Reduce leaf hook data actions

API.md

@@ -168,6 +168,10 @@ impl<T, LeafError> NodeRuntime<T, LeafError> {
 
     pub fn dispatch_local_effects(&mut self) -> Result<usize, LeafDispatchError<LeafError>>;
 
+    pub fn reduce_leaf_actions(&mut self) -> Result<usize, NodeRuntimeError<T::Error>>
+    where
+        T: Transport;
+
     pub fn drain_leaf_actions(&mut self) -> impl Iterator<Item = (LeafId, LeafAction)>;
 }
 
@@ -325,21 +329,24 @@ connection closes or unregisters
 
 ## Known Gaps In The Current Branch
 
-- `LeafAction` values are queued by `LeafContext` but not yet applied by
-  `NodeRuntime`.
+- `LeafAction::SendHookData` is reduced by `NodeRuntime`; other action variants
+  are still unsupported and must remain queued when encountered.
 - Local outbound calls through the runtime are not implemented.
+- Hook fault actions through the runtime are not implemented.
+- Connection actions through the runtime are not implemented.
 - Disconnect does not yet clean hooks, sessions, route state, and queued effects.
 - Child ingress still allocates because the existing `Ingress::Child` owns a
   `Vec<String>`.
 
 ## Next Implementation Slice
 
-Implement one narrow end-to-end path:
+Implement the next narrow leaf-action path:
 
-1. Apply queued `LeafAction::SendHookData` through endpoint packet state.
-2. Route the produced frame through `Transport`.
-3. Add tests proving a leaf reply is framed and
-   sent through a registered connection.
+1. Apply queued `LeafAction::SendCall` through endpoint packet state.
+2. Preserve hook reservation and routing failure semantics without dropping
+   unprocessed actions.
+3. Add tests proving a local leaf can initiate an outbound call and receive the
+   response through the existing dispatch path.
 
-That slice forces the real architecture to work without overbuilding the rest of
-the migration.
+That slice should continue the one-variant-at-a-time reducer approach without
+implementing hook faults or connection actions early.

unshell-protocol/src/protocol/tree/endpoint/hooks.rs

@@ -133,10 +133,19 @@ impl ProtocolEndpoint {
         Ok(EndpointOutcome::Dropped)
     }
 
-    pub(crate) fn decide_route(&self, dst_path: &[String]) -> RouteDecision {
+    /// Returns the current route decision for an absolute destination path.
+    ///
+    /// Runtime owners use this to validate transport availability before invoking
+    /// endpoint operations that also mutate hook state.
+    #[must_use]
+    pub fn route_decision(&self, dst_path: &[String]) -> RouteDecision {
         self.routing.route(dst_path)
     }
 
+    pub(crate) fn decide_route(&self, dst_path: &[String]) -> RouteDecision {
+        self.route_decision(dst_path)
+    }
+
     /// Returns whether one `src_path` is topologically valid for the ingress side that delivered
     /// the frame.
     ///

unshell-runtime/src/node/packet.rs

@@ -68,6 +68,25 @@ impl EndpointState {
         &mut self.endpoint
     }
 
+    /// Returns the endpoint's current route decision for an absolute path.
+    #[must_use]
+    pub fn route_decision(&self, dst_path: &[alloc::string::String]) -> RouteDecision {
+        self.endpoint.route_decision(dst_path)
+    }
+
+    /// Builds and routes one hook-data packet through the wrapped endpoint state.
+    pub fn send_hook_data(
+        &mut self,
+        dst_path: alloc::vec::Vec<alloc::string::String>,
+        hook_id: u64,
+        procedure_id: alloc::string::String,
+        data: alloc::vec::Vec<u8>,
+        end_hook: bool,
+    ) -> Result<EndpointOutcome, EndpointError> {
+        self.endpoint
+            .send_data(dst_path, hook_id, procedure_id, data, end_hook)
+    }
+
     /// Consumes the wrapper and returns the underlying protocol endpoint.
     #[must_use]
     pub fn into_endpoint(self) -> ProtocolEndpoint {

unshell-runtime/src/node/runtime.rs

@@ -2,8 +2,8 @@
 //!
 //! This first slice owns transport and connection metadata, derives ingress from
 //! registered connections, delegates packet invariants to [`EndpointState`], and
-//! queues concrete runtime effects. Leaf action application is intentionally not
-//! implemented in this slice.
+//! queues concrete runtime effects. Leaf action reduction is intentionally
+//! narrow: this slice only turns hook-data replies into endpoint outcomes.
 
 use crate::alloc::{string::String, vec::Vec};
 use crate::connections::{
@@ -65,6 +65,13 @@ pub enum NodeRuntimeError<TransportError> {
     Endpoint(EndpointError),
     /// Transport send, receive, or flush failed.
     Transport(TransportError),
+    /// A queued leaf action is not implemented by this runtime slice.
+    UnsupportedLeafAction {
+        /// Leaf id that requested the action.
+        leaf_id: LeafId,
+        /// Stable action name for diagnostics.
+        action: &'static str,
+    },
 }
 
 /// Error returned when a leaf callback rejects a local event.
@@ -107,6 +114,13 @@ where
             Self::MissingRouteConnection => f.write_str("route has no registered connection"),
             Self::Endpoint(error) => write!(f, "{error}"),
             Self::Transport(error) => write!(f, "{error}"),
+            Self::UnsupportedLeafAction { leaf_id, action } => {
+                write!(
+                    f,
+                    "leaf {} requested unsupported action {action}",
+                    leaf_id.as_str()
+                )
+            }
         }
     }
 }
@@ -343,9 +357,6 @@ impl<T, LeafError> NodeRuntime<T, LeafError> {
     }
 
     /// Returns leaf actions queued by dispatched callbacks.
-    ///
-    /// These actions are intentionally only retained here; reducing them into
-    /// endpoint packets or connection changes belongs to a later runtime slice.
     #[must_use]
     pub fn leaf_actions(&self) -> &[(LeafId, LeafAction)] {
         &self.leaf_actions
@@ -530,29 +541,76 @@ where
         self.apply_outcome(outcome)
     }
 
-    fn apply_outcome(
-        &mut self,
-        outcome: EndpointOutcome,
-    ) -> Result<(), NodeRuntimeError<T::Error>> {
-        match outcome {
-            EndpointOutcome::Forward { route, frame } => self.queue_forward(route, frame),
-            EndpointOutcome::Local(event) => {
-                self.effects.push(RuntimeEffect::Local(event));
-                Ok(())
-            }
-            EndpointOutcome::Dropped => {
-                self.effects.push(RuntimeEffect::Dropped);
-                Ok(())
+    /// Reduces queued leaf actions through endpoint packet state.
+    ///
+    /// Only [`LeafAction::SendHookData`] is implemented in this slice. Unsupported
+    /// actions stop reduction and remain queued with all later actions so callers
+    /// can retry after a future runtime gains support.
+    pub fn reduce_leaf_actions(&mut self) -> Result<usize, NodeRuntimeError<T::Error>> {
+        let mut reduced = 0usize;
+        let mut retained = Vec::new();
+        let mut pending = core::mem::take(&mut self.leaf_actions).into_iter();
+
+        while let Some((leaf_id, action)) = pending.next() {
+            match action {
+                LeafAction::SendHookData(data) => {
+                    let original_action = LeafAction::SendHookData(data.clone());
+                    let route = self.endpoint.route_decision(&data.dst_path);
+                    if route_requires_connection(route)
+                        && self.connection_for_route(route).is_none()
+                    {
+                        retained.push((leaf_id, original_action));
+                        retained.extend(pending);
+                        self.leaf_actions = retained;
+                        return Err(NodeRuntimeError::MissingRouteConnection);
+                    }
+
+                    let outcome = match self.endpoint.send_hook_data(
+                        data.dst_path,
+                        data.hook_id,
+                        data.procedure_id,
+                        data.payload,
+                        data.end_hook,
+                    ) {
+                        Ok(outcome) => outcome,
+                        Err(error) => {
+                            retained.push((leaf_id, original_action));
+                            retained.extend(pending);
+                            self.leaf_actions = retained;
+                            return Err(NodeRuntimeError::Endpoint(error));
+                        }
+                    };
+
+                    if let Err(error) = self.apply_outcome(outcome) {
+                        retained.push((leaf_id, original_action));
+                        retained.extend(pending);
+                        self.leaf_actions = retained;
+                        return Err(error);
+                    }
+                    reduced += 1;
+                }
+                unsupported => {
+                    let action_name = leaf_action_name(&unsupported);
+                    retained.push((leaf_id.clone(), unsupported));
+                    retained.extend(pending);
+                    self.leaf_actions = retained;
+                    return Err(NodeRuntimeError::UnsupportedLeafAction {
+                        leaf_id,
+                        action: action_name,
+                    });
+                }
             }
         }
+
+        self.leaf_actions = retained;
+        Ok(reduced)
     }
 
-    fn queue_forward(
-        &mut self,
+    fn connection_for_route(
+        &self,
         route: RouteDecision,
-        frame: FrameBytes,
-    ) -> Result<(), NodeRuntimeError<T::Error>> {
-        let (connection, generation) = match route {
+    ) -> Option<(ConnectionId, ConnectionGeneration)> {
+        match route {
             RouteDecision::Parent => self
                 .connections
                 .registered_by_direction(ConnectionDirection::Parent)
@@ -582,7 +640,33 @@ where
                 }),
             RouteDecision::Local | RouteDecision::Drop => None,
         }
-        .ok_or(NodeRuntimeError::MissingRouteConnection)?;
+    }
+
+    fn apply_outcome(
+        &mut self,
+        outcome: EndpointOutcome,
+    ) -> Result<(), NodeRuntimeError<T::Error>> {
+        match outcome {
+            EndpointOutcome::Forward { route, frame } => self.queue_forward(route, frame),
+            EndpointOutcome::Local(event) => {
+                self.effects.push(RuntimeEffect::Local(event));
+                Ok(())
+            }
+            EndpointOutcome::Dropped => {
+                self.effects.push(RuntimeEffect::Dropped);
+                Ok(())
+            }
+        }
+    }
+
+    fn queue_forward(
+        &mut self,
+        route: RouteDecision,
+        frame: FrameBytes,
+    ) -> Result<(), NodeRuntimeError<T::Error>> {
+        let (connection, generation) = self
+            .connection_for_route(route)
+            .ok_or(NodeRuntimeError::MissingRouteConnection)?;
 
         self.effects.push(RuntimeEffect::SendFrame {
             connection,
@@ -649,6 +733,19 @@ fn local_event_leaf_name(event: &LocalEvent) -> Option<&str> {
     }
 }
 
+fn leaf_action_name(action: &LeafAction) -> &'static str {
+    match action {
+        LeafAction::SendCall(_) => "SendCall",
+        LeafAction::SendHookData(_) => "SendHookData",
+        LeafAction::FailHook { .. } => "FailHook",
+        LeafAction::Connection(_) => "Connection",
+    }
+}
+
+const fn route_requires_connection(route: RouteDecision) -> bool {
+    matches!(route, RouteDecision::Parent | RouteDecision::Child(_))
+}
+
 #[cfg(test)]
 mod tests {
     use core::cell::RefCell;
@@ -659,16 +756,20 @@ mod tests {
     use crate::alloc::vec;
     use crate::alloc::vec::Vec;
     use crate::connections::{
-        Connection, ConnectionDirection, ConnectionGeneration, ConnectionId, Connections,
+        Connection, ConnectionDirection, ConnectionGeneration, ConnectionId, ConnectionState,
+        Connections,
     };
-    use crate::context::{LeafAction, OutboundHookData};
+    use crate::context::{ConnectionAction, LeafAction, OutboundCall, OutboundHookData};
     use crate::effects::RuntimeEffect;
     use crate::leaf::{Leaf, LeafCapabilities, LeafPermissions};
     use crate::transport::Transport;
     use unshell_protocol::tree::{
         ChildRoute, EndpointError, IncomingCall, LeafSpec, LocalEvent, ProtocolEndpoint,
     };
-    use unshell_protocol::{CallMessage, FrameBytes, PacketHeader, PacketType, encode_packet};
+    use unshell_protocol::{
+        CallMessage, FrameBytes, HookTarget, PacketHeader, PacketType, ProtocolFault, decode_frame,
+        encode_packet,
+    };
 
     use super::{EndpointState, NodeRuntime, NodeRuntimeError, TickBudget};
 
@@ -1304,6 +1405,232 @@ mod tests {
         assert!(runtime.transport().sent.is_empty());
     }
 
+    #[test]
+    fn leaf_hook_data_reduces_to_parent_transport_frame() {
+        let parent = ConnectionId::new(1);
+        let mut connections = Connections::new();
+        connections.push(Connection::registered(
+            parent,
+            ConnectionDirection::Parent,
+            vec![],
+            ConnectionGeneration::INITIAL,
+        ));
+
+        let leaf_name = "org.example.v1.echo";
+        let endpoint = ProtocolEndpoint::new(
+            vec![String::from("agent")],
+            Some(vec![]),
+            vec![],
+            vec![LeafSpec {
+                name: String::from(leaf_name),
+                procedures: vec![String::from("org.example.v1.echo.invoke")],
+            }],
+        );
+        let frame = encode_packet(
+            &PacketHeader {
+                packet_type: PacketType::Call,
+                src_path: vec![],
+                dst_path: vec![String::from("agent")],
+                dst_leaf: Some(String::from(leaf_name)),
+                hook_id: None,
+            },
+            &CallMessage {
+                procedure_id: String::from("org.example.v1.echo.invoke"),
+                data: vec![9],
+                response_hook: Some(HookTarget {
+                    hook_id: 7,
+                    return_path: vec![],
+                }),
+            },
+        )
+        .expect("frame encodes");
+        let calls = Rc::new(RefCell::new(Vec::new()));
+        let mut runtime = NodeRuntime::new(
+            EndpointState::new(endpoint),
+            connections,
+            RecordingTransport::default(),
+        );
+        runtime.register_leaf(RecordingLeaf::new(leaf_name, Rc::clone(&calls)));
+
+        runtime
+            .receive_frame(parent, frame)
+            .expect("frame processes");
+        runtime.dispatch_local_effects().expect("dispatch succeeds");
+        let reduced = runtime.reduce_leaf_actions().expect("hook data reduces");
+        let outcome = runtime.tick(TickBudget::default()).expect("tick flushes");
+
+        assert_eq!(reduced, 1);
+        assert!(runtime.leaf_actions().is_empty());
+        assert_eq!(outcome.outbound_frames, 1);
+        assert_eq!(runtime.transport().sent.len(), 1);
+        assert_eq!(runtime.transport().sent[0].0, parent);
+        let parsed = decode_frame(&runtime.transport().sent[0].1).expect("sent data decodes");
+        let header = parsed.header();
+        assert_eq!(header.packet_type, PacketType::Data);
+        assert_eq!(header.src_path, [String::from("agent")]);
+        assert_eq!(header.dst_path, Vec::<String>::new());
+        assert_eq!(header.hook_id, Some(7));
+        let data = parsed.deserialize_data().expect("payload is data");
+        assert_eq!(data.procedure_id, "org.example.v1.echo.invoke");
+        assert_eq!(data.data, [1, 2, 3]);
+        assert!(data.end_hook);
+    }
+
+    #[test]
+    fn unsupported_leaf_action_is_reported_and_retained() {
+        let leaf_id = crate::leaf::LeafId::new(String::from("org.example.v1.echo"));
+        let mut runtime = NodeRuntime::new(
+            EndpointState::new(ProtocolEndpoint::new(
+                vec![String::from("agent")],
+                Some(vec![]),
+                vec![],
+                vec![],
+            )),
+            Connections::new(),
+            RecordingTransport::default(),
+        );
+        runtime.leaf_actions.push((
+            leaf_id.clone(),
+            LeafAction::SendCall(OutboundCall {
+                dst_path: vec![],
+                dst_leaf: None,
+                procedure_id: String::from("org.example.v1.echo.invoke"),
+                payload: vec![],
+                expects_response: false,
+            }),
+        ));
+        runtime.leaf_actions.push((
+            leaf_id.clone(),
+            LeafAction::Connection(ConnectionAction::Unregister {
+                connection: ConnectionId::new(99),
+            }),
+        ));
+
+        let error = runtime
+            .reduce_leaf_actions()
+            .expect_err("unsupported action is reported");
+
+        assert!(matches!(
+            error,
+            NodeRuntimeError::UnsupportedLeafAction { ref leaf_id, action }
+                if leaf_id.as_str() == "org.example.v1.echo" && action == "SendCall"
+        ));
+        assert_eq!(runtime.leaf_actions().len(), 2);
+        assert!(matches!(
+            runtime.leaf_actions()[0].1,
+            LeafAction::SendCall(_)
+        ));
+        assert!(matches!(
+            runtime.leaf_actions()[1].1,
+            LeafAction::Connection(_)
+        ));
+    }
+
+    #[test]
+    fn failed_leaf_hook_data_routing_retains_failed_and_remaining_actions() {
+        let parent = ConnectionId::new(1);
+        let mut connections = Connections::new();
+        connections.push(Connection::registered(
+            parent,
+            ConnectionDirection::Parent,
+            vec![],
+            ConnectionGeneration::INITIAL,
+        ));
+
+        let leaf_name = "org.example.v1.echo";
+        let endpoint = ProtocolEndpoint::new(
+            vec![String::from("agent")],
+            Some(vec![]),
+            vec![],
+            vec![LeafSpec {
+                name: String::from(leaf_name),
+                procedures: vec![String::from("org.example.v1.echo.invoke")],
+            }],
+        );
+        let frame = encode_packet(
+            &PacketHeader {
+                packet_type: PacketType::Call,
+                src_path: vec![],
+                dst_path: vec![String::from("agent")],
+                dst_leaf: Some(String::from(leaf_name)),
+                hook_id: None,
+            },
+            &CallMessage {
+                procedure_id: String::from("org.example.v1.echo.invoke"),
+                data: vec![],
+                response_hook: Some(HookTarget {
+                    hook_id: 7,
+                    return_path: vec![],
+                }),
+            },
+        )
+        .expect("frame encodes");
+        let calls = Rc::new(RefCell::new(Vec::new()));
+        let mut runtime = NodeRuntime::new(
+            EndpointState::new(endpoint),
+            connections,
+            RecordingTransport::default(),
+        );
+        runtime.register_leaf(RecordingLeaf::new(leaf_name, Rc::clone(&calls)));
+        runtime
+            .receive_frame(parent, frame)
+            .expect("frame processes and activates response hook");
+        runtime.dispatch_local_effects().expect("dispatch succeeds");
+        runtime.leaf_actions.push((
+            crate::leaf::LeafId::new(String::from(leaf_name)),
+            LeafAction::FailHook {
+                hook_id: 7,
+                fault: ProtocolFault::INTERNAL_ERROR,
+            },
+        ));
+        runtime
+            .connections
+            .get_mut(parent)
+            .expect("parent connection exists")
+            .set_state(ConnectionState::Connected {
+                generation: ConnectionGeneration::INITIAL,
+            });
+
+        let error = runtime
+            .reduce_leaf_actions()
+            .expect_err("missing route connection is reported");
+
+        assert!(matches!(error, NodeRuntimeError::MissingRouteConnection));
+        assert_eq!(runtime.leaf_actions().len(), 2);
+        assert!(matches!(
+            runtime.leaf_actions()[0].1,
+            LeafAction::SendHookData(_)
+        ));
+        assert!(matches!(
+            runtime.leaf_actions()[1].1,
+            LeafAction::FailHook { .. }
+        ));
+
+        runtime
+            .register_parent_connection(parent, vec![], ConnectionGeneration::INITIAL)
+            .expect("parent route restored");
+        let retry_error = runtime
+            .reduce_leaf_actions()
+            .expect_err("later unsupported action is still reported");
+
+        assert!(matches!(
+            retry_error,
+            NodeRuntimeError::UnsupportedLeafAction {
+                action: "FailHook",
+                ..
+            }
+        ));
+        assert_eq!(runtime.leaf_actions().len(), 1);
+        assert!(matches!(
+            runtime.leaf_actions()[0].1,
+            LeafAction::FailHook { .. }
+        ));
+        assert!(matches!(
+            runtime.effects()[0],
+            RuntimeEffect::SendFrame { connection, .. } if connection == parent
+        ));
+    }
+
     #[test]
     fn unmatched_local_event_remains_queued() {
         let mut runtime = NodeRuntime::new(