diff --git a/Cargo.lock b/Cargo.lock
index e1f515d..e49f82a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -883,7 +883,7 @@ checksum = "ac74c624d6b2d21f425f752262f42188365d7b8ff1aff74c82e45136510a4857"
 
 [[package]]
 name = "preserves"
-version = "0.17.2"
+version = "0.19.0"
 dependencies = [
  "base64",
  "dtoa",
@@ -895,7 +895,7 @@ dependencies = [
 
 [[package]]
 name = "preserves-schema"
-version = "0.5.0"
+version = "0.7.0"
 dependencies = [
  "convert_case",
  "glob",
diff --git a/syndicate-server/examples/pingpong.rs b/syndicate-server/examples/pingpong.rs
index f9869ce..b5674ac 100644
--- a/syndicate-server/examples/pingpong.rs
+++ b/syndicate-server/examples/pingpong.rs
@@ -170,7 +170,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
                     ds.assert(t, &Observe {
                         pattern: {
-                            let recv_label = Value::symbol(recv_label).wrap();
+                            let recv_label = AnyValue::symbol(recv_label);
                             syndicate_macros::pattern!("<=recv_label $ $>")
                         },
                         observer: Arc::clone(&consumer),
@@ -194,7 +194,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                         let action_count = c.action_count;
                         let account = Arc::clone(t.account());
                         t.linked_task(syndicate::name!("boot-ping"), async move {
-                            let padding: AnyValue = Value::ByteString(vec![0; bytes_padding]).wrap();
+                            let padding = AnyValue::bytestring(vec![0; bytes_padding]);
                             for _ in 0..turn_count {
                                 let mut events: PendingEventQueue = vec![];
                                 let current_rec = simple_record2(send_label,
diff --git a/syndicate-server/src/gatekeeper.rs b/syndicate-server/src/gatekeeper.rs
index b65bc34..52b35dd 100644
--- a/syndicate-server/src/gatekeeper.rs
+++ b/syndicate-server/src/gatekeeper.rs
@@ -8,9 +8,9 @@ use syndicate::value::NestedValue;
 
 pub fn bind(
     t: &mut Activation,
+    ds: &Arc<Cap>,
     oid: syndicate::schemas::sturdy::_Any,
     key: [u8; 16],
-    ds: &Arc<Cap>,
     target: Arc<Cap>,
 ) {
     let sr = sturdy::SturdyRef::mint(oid.clone(), &key);
diff --git a/syndicate-server/src/main.rs b/syndicate-server/src/main.rs
index 4133e60..3ea7436 100644
--- a/syndicate-server/src/main.rs
+++ b/syndicate-server/src/main.rs
@@ -60,11 +60,18 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     Actor::new().boot(tracing::Span::current(), move |t| {
         let root_ds = Cap::new(&t.create(Dataspace::new()));
+        let server_config_ds = Cap::new(&t.create(Dataspace::new()));
 
-        gatekeeper::bind(t, AnyValue::new("syndicate"), [0; 16], &root_ds, Arc::clone(&root_ds));
+        gatekeeper::bind(t, &root_ds, AnyValue::new("syndicate"), [0; 16],
+                         Arc::clone(&root_ds));
+        gatekeeper::bind(t, &root_ds, AnyValue::new("server-config"), [0; 16],
+                         Arc::clone(&server_config_ds));
 
+        services::debt_reporter::on_demand(t, Arc::clone(&server_config_ds));
         if config.debt_reporter {
-            services::debt_reporter::spawn(t);
+            server_config_ds.assert(t, &syndicate::schemas::service::RequireService {
+                service_name: AnyValue::symbol("debt-reporter")
+            });
         }
 
         if config.inferior {
diff --git a/syndicate-server/src/services/debt_reporter.rs b/syndicate-server/src/services/debt_reporter.rs
index 139e442..bc4e28e 100644
--- a/syndicate-server/src/services/debt_reporter.rs
+++ b/syndicate-server/src/services/debt_reporter.rs
@@ -1,18 +1,44 @@
-use syndicate::actor::*;
+use std::sync::Arc;
 
-pub fn spawn(t: &mut Activation) {
-    t.spawn(syndicate::name!("debt-reporter"), |t| {
-        t.linked_task(syndicate::name!("tick"), async {
-            let mut timer = tokio::time::interval(core::time::Duration::from_secs(1));
-            loop {
-                timer.tick().await;
-                for (id, (name, debt)) in syndicate::actor::ACCOUNTS.read().unwrap().iter() {
-                    let _enter = name.enter();
-                    tracing::info!(id, debt = debug(
-                        debt.load(std::sync::atomic::Ordering::Relaxed)));
-                }
-            }
+use syndicate::actor::*;
+use syndicate::during::entity;
+use syndicate::schemas::dataspace::Observe;
+use syndicate::value::NestedValue;
+
+const SERVICE_NAME: &str = "debt-reporter";
+
+pub fn on_demand(t: &mut Activation, ds: Arc<Cap>) {
+    t.spawn(syndicate::name!("on_demand", service = SERVICE_NAME), move |t| {
+        let monitor = entity(())
+            .on_asserted_facet(|_, t, _| {
+                t.spawn_link(syndicate::name!(SERVICE_NAME), run);
+                Ok(())
+            })
+            .create_cap(t);
+        let service_sym = AnyValue::symbol(SERVICE_NAME);
+        ds.assert(t, &Observe {
+            pattern: syndicate_macros::pattern!("<require-service =service_sym>"),
+            observer: monitor,
         });
         Ok(())
-    });
+    })
+}
+
+// pub fn spawn(t: &mut Activation) {
+//     t.spawn(syndicate::name!(SERVICE_NAME), run);
+// }
+
+fn run(t: &mut Activation) -> ActorResult {
+    t.linked_task(syndicate::name!("tick"), async {
+        let mut timer = tokio::time::interval(core::time::Duration::from_secs(1));
+        loop {
+            timer.tick().await;
+            for (id, (name, debt)) in syndicate::actor::ACCOUNTS.read().unwrap().iter() {
+                let _enter = name.enter();
+                tracing::info!(id, debt = debug(
+                    debt.load(std::sync::atomic::Ordering::Relaxed)));
+            }
+        }
+    });
+    Ok(())
 }
diff --git a/syndicate/Cargo.toml b/syndicate/Cargo.toml
index 94c6018..f0d772e 100644
--- a/syndicate/Cargo.toml
+++ b/syndicate/Cargo.toml
@@ -13,11 +13,11 @@ license = "Apache-2.0"
 vendored-openssl = ["openssl/vendored"]
 
 [build-dependencies]
-preserves-schema = "0.5.0"
+preserves-schema = "0.7.0"
 
 [dependencies]
-preserves = "0.17.2"
-preserves-schema = "0.5.0"
+preserves = "0.19.0"
+preserves-schema = "0.7.0"
 
 tokio = { version = "1.10.0", features = ["io-util", "macros", "sync", "net", "rt", "rt-multi-thread", "time"] }
 tokio-util = "0.6.7"
diff --git a/syndicate/benches/bench_dataspace.rs b/syndicate/benches/bench_dataspace.rs
index 43b0231..2619897 100644
--- a/syndicate/benches/bench_dataspace.rs
+++ b/syndicate/benches/bench_dataspace.rs
@@ -104,7 +104,7 @@ pub fn bench_pub(c: &mut Criterion) {
                         ds.assert(t, &Observe {
                             pattern: p::Pattern::DBind(Box::new(p::DBind {
                                 pattern: p::Pattern::DLit(Box::new(p::DLit {
-                                    value: Value::symbol("consumer").wrap(),
+                                    value: AnyValue::symbol("consumer"),
                                 })),
                             })),
                             observer: shutdown,
@@ -126,7 +126,7 @@ pub fn bench_pub(c: &mut Criterion) {
                             ds.assert(t, &Observe {
                                 pattern: p::Pattern::DCompound(Box::new(p::DCompound::Rec {
                                     ctor: Box::new(p::CRec {
-                                        label: Value::symbol("Says").wrap(),
+                                        label: AnyValue::symbol("Says"),
                                         arity: 2.into(),
                                     }),
                                     members: Map::from_iter(vec![
diff --git a/syndicate/src/actor.rs b/syndicate/src/actor.rs
index 94eb5a4..a68bdc5 100644
--- a/syndicate/src/actor.rs
+++ b/syndicate/src/actor.rs
@@ -393,6 +393,10 @@ where
     underlying: Arc<Ref<M>>
 }
 
+/// Simple entity that stops its containing facet when any assertion it receives is
+/// subsequently retracted.
+pub struct StopOnRetract;
+
 //---------------------------------------------------------------------------
 
 const BUMP_AMOUNT: u8 = 10;
@@ -578,13 +582,7 @@ impl<'activation> Activation<'activation> {
     pub fn assert<M: 'static + Send>(&mut self, r: &Arc<Ref<M>>, a: M) -> Handle {
         let handle = next_handle();
         if let Some(f) = self.active_facet() {
-            {
-                let r = Arc::clone(r);
-                f.cleanup_actions.insert(
-                    handle,
-                    CleanupAction::ForAnother(Arc::clone(&r.mailbox), Box::new(
-                        move |t| t.with_entity(&r, |t, e| e.retract(t, handle)))));
-            }
+            f.insert_retract_cleanup_action(&r, handle);
             drop(f);
             {
                 let r = Arc::clone(r);
@@ -630,6 +628,13 @@ impl<'activation> Activation<'activation> {
         handle
     }
 
+    fn half_link(&mut self, t_other: &mut Activation) {
+        let entity_ref = t_other.create::<AnyValue, _>(StopOnRetract);
+        let handle = next_handle();
+        self.active_facet().unwrap().insert_retract_cleanup_action(&entity_ref, handle);
+        t_other.with_entity(&entity_ref, |t, e| e.assert(t, AnyValue::new(true), handle)).unwrap();
+    }
+
     /// Core API: retract a previously-established assertion.
     pub fn retract(&mut self, handle: Handle) {
         if let Some(f) = self.active_facet() {
@@ -782,9 +787,28 @@ impl<'activation> Activation<'activation> {
         }));
     }
 
+    /// Schedule the creation of a new actor when the Activation commits.
+    ///
+    /// The new actor will be "linked" to the active facet: if the new actor terminates, the
+    /// active facet is stopped, and if the active facet stops, the new actor's root facet is
+    /// stopped.
+    pub fn spawn_link<F: 'static + Send + FnOnce(&mut Activation) -> ActorResult>(
+        &mut self,
+        name: tracing::Span,
+        boot: F,
+    ) {
+        let facet_id = self.facet.facet_id;
+        self.enqueue_for_myself_at_commit(Box::new(move |t| {
+            t.with_facet(true, facet_id, move |t| {
+                Actor::new().link(t).boot(name, boot);
+                Ok(())
+            })
+        }));
+    }
+
     /// Create a new subfacet of the currently-active facet. Runs `boot` in the new facet's
     /// context. If `boot` returns leaving the new facet [inert][Facet#inert-facets],
-    pub fn facet<F: 'static + Send + FnOnce(&mut Activation) -> ActorResult>(
+    pub fn facet<F: FnOnce(&mut Activation) -> ActorResult>(
         &mut self,
         boot: F,
     ) -> Result<FacetId, Error> {
@@ -847,9 +871,13 @@ impl<'activation> Activation<'activation> {
     }
 
     fn stop_if_inert(&mut self) {
-        if self.state.facet_exists_and_is_inert(self.facet.facet_id) {
-            self.stop_facet(self.facet.facet_id, None);
-        }
+        let facet_id = self.facet.facet_id;
+        self.enqueue_for_myself_at_commit(Box::new(move |t| {
+            if t.state.facet_exists_and_is_inert(facet_id) {
+                t.stop_facet(facet_id, None);
+            }
+            Ok(())
+        }))
     }
 
     fn _terminate_facet(&mut self, facet_id: FacetId, orderly: bool) -> ActorResult {
@@ -1082,6 +1110,18 @@ impl Actor {
         }
     }
 
+    fn link(self, t_parent: &mut Activation) -> Self {
+        if t_parent.active_facet().is_none() {
+            panic!("No active facet when calling spawn_link");
+        }
+        self.ac_ref.root_facet_ref().activate(Account::new(crate::name!("link")), |t_child| {
+            t_parent.half_link(t_child);
+            t_child.half_link(t_parent);
+            Ok(())
+        }).expect("Failed during link");
+        self
+    }
+
     /// Start the actor's mainloop. Takes ownership of `self`. The
     /// `name` is used as context for any log messages emitted by the
     /// actor. The `boot` function is called in the actor's context,
@@ -1111,12 +1151,7 @@ impl Actor {
         &mut self,
         boot: F,
     ) -> () {
-        let root = self.ac_ref.access(|s| match s.expect("New actor missing its state") {
-            ActorState::Terminated { .. } => panic!("New actor unexpectedly in terminated state"),
-            ActorState::Running(ra) => ra.root, // what a lot of work to get this one number
-        });
-
-        let root_facet_ref = self.ac_ref.facet_ref(root);
+        let root_facet_ref = self.ac_ref.root_facet_ref();
 
         let terminate = |result: ActorResult| {
             let _ = root_facet_ref.activate_exit(Account::new(crate::name!("shutdown")),
@@ -1185,6 +1220,14 @@ impl Facet {
             }
         }
     }
+
+    fn insert_retract_cleanup_action<M: 'static + Send>(&mut self, r: &Arc<Ref<M>>, handle: Handle) {
+        let r = Arc::clone(r);
+        self.cleanup_actions.insert(
+            handle,
+            CleanupAction::ForAnother(Arc::clone(&r.mailbox), Box::new(
+                move |t| t.with_entity(&r, |t, e| e.retract(t, handle)))));
+    }
 }
 
 fn panicked_err() -> Option<ActorResult> {
@@ -1221,6 +1264,17 @@ impl ActorRef {
             facet_id,
         }
     }
+
+    fn root_facet_id(&self) -> FacetId {
+        self.access(|s| match s.expect("Actor missing its state") {
+            ActorState::Terminated { .. } => panic!("Actor unexpectedly in terminated state"),
+            ActorState::Running(ra) => ra.root, // what a lot of work to get this one number
+        })
+    }
+
+    fn root_facet_ref(&self) -> FacetRef {
+        self.facet_ref(self.root_facet_id())
+    }
 }
 
 impl RunningActor {
@@ -1494,6 +1548,13 @@ where
     }
 }
 
+impl<M> Entity<M> for StopOnRetract {
+    fn retract(&mut self, t: &mut Activation, _h: Handle) -> ActorResult {
+        t.stop();
+        Ok(())
+    }
+}
+
 /// A convenient Syndicate-enhanced variation on
 /// [`tracing::info_span`].
 ///
diff --git a/syndicate/src/during.rs b/syndicate/src/during.rs
index 911c3eb..a5f9773 100644
--- a/syndicate/src/during.rs
+++ b/syndicate/src/during.rs
@@ -85,6 +85,22 @@ where
         }
     }
 
+    pub fn on_asserted_facet<Fa1>(
+        self,
+        mut assertion_handler: Fa1,
+    ) -> DuringEntity<M, E, Box<dyn 'static + Send + FnMut(&mut E, &mut Activation, M) -> DuringResult<E>>, Fm>
+    where
+        Fa1: 'static + Send + FnMut(&mut E, &mut Activation, M) -> ActorResult
+    {
+        self.on_asserted(Box::new(move |state, t, a| {
+            let facet_id = t.facet(|t| assertion_handler(state, t, a))?;
+            Ok(Some(Box::new(move |_state, t| {
+                t.stop_facet(facet_id, None);
+                Ok(())
+            })))
+        }))
+    }
+
     pub fn on_message<Fm1>(self, message_handler: Fm1) -> DuringEntity<M, E, Fa, Fm1>
     where
         Fm1: 'static + Send + FnMut(&mut E, &mut Activation, M) -> ActorResult,
diff --git a/syndicate/src/error.rs b/syndicate/src/error.rs
index e13c0e6..16f674c 100644
--- a/syndicate/src/error.rs
+++ b/syndicate/src/error.rs
@@ -36,12 +36,12 @@ pub fn error<Detail>(message: &str, detail: Detail) -> Error where _Any: From<De
 pub fn encode_error(result: Result<(), Error>) -> _Any {
     match result {
         Ok(()) => {
-            let mut r = Value::record(Value::symbol("Ok").wrap(), 1);
-            r.fields_vec_mut().push(Value::record(Value::symbol("tuple").wrap(), 0).finish().wrap());
+            let mut r = Value::record(_Any::symbol("Ok"), 1);
+            r.fields_vec_mut().push(Value::record(_Any::symbol("tuple"), 0).finish().wrap());
             r.finish().wrap()
         }
         Err(e) => {
-            let mut r = Value::record(Value::symbol("Err").wrap(), 1);
+            let mut r = Value::record(_Any::symbol("Err"), 1);
             r.fields_vec_mut().push((&e).into());
             r.finish().wrap()
         }