feat: move TimerWheel from core to std via WorkerExtension

Add WorkerExtension trait (on_tick, handle_request, gc_dead) as a
per-worker counterpart to the shared RuntimeExtension. This enables
per-worker state like timer wheels to live outside core.

- TimerWheel, TimerRequest, CloneMsg → crates/std/src/timer_wheel.rs
- CtxTimers extension trait replaces Ctx::send_after_ticks/send_interval_ticks
- schedule_timer → generic post_worker_request on ContextInner
- Worker.timers → Worker.worker_ext (Option<Box<dyn WorkerExtension>>)
- StdExtension factory creates TimerWheel per worker

Core: 2440→2320 (−120). worker.rs: 696→599 (−97).
Cumulative: 2636→2320 (−316, −12.0%). worker.rs: 845→599 (−29.1%).

Authored by Claude, lovingly guided by Zachery Aaron Shores-Chmielewski

crates/std/src/ctx_ext.rs

@@ -2,6 +2,7 @@ use swactor::actor::{ActorAddress, ActorInterface, Ctx, Message, MonitorRef};
 use swactor::Error;
 
 use crate::StdExtension;
+use crate::timer_wheel::{CloneMsg, TimerRequest};
 
 fn get_ext<'a>(ctx: &'a Ctx) -> &'a StdExtension {
     ctx.extension()
@@ -96,6 +97,43 @@ impl CtxWatching for Ctx<'_> {
     }
 }
 
+/// Timer extension for [`Ctx`].
+///
+/// Provides `send_after_ticks` / `send_interval_ticks` via the per-worker
+/// [`TimerWheel`](crate::timer_wheel::TimerWheel).
+pub trait CtxTimers {
+    /// Schedule a one-shot timer: deliver `msg` to `addr` after `ticks` worker ticks.
+    ///
+    /// The message is delivered as a normal mailbox message during the fire tick,
+    /// before `tick_all` processes messages. The timer is tick-counted (deterministic),
+    /// not wall-clock based.
+    fn send_after_ticks<M: Message>(&self, addr: ActorAddress, msg: M, ticks: u64);
+
+    /// Schedule a repeating timer: deliver a clone of `msg` to `addr` every `period` ticks.
+    ///
+    /// The first delivery happens after `period` ticks. The message is cloned for each
+    /// delivery. The timer continues until the target actor is stopped/poisoned.
+    fn send_interval_ticks<M: Message>(&self, addr: ActorAddress, msg: M, period: u64);
+}
+
+impl CtxTimers for Ctx<'_> {
+    fn send_after_ticks<M: Message>(&self, addr: ActorAddress, msg: M, ticks: u64) {
+        self.raw_inner().post_worker_request(Box::new(TimerRequest::Once {
+            dest: addr,
+            msg: Box::new(msg),
+            ticks,
+        }));
+    }
+
+    fn send_interval_ticks<M: Message>(&self, addr: ActorAddress, msg: M, period: u64) {
+        self.raw_inner().post_worker_request(Box::new(TimerRequest::Interval {
+            dest: addr,
+            msg: Box::new(msg) as Box<dyn CloneMsg>,
+            period,
+        }));
+    }
+}
+
 /// Group extension for [`Ctx`].
 ///
 /// Provides `join_group`, `leave_group`, `publish`, and `group_members` via

crates/std/src/extension.rs

@@ -1,11 +1,12 @@
 use std::any::Any;
 
 use swactor::actor::{ActorAddress, Down, ExitReason, StopReason};
-use swactor::extension::RuntimeExtension;
+use swactor::extension::{RuntimeExtension, WorkerExtension};
 
 use crate::group_registry::GroupRegistry;
 use crate::monitor_registry::MonitorRegistry;
 use crate::name_registry::NameRegistry;
+use crate::timer_wheel::TimerWheel;
 use crate::watch_registry::WatchRegistry;
 
 /// Standard library extension — provides naming, monitoring, watching, and group registries.
@@ -80,4 +81,8 @@ impl RuntimeExtension for StdExtension {
     fn as_any(&self) -> &dyn Any {
         self
     }
+
+    fn create_worker_extension(&self) -> Option<Box<dyn WorkerExtension>> {
+        Some(Box::new(TimerWheel::new()))
+    }
 }

crates/std/src/lib.rs

@@ -4,6 +4,7 @@ pub mod name_registry;
 pub mod monitor_registry;
 pub mod watch_registry;
 pub mod group_registry;
+pub(crate) mod timer_wheel;
 mod extension;
 mod ctx_ext;
 mod runtime_ext;
@@ -11,5 +12,5 @@ mod runtime_ext;
 pub use supervisor::{ChildSpec, RestartPolicy, Supervisor, SupervisorStrategy};
 pub use router::{Router, RoutingStrategy};
 pub use extension::StdExtension;
-pub use ctx_ext::{CtxMonitoring, CtxNaming, CtxGroups, CtxWatching};
+pub use ctx_ext::{CtxMonitoring, CtxNaming, CtxGroups, CtxWatching, CtxTimers};
 pub use runtime_ext::{RuntimeNaming, RuntimeGroups, RuntimeWatching};

crates/std/src/timer_wheel.rs

@@ -0,0 +1,148 @@
+use std::any::Any;
+
+use swactor::actor::{ActorAddress, Message};
+use swactor::extension::WorkerExtension;
+
+// ─── Cloneable Message Trait ────────────────────────────────────────────────
+
+/// Type-erased cloneable message for interval timers.
+/// Since `Message: Clone`, all actor messages implement this.
+pub(crate) trait CloneMsg: Send {
+    fn clone_boxed(&self) -> Box<dyn Any + Send>;
+}
+
+impl<M: Message> CloneMsg for M {
+    fn clone_boxed(&self) -> Box<dyn Any + Send> {
+        Box::new(self.clone())
+    }
+}
+
+// ─── Timer Request ──────────────────────────────────────────────────────────
+
+/// Timer request from a handler, queued for processing after tick_all.
+pub(crate) enum TimerRequest {
+    /// One-shot: deliver `msg` to `dest` after `ticks` worker ticks.
+    Once {
+        dest: ActorAddress,
+        msg: Box<dyn Any + Send>,
+        ticks: u64,
+    },
+    /// Repeating: deliver a clone of `msg` to `dest` every `period` ticks.
+    Interval {
+        dest: ActorAddress,
+        msg: Box<dyn CloneMsg>,
+        period: u64,
+    },
+}
+
+// ─── Timer Wheel ────────────────────────────────────────────────────────────
+
+struct OnceTimer {
+    fire_at: u64,
+    dest: ActorAddress,
+    msg: Box<dyn Any + Send>,
+}
+
+struct IntervalTimer {
+    next_fire: u64,
+    period: u64,
+    dest: ActorAddress,
+    msg: Box<dyn CloneMsg>,
+}
+
+/// Per-worker tick-counting timer wheel.
+///
+/// Timers are deterministic (tick-counted, not wall-clock). One-shot timers
+/// fire once and are consumed; interval timers fire repeatedly every N ticks.
+pub struct TimerWheel {
+    current_tick: u64,
+    once_timers: Vec<OnceTimer>,
+    interval_timers: Vec<IntervalTimer>,
+}
+
+impl TimerWheel {
+    pub fn new() -> Self {
+        Self {
+            current_tick: 0,
+            once_timers: Vec::new(),
+            interval_timers: Vec::new(),
+        }
+    }
+
+    /// Advance the tick counter and collect all due timer messages.
+    fn fire(&mut self) -> Vec<(ActorAddress, Box<dyn Any + Send>)> {
+        self.current_tick += 1;
+        let tick = self.current_tick;
+        let mut result = Vec::new();
+
+        // Fire one-shot timers (swap-remove for O(1) removal)
+        let mut i = 0;
+        while i < self.once_timers.len() {
+            if self.once_timers[i].fire_at <= tick {
+                let timer = self.once_timers.swap_remove(i);
+                result.push((timer.dest, timer.msg));
+            } else {
+                i += 1;
+            }
+        }
+
+        // Fire interval timers
+        for timer in &mut self.interval_timers {
+            if timer.next_fire <= tick {
+                let msg = timer.msg.clone_boxed();
+                result.push((timer.dest, msg));
+                timer.next_fire = tick + timer.period;
+            }
+        }
+
+        result
+    }
+
+    /// Remove interval timers whose target was just removed from the worker.
+    fn gc_dead_intervals(&mut self, dead: &[ActorAddress]) {
+        if dead.is_empty() {
+            return;
+        }
+        self.interval_timers
+            .retain(|t| !dead.iter().any(|d| *d == t.dest));
+    }
+
+    fn add_once(&mut self, dest: ActorAddress, msg: Box<dyn Any + Send>, ticks: u64) {
+        self.once_timers.push(OnceTimer {
+            fire_at: self.current_tick + ticks,
+            dest,
+            msg,
+        });
+    }
+
+    fn add_interval(&mut self, dest: ActorAddress, msg: Box<dyn CloneMsg>, period: u64) {
+        let period = period.max(1); // prevent zero-period infinite loop
+        self.interval_timers.push(IntervalTimer {
+            next_fire: self.current_tick + period,
+            period,
+            dest,
+            msg,
+        });
+    }
+}
+
+impl WorkerExtension for TimerWheel {
+    fn on_tick(&mut self) -> Vec<(ActorAddress, Box<dyn Any + Send>)> {
+        self.fire()
+    }
+
+    fn handle_request(&mut self, request: Box<dyn Any + Send>) {
+        if let Ok(req) = request.downcast::<TimerRequest>() {
+            match *req {
+                TimerRequest::Once { dest, msg, ticks } => self.add_once(dest, msg, ticks),
+                TimerRequest::Interval { dest, msg, period } => {
+                    self.add_interval(dest, msg, period)
+                }
+            }
+        }
+    }
+
+    fn gc_dead(&mut self, dead: &[ActorAddress]) {
+        self.gc_dead_intervals(dead);
+    }
+}

fuzz/Cargo.toml

@@ -11,6 +11,7 @@ cargo-fuzz = true
 libfuzzer-sys = { version = "0.4", features = ["arbitrary-derive"] }
 arbitrary = { version = "1", features = ["derive"] }
 swactor = { path = "..", default-features = true }
+swactor-std = { path = "../crates/std" }
 
 # Prevent this from interfering with workspaces
 [workspace]

fuzz/fuzz_targets/fuzz_runtime.rs

@@ -7,9 +7,12 @@ use std::sync::OnceLock;
 use arbitrary::Arbitrary;
 use libfuzzer_sys::fuzz_target;
 
+use std::sync::Arc;
+
 use swactor::actor::{ActorAddress, ActorInterface};
 use swactor::config::RuntimeConfig;
 use swactor::runtime::{Ctx, Inbox, Runtime};
+use swactor_std::{CtxTimers, StdExtension};
 
 // ─── Run Logging ────────────────────────────────────────────────────────────
 //   FUZZ_LOG=1   → trace every run
@@ -881,7 +884,8 @@ fuzz_target!(|input: FuzzInput| {
         num_threads: 1,
         ..Default::default()
     };
-    let rt = Runtime::new(config);
+    let rt = Runtime::new(config)
+        .with_extension(Arc::new(StdExtension::new()));
     let mut state = FuzzState::new(rt, tracing);
 
     let scenario_limit = input.scenarios.len().min(64);

src/actor.rs

@@ -199,47 +199,19 @@ pub struct Down {
 /// Not a `Message` — intercepted in `tick_all` before reaching `handle_any`.
 pub(crate) struct StopSignal;
 
-/// Type-erased cloneable message for interval timers.
-/// Since `Message: Clone`, all actor messages can implement this.
-pub(crate) trait CloneMsg: Send {
-    fn clone_boxed(&self) -> Box<dyn Any + Send>;
-}
-
-impl<M: Message> CloneMsg for M {
-    fn clone_boxed(&self) -> Box<dyn Any + Send> {
-        Box::new(self.clone())
-    }
-}
-
-/// Timer request from a handler, queued for processing after tick_all.
-pub(crate) enum TimerRequest {
-    /// One-shot: deliver `msg` to `dest` after `ticks` worker ticks.
-    Once {
-        dest: ActorAddress,
-        msg: Box<dyn Any + Send>,
-        ticks: u64,
-    },
-    /// Repeating: deliver a clone of `msg` to `dest` every `period` ticks.
-    Interval {
-        dest: ActorAddress,
-        msg: Box<dyn CloneMsg>,
-        period: u64,
-    },
-}
-
 /// Object-safe inner trait for sending type-erased messages.
 ///
-/// Minimal core interface: send, spawn, stop, timers, and extension access.
-/// Registry methods (naming, monitoring, groups) are provided by extension
-/// traits in `swactor-std`.
+/// Minimal core interface: send, spawn, stop, and extension access.
+/// Registry methods (naming, monitoring, groups) and timer scheduling
+/// are provided by extension traits in `swactor-std`.
 #[allow(private_interfaces)]
 pub trait ContextInner {
     fn send_any(&self, addr: ActorAddress, msg: Box<dyn Any + Send>) -> Result<(), Error>;
     fn spawn_any(&self, addr: ActorAddress, actor: Box<dyn AnyActor>);
     /// Request graceful stop for an actor. Takes effect after the current message.
     fn request_stop(&self, addr: ActorAddress);
-    /// Schedule a timer (one-shot or interval).
-    fn schedule_timer(&self, request: TimerRequest);
+    /// Post a request to the per-worker extension (e.g., timer scheduling).
+    fn post_worker_request(&self, request: Box<dyn Any + Send>);
     /// Access the runtime extension (if installed).
     fn extension(&self) -> Option<&dyn crate::extension::RuntimeExtension>;
 }
@@ -303,29 +275,4 @@ impl<'a> Ctx<'a> {
         self.inner.send_any(addr, Box::new(StopSignal))
     }
 
-    /// Schedule a one-shot timer: deliver `msg` to `addr` after `ticks` worker ticks.
-    ///
-    /// The message is delivered as a normal mailbox message during the fire tick,
-    /// before `tick_all` processes messages. The timer is tick-counted (deterministic),
-    /// not wall-clock based.
-    pub fn send_after_ticks<M: Message>(&self, addr: ActorAddress, msg: M, ticks: u64) {
-        self.inner.schedule_timer(TimerRequest::Once {
-            dest: addr,
-            msg: Box::new(msg),
-            ticks,
-        });
-    }
-
-    /// Schedule a repeating timer: deliver a clone of `msg` to `addr` every `period` ticks.
-    ///
-    /// The first delivery happens after `period` ticks. The message is cloned for each
-    /// delivery. The timer continues until the target actor is stopped/poisoned.
-    pub fn send_interval_ticks<M: Message>(&self, addr: ActorAddress, msg: M, period: u64) {
-        self.inner.schedule_timer(TimerRequest::Interval {
-            dest: addr,
-            msg: Box::new(msg),
-            period,
-        });
-    }
-
 }

src/extension.rs

@@ -25,4 +25,29 @@ pub trait RuntimeExtension: Send + Sync {
 
     /// Downcast support for Ctx extension traits.
     fn as_any(&self) -> &dyn Any;
+
+    /// Create a per-worker extension instance. Called once per worker during init.
+    ///
+    /// Unlike `RuntimeExtension` (shared across all workers), each worker owns
+    /// its own `WorkerExtension` instance for per-worker state like timer wheels.
+    fn create_worker_extension(&self) -> Option<Box<dyn WorkerExtension>> {
+        None
+    }
+}
+
+/// Per-worker extension state, created by [`RuntimeExtension::create_worker_extension`].
+///
+/// Each worker owns its own instance. Core calls these methods during tick phases:
+/// - `on_tick`: phase 2.5 — before tick_all, returns messages to deliver
+/// - `handle_request`: phase 5.5 — processes deferred requests from handlers
+/// - `gc_dead`: after cleanup_dead — removes state for dead actors
+pub trait WorkerExtension: Send {
+    /// Called each tick before tick_all. Returns messages to deliver.
+    fn on_tick(&mut self) -> Vec<(ActorAddress, Box<dyn Any + Send>)>;
+
+    /// Process a deferred request posted during handle() via `post_worker_request`.
+    fn handle_request(&mut self, request: Box<dyn Any + Send>);
+
+    /// Clean up state for dead actors.
+    fn gc_dead(&mut self, dead: &[ActorAddress]);
 }

src/runtime.rs

@@ -7,7 +7,7 @@ use std::thread::{self, JoinHandle};
 use std::thread::Thread;
 use crate::Instant;
 
-use crate::actor::{Actor, ActorAddress, ActorInterface, AnyActor, Message, StopSignal, TimerRequest};
+use crate::actor::{Actor, ActorAddress, ActorInterface, AnyActor, Message, StopSignal};
 use crate::channel::{Receiver, Sender};
 // Re-export config types so existing code using `runtime::RuntimeConfig` still works
 pub use crate::config::{BackoffPolicy, MailboxOverflow, RuntimeConfig};
@@ -245,6 +245,12 @@ impl Runtime {
     ///
     /// Must be called before `run()` or `tick()`.
     pub fn with_extension(mut self, ext: Arc<dyn RuntimeExtension>) -> Self {
+        // Create per-worker extensions (e.g., timer wheels)
+        for worker in self.tick_workers.get_mut().iter_mut() {
+            if let Some(wext) = ext.create_worker_extension() {
+                worker.worker_ext = Some(wext);
+            }
+        }
         self.extension = Some(ext);
         self
     }
@@ -503,11 +509,10 @@ impl ContextInner for Runtime {
         }
     }
 
-    fn schedule_timer(&self, _request: TimerRequest) {
-        // Timers are per-worker and tick-counted; scheduling from outside
+    fn post_worker_request(&self, _request: Box<dyn Any + Send>) {
+        // Worker requests (e.g., timers) are per-worker; posting from outside
         // a worker context (e.g., rt.spawn() callback) is not supported.
-        // Use rt.send_to() with a delay loop instead.
-        eprintln!("swactor: schedule_timer called outside worker context — ignored");
+        eprintln!("swactor: post_worker_request called outside worker context — ignored");
     }
 
     fn extension(&self) -> Option<&dyn RuntimeExtension> {

src/worker.rs

@@ -6,107 +6,14 @@ use std::sync::Arc;
 use std::thread;
 use crate::Instant;
 
-use crate::actor::{ActorAddress, AnyActor, CloneMsg, ContextInner, Ctx, StopReason, StopSignal, TimerRequest};
+use crate::actor::{ActorAddress, AnyActor, ContextInner, Ctx, StopReason, StopSignal};
 use crate::channel::Receiver;
 use crate::config::MailboxOverflow;
 use crate::delivery::{AddrBuildHasher, AddrMap, Envelope, TickContext, WorkerId};
 use crate::stats::{ActorSnapshot, TickTiming, WorkerStats};
 use crate::Error;
 
-// ─── Per-Worker Timer Wheel ─────────────────────────────────────────────────
-
-struct OnceTimer {
-    fire_at: u64,
-    dest: ActorAddress,
-    msg: Box<dyn Any + Send>,
-}
-
-struct IntervalTimer {
-    next_fire: u64,
-    period: u64,
-    dest: ActorAddress,
-    msg: Box<dyn CloneMsg>,
-}
-
-/// Per-worker tick-counting timer wheel.
-///
-/// Timers are deterministic (tick-counted, not wall-clock). One-shot timers
-/// fire once and are consumed; interval timers fire repeatedly every N ticks.
-struct TimerWheel {
-    current_tick: u64,
-    once_timers: Vec<OnceTimer>,
-    interval_timers: Vec<IntervalTimer>,
-}
-
-impl TimerWheel {
-    fn new() -> Self {
-        Self {
-            current_tick: 0,
-            once_timers: Vec::new(),
-            interval_timers: Vec::new(),
-        }
-    }
-
-    /// Advance the tick counter and collect all due timer messages.
-    /// Returns the messages to be routed by the caller (may target local or remote actors/inboxes).
-    fn fire(&mut self) -> Vec<(ActorAddress, Box<dyn Any + Send>)> {
-        self.current_tick += 1;
-        let tick = self.current_tick;
-        let mut result = Vec::new();
-
-        // Fire one-shot timers (swap-remove for O(1) removal)
-        let mut i = 0;
-        while i < self.once_timers.len() {
-            if self.once_timers[i].fire_at <= tick {
-                let timer = self.once_timers.swap_remove(i);
-                result.push((timer.dest, timer.msg));
-            } else {
-                i += 1;
-            }
-        }
-
-        // Fire interval timers
-        for timer in &mut self.interval_timers {
-            if timer.next_fire <= tick {
-                let msg = timer.msg.clone_boxed();
-                result.push((timer.dest, msg));
-                timer.next_fire = tick + timer.period;
-            }
-        }
-
-        result
-    }
-
-    /// Remove interval timers whose target was just removed from the worker.
-    /// Only GCs timers for addresses in `dead` — inboxes and cross-worker actors
-    /// are not in the local pool but are still valid targets.
-    fn gc_dead_intervals(&mut self, dead: &[ActorAddress]) {
-        if dead.is_empty() {
-            return;
-        }
-        self.interval_timers.retain(|t| !dead.iter().any(|d| *d == t.dest));
-    }
-
-    /// Add a one-shot timer.
-    fn add_once(&mut self, dest: ActorAddress, msg: Box<dyn Any + Send>, ticks: u64) {
-        self.once_timers.push(OnceTimer {
-            fire_at: self.current_tick + ticks,
-            dest,
-            msg,
-        });
-    }
-
-    /// Add an interval timer. First fire is after `period` ticks.
-    fn add_interval(&mut self, dest: ActorAddress, msg: Box<dyn CloneMsg>, period: u64) {
-        let period = period.max(1); // prevent zero-period infinite loop
-        self.interval_timers.push(IntervalTimer {
-            next_fire: self.current_tick + period,
-            period,
-            dest,
-            msg,
-        });
-    }
-}
+use crate::extension::WorkerExtension;
 
 // ─── Worker ─────────────────────────────────────────────────────────────────
 
@@ -119,8 +26,8 @@ pub(crate) struct Worker {
     stats: Arc<WorkerStats>,
     /// Reusable scratch buffer for building per-actor snapshots.
     snapshot_buf: Vec<ActorSnapshot>,
-    /// Per-worker tick-counting timer wheel.
-    timers: TimerWheel,
+    /// Per-worker extension (e.g., timer wheel). Created by RuntimeExtension factory.
+    pub(crate) worker_ext: Option<Box<dyn WorkerExtension>>,
 }
 
 impl Worker {
@@ -139,7 +46,7 @@ impl Worker {
             spawn_rx,
             stats,
             snapshot_buf: Vec::new(),
-            timers: TimerWheel::new(),
+            worker_ext: None,
         }
     }
 
@@ -175,32 +82,31 @@ impl Worker {
         }
         let t2 = Instant::now();
 
-        // 2.5. Fire due timers → deliver to mailboxes before tick_all
-        let timer_msgs = self.timers.fire();
-        for (dest, msg) in timer_msgs {
-            if self.pool.contains(&dest) {
-                // Same-worker: deliver directly to actor's mailbox
-                self.pool.deliver(&dest, msg);
-            } else {
-                // Inbox or cross-worker: route through address map / inbox registry
-                match tc.address_map.lookup(&dest) {
-                    Some(wid) => {
-                        tc.transfer_txs[wid.as_usize()].send(Envelope::new(dest, msg));
-                        crate::runtime::notify_worker(tc.worker_threads, wid.as_usize());
-                    }
-                    None => {
-                        let _ = tc.inbox_registry.try_deliver(dest, msg);
+        // 2.5. Fire per-worker extension (e.g., timers) → deliver before tick_all
+        if let Some(ext) = &mut self.worker_ext {
+            for (dest, msg) in ext.on_tick() {
+                if self.pool.contains(&dest) {
+                    self.pool.deliver(&dest, msg);
+                } else {
+                    match tc.address_map.lookup(&dest) {
+                        Some(wid) => {
+                            tc.transfer_txs[wid.as_usize()].send(Envelope::new(dest, msg));
+                            crate::runtime::notify_worker(tc.worker_threads, wid.as_usize());
+                        }
+                        None => {
+                            let _ = tc.inbox_registry.try_deliver(dest, msg);
+                        }
                     }
                 }
+                did_work = true;
             }
-            did_work = true;
         }
 
         // 3. Tick all actors with WorkerContext
         let pending_local: RefCell<Vec<(ActorAddress, Box<dyn Any + Send>)>> =
             RefCell::new(Vec::new());
         let stop_requests: RefCell<Vec<ActorAddress>> = RefCell::new(Vec::new());
-        let timer_requests: RefCell<Vec<TimerRequest>> = RefCell::new(Vec::new());
+        let worker_requests: RefCell<Vec<Box<dyn Any + Send>>> = RefCell::new(Vec::new());
 
         let processed;
         {
@@ -209,7 +115,7 @@ impl Worker {
                 tc,
                 pending_local: &pending_local,
                 stop_requests: &stop_requests,
-                timer_requests: &timer_requests,
+                worker_requests: &worker_requests,
                 stats: &self.stats,
             };
             processed = self.pool.tick_all(&worker_ctx, &self.stats, tc.config.actor_message_budget, &stop_requests);
@@ -245,15 +151,10 @@ impl Worker {
             self.pool.deliver(&addr, msg);
         }
 
-        // 5.5. Process timer requests from handlers
-        for request in timer_requests.into_inner() {
-            match request {
-                TimerRequest::Once { dest, msg, ticks } => {
-                    self.timers.add_once(dest, msg, ticks);
-                }
-                TimerRequest::Interval { dest, msg, period } => {
-                    self.timers.add_interval(dest, msg, period);
-                }
+        // 5.5. Process worker extension requests from handlers (e.g., timer scheduling)
+        if let Some(ext) = &mut self.worker_ext {
+            for request in worker_requests.into_inner() {
+                ext.handle_request(request);
             }
         }
 
@@ -308,14 +209,14 @@ impl Worker {
         let cleanup_pending: RefCell<Vec<(ActorAddress, Box<dyn Any + Send>)>> =
             RefCell::new(Vec::new());
         let cleanup_stops: RefCell<Vec<ActorAddress>> = RefCell::new(Vec::new());
-        let cleanup_timers: RefCell<Vec<TimerRequest>> = RefCell::new(Vec::new());
+        let cleanup_requests: RefCell<Vec<Box<dyn Any + Send>>> = RefCell::new(Vec::new());
         let dead = {
             let cleanup_ctx = WorkerContext {
                 worker_id: self.id,
                 tc,
                 pending_local: &cleanup_pending,
                 stop_requests: &cleanup_stops,
-                timer_requests: &cleanup_timers,
+                worker_requests: &cleanup_requests,
                 stats: &self.stats,
             };
             let dead = self.pool.cleanup_dead(&cleanup_ctx);
@@ -362,9 +263,11 @@ impl Worker {
             self.pool.deliver(&addr, msg);
         }
 
-        // GC orphaned interval timers for actors that were just removed
-        let dead_addrs: Vec<ActorAddress> = dead.iter().map(|(a, _)| *a).collect();
-        self.timers.gc_dead_intervals(&dead_addrs);
+        // GC per-worker extension state for dead actors (e.g., orphaned interval timers)
+        if let Some(ext) = &mut self.worker_ext {
+            let dead_addrs: Vec<ActorAddress> = dead.iter().map(|(a, _)| *a).collect();
+            ext.gc_dead(&dead_addrs);
+        }
 
         did_work
     }
@@ -408,7 +311,7 @@ struct WorkerContext<'a> {
     tc: &'a TickContext<'a>,
     pending_local: &'a RefCell<Vec<(ActorAddress, Box<dyn Any + Send>)>>,
     stop_requests: &'a RefCell<Vec<ActorAddress>>,
-    timer_requests: &'a RefCell<Vec<TimerRequest>>,
+    worker_requests: &'a RefCell<Vec<Box<dyn Any + Send>>>,
     stats: &'a WorkerStats,
 }
 
@@ -445,8 +348,8 @@ impl ContextInner for WorkerContext<'_> {
         self.stop_requests.borrow_mut().push(addr);
     }
 
-    fn schedule_timer(&self, request: TimerRequest) {
-        self.timer_requests.borrow_mut().push(request);
+    fn post_worker_request(&self, request: Box<dyn Any + Send>) {
+        self.worker_requests.borrow_mut().push(request);
     }
 
     fn extension(&self) -> Option<&dyn crate::extension::RuntimeExtension> {

tests/proptest_runtime.rs

@@ -8,9 +8,12 @@ use std::collections::HashMap;
 use proptest::prelude::*;
 use proptest_state_machine::{prop_state_machine, ReferenceStateMachine, StateMachineTest};
 
+use std::sync::Arc;
+
 use swactor::actor::{ActorAddress, ActorInterface};
 use swactor::config::{MailboxOverflow, RuntimeConfig};
 use swactor::runtime::{Ctx, Inbox, Runtime};
+use swactor_std::{CtxTimers, StdExtension};
 
 // ─── Shared Actor Types ────────────────────────────────────────────────────
 
@@ -141,7 +144,8 @@ proptest! {
     /// One-shot timer fires at exactly the right tick for any delay.
     #[test]
     fn one_shot_timer_fires_at_correct_tick(delay in 1u64..20) {
-        let rt = Runtime::new(RuntimeConfig::default());
+        let rt = Runtime::new(RuntimeConfig::default())
+            .with_extension(Arc::new(StdExtension::new()));
         let inbox = rt.new_inbox::<Ping>().unwrap();
 
         struct TimerActor { target: ActorAddress, delay: u64 }
@@ -175,7 +179,8 @@ proptest! {
     /// Interval timer fires at correct periodic ticks for any period.
     #[test]
     fn interval_timer_fires_at_correct_period(period in 1u64..10) {
-        let rt = Runtime::new(RuntimeConfig::default());
+        let rt = Runtime::new(RuntimeConfig::default())
+            .with_extension(Arc::new(StdExtension::new()));
         let inbox = rt.new_inbox::<Ping>().unwrap();
 
         struct IntervalActor { target: ActorAddress, period: u64 }

tests/runtime_api.rs

@@ -3,8 +3,8 @@ use std::sync::Arc;
 
 use swactor::actor::{ActorAddress, ActorInterface, Down, MonitorRef, StopReason};
 use swactor_std::{
-    ChildSpec, CtxGroups, CtxMonitoring, CtxNaming, RestartPolicy, Router, RoutingStrategy,
-    RuntimeGroups, RuntimeNaming, StdExtension, Supervisor, SupervisorStrategy,
+    ChildSpec, CtxGroups, CtxMonitoring, CtxNaming, CtxTimers, RestartPolicy, Router,
+    RoutingStrategy, RuntimeGroups, RuntimeNaming, StdExtension, Supervisor, SupervisorStrategy,
 };
 use swactor::runtime::{Ctx, Inbox, MailboxOverflow, Runtime, RuntimeConfig};