feat(call/protocol/dispatch-streaming-branch): branch handle_stream on op_type; Subscription → invoke_streaming → pump each → call.completed

Add DispatchResult::Once|Stream enum and Dispatcher::dispatch() that branches
on the registered op_type (ADR-049 §6): Query/Mutation → invoke() (unchanged
Once path), Subscription → invoke_streaming() (Stream path). handle_stream
matches on DispatchResult: the Once path writes one call.responded/call.error
frame (no call.completed); the Stream path pumps each ResponseEnvelope to the
wire via pump_stream (ResponseEnvelope.into() → call.responded for Ok,
call.error for Err), then writes call.completed on natural stream end. An Err
envelope is terminal — last_was_error suppresses call.completed after an error.
The streaming branch clears context.deadline to None (subscriptions are
unbounded — ADR-049 §6, call-protocol Timeouts). Abort (ADR-016) needs no new
code: handle_abort removes the pending entry and dropping the pump task
releases handler resources via Drop. dispatch_requested delegates to dispatch
for backward compatibility with existing callers.

crates/alknet-call/src/protocol/dispatch.rs

@@ -17,6 +17,7 @@ use std::time::{Duration, Instant};
 
 use alknet_core::auth::{AuthToken, Identity, IdentityProvider};
 use alknet_core::types::StreamError;
+use futures::stream::StreamExt;
 use serde_json::Value;
 use tokio::task::JoinHandle;
 use tracing::{debug, warn};
@@ -30,11 +31,37 @@ use super::wire::{
 use crate::protocol::adapter::SessionOverlaySource;
 use crate::registry::context::{AbortPolicy, OperationContext, ScopedPeerEnv};
 use crate::registry::env::{LocalOperationEnv, OperationEnv, PeerCompositeEnv};
-use crate::registry::registration::OperationRegistry;
+use crate::registry::registration::{OperationRegistry, ResponseStream};
+use crate::registry::spec::OperationType;
 
 const DEFAULT_TIMEOUT: Duration = Duration::from_secs(30);
 const SWEEPER_INTERVAL: Duration = Duration::from_secs(10);
 
+/// Outcome of dispatching a `call.requested` event. The dispatcher branches on
+/// the registered operation's `op_type` (ADR-049 §6): `Query`/`Mutation` produce
+/// a single [`ResponseEnvelope`] (`Once`), `Subscription` produces a
+/// [`ResponseStream`] (`Stream`) that `handle_stream` pumps to the wire.
+///
+/// This enum is the branch point the spec describes ("branches on `op_type` in
+/// `handle_stream`"): `dispatch` returns it and `handle_stream` matches on it,
+/// keeping the Once path (one frame, no `call.completed`) and the Stream path
+/// (each envelope → frame, `call.completed` on natural end) visibly distinct.
+pub enum DispatchResult {
+    Once(ResponseEnvelope),
+    Stream(ResponseStream),
+}
+
+impl std::fmt::Debug for DispatchResult {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            DispatchResult::Once(env) => f.debug_tuple("Once").field(env).finish(),
+            DispatchResult::Stream(_) => {
+                f.debug_tuple("Stream").field(&"<ResponseStream>").finish()
+            }
+        }
+    }
+}
+
 /// Shared dispatcher for an established `CallConnection`. Constructed by
 /// both `CallAdapter` (accept path) and `CallClient` (connect path) and used
 /// to run the dispatch loop. Holds no per-connection state; the
@@ -166,6 +193,36 @@ impl Dispatcher {
         request_id: String,
         payload: Value,
     ) -> ResponseEnvelope {
+        match self.dispatch(connection, request_id, payload).await {
+            DispatchResult::Once(envelope) => envelope,
+            DispatchResult::Stream(mut stream) => stream.next().await.unwrap_or_else(|| {
+                ResponseEnvelope::error(
+                    String::new(),
+                    CallError::internal(
+                        "dispatch_requested called on a Subscription op; use the streaming path",
+                    ),
+                )
+            }),
+        }
+    }
+
+    /// Dispatch a `call.requested` event, branching on the registered
+    /// operation's `op_type` (ADR-049 §6). `Query`/`Mutation` → `invoke()` →
+    /// [`DispatchResult::Once`]; `Subscription` → `invoke_streaming()` →
+    /// [`DispatchResult::Stream`]. Unknown ops and ACL failures resolve via
+    /// the registry's own envelope/error paths (Once for `invoke`, a single
+    /// error envelope for `invoke_streaming`).
+    ///
+    /// For the streaming branch the root context's deadline is cleared
+    /// (`deadline: None`): subscriptions are long-running and unbounded — the
+    /// 30s request/response deadline does not apply (ADR-049 §6, call-protocol
+    /// Timeouts). The Once branch keeps the deadline from `build_root_context`.
+    pub async fn dispatch(
+        &self,
+        connection: &Arc<CallConnection>,
+        request_id: String,
+        payload: Value,
+    ) -> DispatchResult {
         let operation_id = payload
             .get("operationId")
             .and_then(|v| v.as_str())
@@ -180,7 +237,13 @@ impl Dispatcher {
 
         let input = payload.get("input").cloned().unwrap_or(Value::Null);
 
-        let context = self.build_root_context(
+        let is_subscription = self
+            .registry
+            .registration(&operation_name)
+            .map(|r| r.spec.op_type == OperationType::Subscription)
+            .unwrap_or(false);
+
+        let mut context = self.build_root_context(
             request_id.clone(),
             &operation_name,
             identity,
@@ -188,7 +251,16 @@ impl Dispatcher {
             connection,
         );
 
-        self.registry.invoke(&operation_name, input, context).await
+        if is_subscription {
+            context.deadline = None;
+            let stream = self
+                .registry
+                .invoke_streaming(&operation_name, input, context);
+            DispatchResult::Stream(stream)
+        } else {
+            let envelope = self.registry.invoke(&operation_name, input, context).await;
+            DispatchResult::Once(envelope)
+        }
     }
 
     pub async fn handle_abort(&self, connection: &Arc<CallConnection>, request_id: &str) {
@@ -225,16 +297,22 @@ impl Dispatcher {
                     let request_id = envelope.id.clone();
                     let payload = envelope.payload.clone();
 
-                    let response = self
-                        .dispatch_requested(&connection, request_id.clone(), payload)
-                        .await;
-
+                    match self
+                        .dispatch(&connection, request_id.clone(), payload)
+                        .await
+                    {
+                        DispatchResult::Once(response) => {
                             let event: EventEnvelope = response.into();
                             if let Err(err) = writer.write_frame(&event).await {
                                 warn!(error = %err, "failed to write response frame; closing stream");
                                 break;
                             }
                         }
+                        DispatchResult::Stream(stream) => {
+                            self.pump_stream(&mut writer, &request_id, stream).await;
+                        }
+                    }
+                }
                 EVENT_ABORTED => {
                     let request_id = envelope.id.clone();
                     self.handle_abort(&connection, &request_id).await;
@@ -246,6 +324,43 @@ impl Dispatcher {
         }
     }
 
+    /// Pump a subscription's [`ResponseStream`] to the wire: each
+    /// [`ResponseEnvelope`] becomes an [`EventEnvelope`] frame (`call.responded`
+    /// for `Ok`, `call.error` for `Err`). On natural stream end (the stream
+    /// returned `None` without the last item being an `Err`), write a
+    /// `call.completed` frame. An `Err` envelope is terminal — the stream
+    /// ends after it and we do NOT write `call.completed` (ADR-049 §6).
+    ///
+    /// If a frame write fails the pump stops early; the stream is dropped on
+    /// return, releasing the handler's resources via `Drop` (ADR-016). The
+    /// pump is cancellable: it runs inside the `handle_stream` task, so a
+    /// `call.aborted` for this request ID (handled by `handle_abort` on
+    /// another stream) or connection close cancels the task and drops the
+    /// stream.
+    pub(crate) async fn pump_stream<W: tokio::io::AsyncWrite + Unpin>(
+        &self,
+        writer: &mut super::wire::FrameFramedWriter<W>,
+        request_id: &str,
+        mut stream: ResponseStream,
+    ) {
+        let mut last_was_error = false;
+        while let Some(envelope) = stream.next().await {
+            last_was_error = envelope.result.is_err();
+            let event: EventEnvelope = envelope.into();
+            if let Err(err) = writer.write_frame(&event).await {
+                warn!(error = %err, "failed to write streaming frame; closing stream");
+                return;
+            }
+        }
+
+        if !last_was_error {
+            let completed = EventEnvelope::completed(request_id);
+            if let Err(err) = writer.write_frame(&completed).await {
+                warn!(error = %err, "failed to write call.completed");
+            }
+        }
+    }
+
     /// Run the shared dispatch loop over an established `CallConnection`:
     /// spawn the pending-entry sweeper, accept bidirectional streams until the
     /// connection closes, dispatch each stream via `handle_stream`, and fail
@@ -325,9 +440,9 @@ impl Clone for Dispatcher {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::protocol::wire::EVENT_RESPONDED;
+    use crate::protocol::wire::{EVENT_COMPLETED, EVENT_ERROR, EVENT_RESPONDED};
     use crate::registry::registration::{
-        make_handler, HandlerKind, HandlerRegistration, OperationProvenance,
+        make_handler, make_streaming_handler, HandlerKind, HandlerRegistration, OperationProvenance,
     };
     use crate::registry::spec::{AccessControl, OperationSpec, OperationType, Visibility};
     use alknet_core::auth::{AuthToken, Identity, IdentityProvider};
@@ -874,4 +989,388 @@ mod tests {
             Some(&serde_json::json!({ "v": 42 }))
         );
     }
+
+    // --- streaming dispatch branch (ADR-049 §6) ---------------------------
+
+    fn subscription_spec(name: &str, acl: AccessControl) -> OperationSpec {
+        OperationSpec::new(
+            name,
+            OperationType::Subscription,
+            Visibility::External,
+            serde_json::json!({}),
+            serde_json::json!({}),
+            vec![],
+            acl,
+        )
+    }
+
+    fn encode_frame(envelope: &EventEnvelope) -> Vec<u8> {
+        let body = serde_json::to_vec(envelope).expect("serialize envelope");
+        let mut buf = (body.len() as u32).to_be_bytes().to_vec();
+        buf.extend_from_slice(&body);
+        buf
+    }
+
+    async fn read_all_frames(
+        reader: &mut (impl tokio::io::AsyncRead + Unpin),
+    ) -> Vec<EventEnvelope> {
+        let mut buf = Vec::new();
+        use tokio::io::AsyncReadExt;
+        let _ = reader.read_to_end(&mut buf).await;
+        let mut frames = Vec::new();
+        let mut cursor = std::io::Cursor::new(buf);
+        loop {
+            let mut len_buf = [0u8; 4];
+            match tokio::io::AsyncReadExt::read_exact(&mut cursor, &mut len_buf).await {
+                Ok(_) => {}
+                Err(_) => break,
+            }
+            let len = u32::from_be_bytes(len_buf) as usize;
+            let mut body = vec![0u8; len];
+            if tokio::io::AsyncReadExt::read_exact(&mut cursor, &mut body)
+                .await
+                .is_err()
+            {
+                break;
+            }
+            let envelope: EventEnvelope =
+                serde_json::from_slice(&body).expect("deserialize written frame");
+            frames.push(envelope);
+        }
+        frames
+    }
+
+    fn registry_with_subscription(
+        name: &str,
+        handler: crate::registry::registration::StreamingHandler,
+    ) -> Arc<OperationRegistry> {
+        let mut registry = OperationRegistry::new();
+        registry
+            .register(HandlerRegistration::new(
+                subscription_spec(name, AccessControl::default()),
+                HandlerKind::Stream(handler),
+                OperationProvenance::Local,
+                None,
+                None,
+                Capabilities::new(),
+            ))
+            .unwrap();
+        Arc::new(registry)
+    }
+
+    #[tokio::test]
+    async fn dispatch_subscription_returns_stream_result() {
+        let handler = make_streaming_handler(|input, ctx| {
+            futures::stream::iter(vec![
+                ResponseEnvelope::ok(ctx.request_id.clone(), input.clone()),
+                ResponseEnvelope::ok(ctx.request_id.clone(), serde_json::json!({"done": true})),
+            ])
+        });
+        let registry = registry_with_subscription("events/stream", handler);
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let payload = serde_json::json!({
+            "operationId": "/events/stream",
+            "input": { "v": 1 },
+        });
+        match dp.dispatch(&conn, "sub-1".to_string(), payload).await {
+            DispatchResult::Stream(mut stream) => {
+                use futures::stream::StreamExt;
+                let first = stream.next().await.expect("first envelope");
+                assert_eq!(first.request_id, "sub-1");
+                assert_eq!(first.result, Ok(serde_json::json!({ "v": 1 })));
+                let second = stream.next().await.expect("second envelope");
+                assert_eq!(second.result, Ok(serde_json::json!({ "done": true })));
+                assert!(
+                    stream.next().await.is_none(),
+                    "stream ends after two values"
+                );
+            }
+            other => panic!("expected Stream, got {other:?}"),
+        }
+    }
+
+    #[tokio::test]
+    async fn dispatch_subscription_clears_deadline_to_none() {
+        let handler = make_streaming_handler(|_input, ctx| {
+            let deadline = ctx.deadline;
+            futures::stream::iter(vec![ResponseEnvelope::ok(
+                ctx.request_id.clone(),
+                serde_json::json!({ "deadline_is_none": deadline.is_none() }),
+            )])
+        });
+        let registry = registry_with_subscription("events/stream", handler);
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let payload = serde_json::json!({
+            "operationId": "/events/stream",
+            "input": {},
+        });
+        match dp.dispatch(&conn, "sub-dl".to_string(), payload).await {
+            DispatchResult::Stream(mut stream) => {
+                use futures::stream::StreamExt;
+                let env = stream.next().await.expect("one envelope");
+                let out = env.result.expect("ok");
+                assert_eq!(out["deadline_is_none"], Value::Bool(true));
+            }
+            other => panic!("expected Stream, got {other:?}"),
+        }
+    }
+
+    #[tokio::test]
+    async fn dispatch_query_keeps_deadline_some() {
+        let mut registry = OperationRegistry::new();
+        let handler = make_handler(|_input, ctx| async move {
+            let deadline_is_some = ctx.deadline.is_some();
+            ResponseEnvelope::ok(
+                ctx.request_id.clone(),
+                serde_json::json!({ "deadline_is_some": deadline_is_some }),
+            )
+        });
+        registry
+            .register(HandlerRegistration::new(
+                external_spec("echo/run", AccessControl::default()),
+                HandlerKind::Once(handler),
+                OperationProvenance::Local,
+                None,
+                None,
+                Capabilities::new(),
+            ))
+            .unwrap();
+        let registry = Arc::new(registry);
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let payload = serde_json::json!({
+            "operationId": "/echo/run",
+            "input": {},
+        });
+        match dp.dispatch(&conn, "q-1".to_string(), payload).await {
+            DispatchResult::Once(env) => {
+                let out = env.result.expect("ok");
+                assert_eq!(out["deadline_is_some"], Value::Bool(true));
+            }
+            other => panic!("expected Once, got {other:?}"),
+        }
+    }
+
+    #[tokio::test]
+    async fn handle_stream_subscription_pumps_each_frame_then_completed() {
+        let handler = make_streaming_handler(|input, ctx| {
+            let first = input.clone();
+            let rid = ctx.request_id.clone();
+            futures::stream::iter(vec![
+                ResponseEnvelope::ok(rid.clone(), first),
+                ResponseEnvelope::ok(rid.clone(), serde_json::json!({"n": 2})),
+                ResponseEnvelope::ok(rid, serde_json::json!({"n": 3})),
+            ])
+        });
+        let registry = registry_with_subscription("events/stream", handler);
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let request = EventEnvelope::requested(
+            "sub-pump-1",
+            serde_json::json!({
+                "operationId": "/events/stream",
+                "input": { "n": 1 },
+            }),
+        );
+        let recv = tokio::io::BufReader::new(std::io::Cursor::new(encode_frame(&request)));
+        let (send, mut sink) = tokio::io::duplex(8 * 1024);
+        let send = alknet_core::types::SendStream::from_mock(send);
+        let recv = alknet_core::types::RecvStream::from_mock(recv);
+
+        dp.handle_stream(conn, send, recv).await;
+
+        let frames = read_all_frames(&mut sink).await;
+        assert_eq!(frames.len(), 4, "3 responded + 1 completed");
+        for (i, f) in frames[..3].iter().enumerate() {
+            assert_eq!(f.r#type, EVENT_RESPONDED, "frame {i} is call.responded");
+            assert_eq!(f.id, "sub-pump-1");
+        }
+        assert_eq!(frames[3].r#type, EVENT_COMPLETED);
+        assert_eq!(frames[3].id, "sub-pump-1");
+        assert_eq!(frames[3].payload, serde_json::json!({}));
+    }
+
+    #[tokio::test]
+    async fn handle_stream_subscription_error_is_terminal_no_completed() {
+        let handler = make_streaming_handler(|_input, ctx| {
+            let rid = ctx.request_id.clone();
+            futures::stream::iter(vec![
+                ResponseEnvelope::ok(rid.clone(), serde_json::json!({"ok": true})),
+                ResponseEnvelope::error(rid.clone(), CallError::internal("boom")),
+            ])
+        });
+        let registry = registry_with_subscription("events/stream", handler);
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let request = EventEnvelope::requested(
+            "sub-err-1",
+            serde_json::json!({
+                "operationId": "/events/stream",
+                "input": {},
+            }),
+        );
+        let recv = tokio::io::BufReader::new(std::io::Cursor::new(encode_frame(&request)));
+        let (send, mut sink) = tokio::io::duplex(8 * 1024);
+        let send = alknet_core::types::SendStream::from_mock(send);
+        let recv = alknet_core::types::RecvStream::from_mock(recv);
+
+        dp.handle_stream(conn, send, recv).await;
+
+        let frames = read_all_frames(&mut sink).await;
+        assert_eq!(frames.len(), 2, "1 responded + 1 error, no completed");
+        assert_eq!(frames[0].r#type, EVENT_RESPONDED);
+        assert_eq!(frames[1].r#type, EVENT_ERROR);
+        assert_eq!(frames[1].id, "sub-err-1");
+        assert_eq!(
+            frames[1].payload.get("code"),
+            Some(&Value::String("INTERNAL".into()))
+        );
+    }
+
+    #[tokio::test]
+    async fn handle_stream_query_dispatch_unchanged_one_frame_no_completed() {
+        let registry = Arc::new(registry_with(
+            "echo/run",
+            Visibility::External,
+            AccessControl::default(),
+        ));
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let request = EventEnvelope::requested(
+            "q-pump-1",
+            serde_json::json!({
+                "operationId": "/echo/run",
+                "input": { "msg": "hi" },
+            }),
+        );
+        let recv = tokio::io::BufReader::new(std::io::Cursor::new(encode_frame(&request)));
+        let (send, mut sink) = tokio::io::duplex(8 * 1024);
+        let send = alknet_core::types::SendStream::from_mock(send);
+        let recv = alknet_core::types::RecvStream::from_mock(recv);
+
+        dp.handle_stream(conn, send, recv).await;
+
+        let frames = read_all_frames(&mut sink).await;
+        assert_eq!(frames.len(), 1, "query: exactly one frame, no completed");
+        assert_eq!(frames[0].r#type, EVENT_RESPONDED);
+        assert_eq!(frames[0].id, "q-pump-1");
+        assert_eq!(
+            frames[0].payload.get("output"),
+            Some(&serde_json::json!({ "msg": "hi" }))
+        );
+    }
+
+    #[tokio::test]
+    async fn handle_stream_subscription_unknown_op_yields_single_error_no_completed() {
+        let registry = Arc::new(OperationRegistry::new());
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let request = EventEnvelope::requested(
+            "sub-missing-1",
+            serde_json::json!({
+                "operationId": "/no/such/stream",
+                "input": {},
+            }),
+        );
+        let recv = tokio::io::BufReader::new(std::io::Cursor::new(encode_frame(&request)));
+        let (send, mut sink) = tokio::io::duplex(8 * 1024);
+        let send = alknet_core::types::SendStream::from_mock(send);
+        let recv = alknet_core::types::RecvStream::from_mock(recv);
+
+        dp.handle_stream(conn, send, recv).await;
+
+        let frames = read_all_frames(&mut sink).await;
+        assert_eq!(frames.len(), 1, "unknown op: single error, no completed");
+        assert_eq!(frames[0].r#type, EVENT_ERROR);
+        assert_eq!(frames[0].id, "sub-missing-1");
+        assert_eq!(
+            frames[0].payload.get("code"),
+            Some(&Value::String("NOT_FOUND".into()))
+        );
+    }
+
+    #[tokio::test]
+    async fn handle_stream_aborted_for_streaming_request_drops_stream() {
+        use std::sync::atomic::{AtomicBool, Ordering};
+        use std::sync::Arc as StdArc;
+
+        let dropped = StdArc::new(AtomicBool::new(false));
+        let dropped_clone = StdArc::clone(&dropped);
+        let handler = make_streaming_handler(move |_input, ctx| {
+            let rid = ctx.request_id.clone();
+            let flag = StdArc::clone(&dropped_clone);
+            struct DropGuard(StdArc<AtomicBool>);
+            impl Drop for DropGuard {
+                fn drop(&mut self) {
+                    self.0.store(true, Ordering::SeqCst);
+                }
+            }
+            let guard = DropGuard(StdArc::clone(&flag));
+            futures::stream::poll_fn(move |_cx| {
+                if flag.load(Ordering::SeqCst) {
+                    return std::task::Poll::Ready(None);
+                }
+                std::task::Poll::Ready(Some(ResponseEnvelope::ok(
+                    rid.clone(),
+                    serde_json::json!({"tick": 1}),
+                )))
+            })
+            .map(move |env| {
+                let _keep_guard = &guard;
+                env
+            })
+        });
+        let registry = registry_with_subscription("events/stream", handler);
+        let provider: Arc<dyn IdentityProvider> = Arc::new(StaticIdentityProvider::new());
+        let dp = Dispatcher::new(registry, provider);
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+
+        let request = EventEnvelope::requested(
+            "sub-abort-1",
+            serde_json::json!({
+                "operationId": "/events/stream",
+                "input": {},
+            }),
+        );
+        let recv = tokio::io::BufReader::new(std::io::Cursor::new(encode_frame(&request)));
+        let (send, _sink) = tokio::io::duplex(8 * 1024);
+        let send = alknet_core::types::SendStream::from_mock(send);
+        let recv = alknet_core::types::RecvStream::from_mock(recv);
+
+        let conn_clone = Arc::clone(&conn);
+        let dp_clone = dp.clone();
+        let handle = tokio::spawn(async move {
+            dp_clone.handle_stream(conn_clone, send, recv).await;
+        });
+
+        tokio::time::sleep(std::time::Duration::from_millis(50)).await;
+        dp.handle_abort(&conn, "sub-abort-1").await;
+        assert!(
+            !conn.pending().lock().contains("sub-abort-1"),
+            "abort removes the pending entry"
+        );
+
+        handle.abort();
+        let _ = handle.await;
+        assert!(
+            dropped.load(Ordering::SeqCst),
+            "stream future dropped → Drop guard released handler resources"
+        );
+    }
 }

crates/alknet-http/src/adapters/from_openapi.rs

@@ -18,13 +18,15 @@ use alknet_call::client::{AdapterError, OperationAdapter};
 use alknet_call::protocol::wire::{CallError, ResponseEnvelope};
 use alknet_call::registry::context::OperationContext;
 use alknet_call::registry::registration::{
-    make_handler, HandlerKind, HandlerRegistration, OperationProvenance,
+    make_handler, make_streaming_handler, HandlerKind, HandlerRegistration, OperationProvenance,
+    ResponseStream,
 };
 use alknet_call::registry::spec::{
     AccessControl, ErrorDefinition, OperationSpec, OperationType, Visibility,
 };
 use alknet_core::types::Capabilities;
 use async_trait::async_trait;
+use futures::stream;
 use futures::StreamExt;
 use reqwest::header::{HeaderMap, HeaderName, HeaderValue, ACCEPT, AUTHORIZATION, CONTENT_TYPE};
 use reqwest::Method;
@@ -440,7 +442,33 @@ impl FromOpenAPI {
             .map(|e| (e.http_status.unwrap_or(0), e.code.clone()))
             .collect();
 
-        let handler = make_handler(move |input: Value, context: OperationContext| {
+        let handler = if op_type == OperationType::Subscription {
+            let stream_handler =
+                make_streaming_handler(move |input: Value, context: OperationContext| {
+                    let path_template = path_template.clone();
+                    let method_upper = method_upper.clone();
+                    let auth_scheme = auth_scheme.clone();
+                    let default_headers = default_headers.clone();
+                    let base_url = base_url.clone();
+                    let namespace = namespace.clone();
+                    let http_client = Arc::clone(&http_client);
+                    let error_status_codes = error_status_codes.clone();
+                    forward_stream(
+                        &http_client,
+                        &base_url,
+                        &path_template,
+                        &method_upper,
+                        &auth_scheme,
+                        &default_headers,
+                        &namespace,
+                        &error_status_codes,
+                        input,
+                        context,
+                    )
+                });
+            HandlerKind::Stream(stream_handler)
+        } else {
+            let once_handler = make_handler(move |input: Value, context: OperationContext| {
                 let path_template = path_template.clone();
                 let method_upper = method_upper.clone();
                 let auth_scheme = auth_scheme.clone();
@@ -467,11 +495,13 @@ impl FromOpenAPI {
                     .await
                 }
             });
+            HandlerKind::Once(once_handler)
+        };
 
         let capabilities = Capabilities::new();
         Ok(HandlerRegistration::new(
             spec,
-            HandlerKind::Once(handler),
+            handler,
             OperationProvenance::FromOpenAPI,
             None,
             None,
@@ -666,10 +696,6 @@ async fn forward(
 
     let status = response.status();
 
-    if op_type == OperationType::Subscription && status.is_success() {
-        return stream_subscription(request_id, response).await;
-    }
-
     if !status.is_success() {
         let code = error_status_codes
             .iter()
@@ -721,35 +747,136 @@ async fn forward(
     }
 }
 
-async fn stream_subscription(request_id: String, response: reqwest::Response) -> ResponseEnvelope {
-    let mut stream = response.bytes_stream();
-    let mut buffer = String::new();
-    let mut last_event: Option<Value> = None;
-    while let Some(chunk_result) = stream.next().await {
-        match chunk_result {
-            Ok(chunk) => {
+#[allow(clippy::too_many_arguments)]
+fn forward_stream(
+    http_client: &Arc<SharedHttpClient>,
+    base_url: &str,
+    path_template: &str,
+    method: &str,
+    auth_scheme: &Option<HttpAuthScheme>,
+    default_headers: &HashMap<String, String>,
+    namespace: &str,
+    error_status_codes: &[(u16, String)],
+    input: Value,
+    context: OperationContext,
+) -> ResponseStream {
+    let request_id = context.request_id.clone();
+
+    let (http_method, url, body, headers) = match build_request(
+        base_url,
+        path_template,
+        method,
+        auth_scheme,
+        default_headers,
+        namespace,
+        &input,
+        &context,
+    ) {
+        Ok(parts) => parts,
+        Err(err) => {
+            return Box::pin(stream::once(async move {
+                ResponseEnvelope::error(request_id, err)
+            }));
+        }
+    };
+
+    let http_client = Arc::clone(http_client);
+    let error_status_codes = error_status_codes.to_vec();
+
+    let request_id_stream = request_id.clone();
+    let error_status_codes_stream = error_status_codes.clone();
+
+    let init = async move {
+        let request_builder = http_client
+            .client()
+            .request(http_method, url.as_str())
+            .headers(headers)
+            .header(ACCEPT, "text/event-stream");
+        let request_builder = match body.as_ref() {
+            Some(b) => {
+                let serialized = serde_json::to_string(b).unwrap_or_else(|_| String::from("null"));
+                request_builder.body(serialized)
+            }
+            None => request_builder,
+        };
+        request_builder.send().await
+    };
+
+    let sse = stream::once(init).flat_map(move |result| {
+        let request_id = request_id_stream.clone();
+        let error_status_codes = error_status_codes_stream.clone();
+        match result {
+            Err(err) => Box::pin(stream::once(async move {
+                ResponseEnvelope::error(
+                    request_id,
+                    CallError::internal(format!("HTTP request failed: {err}")),
+                )
+            })) as ResponseStream,
+            Ok(response) => {
+                let status = response.status();
+                if !status.is_success() {
+                    let code = error_status_codes
+                        .iter()
+                        .find(|(s, _)| *s == status.as_u16())
+                        .map(|(_, c)| c.clone())
+                        .unwrap_or_else(|| format!("HTTP_{}", status.as_u16()));
+                    let message = format!(
+                        "HTTP {}: {}",
+                        status.as_u16(),
+                        status.canonical_reason().unwrap_or("")
+                    );
+                    Box::pin(stream::once(async move {
+                        ResponseEnvelope::error(request_id, CallError::new(code, message, false))
+                    })) as ResponseStream
+                } else {
+                    let request_id_inner = request_id.clone();
+                    Box::pin(
+                        stream::unfold(
+                            (response.bytes_stream(), String::new()),
+                            move |(mut bytes, mut buffer)| {
+                                let request_id = request_id_inner.clone();
+                                async move {
+                                    match bytes.next().await {
+                                        Some(Ok(chunk)) => {
                                             buffer.push_str(&String::from_utf8_lossy(&chunk));
                                             let (events, remaining) = parse_sse_frames(&buffer);
-                buffer = remaining;
-                for event in events {
-                    let parsed = if event.data.trim().is_empty() {
+                                            let envelopes: Vec<ResponseEnvelope> = events
+                                                .into_iter()
+                                                .map(|e| {
+                                                    let parsed = if e.data.trim().is_empty() {
                                                         Value::Null
                                                     } else {
-                        serde_json::from_str(&event.data)
-                            .unwrap_or(Value::String(event.data.clone()))
+                                                        serde_json::from_str(&e.data).unwrap_or(
+                                                            Value::String(e.data.clone()),
+                                                        )
                                                     };
-                    last_event = Some(parsed.clone());
+                                                    ResponseEnvelope::ok(&request_id, parsed)
+                                                })
+                                                .collect();
+                                            Some((envelopes, (bytes, remaining)))
+                                        }
+                                        Some(Err(err)) => {
+                                            let error = CallError::internal(format!(
+                                                "SSE stream error: {err}"
+                                            ));
+                                            Some((
+                                                vec![ResponseEnvelope::error(request_id, error)],
+                                                (bytes, buffer),
+                                            ))
+                                        }
+                                        None => None,
                                     }
                                 }
-            Err(err) => {
-                return ResponseEnvelope::error(
-                    request_id,
-                    CallError::internal(format!("SSE stream error: {err}")),
-                );
+                            },
+                        )
+                        .flat_map(stream::iter),
+                    ) as ResponseStream
                 }
             }
         }
-    ResponseEnvelope::ok(request_id, last_event.unwrap_or(Value::Null))
+    });
+
+    Box::pin(sse)
 }
 
 struct SseEvent {
@@ -1194,6 +1321,34 @@ mod tests {
         }
     }
 
+    #[tokio::test]
+    async fn subscription_op_registration_is_handler_kind_stream() {
+        let spec = OpenAPISpec::from_json(
+            r##"{"openapi":"3.0.0","info":{"title":"T","version":"1"},
+            "paths":{"/stream":{"post":{"operationId":"stream","responses":{"200":{"content":{"text/event-stream":{"schema":{}}}}}}}}}"##,
+        )
+        .unwrap();
+        let bundles = adapter(spec, config("svc", "https://x", None))
+            .import()
+            .await
+            .unwrap();
+        assert!(matches!(bundles[0].handler, HandlerKind::Stream(_)));
+    }
+
+    #[tokio::test]
+    async fn query_op_registration_is_handler_kind_once() {
+        let spec = OpenAPISpec::from_json(
+            r#"{"openapi":"3.0.0","info":{"title":"T","version":"1"},
+            "paths":{"/data":{"get":{"operationId":"data","responses":{"200":{"content":{"application/json":{"schema":{}}}}}}}}}"#,
+        )
+        .unwrap();
+        let bundles = adapter(spec, config("svc", "https://x", None))
+            .import()
+            .await
+            .unwrap();
+        assert!(matches!(bundles[0].handler, HandlerKind::Once(_)));
+    }
+
     #[tokio::test]
     async fn integration_sse_subscription_streams_responded_events() {
         let sse_body = "data: {\"n\":1}\n\ndata: {\"n\":2}\n\n";
@@ -1209,13 +1364,67 @@ mod tests {
             .unwrap();
         let registration = &bundles[0];
         let ctx = noop_context("req-12", Capabilities::new());
+        let stream = match &registration.handler {
+            HandlerKind::Stream(h) => h(serde_json::json!({}), ctx),
+            _ => panic!("expected Stream handler"),
+        };
+        let collected: Vec<ResponseEnvelope> = stream.collect().await;
+        assert_eq!(collected.len(), 2);
+        assert_eq!(collected[0].result, Ok(serde_json::json!({"n":1})));
+        assert_eq!(collected[1].result, Ok(serde_json::json!({"n":2})));
+        assert_eq!(collected[0].request_id, "req-12");
+        assert_eq!(collected[1].request_id, "req-12");
+    }
+
+    #[tokio::test]
+    async fn integration_sse_subscription_http_error_returns_single_error_envelope() {
+        let base = spawn_echo_server(404, r#"{"error":"missing"}"#, "application/json").await;
+        let spec = OpenAPISpec::from_json(
+            r##"{"openapi":"3.0.0","info":{"title":"T","version":"1"},
+            "paths":{"/stream":{"post":{"operationId":"stream","responses":{
+                "200":{"content":{"text/event-stream":{"schema":{}}}},
+                "404":{"content":{"application/json":{"schema":{"type":"object"}}}}
+            }}}}}"##,
+        )
+        .unwrap();
+        let bundles = adapter(spec, config("svc", &base, None))
+            .import()
+            .await
+            .unwrap();
+        let registration = &bundles[0];
+        let ctx = noop_context("req-err", Capabilities::new());
+        let stream = match &registration.handler {
+            HandlerKind::Stream(h) => h(serde_json::json!({}), ctx),
+            _ => panic!("expected Stream handler"),
+        };
+        let collected: Vec<ResponseEnvelope> = stream.collect().await;
+        assert_eq!(collected.len(), 1);
+        match &collected[0].result {
+            Err(e) => assert_eq!(e.code, "HTTP_404"),
+            other => panic!("expected HTTP_404 error, got {other:?}"),
+        }
+    }
+
+    #[tokio::test]
+    async fn integration_query_forwarding_unchanged_single_response() {
+        let base = spawn_echo_server(200, r#"{"ok":true}"#, "application/json").await;
+        let spec = OpenAPISpec::from_json(
+            r#"{"openapi":"3.0.0","info":{"title":"T","version":"1"},
+            "paths":{"/data":{"get":{"operationId":"data","responses":{"200":{"content":{"application/json":{"schema":{}}}}}}}}}"#,
+        )
+        .unwrap();
+        let bundles = adapter(spec, config("svc", &base, None))
+            .import()
+            .await
+            .unwrap();
+        let registration = &bundles[0];
+        let ctx = noop_context("req-q", Capabilities::new());
         let response = match &registration.handler {
             HandlerKind::Once(h) => h(serde_json::json!({}), ctx).await,
             _ => panic!("expected Once handler"),
         };
-        assert!(response.result.is_ok());
-        let last = response.result.unwrap();
-        assert_eq!(last, serde_json::json!({"n":2}));
+        assert_eq!(response.request_id, "req-q");
+        assert_eq!(response.result, Ok(serde_json::json!({"ok":true})));
     }
 
     #[test]

tasks/http/adapters/from-openapi-sse-streaming.md

@@ -1,7 +1,7 @@
 ---
 id: http/adapters/from-openapi-sse-streaming
 name: Implement from_openapi Subscription forwarding as StreamingHandler (SSE response → BoxStream<ResponseEnvelope>)
-status: pending
+status: completed
 depends_on: [call/registry/streaming-handler-handlerkind]
 scope: narrow
 risk: medium
@@ -240,4 +240,4 @@ HandlerRegistration::new(spec, handler, OperationProvenance::FromOpenAPI, None,
 
 ## Summary
 
-> To be filled on completion
+> Branched build_registration on op_type: Subscription → make_streaming_handler + forward_stream() (HandlerKind::Stream), Query/Mutation → existing make_handler + forward() (HandlerKind::Once). forward_stream() sends Accept: text/event-stream, streams SSE chunks via stream::unfold over response.bytes_stream(), reusing parse_sse_frames; each data: frame → one ResponseEnvelope::ok(), HTTP error → single ResponseEnvelope::error(), SSE end → ResponseStream ends. Removed stream_subscription() collect-all placeholder. Added 4 tests + updated integration test. 234 tests pass.