ctx.spawn(PingPongActor)),
-            ChildSpec::new("y", RestartPolicy::Permanent, |ctx| ctx.spawn(PingPongActor)),
-        ],
-    );
-    let sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); rt.tick(); // startup
-
-    assert_eq!(rt.stats().workers[0].num_actors, 3); // sup + 2 children
-
-    // Stop one child
-    let actors: Vec<_> = rt.stats().actors.iter()
-        .filter(|(addr, _)| *addr != sup_addr)
-        .map(|(addr, _)| *addr)
-        .collect();
-    rt.stop_actor(actors[0]).unwrap();
-
-    // Tick enough times for full cycle
-    for _ in 0..10 { rt.tick(); }
-
-    // Should have supervisor + 2 new children
-    assert_eq!(rt.stats().workers[0].num_actors, 3);
-}
-
-/// Given a supervisor that stops, its children also stop.
-#[test]
-fn supervisor_on_stop_kills_children() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    let sup = Supervisor::new(
-        SupervisorStrategy::OneForOne,
-        5,
-        vec![
-            ChildSpec::new("a", RestartPolicy::Permanent, |ctx| ctx.spawn(PingPongActor)),
-            ChildSpec::new("b", RestartPolicy::Permanent, |ctx| ctx.spawn(PingPongActor)),
-        ],
-    );
-    let sup_addr = rt.spawn(sup).unwrap();
-    rt.tick(); rt.tick(); // start up
-
-    assert_eq!(rt.stats().workers[0].num_actors, 3); // sup + 2 children
-
-    // Stop the supervisor
-    rt.stop_actor(sup_addr).unwrap();
-    rt.tick(); // StopSignal delivered to supervisor, on_stop sends stop to children
-    rt.tick(); // supervisor cleaned up, stop signals delivered to children
-    rt.tick(); // children stop
-    rt.tick(); // children cleaned up
-
-    assert_eq!(rt.stats().workers[0].num_actors, 0);
-}
-
-// ── Router tests ─────────────────────────────────────────────────────────────
-
-#[test]
-fn router_round_robin_distributes_across_workers() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let collected = Arc::new(std::sync::Mutex::new(Vec::new()));
-
-    struct Collector(Arc<std::sync::Mutex<Vec<(ActorAddress, usize)>>>);
-    #[derive(Clone)]
-    struct Work(usize);
-    impl ActorInterface for Collector {
-        type Incoming = Work;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, msg: Work) {
-            self.0.lock().unwrap().push((ctx.self_addr(), msg.0));
-        }
-    }
-
-    let c = collected.clone();
-    let router = Router::<Work>::new(
-        RoutingStrategy::RoundRobin,
-        3,
-        move |ctx| ctx.spawn(Collector(c.clone())),
-        10,
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick(); // on_start spawns 3 workers
-
-    for i in 0..6 {
-        rt.send_to(router_addr, Work(i)).unwrap();
-    }
-    rt.tick(); // router receives 6 Work messages, forwards to workers
-    rt.tick(); // workers process their messages
-
-    let data = collected.lock().unwrap();
-    assert_eq!(data.len(), 6);
-
-    // Count how many unique workers received messages
-    let mut per_worker = std::collections::HashMap::new();
-    for (addr, _) in data.iter() {
-        *per_worker.entry(*addr).or_insert(0usize) += 1;
-    }
-    // All 3 workers should have received exactly 2 messages each
-    assert_eq!(per_worker.len(), 3);
-    for count in per_worker.values() {
-        assert_eq!(*count, 2);
-    }
-}
-
-#[test]
-fn router_broadcast_sends_to_all_workers() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let count = Arc::new(AtomicUsize::new(0));
-
-    struct Counter(Arc<AtomicUsize>);
-    #[derive(Clone)]
-    struct Ping;
-    impl ActorInterface for Counter {
-        type Incoming = Ping;
-        type Response = ();
-        fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {
-            self.0.fetch_add(1, Ordering::Relaxed);
-        }
-    }
-
-    let c = count.clone();
-    let router = Router::<Ping>::new(
-        RoutingStrategy::Broadcast,
-        3,
-        move |ctx| ctx.spawn(Counter(c.clone())),
-        10,
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick(); // on_start spawns workers
-
-    rt.send_to(router_addr, Ping).unwrap();
-    rt.tick(); // router broadcasts
-    rt.tick(); // workers process
-
-    assert_eq!(count.load(Ordering::Relaxed), 3);
-}
-
-#[test]
-fn router_random_delivers_to_some_worker() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let collected = Arc::new(std::sync::Mutex::new(Vec::new()));
-
-    struct Collector(Arc<std::sync::Mutex<Vec<ActorAddress>>>);
-    #[derive(Clone)]
-    struct Work;
-    impl ActorInterface for Collector {
-        type Incoming = Work;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, _msg: Work) {
-            self.0.lock().unwrap().push(ctx.self_addr());
-        }
-    }
-
-    let c = collected.clone();
-    let router = Router::<Work>::new(
-        RoutingStrategy::Random,
-        3,
-        move |ctx| ctx.spawn(Collector(c.clone())),
-        10,
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick();
-
-    for _ in 0..30 {
-        rt.send_to(router_addr, Work).unwrap();
-    }
-    rt.tick();
-    rt.tick();
-
-    let data = collected.lock().unwrap();
-    assert_eq!(data.len(), 30);
-
-    let unique: std::collections::HashSet<_> = data.iter().collect();
-    assert!(unique.len() >= 2, "expected at least 2 workers used, got {}", unique.len());
-}
-
-#[test]
-fn router_replaces_dead_worker() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let spawn_count = Arc::new(AtomicUsize::new(0));
-
-    struct PanicOnFirst {
-        first: bool,
-    }
-    #[derive(Clone)]
-    struct Work;
-    impl ActorInterface for PanicOnFirst {
-        type Incoming = Work;
-        type Response = ();
-        fn handle(&mut self, _ctx: &Ctx, _msg: Work) {
-            if self.first {
-                self.first = false;
-                panic!("first message panic");
-            }
-        }
-    }
-
-    let sc = spawn_count.clone();
-    let router = Router::<Work>::new(
-        RoutingStrategy::RoundRobin,
-        3,
-        move |ctx| {
-            let n = sc.fetch_add(1, Ordering::Relaxed);
-            ctx.spawn(PanicOnFirst { first: n == 0 })
-        },
-        10,
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick(); // spawn workers (3 spawned)
-    assert_eq!(spawn_count.load(Ordering::Relaxed), 3);
-
-    // Send a message that will hit worker 0
-    rt.send_to(router_addr, Work).unwrap();
-    rt.tick(); // router forwards to worker 0
-    rt.tick(); // worker 0 panics
-    rt.tick(); // cleanup + Down delivered to router
-    rt.tick(); // router spawns replacement
-    rt.tick(); // replacement starts
-
-    // Should have spawned 4 total (3 original + 1 replacement)
-    assert_eq!(spawn_count.load(Ordering::Relaxed), 4);
-
-    // Verify all 3 slots are live
-    assert_eq!(rt.stats().workers[0].num_actors, 4);
-}
-
-#[test]
-fn router_meltdown_after_max_restarts() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    struct AlwaysPanics;
-    #[derive(Clone)]
-    struct Work;
-    impl ActorInterface for AlwaysPanics {
-        type Incoming = Work;
-        type Response = ();
-        fn handle(&mut self, _ctx: &Ctx, _msg: Work) {
-            panic!("always");
-        }
-    }
-
-    let router = Router::<Work>::new(
-        RoutingStrategy::RoundRobin,
-        1,
-        |ctx| ctx.spawn(AlwaysPanics),
-        2, // max 2 restarts
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick(); // on_start
-
-    // Kill the worker 3 times (> max_restarts=2)
-    for _ in 0..3 {
-        rt.send_to(router_addr, Work).unwrap();
-        for _ in 0..5 {
-            rt.tick();
-        }
-    }
-
-    // After 3 restarts, router should have shut down
-    for _ in 0..5 {
-        rt.tick();
-    }
-    assert_eq!(rt.stats().workers[0].num_actors, 0);
-}
-
-#[test]
-fn router_on_stop_kills_workers() {
-    let rt = std_runtime(RuntimeConfig::default());
-
-    struct Dummy;
-    #[derive(Clone)]
-    struct Work;
-    impl ActorInterface for Dummy {
-        type Incoming = Work;
-        type Response = ();
-        fn handle(&mut self, _ctx: &Ctx, _msg: Work) {}
-    }
-
-    let router = Router::<Work>::new(
-        RoutingStrategy::RoundRobin,
-        3,
-        |ctx| ctx.spawn(Dummy),
-        10,
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick(); // on_start
-    assert_eq!(rt.stats().workers[0].num_actors, 4); // router + 3 workers
-
-    rt.stop_actor(router_addr).unwrap();
-    for _ in 0..5 {
-        rt.tick();
-    }
-
-    assert_eq!(rt.stats().workers[0].num_actors, 0);
-}
-
-#[test]
-fn router_broadcast_multiple_messages_all_received() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let total = Arc::new(AtomicUsize::new(0));
-
-    struct Sink(Arc<AtomicUsize>);
-    #[derive(Clone)]
-    struct Tick;
-    impl ActorInterface for Sink {
-        type Incoming = Tick;
-        type Response = ();
-        fn handle(&mut self, _ctx: &Ctx, _msg: Tick) {
-            self.0.fetch_add(1, Ordering::Relaxed);
-        }
-    }
-
-    let t = total.clone();
-    let router = Router::<Tick>::new(
-        RoutingStrategy::Broadcast,
-        3,
-        move |ctx| ctx.spawn(Sink(t.clone())),
-        10,
-    );
-    let router_addr = rt.spawn(router).unwrap();
-    rt.tick();
-
-    for _ in 0..5 {
-        rt.send_to(router_addr, Tick).unwrap();
-    }
-    rt.tick(); // router broadcasts
-    rt.tick(); // workers process
-
-    assert_eq!(total.load(Ordering::Relaxed), 15);
-}

tests/runtime_timers.rs

@@ -1,213 +0,0 @@
-mod common;
-use common::*;
-
-// ── Timer Helpers ─────────────────────────────────────────────────────────
-
-/// Actor that schedules a one-shot timer in on_start: sends a Ping to target after N ticks.
-struct TimerStartActor {
-    target: ActorAddress,
-    delay_ticks: u64,
-}
-
-impl ActorInterface for TimerStartActor {
-    type Incoming = Ping;
-    type Response = Pong;
-
-    fn on_start(&mut self, ctx: &Ctx) {
-        ctx.send_after_ticks(self.target, Ping { reply_to: ctx.self_addr() }, self.delay_ticks);
-    }
-
-    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {}
-}
-
-/// Actor that schedules a one-shot timer when it receives a Forward message.
-struct DelayPingPongActor;
-
-impl ActorInterface for DelayPingPongActor {
-    type Incoming = Forward;
-    type Response = Done;
-
-    fn handle(&mut self, ctx: &Ctx, msg: Forward) {
-        ctx.send_after_ticks(msg.reply_to, Done(msg.value), 3);
-    }
-}
-
-/// Actor that schedules an interval timer on start: sends Ping every N ticks.
-struct HeartbeatActor {
-    target: ActorAddress,
-    period: u64,
-}
-
-impl ActorInterface for HeartbeatActor {
-    type Incoming = Ping;
-    type Response = Pong;
-
-    fn on_start(&mut self, ctx: &Ctx) {
-        ctx.send_interval_ticks(self.target, Ping { reply_to: ctx.self_addr() }, self.period);
-    }
-
-    fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {}
-}
-
-// ── Timer Tests ───────────────────────────────────────────────────────────
-
-/// Given an actor that schedules a one-shot timer in on_start,
-/// when enough ticks pass,
-/// then the timer message is delivered to the target.
-#[test]
-fn one_shot_timer_fires_after_n_ticks() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Ping>().unwrap();
-
-    let _timer_actor = rt.spawn(TimerStartActor {
-        target: *inbox.addr(),
-        delay_ticks: 3,
-    }).unwrap();
-
-    // Tick 1: on_start schedules timer (fire_at = current_tick + 3 = 4)
-    rt.tick(); // tick 1: on_start, timer scheduled
-    assert!(inbox.try_recv().is_none(), "no delivery before delay");
-
-    rt.tick(); // tick 2
-    assert!(inbox.try_recv().is_none(), "no delivery on tick 2");
-
-    rt.tick(); // tick 3
-    assert!(inbox.try_recv().is_none(), "no delivery on tick 3");
-
-    rt.tick(); // tick 4: timer fires
-    let msg = inbox.try_recv();
-    assert!(msg.is_some(), "timer message delivered after 3-tick delay");
-}
-
-/// Given an actor that schedules a one-shot timer from a message handler,
-/// when enough ticks pass after the triggering message,
-/// then the delayed response arrives.
-#[test]
-fn handler_can_schedule_one_shot_timer() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Done>().unwrap();
-
-    let addr = rt.spawn(DelayPingPongActor).unwrap();
-
-    let _ = rt.send_to(addr, Forward { value: 42, reply_to: *inbox.addr() });
-    rt.tick(); // process Forward, schedule timer (delay=3)
-
-    assert!(inbox.try_recv().is_none(), "no immediate reply");
-
-    rt.tick(); // tick 2
-    rt.tick(); // tick 3
-    assert!(inbox.try_recv().is_none(), "not yet");
-
-    rt.tick(); // tick 4: timer fires
-    let reply = inbox.try_recv();
-    assert_eq!(reply, Some(Done(42)), "delayed reply arrives after 3 ticks");
-}
-
-/// Given a one-shot timer,
-/// when it fires,
-/// then it does NOT fire again on subsequent ticks (consumed).
-#[test]
-fn one_shot_timer_fires_only_once() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Ping>().unwrap();
-
-    let _timer_actor = rt.spawn(TimerStartActor {
-        target: *inbox.addr(),
-        delay_ticks: 1,
-    }).unwrap();
-
-    rt.tick(); // on_start schedules timer
-    rt.tick(); // timer fires
-    assert!(inbox.try_recv().is_some(), "first fire");
-
-    // Subsequent ticks should NOT fire again
-    for _ in 0..5 { rt.tick(); }
-    assert!(inbox.try_recv().is_none(), "one-shot does not repeat");
-}
-
-/// Given an interval timer with period 2,
-/// when multiple ticks pass,
-/// then the timer fires repeatedly every 2 ticks.
-#[test]
-fn interval_timer_fires_repeatedly() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Ping>().unwrap();
-
-    let _heartbeat = rt.spawn(HeartbeatActor {
-        target: *inbox.addr(),
-        period: 2,
-    }).unwrap();
-
-    rt.tick(); // tick 1: on_start, interval scheduled (next_fire = current + 2 = 3)
-    assert!(inbox.try_recv().is_none(), "no fire on tick 1");
-
-    rt.tick(); // tick 2
-    assert!(inbox.try_recv().is_none(), "no fire on tick 2");
-
-    rt.tick(); // tick 3: first fire
-    assert!(inbox.try_recv().is_some(), "fire on tick 3");
-
-    rt.tick(); // tick 4
-    assert!(inbox.try_recv().is_none(), "no fire on tick 4");
-
-    rt.tick(); // tick 5: second fire
-    assert!(inbox.try_recv().is_some(), "fire on tick 5");
-
-    rt.tick(); // tick 6
-    assert!(inbox.try_recv().is_none(), "no fire on tick 6");
-
-    rt.tick(); // tick 7: third fire
-    assert!(inbox.try_recv().is_some(), "fire on tick 7");
-}
-
-/// Given an interval timer targeting an actor that gets stopped,
-/// when the actor is removed,
-/// then the interval timer is cleaned up (no orphan timers).
-#[test]
-fn interval_timer_cleaned_up_when_actor_dies() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let _inbox = rt.new_inbox::<Ping>().unwrap();
-
-    // Heartbeat sends to a counter that we'll kill
-    let counter_addr = rt.spawn(CounterActor { count: 0 }).unwrap();
-
-    // HeartbeatActor sends Ping to counter every tick
-    let _hb = rt.spawn(HeartbeatActor {
-        target: counter_addr,
-        period: 1,
-    }).unwrap();
-
-    // Let it run a few ticks
-    for _ in 0..3 { rt.tick(); }
-
-    // Stop the counter
-    rt.stop_actor(counter_addr).unwrap();
-    for _ in 0..5 { rt.tick(); }
-
-    // Counter is gone, interval timer should be GC'd.
-    let stats = rt.stats();
-    // Only the heartbeat actor should remain
-    assert_eq!(stats.workers[0].num_actors, 1);
-}
-
-/// Given a timer with delay 0,
-/// when the next tick fires,
-/// then the message is delivered immediately on the next tick.
-#[test]
-fn timer_with_zero_delay_fires_next_tick() {
-    let rt = std_runtime(RuntimeConfig::default());
-    let inbox = rt.new_inbox::<Ping>().unwrap();
-
-    let _timer_actor = rt.spawn(TimerStartActor {
-        target: *inbox.addr(),
-        delay_ticks: 0,
-    }).unwrap();
-
-    rt.tick(); // on_start schedules timer with delay=0
-    // Timer requests are processed after tick_all (phase 5.5)
-    // Timer fires on the NEXT tick (phase 2.5)
-    assert!(inbox.try_recv().is_none(), "not yet -- timer fires next tick");
-
-    rt.tick(); // timer fires
-    assert!(inbox.try_recv().is_some(), "zero-delay timer fires on next tick");
-}

tests/std_extension.rs

@@ -0,0 +1,742 @@
+//! StdExtension Tests — higher-level patterns from swactor-std.
+//!
+//! Covers: naming registry, groups/pub-sub, ask pattern, supervision
+//! strategies and restart policies, and router work distribution.
+
+mod common;
+use common::*;
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+// ── Local actors ────────────────────────────────────────────────────────────
+
+/// Looks up a peer by name using ctx.where_is().
+struct NameLookupActor {
+    target_name: &'static str,
+    reply_to: ActorAddress,
+}
+
+impl ActorInterface for NameLookupActor {
+    type Incoming = Ping;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
+        if let Some(peer) = ctx.where_is(self.target_name) {
+            ctx.send(self.reply_to, MyAddr(peer)).unwrap();
+        }
+    }
+}
+
+/// Spawns a named child from a handler.
+struct NamedSpawnerActor {
+    reply_to: ActorAddress,
+}
+
+impl ActorInterface for NamedSpawnerActor {
+    type Incoming = Ping;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
+        if let Ok(addr) = ctx.spawn_named("child", PingPongActor) {
+            ctx.send(self.reply_to, MyAddr(addr)).unwrap();
+        }
+    }
+}
+
+/// Panics after `trigger` messages.
+struct PanicAfterN {
+    trigger: usize,
+    count: usize,
+    counter: Arc<AtomicUsize>,
+}
+
+impl ActorInterface for PanicAfterN {
+    type Incoming = Ping;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, msg: Ping) {
+        self.count += 1;
+        self.counter.fetch_add(1, Ordering::SeqCst);
+        let _ = ctx.send(msg.reply_to, Pong);
+        if self.count >= self.trigger {
+            panic!("intentional panic at message {}", self.count);
+        }
+    }
+}
+
+/// Stops itself on first message.
+struct StopsAfterFirst;
+impl ActorInterface for StopsAfterFirst {
+    type Incoming = Ping;
+    type Response = ();
+    fn handle(&mut self, ctx: &Ctx, _msg: Ping) {
+        ctx.stop_self();
+    }
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Naming Registry
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Full naming lifecycle: register, lookup, send, duplicate fails, auto-unregister
+/// on stop and panic, name reuse, registered_names list, manual unregister.
+#[test]
+fn naming_registry_lifecycle() {
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+
+    // Register "alice", lookup, send Ping → Pong
+    let alice = rt.spawn_named("alice", PingPongActor).unwrap();
+    assert_eq!(rt.where_is("alice"), Some(alice));
+    rt.send_to(alice, Ping { reply_to: *inbox.addr() }).unwrap();
+    rt.tick();
+    assert!(inbox.try_recv().is_some(), "named actor processes messages");
+
+    // Duplicate fails, original binding preserved
+    assert!(rt.spawn_named("alice", PingPongActor).is_err());
+    assert_eq!(rt.where_is("alice"), Some(alice));
+
+    // Unknown name → None
+    assert_eq!(rt.where_is("ghost"), None);
+
+    // Stop "alice" → name freed
+    rt.stop_actor(alice).unwrap();
+    rt.tick();
+    assert_eq!(rt.where_is("alice"), None, "name freed after stop");
+
+    // Reuse the name
+    let alice2 = rt.spawn_named("alice", PingPongActor).unwrap();
+    assert_ne!(alice, alice2);
+    assert_eq!(rt.where_is("alice"), Some(alice2));
+
+    // Panic also frees the name
+    let bob = rt.spawn_named("bob", PanicActor).unwrap();
+    rt.tick();
+    rt.send_to(bob, PanicMsg).unwrap();
+    rt.tick();
+    assert_eq!(rt.where_is("bob"), None, "name freed after panic");
+    let _bob2 = rt.spawn_named("bob", PingPongActor).unwrap();
+    assert!(rt.where_is("bob").is_some());
+
+    // registered_names enumerates all
+    rt.spawn_named("gamma", PingPongActor).unwrap();
+    let mut names = rt.registered_names();
+    names.sort();
+    assert!(names.contains(&"alice".to_string()));
+    assert!(names.contains(&"bob".to_string()));
+    assert!(names.contains(&"gamma".to_string()));
+
+    // Manual unregister: name freed but actor lives
+    let charlie_inbox = rt.new_inbox::<Pong>().unwrap();
+    let charlie = rt.spawn_named("charlie", PingPongActor).unwrap();
+    rt.tick();
+    let removed = rt.unregister("charlie");
+    assert_eq!(removed, Some(charlie));
+    assert_eq!(rt.where_is("charlie"), None, "name freed by unregister");
+    rt.send_to(charlie, Ping { reply_to: *charlie_inbox.addr() }).unwrap();
+    rt.tick();
+    assert!(charlie_inbox.try_recv().is_some(), "actor still alive after name unregistered");
+}
+
+/// Actors resolve and register names from handlers using ctx.
+#[test]
+fn naming_from_actor_handlers() {
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<MyAddr>().unwrap();
+
+    // ctx.where_is from handler
+    let target = rt.spawn_named("target", PingPongActor).unwrap();
+    let looker = rt.spawn(NameLookupActor {
+        target_name: "target",
+        reply_to: *inbox.addr(),
+    }).unwrap();
+    rt.tick();
+    rt.send_to(looker, Ping { reply_to: ActorAddress::default() }).unwrap();
+    tick_n(&rt, 3);
+    assert_eq!(inbox.try_recv(), Some(MyAddr(target)), "ctx.where_is resolves");
+
+    // ctx.spawn_named from handler
+    let spawner = rt.spawn(NamedSpawnerActor { reply_to: *inbox.addr() }).unwrap();
+    rt.tick();
+    rt.send_to(spawner, Ping { reply_to: ActorAddress::default() }).unwrap();
+    tick_n(&rt, 3);
+    let child_addr = inbox.try_recv().expect("child address returned");
+    assert_eq!(rt.where_is("child"), Some(child_addr.0), "name registered from handler");
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Groups / Pub-Sub
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Full groups lifecycle: join, publish broadcasts, leave stops delivery,
+/// dead actor auto-removed, multi-group cleanup, empty group deleted,
+/// join and publish from handlers.
+#[test]
+fn groups_pub_sub_lifecycle() {
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+
+    // Join 3 actors, publish → all 3 get it
+    let a = rt.spawn(PingPongActor).unwrap();
+    let b = rt.spawn(PingPongActor).unwrap();
+    let c = rt.spawn(PingPongActor).unwrap();
+    rt.join_group(a, "workers");
+    rt.join_group(b, "workers");
+    rt.join_group(c, "workers");
+    rt.tick();
+
+    let count = rt.publish_to("workers", Ping { reply_to: *inbox.addr() });
+    assert_eq!(count, 3, "3 members, 3 messages sent");
+    rt.tick();
+    let mut pongs = 0;
+    while inbox.try_recv().is_some() { pongs += 1; }
+    assert_eq!(pongs, 3, "all 3 received");
+
+    // Leave stops delivery
+    rt.leave_group(c, "workers");
+    let count = rt.publish_to("workers", Ping { reply_to: *inbox.addr() });
+    assert_eq!(count, 2, "2 after leave");
+    rt.tick();
+    let mut pongs = 0;
+    while inbox.try_recv().is_some() { pongs += 1; }
+    assert_eq!(pongs, 2);
+
+    // Dead actor auto-removed
+    rt.stop_actor(b).unwrap();
+    rt.tick();
+    let count = rt.publish_to("workers", Ping { reply_to: *inbox.addr() });
+    assert_eq!(count, 1, "dead actor removed");
+
+    // Multi-group cleanup: actor in alpha/beta/gamma dies → all cleaned
+    let rt = std_runtime(RuntimeConfig::default());
+    let actor = rt.spawn(PingPongActor).unwrap();
+    rt.join_group(actor, "alpha");
+    rt.join_group(actor, "beta");
+    rt.join_group(actor, "gamma");
+    rt.tick();
+    rt.stop_actor(actor).unwrap();
+    rt.tick();
+    assert!(rt.group_members("alpha").is_empty());
+    assert!(rt.group_members("beta").is_empty());
+    assert!(rt.group_members("gamma").is_empty());
+
+    // Empty group auto-deleted
+    let rt = std_runtime(RuntimeConfig::default());
+    let actor = rt.spawn(PingPongActor).unwrap();
+    rt.join_group(actor, "temp");
+    assert!(rt.groups().contains(&"temp".to_string()));
+    rt.leave_group(actor, "temp");
+    assert!(!rt.groups().contains(&"temp".to_string()), "empty group removed");
+
+    // Empty group query
+    let rt = std_runtime(RuntimeConfig::default());
+    assert!(rt.group_members("nonexistent").is_empty());
+
+    // ctx.join_group from on_start
+    struct GroupJoiner;
+    impl ActorInterface for GroupJoiner {
+        type Incoming = Ping;
+        type Response = ();
+        fn on_start(&mut self, ctx: &Ctx) {
+            ctx.join_group("auto-joined");
+        }
+        fn handle(&mut self, _ctx: &Ctx, _msg: Ping) {}
+    }
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let x = rt.spawn(GroupJoiner).unwrap();
+    let y = rt.spawn(GroupJoiner).unwrap();
+    rt.tick();
+    let members = rt.group_members("auto-joined");
+    assert_eq!(members.len(), 2);
+    assert!(members.contains(&x));
+    assert!(members.contains(&y));
+
+    // ctx.publish from handler
+    #[derive(Clone)]
+    struct BroadcastCmd { reply_to: ActorAddress }
+
+    struct Broadcaster;
+    impl ActorInterface for Broadcaster {
+        type Incoming = BroadcastCmd;
+        type Response = ();
+        fn on_start(&mut self, ctx: &Ctx) {
+            ctx.join_group("bcast");
+        }
+        fn handle(&mut self, ctx: &Ctx, msg: BroadcastCmd) {
+            ctx.publish("bcast", Ping { reply_to: msg.reply_to });
+        }
+    }
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let p1 = rt.spawn(PingPongActor).unwrap();
+    let p2 = rt.spawn(PingPongActor).unwrap();
+    rt.join_group(p1, "bcast");
+    rt.join_group(p2, "bcast");
+    let broadcaster = rt.spawn(Broadcaster).unwrap();
+    rt.tick();
+    rt.send_to(broadcaster, BroadcastCmd { reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 3);
+    let mut pongs = 0;
+    while inbox.try_recv().is_some() { pongs += 1; }
+    assert!(pongs >= 2, "at least 2 PingPong members replied, got {pongs}");
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Ask Pattern
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Ask pattern: basic ask, repeated asks track state, try_recv before/after
+/// tick, dead actor times out.
+#[test]
+fn ask_pattern() {
+    let rt = std_runtime(RuntimeConfig::default());
+
+    // Basic ask
+    let actor = rt.spawn(PingPongActor).unwrap();
+    rt.tick();
+    let pong: Pong = rt.ask(actor, |reply_to| Ping { reply_to })
+        .unwrap().recv_ticking(&rt, 10).unwrap();
+    assert_eq!(pong, Pong);
+
+    // Repeated asks track state
+    let counter = rt.spawn(CounterActor { count: 0 }).unwrap();
+    rt.tick();
+    let c1: Count = rt.ask(counter, |reply_to| Increment { reply_to })
+        .unwrap().recv_ticking(&rt, 10).unwrap();
+    let c2: Count = rt.ask(counter, |reply_to| Increment { reply_to })
+        .unwrap().recv_ticking(&rt, 10).unwrap();
+    let c3: Count = rt.ask(counter, |reply_to| Increment { reply_to })
+        .unwrap().recv_ticking(&rt, 10).unwrap();
+    assert_eq!((c1, c2, c3), (Count(1), Count(2), Count(3)));
+
+    // try_recv: None before tick, Some after
+    let rt = std_runtime(RuntimeConfig::default());
+    let actor = rt.spawn(PingPongActor).unwrap();
+    rt.tick();
+    let ask = rt.ask::<Ping, Pong>(actor, |reply_to| Ping { reply_to }).unwrap();
+    assert!(ask.try_recv().is_none(), "no response before tick");
+    rt.tick();
+    assert_eq!(ask.try_recv(), Some(Pong));
+
+    // Dead actor → timeout
+    let rt = std_runtime(RuntimeConfig::default());
+    let actor = rt.spawn(PingPongActor).unwrap();
+    rt.tick();
+    rt.stop_actor(actor).unwrap();
+    rt.tick();
+    if let Ok(ask) = rt.ask::<Ping, Pong>(actor, |reply_to| Ping { reply_to }) {
+        assert!(ask.recv_ticking(&rt, 5).is_err(), "timeout with dead actor");
+    }
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Supervision
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Restart policies: permanent always restarts, transient only on panic,
+/// temporary never restarts, meltdown after max_restarts.
+#[test]
+fn supervision_restart_policies() {
+    // Permanent child panics → restarted
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter = Arc::new(AtomicUsize::new(0));
+    let counter_c = counter.clone();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 5,
+        vec![ChildSpec::new("worker", RestartPolicy::Permanent, move |ctx| {
+            ctx.spawn(PanicAfterN { trigger: 2, count: 0, counter: counter_c.clone() })
+        })],
+    );
+    let sup_addr = rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let child = rt.stats().actors.iter()
+        .find(|(a, _)| *a != sup_addr).map(|(a, _)| *a).unwrap();
+    rt.send_to(child, Ping { reply_to: *inbox.addr() }).unwrap();
+    rt.tick();
+    assert_eq!(counter.load(Ordering::SeqCst), 1);
+    rt.send_to(child, Ping { reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 5); // panics, supervisor restarts
+    assert_eq!(rt.stats().workers[0].num_actors, 2, "supervisor + restarted child");
+
+    // Transient stops normally → NOT restarted
+    let rt = std_runtime(RuntimeConfig::default());
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 5,
+        vec![ChildSpec::new("worker", RestartPolicy::Transient, |ctx| {
+            ctx.spawn(StopsAfterFirst)
+        })],
+    );
+    let sup_addr = rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let child = rt.stats().actors.iter()
+        .find(|(a, _)| *a != sup_addr).map(|(a, _)| *a).unwrap();
+    rt.send_to(child, Ping { reply_to: ActorAddress::default() }).unwrap();
+    tick_n(&rt, 4);
+    assert_eq!(rt.stats().workers[0].num_actors, 1, "transient+normal → no restart");
+
+    // Transient panics → restarted
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter = Arc::new(AtomicUsize::new(0));
+    let counter_c = counter.clone();
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 5,
+        vec![ChildSpec::new("worker", RestartPolicy::Transient, move |ctx| {
+            ctx.spawn(PanicAfterN { trigger: 1, count: 0, counter: counter_c.clone() })
+        })],
+    );
+    let sup_addr = rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let child = rt.stats().actors.iter()
+        .find(|(a, _)| *a != sup_addr).map(|(a, _)| *a).unwrap();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    rt.send_to(child, Ping { reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(rt.stats().workers[0].num_actors, 2, "transient+panic → restarted");
+
+    // Temporary never restarts
+    let rt = std_runtime(RuntimeConfig::default());
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 5,
+        vec![ChildSpec::new("worker", RestartPolicy::Temporary, |ctx| ctx.spawn(PanicActor))],
+    );
+    let sup_addr = rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let child = rt.stats().actors.iter()
+        .find(|(a, _)| *a != sup_addr).map(|(a, _)| *a).unwrap();
+    rt.send_to(child, PanicMsg).unwrap();
+    tick_n(&rt, 4);
+    assert_eq!(rt.stats().workers[0].num_actors, 1, "temporary → no restart");
+
+    // Meltdown: max_restarts=2, crash 3 times → supervisor stops
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter = Arc::new(AtomicUsize::new(0));
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 2,
+        vec![ChildSpec::new("crasher", RestartPolicy::Permanent, {
+            let c = counter.clone();
+            move |ctx| ctx.spawn(PanicAfterN { trigger: 1, count: 0, counter: c.clone() })
+        })],
+    );
+    let sup_addr = rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    for _ in 0..3 {
+        if let Some((child, _)) = rt.stats().actors.iter()
+            .find(|(a, _)| *a != sup_addr)
+        {
+            let inbox = rt.new_inbox::<Pong>().unwrap();
+            let _ = rt.send_to(*child, Ping { reply_to: *inbox.addr() });
+            tick_n(&rt, 5);
+        }
+    }
+    let sup_alive = rt.stats().actors.iter().any(|(a, _)| *a == sup_addr);
+    assert!(!sup_alive, "supervisor stopped after exceeding max_restarts");
+}
+
+/// Strategies: OneForOne, OneForAll, RestForOne. Stopping supervisor kills children.
+#[test]
+fn supervision_strategies() {
+    // OneForOne: only failed child restarted
+    let rt = std_runtime(RuntimeConfig::default());
+    let counter_a = Arc::new(AtomicUsize::new(0));
+    let counter_b = Arc::new(AtomicUsize::new(0));
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 5,
+        vec![
+            ChildSpec::new("crasher", RestartPolicy::Permanent, {
+                let c = counter_a.clone();
+                move |ctx| ctx.spawn_named("ofo_a", PanicAfterN {
+                    trigger: 1, count: 0, counter: c.clone(),
+                })
+            }),
+            ChildSpec::new("stable", RestartPolicy::Permanent, {
+                let c = counter_b.clone();
+                move |ctx| ctx.spawn_named("ofo_b", CountingPingActor { counter: c.clone() })
+            }),
+        ],
+    );
+    rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let child_a = rt.where_is("ofo_a").unwrap();
+    let child_b = rt.where_is("ofo_b").unwrap();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    rt.send_to(child_a, Ping { reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 5);
+    let child_b_after = rt.where_is("ofo_b").unwrap();
+    assert_eq!(child_b, child_b_after, "child_b unchanged in OneForOne");
+    rt.send_to(child_b, Ping { reply_to: *inbox.addr() }).unwrap();
+    rt.tick();
+    assert!(counter_b.load(Ordering::SeqCst) >= 1, "child_b still processing");
+
+    // OneForAll: all children restarted
+    let rt = std_runtime(RuntimeConfig::default());
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForAll, 5,
+        vec![
+            ChildSpec::new("a", RestartPolicy::Permanent, {
+                let c = Arc::new(AtomicUsize::new(0));
+                move |ctx| ctx.spawn_named("ofa_a", PanicAfterN {
+                    trigger: 1, count: 0, counter: c.clone(),
+                })
+            }),
+            ChildSpec::new("b", RestartPolicy::Permanent, {
+                let c = Arc::new(AtomicUsize::new(0));
+                move |ctx| ctx.spawn_named("ofa_b", CountingPingActor { counter: c.clone() })
+            }),
+        ],
+    );
+    rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let old_b = rt.where_is("ofa_b").unwrap();
+    let child_a = rt.where_is("ofa_a").unwrap();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    rt.send_to(child_a, Ping { reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 8);
+    let new_b = rt.where_is("ofa_b").expect("ofa_b re-registered");
+    assert_ne!(old_b, new_b, "child_b restarted in OneForAll");
+
+    // RestForOne: failed child + later children restarted, earlier unaffected
+    let rt = std_runtime(RuntimeConfig::default());
+    let sup = Supervisor::new(
+        SupervisorStrategy::RestForOne, 5,
+        vec![
+            ChildSpec::new("a", RestartPolicy::Permanent, {
+                let c = Arc::new(AtomicUsize::new(0));
+                move |ctx| ctx.spawn_named("rfo_a", CountingPingActor { counter: c.clone() })
+            }),
+            ChildSpec::new("b", RestartPolicy::Permanent, {
+                let c = Arc::new(AtomicUsize::new(0));
+                move |ctx| ctx.spawn_named("rfo_b", PanicAfterN {
+                    trigger: 1, count: 0, counter: c.clone(),
+                })
+            }),
+            ChildSpec::new("c", RestartPolicy::Permanent, {
+                let c = Arc::new(AtomicUsize::new(0));
+                move |ctx| ctx.spawn_named("rfo_c", CountingPingActor { counter: c.clone() })
+            }),
+        ],
+    );
+    rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    let old_a = rt.where_is("rfo_a").unwrap();
+    let old_c = rt.where_is("rfo_c").unwrap();
+    let child_b = rt.where_is("rfo_b").unwrap();
+    let inbox = rt.new_inbox::<Pong>().unwrap();
+    rt.send_to(child_b, Ping { reply_to: *inbox.addr() }).unwrap();
+    tick_n(&rt, 8);
+    let new_a = rt.where_is("rfo_a").unwrap();
+    let new_c = rt.where_is("rfo_c").expect("rfo_c re-registered");
+    assert_eq!(old_a, new_a, "child_a unchanged in RestForOne");
+    assert_ne!(old_c, new_c, "child_c restarted in RestForOne");
+
+    // Stopping supervisor kills children
+    let rt = std_runtime(RuntimeConfig::default());
+    let sup = Supervisor::new(
+        SupervisorStrategy::OneForOne, 5,
+        vec![
+            ChildSpec::new("a", RestartPolicy::Permanent, |ctx| ctx.spawn(PingPongActor)),
+            ChildSpec::new("b", RestartPolicy::Permanent, |ctx| ctx.spawn(PingPongActor)),
+        ],
+    );
+    let sup_addr = rt.spawn(sup).unwrap();
+    tick_n(&rt, 2);
+    assert_eq!(rt.stats().workers[0].num_actors, 3);
+    rt.stop_actor(sup_addr).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(rt.stats().workers[0].num_actors, 0, "stopping supervisor kills children");
+}
+
+/// handle_down dispatch and ctx.stop_actor from handler.
+#[test]
+fn handle_down_dispatch() {
+    // ctx.stop_actor from handler stops target
+    #[derive(Clone)]
+    struct StopCmd { target: ActorAddress }
+    struct Stopper;
+    impl ActorInterface for Stopper {
+        type Incoming = StopCmd;
+        type Response = ();
+        fn handle(&mut self, ctx: &Ctx, msg: StopCmd) {
+            let _ = ctx.stop_actor(msg.target);
+        }
+    }
+
+    let rt = std_runtime(RuntimeConfig::default());
+    let target = rt.spawn(PingPongActor).unwrap();
+    let stopper = rt.spawn(Stopper).unwrap();
+    rt.tick();
+    rt.send_to(stopper, StopCmd { target }).unwrap();
+    tick_n(&rt, 4);
+    assert!(rt.send_to(target, Ping { reply_to: ActorAddress::default() }).is_err(),
+        "target stopped by ctx.stop_actor");
+    assert!(rt.send_to(stopper, StopCmd { target }).is_ok(), "stopper still alive");
+}
+
+// ═══════════════════════════════════════════════════════════════════════════
+// Router
+// ═══════════════════════════════════════════════════════════════════════════
+
+/// Router distributes work: round-robin is even, broadcast hits all, random
+/// uses multiple workers. Dead workers replaced. Stop router kills workers.
+/// Meltdown after max restarts.
+#[test]
+fn router_work_distribution() {
+    // Round-robin: 3 workers, 6 msgs → 2 each
+    let rt = std_runtime(RuntimeConfig::default());
+    let collected = Arc::new(std::sync::Mutex::new(Vec::new()));
+    struct Collector(Arc<std::sync::Mutex<Vec<(ActorAddress, usize)>>>);
+    #[derive(Clone)]
+    struct Work(usize);
+    impl ActorInterface for Collector {
+        type Incoming = Work;
+        type Response = ();
+        fn handle(&mut self, ctx: &Ctx, msg: Work) {
+            self.0.lock().unwrap().push((ctx.self_addr(), msg.0));
+        }
+    }
+
+    let c = collected.clone();
+    let router = Router::<Work>::new(
+        RoutingStrategy::RoundRobin, 3,
+        move |ctx| ctx.spawn(Collector(c.clone())), 10,
+    );
+    let router_addr = rt.spawn(router).unwrap();
+    rt.tick();
+    for i in 0..6 {
+        rt.send_to(router_addr, Work(i)).unwrap();
+    }
+    tick_n(&rt, 3);
+    let data = collected.lock().unwrap();
+    assert_eq!(data.len(), 6);
+    let mut per_worker = std::collections::HashMap::new();
+    for (addr, _) in data.iter() {
+        *per_worker.entry(*addr).or_insert(0usize) += 1;
+    }
+    assert_eq!(per_worker.len(), 3, "3 distinct workers");
+    for count in per_worker.values() {
+        assert_eq!(*count, 2, "each worker gets exactly 2");
+    }
+
+    // Broadcast: 5 msgs to 3 workers → 15 total
+    let rt = std_runtime(RuntimeConfig::default());
+    let total = Arc::new(AtomicUsize::new(0));
+    struct BCounter(Arc<AtomicUsize>);
+    #[derive(Clone)]
+    struct BPing;
+    impl ActorInterface for BCounter {
+        type Incoming = BPing;
+        type Response = ();
+        fn handle(&mut self, _ctx: &Ctx, _msg: BPing) {
+            self.0.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    let t = total.clone();
+    let router = Router::<BPing>::new(
+        RoutingStrategy::Broadcast, 3,
+        move |ctx| ctx.spawn(BCounter(t.clone())), 10,
+    );
+    let router_addr = rt.spawn(router).unwrap();
+    rt.tick();
+    for _ in 0..5 {
+        rt.send_to(router_addr, BPing).unwrap();
+    }
+    tick_n(&rt, 3);
+    assert_eq!(total.load(Ordering::Relaxed), 15, "5 broadcasts × 3 workers = 15");
+
+    // Random: 30 msgs → at least 2 workers used
+    let rt = std_runtime(RuntimeConfig::default());
+    let rcollected = Arc::new(std::sync::Mutex::new(Vec::new()));
+    struct RCollector(Arc<std::sync::Mutex<Vec<ActorAddress>>>);
+    #[derive(Clone)]
+    struct RWork;
+    impl ActorInterface for RCollector {
+        type Incoming = RWork;
+        type Response = ();
+        fn handle(&mut self, ctx: &Ctx, _msg: RWork) {
+            self.0.lock().unwrap().push(ctx.self_addr());
+        }
+    }
+    let c = rcollected.clone();
+    let router = Router::<RWork>::new(
+        RoutingStrategy::Random, 3,
+        move |ctx| ctx.spawn(RCollector(c.clone())), 10,
+    );
+    let router_addr = rt.spawn(router).unwrap();
+    rt.tick();
+    for _ in 0..30 {
+        rt.send_to(router_addr, RWork).unwrap();
+    }
+    tick_n(&rt, 3);
+    let data = rcollected.lock().unwrap();
+    let unique: std::collections::HashSet<_> = data.iter().collect();
+    assert!(unique.len() >= 2, "random uses at least 2 workers");
+
+    // Dead worker replaced
+    let rt = std_runtime(RuntimeConfig::default());
+    let spawn_count = Arc::new(AtomicUsize::new(0));
+    struct PanicOnFirst { first: bool }
+    #[derive(Clone)]
+    struct DWork;
+    impl ActorInterface for PanicOnFirst {
+        type Incoming = DWork;
+        type Response = ();
+        fn handle(&mut self, _ctx: &Ctx, _msg: DWork) {
+            if self.first { self.first = false; panic!("first message panic"); }
+        }
+    }
+    let sc = spawn_count.clone();
+    let router = Router::<DWork>::new(
+        RoutingStrategy::RoundRobin, 3,
+        move |ctx| { sc.fetch_add(1, Ordering::Relaxed); ctx.spawn(PanicOnFirst { first: sc.load(Ordering::Relaxed) == 1 }) },
+        10,
+    );
+    let router_addr = rt.spawn(router).unwrap();
+    rt.tick();
+    rt.send_to(router_addr, DWork).unwrap();
+    tick_n(&rt, 5);
+    assert!(spawn_count.load(Ordering::Relaxed) >= 4, "replacement spawned");
+
+    // Meltdown: max_restarts=2
+    let rt = std_runtime(RuntimeConfig::default());
+    struct AlwaysPanics;
+    #[derive(Clone)]
+    struct MWork;
+    impl ActorInterface for AlwaysPanics {
+        type Incoming = MWork;
+        type Response = ();
+        fn handle(&mut self, _ctx: &Ctx, _msg: MWork) { panic!("always"); }
+    }
+    let router = Router::<MWork>::new(
+        RoutingStrategy::RoundRobin, 1,
+        |ctx| ctx.spawn(AlwaysPanics), 2,
+    );
+    let router_addr = rt.spawn(router).unwrap();
+    rt.tick();
+    for _ in 0..3 {
+        rt.send_to(router_addr, MWork).unwrap();
+        tick_n(&rt, 5);
+    }
+    tick_n(&rt, 5);
+    assert_eq!(rt.stats().workers[0].num_actors, 0, "router melted down");
+
+    // Stop router kills workers
+    let rt = std_runtime(RuntimeConfig::default());
+    struct Dummy;
+    #[derive(Clone)]
+    struct SWork;
+    impl ActorInterface for Dummy {
+        type Incoming = SWork;
+        type Response = ();
+        fn handle(&mut self, _ctx: &Ctx, _msg: SWork) {}
+    }
+    let router = Router::<SWork>::new(
+        RoutingStrategy::RoundRobin, 3,
+        |ctx| ctx.spawn(Dummy), 10,
+    );
+    let router_addr = rt.spawn(router).unwrap();
+    rt.tick();
+    assert_eq!(rt.stats().workers[0].num_actors, 4);
+    rt.stop_actor(router_addr).unwrap();
+    tick_n(&rt, 5);
+    assert_eq!(rt.stats().workers[0].num_actors, 0, "stop router kills workers");
+}

tests/watch_api.rs

@@ -1,335 +0,0 @@
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::Arc;
-
-use swactor::actor::{ActorAddress, ActorExited, ActorInterface, ExitReason};
-use swactor::runtime::{Ctx, Runtime, RuntimeConfig};
-use swactor_std::{CtxWatching, RuntimeWatching, StdExtension};
-
-// ── Actors ──────────────────────────────────────────────────────────────────
-
-/// An actor that panics when it receives PanicMsg.
-struct PanicOnCommand;
-
-#[derive(Clone)]
-struct PanicMsg;
-
-impl ActorInterface for PanicOnCommand {
-    type Incoming = PanicMsg;
-    type Response = ();
-    fn handle(&mut self, _ctx: &Ctx, _msg: PanicMsg) {
-        panic!("deliberate panic for test");
-    }
-}
-
-/// An actor that watches targets and counts exit notifications.
-struct ExitWatcher {
-    exit_count: Arc<AtomicUsize>,
-    last_reason: Arc<std::sync::Mutex<Option<ExitReason>>>,
-    last_addr: Arc<std::sync::Mutex<Option<ActorAddress>>>,
-}
-
-#[derive(Clone)]
-enum WatcherCmd {
-    WatchThis(ActorAddress),
-    UnwatchThis(ActorAddress),
-}
-
-impl ActorInterface for ExitWatcher {
-    type Incoming = WatcherCmd;
-    type Response = ();
-    fn handle(&mut self, ctx: &Ctx, msg: WatcherCmd) {
-        match msg {
-            WatcherCmd::WatchThis(target) => {
-                ctx.watch(target);
-            }
-            WatcherCmd::UnwatchThis(target) => {
-                ctx.unwatch(target);
-            }
-        }
-    }
-
-    fn on_actor_exit(&mut self, _ctx: &Ctx, exited: ActorExited) {
-        self.exit_count.fetch_add(1, Ordering::SeqCst);
-        *self.last_reason.lock().unwrap() = Some(exited.reason);
-        *self.last_addr.lock().unwrap() = Some(exited.addr);
-    }
-}
-
-impl ExitWatcher {
-    fn new() -> (Self, WatcherState) {
-        let exit_count = Arc::new(AtomicUsize::new(0));
-        let last_reason = Arc::new(std::sync::Mutex::new(None));
-        let last_addr = Arc::new(std::sync::Mutex::new(None));
-        let state = WatcherState {
-            exit_count: exit_count.clone(),
-            last_reason: last_reason.clone(),
-            last_addr: last_addr.clone(),
-        };
-        (
-            ExitWatcher {
-                exit_count,
-                last_reason,
-                last_addr,
-            },
-            state,
-        )
-    }
-}
-
-/// Shared state for inspecting what ExitWatcher observed.
-struct WatcherState {
-    exit_count: Arc<AtomicUsize>,
-    last_reason: Arc<std::sync::Mutex<Option<ExitReason>>>,
-    last_addr: Arc<std::sync::Mutex<Option<ActorAddress>>>,
-}
-
-impl WatcherState {
-    fn count(&self) -> usize {
-        self.exit_count.load(Ordering::SeqCst)
-    }
-    fn last_reason(&self) -> Option<ExitReason> {
-        self.last_reason.lock().unwrap().clone()
-    }
-    fn last_addr(&self) -> Option<ActorAddress> {
-        *self.last_addr.lock().unwrap()
-    }
-}
-
-/// A silent actor that does nothing (for targets that shouldn't panic).
-struct Sleeper;
-
-#[derive(Clone)]
-struct Noop;
-
-impl ActorInterface for Sleeper {
-    type Incoming = Noop;
-    type Response = ();
-    fn handle(&mut self, _ctx: &Ctx, _msg: Noop) {}
-}
-
-// ── Helper ──────────────────────────────────────────────────────────────────
-
-fn tick_n(rt: &Runtime, n: usize) {
-    for _ in 0..n {
-        rt.tick();
-    }
-}
-
-fn watch_config() -> RuntimeConfig {
-    RuntimeConfig {
-        num_threads: 1,
-        ..RuntimeConfig::default()
-    }
-}
-
-fn watch_runtime() -> Runtime {
-    Runtime::new(watch_config())
-        .with_extension(Arc::new(StdExtension::new()))
-}
-
-// ── Tests ───────────────────────────────────────────────────────────────────
-
-/// Given a watcher and a target actor,
-/// when the target panics,
-/// then the watcher's on_actor_exit fires with ExitReason::Panicked.
-#[test]
-fn watch_receives_notification_on_panic() {
-    let rt = watch_runtime();
-    let (watcher_actor, state) = ExitWatcher::new();
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let watcher = rt.spawn(watcher_actor).unwrap();
-
-    // Tell watcher to watch the target
-    rt.send_to(watcher, WatcherCmd::WatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-
-    // Kill the target
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    assert_eq!(state.count(), 1, "watcher should have received exactly one ActorExited");
-    assert_eq!(state.last_reason(), Some(ExitReason::Panicked));
-    assert_eq!(state.last_addr(), Some(target));
-}
-
-/// Given a watcher that watches then unwatches a target,
-/// when the target panics,
-/// then the watcher receives NO notification.
-#[test]
-fn unwatch_prevents_notification() {
-    let rt = watch_runtime();
-    let (watcher_actor, state) = ExitWatcher::new();
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let watcher = rt.spawn(watcher_actor).unwrap();
-
-    // Watch
-    rt.send_to(watcher, WatcherCmd::WatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-
-    // Unwatch
-    rt.send_to(watcher, WatcherCmd::UnwatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-
-    // Kill target
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    assert_eq!(state.count(), 0, "after unwatch, no notification should be delivered");
-}
-
-/// Given a watcher that dies before the target,
-/// when the target subsequently panics,
-/// then there is no panic or leak.
-#[test]
-fn watcher_dies_before_target_no_panic() {
-    let rt = watch_runtime();
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let target2 = rt.spawn(PanicOnCommand).unwrap();
-
-    // Watch via runtime-level API
-    rt.watch(target2, target);
-    tick_n(&rt, 3);
-
-    // Kill watcher (target2) first
-    rt.send_to(target2, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    // Kill target — should not crash
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    // If we got here, no crash.
-}
-
-/// Given a watcher that calls watch() twice on the same target,
-/// when the target panics,
-/// then the watcher receives exactly one notification.
-#[test]
-fn idempotent_watch_delivers_one_notification() {
-    let rt = watch_runtime();
-    let (watcher_actor, state) = ExitWatcher::new();
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let watcher = rt.spawn(watcher_actor).unwrap();
-
-    // Watch twice
-    rt.send_to(watcher, WatcherCmd::WatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-    rt.send_to(watcher, WatcherCmd::WatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-
-    // Kill target
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    assert_eq!(state.count(), 1, "double watch should produce exactly one notification");
-}
-
-/// Given multiple watchers on the same target,
-/// when the target panics,
-/// then all watchers receive the notification.
-#[test]
-fn multiple_watchers_all_notified() {
-    let rt = watch_runtime();
-    let (w1_actor, s1) = ExitWatcher::new();
-    let (w2_actor, s2) = ExitWatcher::new();
-    let (w3_actor, s3) = ExitWatcher::new();
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let w1 = rt.spawn(w1_actor).unwrap();
-    let w2 = rt.spawn(w2_actor).unwrap();
-    let w3 = rt.spawn(w3_actor).unwrap();
-
-    rt.send_to(w1, WatcherCmd::WatchThis(target)).unwrap();
-    rt.send_to(w2, WatcherCmd::WatchThis(target)).unwrap();
-    rt.send_to(w3, WatcherCmd::WatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    assert_eq!(s1.count(), 1, "watcher 1 should be notified");
-    assert_eq!(s2.count(), 1, "watcher 2 should be notified");
-    assert_eq!(s3.count(), 1, "watcher 3 should be notified");
-}
-
-/// Self-watch doesn't crash the runtime.
-#[test]
-fn self_watch_does_not_crash() {
-    let rt = watch_runtime();
-    let (watcher_actor, _state) = ExitWatcher::new();
-
-    let actor = rt.spawn(watcher_actor).unwrap();
-    rt.send_to(actor, WatcherCmd::WatchThis(actor)).unwrap();
-    tick_n(&rt, 5);
-
-    // No crash = pass
-}
-
-/// Runtime-level watch (outside actor context) delivers notification.
-#[test]
-fn runtime_level_watch_delivers_notification() {
-    let rt = watch_runtime();
-    let (watcher_actor, state) = ExitWatcher::new();
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let watcher = rt.spawn(watcher_actor).unwrap();
-    tick_n(&rt, 2); // ensure both spawned
-
-    rt.watch(watcher, target);
-
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    assert_eq!(state.count(), 1, "runtime-level watch should deliver notification");
-    assert_eq!(state.last_reason(), Some(ExitReason::Panicked));
-}
-
-/// Given a watcher watching target via on_actor_exit,
-/// when target panics,
-/// then the watcher can react by spawning a replacement (supervision pattern).
-#[test]
-fn watcher_can_react_to_death_by_spawning() {
-    let rt = watch_runtime();
-    let spawned = Arc::new(AtomicUsize::new(0));
-
-    struct Supervisor {
-        spawned_count: Arc<AtomicUsize>,
-    }
-
-    #[derive(Clone)]
-    enum SupervisorMsg {
-        WatchThis(ActorAddress),
-    }
-
-    impl ActorInterface for Supervisor {
-        type Incoming = SupervisorMsg;
-        type Response = ();
-        fn handle(&mut self, ctx: &Ctx, msg: SupervisorMsg) {
-            match msg {
-                SupervisorMsg::WatchThis(target) => ctx.watch(target),
-            }
-        }
-
-        fn on_actor_exit(&mut self, ctx: &Ctx, _exited: ActorExited) {
-            // React: spawn a replacement
-            let replacement = ctx.spawn(Sleeper).unwrap();
-            let _ = replacement;
-            self.spawned_count.fetch_add(1, Ordering::SeqCst);
-        }
-    }
-
-    let target = rt.spawn(PanicOnCommand).unwrap();
-    let sup = rt.spawn(Supervisor { spawned_count: spawned.clone() }).unwrap();
-
-    rt.send_to(sup, SupervisorMsg::WatchThis(target)).unwrap();
-    tick_n(&rt, 3);
-
-    rt.send_to(target, PanicMsg).unwrap();
-    tick_n(&rt, 5);
-
-    assert_eq!(spawned.load(Ordering::SeqCst), 1, "supervisor should have spawned a replacement");
-}