feat(causal): wall-anchored send_after — user-facing timer opt-out (RFC 007)

send_after_wall / send_after_named_wall (+ Timers::insert_send_wall) arm a
message-delivery timer that opts out of the RFC 007 virtual-time shift and
fires at its raw deadline regardless of injected delay — the Send-reason
sibling of sleep_wall, closing the jar item whose substrate efbc254 landed.
For deadlines that reflect the outside world (protocol timeouts, wall-clock
schedules) rather than workload pacing. cancel_timer is anchor-agnostic and
unchanged; without the feature the API exists and is identical to send_after.

The gen_server timer layer (send_after_to, RFC 015 §5) deliberately stays
virtual-only — an opt-out there means new options on the gen_server/statem
timeout API, out of scope for now.

Tests: wall send fires at raw deadline while a virtual sibling shifts;
cancel on a wall send with debt outstanding; featureless delivery/cancel
smokes through the public named API. 15/15 causal, 34/34 binaries both
feature configs, lib clippy clean both.

src/lib.rs

@@ -80,7 +80,8 @@ pub use registry::{
 };
 pub use runtime::{init, Config, Runtime};
 pub use scheduler::{
-    block_on_io, cancel_timer, request_stop, run, self_pid, send_after, send_after_named, sleep, sleep_wall,
+    block_on_io, cancel_timer, request_stop, run, self_pid, send_after, send_after_named,
+    send_after_named_wall, send_after_wall, sleep, sleep_wall,
     spawn, spawn_addr, spawn_under, wait_readable, wait_readable_timeout, wait_writable,
     wait_writable_timeout, yield_now, FdArm, JoinError, JoinHandle,
 };

src/scheduler.rs

@@ -497,6 +497,51 @@ pub fn send_after_named<M: Send + 'static>(
     })
 }
 
+/// Wall-anchored [`send_after`] (RFC 007): under causal profiling the timer
+/// opts out of the virtual-time shift and fires at its raw deadline instead
+/// of dilating with injected delay — the user-facing opt-out whose substrate
+/// [`sleep_wall`] landed. Use it for deadlines that reflect the outside
+/// world (protocol timeouts, wall-clock schedules) rather than workload
+/// pacing. Without the `smarm-causal` feature it is identical to
+/// [`send_after`]. Cancellation via [`cancel_timer`] is unchanged.
+pub fn send_after_wall<A: crate::pid::Addressable>(
+    after: std::time::Duration,
+    dest: Pid<A>,
+    msg: A::Msg,
+) -> crate::timer::TimerId {
+    let deadline = crate::timer::deadline_from_now(after);
+    let fire = Box::new(move || {
+        let _ = crate::registry::send_to(dest, msg);
+    });
+    with_runtime(|inner| {
+        match inner.timers.lock() {
+            Ok(mut timers) => timers.insert_send_wall(deadline, dest.erase(), fire),
+            Err(e) => panic!("smarm: timers lock poisoned (core corrupt): {e}"),
+        }
+    })
+}
+
+/// Wall-anchored [`send_after_named`] (RFC 007): re-resolving name delivery,
+/// raw-deadline anchor — see [`send_after_wall`] for the semantics.
+pub fn send_after_named_wall<M: Send + 'static>(
+    after: std::time::Duration,
+    dest: Name<M>,
+    msg: M,
+) -> crate::timer::TimerId {
+    let deadline = crate::timer::deadline_from_now(after);
+    // Informational only (who armed it); not used for delivery.
+    let armed_by = current_pid().unwrap_or(Pid::new(0, 0));
+    let fire = Box::new(move || {
+        let _ = crate::registry::send(dest, msg);
+    });
+    with_runtime(|inner| {
+        match inner.timers.lock() {
+            Ok(mut timers) => timers.insert_send_wall(deadline, armed_by, fire),
+            Err(e) => panic!("smarm: timers lock poisoned (core corrupt): {e}"),
+        }
+    })
+}
+
 /// Deliver `msg` onto a channel the caller owns after `after`, rather than to a
 /// registry address. The sibling of [`send_after`] used by the gen_server timer
 /// layer (RFC 015 §5): arming a server timer must land the fire on the loop's

src/timer.rs

@@ -193,6 +193,22 @@ impl Timers {
         TimerId(self.push(deadline, pid, Reason::Send { fire }, false))
     }
 
+    /// Arm a *wall-anchored* cancellable `send_after` timer (RFC 007): the
+    /// same contract as [`insert_send`](Self::insert_send), but the entry
+    /// opts out of the virtual-time shift and fires at its raw deadline
+    /// regardless of injected delay — the `Send`-reason sibling of
+    /// [`insert_sleep_wall`](Self::insert_sleep_wall). Without the
+    /// `smarm-causal` feature this is identical to `insert_send`.
+    pub fn insert_send_wall(
+        &mut self,
+        deadline: Instant,
+        pid: Pid,
+        fire: Box<dyn FnOnce() + Send>,
+    ) -> TimerId {
+        self.armed.insert(self.next_seq);
+        TimerId(self.push(deadline, pid, Reason::Send { fire }, true))
+    }
+
     /// Cancel an armed `send_after` timer. Returns `true` if the timer was
     /// still armed (delivery is now prevented), `false` if it had already
     /// fired or been cancelled. The heap entry, if still pending, is left to be