feat(channels): implement the single-publish fixes — S-01..S-04 (reviews 010/011; ADR-047 am. 4, ADR-052, ADR-053, ADR-022 am.)

S-01 — the marked-pub open contract (ADR-047 amendment 4):
- ChannelCore::register_pub_openable + PubOpenHandler (the put path's
  handler returns its result for the merged single response; the
  wrapper awaits inline, teardown is EOF-driven, handler_task stays
  None); register_openable* refuses Pub-typed specs; the wrapper entry
  points refuse unmarked/non-Pub shapes
- the reserved input key `channel_id` (the initiator-allocated id):
  stripped pre-validation by resolve_sink_handler (the single source of
  truth, P-08), handed to the wrapper via OperationContext.metadata, a
  missing key rejected INVALID_INPUT; adopt parity enforced
  (ManagerError::InvalidAdopt) and adopt failures answer
  channel:open_failed / adopt_failed
- zero call.published on marked ops: the first publish chunk on a
  marked op is rejected loudly (channel:publish_chunks_rejected) in
  both dispatch loops; the handler is never fed
- relay put-translation replaces RelayError::PubTypedOpen: hub
  allocates odd on the producer leg, opens the spoke op in the
  background (put-acks-in-result), one-direction pump, response-mirror
  with the producer's reserved key stripped
- ChannelClient::open_pub_channel + PubOpenReply (the initiator-
  allocates put open capability)

S-02 — channel/control implemented (ADR-052): establisher-contributed
ChannelControl (Establishment::with_control), manager-owned registry,
teardown removals, channel:no_control_handle capability answer.

S-03 — channel/resources/subscribe implemented (ADR-053): the
ResourceEnumerators registry (shared per peer), snapshot-then-changes
enumerators, scan-once aggregation, the empty seed; the
always-failing one-shot error stream removed.

S-04 — op/register forward-through (ADR-022 amendment): announced
unmarked Sub/Pub register the real streaming/sink forwarding shapes;
marked announcements refused with MARKED_SPEC_UNSUPPORTED; marked
specs refuse the generic registration path and register_imported
(Result-returning now).

Guard (review 010 action 3): tests/stub_guard.rs greps src/ for
not_implemented; the four pinned stub tests are deleted and the
marked-spec registration refusals are pinned by tests.

Verified: cargo test (696 + guard), clippy --all-targets -D warnings,
fmt --check, fuzz corpus replay.

src/channels/client.rs

@@ -70,8 +70,8 @@ impl ChannelOpenError {
 
     /// The establishment-failure reason code — `details.reason` of a
     /// `channel:open_failed` error (`dial_failed`, `unknown_resource`,
-    /// `resource_shortage`, `handler_error`, `timeout`). `None` for
+    /// `resource_shortage`, `handler_error`, `timeout`, `adopt_failed`).
-    /// any other failure shape.
+    /// `None` for any other failure shape.
     pub fn establishment_reason(&self) -> Option<&str> {
         match self {
             ChannelOpenError::CallFailed { error }
@@ -88,6 +88,30 @@ impl ChannelOpenError {
     }
 }
 
+/// The awaited single merged response of a put open
+/// ([`ChannelClient::open_pub_channel`], ADR-047 amendment 4 §4.9 —
+/// the put ack rides in the result, ADR-047 amendment 4 §4.5). The
+/// putter writes bytes on the returned `send` half (or spawns pumps)
+/// and awaits this for the put's wire contract (e.g. alkblobs' put
+/// replying `{ token, digest }`). Await this after (or alongside) the
+/// byte stream, never before it — the response cannot exist before the
+/// byte stream completes.
+pub struct PubOpenReply {
+    rx: tokio::sync::oneshot::Receiver<Result<Value, ChannelOpenError>>,
+}
+
+impl PubOpenReply {
+    /// The putter-side await: the merged response output (`Ok`);
+    /// `Err` carries the wire `CallError` verbatim
+    /// (`channel:open_failed` + `details.reason` per ADR-049 §3).
+    pub async fn resolve(self) -> Result<Value, ChannelOpenError> {
+        match self.rx.await {
+            Ok(result) => result,
+            Err(_) => Err(ChannelOpenError::MissingChannelId),
+        }
+    }
+}
+
 /// The client-side handle for a channels connection. Constructed via
 /// [`ChannelClient::from_connection`] from an established
 /// `Connection`. Holds the `ChannelManager` (for the demux/mux state)
@@ -382,6 +406,110 @@ impl ChannelClient {
             .map(|(send, recv)| (channel_id, out, send, recv))
     }
 
+    /// The putter-facing open (ADR-047 amendment 4 §4.9 — the
+    /// initiator-allocates capability `open_channel`/`open_channel_with_reply`
+    /// cannot provide, because those await the open reply before
+    /// returning the halves and a put's bytes flow before the reply
+    /// exists, review 011 §2.7): allocates the connect-side odd id
+    /// locally, inserts the reserved input key, sends the open op in a
+    /// background task, and returns **immediately** — the caller
+    /// writes bytes on `send` without waiting for anything (the
+    /// put ack rides in the merged response; ADR-047 amendment 4 §4.5).
+    ///
+    /// Returns `(channel_id, send, recv, reply)`; `reply` is the
+    /// awaited single merged response — `Ok(Value)` (the full output,
+    /// e.g. `{ token, digest }`) or the wire error. On a failed open
+    /// the local adopt entry is torn down and `send`/`recv` are
+    /// already EOF'd (teardown); the caller still holds them but every
+    /// write is EOF-shaped. The `recv` half is the (bidirectional)
+    /// channel's read side — a put that also receives reads it.
+    pub async fn open_pub_channel(
+        &self,
+        operation_id: &str,
+        input: Value,
+        alpn: &str,
+    ) -> Result<(u32, MpscSendStream, MpscRecvStream, PubOpenReply), ChannelOpenError> {
+        use crate::registry::spec::RESERVED_OPEN_INPUT_KEY;
+
+        let (channel_id, send, recv) = self
+            .manager
+            .open_channel(
+                alpn,
+                // The opener ledger is inert on the connect side (it
+                // does not enforce the per-identity cap, ADR-041) —
+                // the record is observability only.
+                "channel-client",
+                None,
+            )
+            .await
+            .map_err(|e| match e {
+                crate::channels::manager::ManagerError::TooManyChannels { count, max } => {
+                    ChannelOpenError::CallFailed {
+                        error: crate::protocol::wire::CallError::new(
+                            "channel:too_many_channels",
+                            format!("per-connection channel cap exceeded: {count}/{max}"),
+                            false,
+                        )
+                        .with_details(serde_json::json!({ "count": count, "max": max })),
+                    }
+                }
+                other => ChannelOpenError::CallFailed {
+                    error: crate::protocol::wire::CallError::new(
+                        "channel:allocation_failed",
+                        format!("channel allocation failed: {other}"),
+                        false,
+                    ),
+                },
+            })?;
+
+        let mut op_input = input;
+        match op_input.as_object_mut() {
+            Some(obj) => {
+                obj.insert(
+                    RESERVED_OPEN_INPUT_KEY.to_string(),
+                    serde_json::json!(channel_id),
+                );
+            }
+            None => {
+                return Err(ChannelOpenError::CallFailed {
+                    error: crate::protocol::wire::CallError::invalid_input(
+                        "marked pub open op input must be an object (ADR-047 amendment 4 §4.3)",
+                    ),
+                });
+            }
+        }
+
+        let call_conn = {
+            let guard = self.call_connection.lock().await;
+            guard.as_ref().map(Arc::clone)
+        };
+        let manager = self.manager.clone();
+        let op_id = operation_id.to_string();
+        let (reply_tx, reply_rx) = tokio::sync::oneshot::channel();
+        tokio::spawn(async move {
+            let response = match &call_conn {
+                Some(conn) => conn.call(&op_id, op_input).await,
+                None => ResponseEnvelope::error(
+                    "channel-client",
+                    crate::protocol::wire::CallError::internal("channel client closed"),
+                ),
+            };
+            // A failed open tears the allocator-side entry down: the
+            // responder refused, the channel is dead, and the local
+            // half must not linger in the connection's channel map.
+            if response.result.is_err() {
+                let _ = manager.teardown_channel(channel_id);
+            }
+            let reply = match response.result {
+                Ok(out) => Ok(out),
+                Err(error) => Err(ChannelOpenError::CallFailed { error }),
+            };
+            let _ = reply_tx.send(reply);
+        });
+
+        Ok((channel_id, send, recv, PubOpenReply { rx: reply_rx }))
+    }
+
     /// Take the `CallConnection` — used by the consumer to register
     /// imported ops (`from_call`) on the connection's overlay. After
     /// this, `call_open_op` returns an error (the connection is owned

src/channels/gate2_tests.rs

@@ -62,6 +62,7 @@ const TTY_OP: &str = "channels/tty/sub";
 const TTY_ALPN: &str = "alk/tty";
 const ALPN: &str = "alk/tunnel";
 const PLAIN_OP: &str = "fs/read";
+const PUT_OP: &str = "channels/put/bulk";
 
 fn identity(id: &str, scopes: &[&str]) -> Identity {
     Identity {
@@ -256,6 +257,49 @@ fn make_spoke_install(
             )
             .expect("spoke registers the tty open op");
 
+            // The marked pub openable (ADR-047 amendment 4 §4.7's
+            // relay-translation gate): a put handler that consumes the
+            // adopted channel's data plane to EOF and replies with the
+            // digest over the streamed bytes.
+            let put_spec = OperationSpec::new(
+                PUT_OP,
+                OperationType::Pub,
+                Visibility::External,
+                json!({ "type": "object" }),
+                json!({
+                    "type": "object",
+                    "properties": {
+                        "channel_id": { "type": "integer" },
+                        "digest": { "type": "string" }
+                    }
+                }),
+                vec![],
+                AccessControl::default(),
+                None,
+            )
+            .with_channel_open(ChannelOpenSpec::new("alk/blobs"));
+            let put_handler: crate::channels::operations::PubOpenHandler =
+                Arc::new(move |_input, _plan, channel_conn, _auth| {
+                    Box::pin(async move {
+                        let mut bidi = channel_conn.accept_bi().await.map_err(|_| {
+                            crate::protocol::wire::CallError::internal(
+                                "spoke put: the data plane never opened",
+                            )
+                        })?;
+                        let mut buf = Vec::new();
+                        tokio::io::AsyncReadExt::read_to_end(&mut bidi, &mut buf)
+                            .await
+                            .map_err(|e| {
+                                crate::protocol::wire::CallError::internal(format!(
+                                    "spoke put read failed: {e}"
+                                ))
+                            })?;
+                        Ok(json!({ "digest": format!("spoke-{}", buf.len()) }))
+                    })
+                });
+            core.register_pub_openable(put_spec, None, put_handler, &registry, auth.clone(), None)
+                .expect("spoke registers the marked pub openable");
+
             registry
                 .register(HandlerRegistration::new(
                     plain_spec(PLAIN_OP),
@@ -740,3 +784,51 @@ async fn gate2_tty_standard_shape_relays_with_no_regression() {
         "the tty relay's ledger decremented"
     );
 }
+
+// --- gate: the pub-openables relay translation (ADR-047 amendment 4 §4.7) ---
+
+/// A hub translating a pub openable end-to-end (review 011 §3): the
+/// browser's put via `open_pub_channel` on the consumer leg; bytes
+/// flow browser → hub → spoke (the hub never parses them); the
+/// spoke's single response loses its reserved key and its result
+/// fields ride the consumer reply; the consumer replies exactly once
+/// with the hub-allocated consumer-leg id.
+#[tokio::test]
+async fn gate_pub_relay_put_end_to_end() {
+    let h = start().await;
+
+    let (id, mut send, _recv, reply) = h
+        .consumer
+        .open_pub_channel(PUT_OP, json!({ "path": "g" }), "alk/blobs")
+        .await
+        .expect("the put opens through the relayed pub openable");
+    send.write_all(b"payload!").await.expect("stream the bytes");
+    drop(send);
+
+    let merged = reply
+        .resolve()
+        .await
+        .expect("the put's single merged response");
+    assert_eq!(
+        merged["digest"],
+        json!("spoke-8"),
+        "the spoke's result rode the relay (the producer's reserved key stripped)"
+    );
+    assert_eq!(
+        merged["channel_id"],
+        json!(id),
+        "the reply carries the hub-allocated consumer-leg id"
+    );
+    assert_eq!(id % 2, 1, "the browser (connect side) allocated odd");
+
+    wait_for(
+        || data_channels(&h.hub_consumer_manager) == 0,
+        "the consumer-leg put channel reclaimed at the wrapper's completion teardown",
+    )
+    .await;
+    wait_for(
+        || data_channels(&h.hub_producer_manager) == 0,
+        "the producer-leg put channel reclaimed at the plan's drop guard",
+    )
+    .await;
+}

src/channels/hub_leg_tests.rs

@@ -668,7 +668,11 @@ async fn template_plain_bundle_registration_failure_is_loud_at_install() {
 /// call to any op — including the bootstrap discovery ops — does not
 /// resolve). Never a silent stub.
 #[tokio::test]
-async fn template_pub_typed_marked_spec_is_loud_at_install() {
+async fn template_pub_typed_marked_spec_registers_through_the_relay() {
+    // ADR-047 amendment 4 §4.7: the put-forwarding translation replaced
+    // the `PubTypedOpen` assembly error — a pub-typed marked spec in
+    // the stash composes through `register_pub_openable` and the op
+    // re-exposes on the consumer leg.
     let pub_bundle = HandlerRegistration::new(
         relay_spec(
             "channels/x/pub",
@@ -685,15 +689,19 @@ async fn template_pub_typed_marked_spec_is_loud_at_install() {
     );
     let imports = HubLegImports::from_bundles(vec![pub_bundle]);
     let consumer = start_hub(None, Some(imports), None, false).await;
-    let response = tokio::time::timeout(
+    let response = consumer.call_open_op("services/list", json!({})).await;
-        std::time::Duration::from_secs(3),
+    let out = response
-        consumer.call_open_op("services/list", json!({})),
+        .result
-    )
+        .expect("the leg dispatches; the op re-exposed");
-    .await;
+    let names: Vec<&str> = out["operations"]
+        .as_array()
+        .expect("operations")
+        .iter()
+        .filter_map(|o| o.get("name").and_then(|n| n.as_str()))
+        .collect();
     assert!(
-        response.is_err(),
+        names.contains(&"channels/x/pub"),
-        "the leg's channel 0 never dispatches after the loud assembly error, got {:?}",
+        "the pub openable is re-exposed through the relay, got: {names:?}"
-        response
     );
 }
 

src/channels/manager.rs

@@ -18,6 +18,9 @@ use tokio::sync::mpsc;
 use tokio::task::JoinHandle;
 use tracing::debug;
 
+use crate::protocol::wire::CallError;
+use serde_json::Value;
+
 use super::mux::{MuxHandle, OpenerLedger};
 use super::reassembly::{MpscRecvStream, MpscSendStream, DEFAULT_BUFFER_CAP};
 
@@ -38,6 +41,15 @@ pub enum ChannelSide {
 /// `ChannelLifecyclePolicy` (ADR-041, amended by ADR-047 §7).
 pub const DEFAULT_MAX_CHANNELS: usize = 256;
 
+/// The per-channel out-of-band control callback (ADR-052): received
+/// from the open-op establisher (`Establishment::with_control`),
+/// installed by the open-op wrapper under the channel's id, routed to
+/// by `channel/control`, removed by every teardown path. The manager
+/// stays blind to what the closure does (ADR-039).
+pub type ChannelControl = Arc<
+    dyn Fn(Value) -> futures::future::BoxFuture<'static, Result<Value, CallError>> + Send + Sync,
+>;
+
 /// The per-channel state — the reassembly sender (the demux feeds chunk
 /// payloads into it; the handler reads them out via `MpscRecvStream`),
 /// the handler task handle, and the ALPN (for observability).
@@ -62,6 +74,13 @@ pub enum ManagerError {
     UnknownChannel(u32),
     #[error("channel already exists: {0}")]
     ChannelExists(u32),
+    #[error(
+        "channel {channel_id} is outside the remote side's allocation range (expected {expected})"
+    )]
+    InvalidAdopt {
+        channel_id: u32,
+        expected: &'static str,
+    },
 }
 
 /// The shared state for a channels connection. `Clone` (cheap — `Arc`
@@ -101,6 +120,10 @@ struct Inner {
     /// drains them into the new receiver. `clear_all` drops the map.
     early_arrivals: Mutex<HashMap<u32, VecDeque<Bytes>>>,
     early_arrival_count: AtomicU64,
+    /// Per-channel out-of-band control callbacks (ADR-052). Installed
+    /// by the open-op wrapper from the establisher's
+    /// `Establishment::with_control`; removed by every teardown path.
+    control_handles: Mutex<HashMap<u32, ChannelControl>>,
 }
 
 /// The per-channel cap on parked early-arrival chunks (`route_payload`
@@ -151,6 +174,7 @@ impl ChannelManager {
                 dropped_unknown_chunks: AtomicU64::new(0),
                 early_arrivals: Mutex::new(HashMap::new()),
                 early_arrival_count: AtomicU64::new(0),
+                control_handles: Mutex::new(HashMap::new()),
             }),
         }
     }
@@ -317,6 +341,32 @@ impl ChannelManager {
         alpn: impl Into<String>,
         handler_task: Option<JoinHandle<()>>,
     ) -> Result<(MpscSendStream, MpscRecvStream), ManagerError> {
+        // The adopt range is the remote side's allocation range (the
+        // odd/even split, ADR-047 §5): the connect side allocates odd,
+        // so the accept side adopts odd; the accept side allocates
+        // even, so the connect side adopts even. Adopting inside the
+        // local range would collide with this side's own monotonic
+        // allocator shortly after. The duplicate check comes first —
+        // adopting an id this side already holds returns
+        // `ChannelExists` and must never touch the live channel (the
+        // 0.8.1 regression pin).
+        let expected = match self.inner.side {
+            ChannelSide::Connect => "even (the accept side's allocated ids; ADR-047 §5)",
+            ChannelSide::Accept => "odd (the connect side's allocated ids; ADR-047 §5)",
+        };
+        if self.inner.channels.lock().contains_key(&channel_id) {
+            return Err(ManagerError::ChannelExists(channel_id));
+        }
+        let parity_ok = match self.inner.side {
+            ChannelSide::Connect => channel_id.is_multiple_of(2),
+            ChannelSide::Accept => !channel_id.is_multiple_of(2),
+        };
+        if !parity_ok {
+            return Err(ManagerError::InvalidAdopt {
+                channel_id,
+                expected,
+            });
+        }
         let alpn = alpn.into();
 
         let send = self
@@ -381,6 +431,30 @@ impl ChannelManager {
         }
     }
 
+    /// Install the out-of-band control callback for a channel
+    /// (ADR-052). Called by the open-op wrapper from the establisher's
+    /// `Establishment::with_control`. Replaces an existing callback for
+    /// the id (the establisher runs once per channel — replacement is
+    /// not an expected path; the last call wins).
+    pub fn set_control_handle(&self, channel_id: u32, control: ChannelControl) {
+        self.inner
+            .control_handles
+            .lock()
+            .insert(channel_id, control);
+    }
+
+    /// The control callback for a channel, for routing (the
+    /// `channel/control` handler). `None` when the channel's ALPN
+    /// registered no control surface (the op answers
+    /// `channel:no_control_handle`).
+    pub fn control_handle(&self, channel_id: u32) -> Option<ChannelControl> {
+        self.inner.control_handles.lock().get(&channel_id).cloned()
+    }
+
+    fn remove_control_handle(&self, channel_id: u32) {
+        self.inner.control_handles.lock().remove(&channel_id);
+    }
+
     /// Install channel 0 (pre-negotiated as `alk/call`, ADR-036).
     /// Channel 0 is special only in that it's pre-allocated (by
     /// `channels-call`); the `ChannelsAdapter` hands the resulting
@@ -530,6 +604,7 @@ impl ChannelManager {
                 // Dropping `state.demux_sender` signals EOF to the
                 // handler's read half (REQ-CH-02).
                 drop(state.demux_sender);
+                self.remove_control_handle(channel_id);
                 Ok(state.handler_task)
             }
             None => Err(ManagerError::UnknownChannel(channel_id)),
@@ -550,6 +625,7 @@ impl ChannelManager {
                 task.abort();
             }
         }
+        self.inner.control_handles.lock().clear();
         // The early-arrival buffers die with the connection too.
         self.inner.early_arrivals.lock().clear();
         // The opener ledger has the opener PeerIds.

src/channels/mod.rs

@@ -31,6 +31,9 @@
 //!   as amended by ADR-051): translate hop + `pump_bidi` byte-forward
 //!   hop for from_call-imported marked specs re-exposed on a hub's
 //!   consumer-leg channel-0 registry.
+//! - [`resource`]: `ResourceEnumerators` — the enumerator registry
+//!   behind `channel/resources/subscribe`'s live subscription
+//!   (ADR-053).
 //! - [`hub_leg`]: `HubLegTemplate` — the hub-leg install template
 //!   (ADR-051 §5): fork + generic channel ops + bootstrap discovery +
 //!   plain bundles + relay openables + serving identity, composed into
@@ -53,5 +56,6 @@ pub mod policy;
 pub mod pump;
 pub mod reassembly;
 pub mod relay;
+pub mod resource;
 pub mod source;
 pub mod wire;

src/channels/pub_open_tests.rs

@@ -0,0 +1,447 @@
+//! The marked-pub open contract gates (review 011 §3; ADR-047
+//! amendment 4). The put path end-to-end over a real channels
+//! connection: response merge order, the digest-in-result wire
+//! contract, publish-chunk rejection, establishment failure
+//! (teardown + ledger + EOF-discarded racing bytes), the reserved-key
+//! rejections, and adopt parity.
+
+use crate::channels::adapter::ChannelsAdapter;
+use crate::channels::client::ChannelClient;
+use crate::channels::manager::ChannelManager;
+use crate::channels::operations::{ChannelCore, Establishment, OpenEstablisher, PubOpenHandler};
+use crate::channels::policy::NoCap;
+use crate::core::auth::{AuthContext, Identity, IdentityProvider};
+use crate::core::types::Connection;
+use crate::protocol::connection::{split_single_stream, CallConnection};
+use crate::protocol::dispatch::Dispatcher;
+use crate::protocol::wire::CallError;
+use crate::registry::discovery::install_bootstrap_discovery;
+use crate::registry::registration::OperationRegistry;
+use crate::registry::spec::{
+    AccessControl, ChannelOpenSpec, OperationSpec, OperationType, Visibility,
+    RESERVED_OPEN_INPUT_KEY,
+};
+use serde_json::{json, Value};
+use std::net::{IpAddr, Ipv4Addr, SocketAddr};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, DuplexStream};
+
+const TEST_ADDR: SocketAddr = SocketAddr::new(IpAddr::V4(Ipv4Addr::LOCALHOST), 4321);
+const PUT_OP: &str = "channels/blobs/put";
+
+struct NoopIdProvider;
+impl IdentityProvider for NoopIdProvider {
+    fn resolve_from_fingerprint(&self, _: &str) -> Option<Identity> {
+        None
+    }
+    fn resolve_from_token(&self, _: &crate::core::auth::AuthToken) -> Option<Identity> {
+        None
+    }
+}
+
+fn pub_put_spec() -> OperationSpec {
+    OperationSpec::new(
+        PUT_OP,
+        OperationType::Pub,
+        Visibility::External,
+        json!({
+            "type": "object",
+            "properties": { "path": { "type": "string" } },
+            "required": ["path"]
+        }),
+        json!({
+            "type": "object",
+            "properties": {
+                "channel_id": { "type": "integer" },
+                "token": { "type": "string" },
+                "digest": { "type": "string" },
+                "priority": { "type": "string" }
+            }
+        }),
+        vec![],
+        AccessControl::default(),
+        None,
+    )
+    .with_channel_open(ChannelOpenSpec::new("alk/blobs"))
+}
+
+/// The put handler: consume the adopted channel's data plane to EOF,
+/// return `{ digest, priority }` — the unknown-length put's wire
+/// contract (the result computed from the streamed bytes). The
+/// `priority` field exists to pin the merge order (the handler's
+/// result wins the collision; ADR-047 amendment 4 §4.4).
+fn digest_handler() -> PubOpenHandler {
+    Arc::new(move |_input, _plan, channel_conn, _auth| {
+        Box::pin(async move {
+            let mut bidi = channel_conn
+                .accept_bi()
+                .await
+                .map_err(|_| CallError::internal("put handler: the data plane never opened"))?;
+            let mut buf = Vec::new();
+            bidi.read_to_end(&mut buf)
+                .await
+                .map_err(|e| CallError::internal(format!("put handler read failed: {e}")))?;
+            Ok(json!({
+                "digest": format!("len-{}", buf.len()),
+                "priority": "handler",
+            }))
+        })
+    })
+}
+
+/// The establisher: contributes an informative-in-result ack field
+/// (`token`) and its own `priority` (the ack — which the handler's
+/// result beats on collision).
+fn token_establisher() -> OpenEstablisher {
+    Arc::new(|_input: Value, _auth| {
+        Box::pin(async {
+            Ok(Establishment::default().with_reply_field("token", json!("tok-1")))
+                .map(|e: Establishment| e.with_reply_field("priority", json!("ack")))
+        })
+    })
+}
+
+/// Build the put-serving side over the duplex's server end: register
+/// the marked pub openable (with the given establisher + handler) and
+/// run the channel-0 dispatch loop. Returns the captured server
+/// manager (the ledger/teardown observability point).
+async fn serve_put_side(
+    server_end: DuplexStream,
+    establisher: OpenEstablisher,
+    handler: PubOpenHandler,
+) -> Arc<tokio::sync::Mutex<Option<ChannelManager>>> {
+    let captured = Arc::new(tokio::sync::Mutex::<Option<ChannelManager>>::new(None));
+    let captured_for_hook = Arc::clone(&captured);
+    let install_hook: crate::channels::adapter::InstallChannelZero =
+        Arc::new(move |manager, channel0_conn, auth| {
+            let establisher = establisher.clone();
+            let handler = Arc::clone(&handler);
+            let manager = manager.clone();
+            let captured = Arc::clone(&captured_for_hook);
+            tokio::spawn(async move {
+                let _ = captured.lock().await.replace(manager.clone());
+                let Ok(channel0_bidi) = channel0_conn.accept_bi().await else {
+                    return;
+                };
+                let (writer, reader) = split_single_stream(channel0_bidi);
+                let core = ChannelCore::new(manager, Arc::new(NoCap));
+                let registry = Arc::new(OperationRegistry::new());
+                install_bootstrap_discovery(&registry).expect("bootstrap discovery");
+                core.register_pub_openable(
+                    pub_put_spec(),
+                    Some(establisher),
+                    handler,
+                    &registry,
+                    auth.clone(),
+                    None,
+                )
+                .expect("register the marked pub openable");
+                let provider: Arc<dyn IdentityProvider> = Arc::new(NoopIdProvider);
+                let call_connection = Arc::new(CallConnection::new_single_stream(
+                    channel0_conn,
+                    Arc::clone(&writer),
+                ));
+                Dispatcher::new(registry, provider)
+                    .run_loop_single_stream(call_connection, reader, writer)
+                    .await;
+            })
+        });
+    let adapter = ChannelsAdapter::new(install_hook, Arc::new(NoCap));
+    let server_conn = Connection::from_bidi(server_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let auth = AuthContext::anonymous(b"alk/channels");
+    tokio::spawn(async move {
+        let _ = crate::core::types::ProtocolHandler::handle(&adapter, server_conn, &auth).await;
+    });
+    captured
+}
+
+#[tokio::test]
+async fn put_e2e_merge_order_and_digest() {
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let _captured = serve_put_side(server_end, token_establisher(), digest_handler()).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("channel client init");
+
+    {
+        // The known-length shape: offer + bytes → one response whose
+        // merge order is `{channel_id}` → ack fields → handler result.
+        let (_id, mut send, _recv, reply) = client
+            .open_pub_channel(PUT_OP, json!({ "path": "b/one" }), "alk/blobs")
+            .await
+            .expect("open_pub_channel");
+        send.write_all(b"hello").await.expect("stream the bytes");
+        drop(send);
+
+        let merged = reply
+            .resolve()
+            .await
+            .expect("the put resolves with the merged response");
+        let _ = _id;
+        assert_eq!(
+            merged["token"],
+            json!("tok-1"),
+            "the ack field rides the result"
+        );
+        assert_eq!(
+            merged["digest"],
+            json!("len-5"),
+            "the handler result rides the result"
+        );
+        assert_eq!(
+            merged["priority"],
+            json!("handler"),
+            "merge order: handler result wins the collision with the ack (§4.4)"
+        );
+        assert!(
+            merged["channel_id"].as_u64().is_some(),
+            "channel_id reserved"
+        );
+    }
+
+    {
+        // The unknown-length shape: larger than the reassembly buffer
+        // (crosses chunk boundaries); the handler's digest is computed
+        // over the streamed bytes.
+        let (_id2, send2, _recv2, reply2) = client
+            .open_pub_channel(PUT_OP, json!({ "path": "b/two" }), "alk/blobs")
+            .await
+            .expect("open_pub_channel");
+        let mut send2 = send2;
+        let chunk = vec![0xAB_u8; 4096];
+        for _ in 0..8 {
+            send2.write_all(&chunk).await.expect("stream a chunk");
+        }
+        drop(send2);
+
+        let merged2 = reply2.resolve().await.expect("unknown-length put");
+        assert_eq!(merged2["digest"], json!("len-32768"));
+        assert_eq!(merged2["token"], json!("tok-1"));
+    }
+}
+
+/// The happy-path put's ids: the putter allocates odd (its side is
+/// Connect); the responder adopts; the reply carries the putter's id.
+#[tokio::test]
+async fn put_e2e_client_parity_is_odd() {
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let _captured = serve_put_side(server_end, token_establisher(), digest_handler()).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("client");
+    let (id, mut send, _recv, reply) = client
+        .open_pub_channel(PUT_OP, json!({ "path": "b/odd" }), "alk/blobs")
+        .await
+        .expect("open_pub_channel");
+    send.write_all(b"zz").await.expect("stream");
+    drop(send);
+    let merged = reply.resolve().await.expect("put");
+    assert_eq!(
+        merged["channel_id"],
+        json!(id),
+        "the reply carries the putter's id"
+    );
+    assert_eq!(id % 2, 1, "the connect side allocates odd (ADR-047 §5)");
+}
+
+/// Publish-chunk rejection (§4.1): a marked op fed via the call-plane
+/// publish path rejects loudly in the initiator's direction and the
+/// handler never consumes a chunk.
+#[tokio::test]
+async fn put_rejects_publish_chunks_loudly() {
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let _captured = serve_put_side(server_end, token_establisher(), digest_handler()).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("client");
+    let conn = Arc::clone(&client.take_call_connection().await.expect("call conn"));
+
+    let chunks = Box::pin(futures::stream::iter(vec![
+        json!({ "chunk": 1 }),
+        json!({ "chunk": 2 }),
+    ]));
+    // The reserved key is present (this client misuses the wire
+    // contract — the open resolves, the chunks are what get rejected).
+    let response = conn
+        .publish_with_payload(
+            json!({ "operationId": PUT_OP, "input": { "path": "b/violating", RESERVED_OPEN_INPUT_KEY: 3 } }),
+            chunks,
+        )
+        .await;
+    let e = response.result.expect_err("chunks rejected loudly");
+    assert_eq!(e.code, crate::registry::spec::MARKED_PUB_CHUNKS_REJECTED);
+    // The put side's own single response may also arrive (the initiator
+    // already resolved with the rejection); the rejection is what the
+    // pending call carries — assert it was NOT a success-shaped result
+    // (done above by expect_err).
+    let _ = conn;
+}
+
+/// Establishment failure (ADR-049 §3 through the pub path): the reply
+/// is `channel:open_failed` with the mapped reason; the channel is
+/// torn down on both sides; racing bytes EOF-discard (the write
+/// completes locally before the failure reply — the adopt entry is
+/// gone afterward, ledger un-incremented).
+#[tokio::test]
+async fn put_establishment_failure_replies_open_failed_and_tears_down() {
+    use crate::channels::operations::EstablishmentError;
+
+    let failing: OpenEstablisher = Arc::new(|_input, _auth| {
+        Box::pin(async {
+            Err(EstablishmentError::UnknownResource {
+                message: "container not found".to_string(),
+            })
+        })
+    });
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let captured = serve_put_side(server_end, failing, digest_handler()).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("client");
+    let (id, mut send, _recv, reply) = client
+        .open_pub_channel(PUT_OP, json!({ "path": "b/gone" }), "alk/blobs")
+        .await
+        .expect("open_pub_channel");
+    // Racing bytes: written before the failure reply arrives — the
+    // responder never adopted, so the bytes park and drop (EOF-shaped
+    // for the putter).
+    let _ = send.write_all(b"racing").await;
+    drop(send);
+
+    let error = reply
+        .resolve()
+        .await
+        .expect_err("the put resolves with the establishment failure");
+    assert_eq!(
+        error.establishment_reason(),
+        Some("unknown_resource"),
+        "the spoke establishment reason maps through (ADR-049 §3)"
+    );
+    assert_eq!(
+        error.call_error().map(|e| e.code.as_str()),
+        Some("channel:open_failed")
+    );
+
+    // The responder's side: no channel lingers (open_failed tears
+    // down; nothing was adopted anyway — but the client-side
+    // open-failure teardown removed the allocator-side entry).
+    tokio::time::sleep(std::time::Duration::from_millis(100)).await;
+    let manager = captured.lock().await.clone().expect("server manager");
+    assert!(
+        !manager.has_channel(id),
+        "a failed establishment leaves no channel (ADR-047 amendment 4 §4.4)"
+    );
+    assert_eq!(
+        manager.opener_ledger().take(id),
+        None,
+        "ledger un-incremented"
+    );
+}
+
+/// A marked pub op whose input lacks the reserved `channel_id` key is
+/// rejected (`INVALID_INPUT`) — the initiator-allocated id is
+/// mandatory (ADR-047 amendment 4 §4.3).
+#[tokio::test]
+async fn put_missing_reserved_key_is_rejected() {
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let _captured = serve_put_side(server_end, token_establisher(), digest_handler()).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("client");
+    let response = client
+        .call_open_op(PUT_OP, json!({ "path": "b/no-id" }))
+        .await;
+    let e = response.result.expect_err("the reserved key is mandatory");
+    assert_eq!(e.code, "INVALID_INPUT");
+    assert!(
+        e.message.contains(RESERVED_OPEN_INPUT_KEY),
+        "the error names the key: {}",
+        e.message
+    );
+}
+
+/// Adopt parity (§4.4 + ADR-047 §5): a reserved id inside the
+/// responder's OWN allocation range (even — an id the accept side
+/// would allocate itself, violating the split) fails the open with
+/// `adopt_failed`; racing bytes are discarded.
+#[tokio::test]
+async fn put_out_of_range_reserved_id_replies_adopt_failed() {
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let _captured = serve_put_side(server_end, token_establisher(), digest_handler()).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("client");
+    let response = client
+        .call_open_op(
+            PUT_OP,
+            json!({ "path": "b/bad", RESERVED_OPEN_INPUT_KEY: 2 }),
+        )
+        .await;
+    let e = response
+        .result
+        .expect_err("the responder refuses its own range");
+    assert_eq!(e.code, "channel:open_failed");
+    assert_eq!(
+        e.details
+            .as_ref()
+            .and_then(|d| d.get("reason"))
+            .and_then(|r| r.as_str()),
+        Some("adopt_failed"),
+        "adoption failure → adopt_failed (ADR-047 amendment 4 §4.4): {e:?}"
+    );
+}
+
+/// The responder-side put handler that returns an error: the single
+/// response IS that error (the wrapper passthrough; §4.4).
+#[tokio::test]
+async fn put_handler_error_becomes_the_response() {
+    let failing_handler: PubOpenHandler = Arc::new(|_input, _plan, channel_conn, _auth| {
+        Box::pin(async move {
+            let mut bidi = channel_conn
+                .accept_bi()
+                .await
+                .map_err(|_| CallError::internal("data plane"))?;
+            let mut buf = [0u8; 3];
+            let _ = bidi.read_exact(&mut buf).await;
+            Err(CallError::new(
+                "blobs:read_only",
+                "the container is read-only",
+                false,
+            ))
+        })
+    });
+    let (client_end, server_end) = tokio::io::duplex(64 * 1024);
+    let client_conn = Connection::from_bidi(client_end, b"alk/channels".to_vec(), Some(TEST_ADDR));
+    let _captured = serve_put_side(server_end, token_establisher(), failing_handler).await;
+
+    let client = ChannelClient::from_connection(client_conn)
+        .await
+        .expect("client");
+    let (_id, mut send, _recv, reply) = client
+        .open_pub_channel(PUT_OP, json!({ "path": "b/ro" }), "alk/blobs")
+        .await
+        .expect("open_pub_channel");
+    send.write_all(b"abc").await.expect("stream");
+    drop(send);
+
+    let error = reply
+        .resolve()
+        .await
+        .expect_err("the handler error IS the response");
+    assert_eq!(
+        error.call_error().map(|e| e.code.clone()),
+        Some("blobs:read_only".to_string())
+    );
+}

src/channels/relay.rs

@@ -35,11 +35,13 @@ use crate::registry::spec::{OperationSpec, OperationType};
 
 use super::manager::ChannelManager;
 use super::operations::{
-    ChannelCore, Establishment, EstablishmentError, OpenEstablisher, OpenHandler,
+    ChannelCore, ChannelPlan, Establishment, EstablishmentError, OpenEstablisher, OpenHandler,
-    CHANNEL_OPEN_FAILED, RESERVED_REPLY_KEY,
+    PubOpenHandler, CHANNEL_OPEN_FAILED, RESERVED_REPLY_KEY,
 };
 use super::pump::pump_bidi;
+
 use super::reassembly::{MpscRecvStream, MpscSendStream};
+use tokio::io::AsyncWriteExt;
 
 /// The producer-leg surface the relay holds (ADR-051 §2): the
 /// `CallConnection` for the translate hop's open call plus the
@@ -81,8 +83,17 @@ struct RelayPlan {
     producer_manager: ChannelManager,
     spoke_send: Option<MpscSendStream>,
     spoke_recv: Option<MpscRecvStream>,
+    /// The put path (ADR-047 amendment 4 §4.7): the producer leg's
+    /// open-op response, awaited by the relay pub handler after the
+    /// consumer EOF (put-acks-in-result — the spoke's response cannot
+    /// exist before its byte stream completes, so the establisher
+    /// never awaits it).
+    pub_reply: Option<tokio::sync::oneshot::Receiver<CallConnectionResponse>>,
 }
 
+/// The producer leg's open-op response, carried on the put path's plan.
+type CallConnectionResponse = crate::protocol::wire::ResponseEnvelope;
+
 impl Drop for RelayPlan {
     fn drop(&mut self) {
         let _ = self.producer_manager.teardown_channel(self.spoke_id);
@@ -120,9 +131,10 @@ impl ChannelRelay {
     ///   produced open op.
     /// - `spec` must carry the `channel_open` marker (reconstructed
     ///   WITH the marker by discovery, ADR-047 amendment 3). A
-    ///   `Pub`-typed marked spec is a loud assembly error
+    ///   `Pub`-typed marked spec composes through the put-forwarding
-    ///   ([`RelayError::PubTypedOpen`] — the C-08 blocker, ADR-051
+    ///   translation (see [`Self::register_relay_pub_openable`]); an
-    ///   §6); an unmarked spec is likewise an error — branch on the
+    ///   unmarked spec is a
+    ///   [`RelayError::UnmarkedSpec`] error — branch on the
     ///   marker before calling.
     /// - The translate hop calls the producer leg with the spec's own
     ///   op name; a hub that re-names the consumer-visible op composes
@@ -145,14 +157,12 @@ impl ChannelRelay {
             });
         }
         if spec.op_type == OperationType::Pub {
-            return Err(RelayError::PubTypedOpen {
+            return self.register_relay_pub_openable(
-                message: format!(
+                consumer_core,
-                    "spec `{}` is a Pub-typed channel-open op — the Pub open path is \
+                consumer_registry,
-                     not implemented (C-08 blocker, `channel:pub_open_not_implemented` \
+                spec,
-                     class; ADR-051 §6)",
+                consumer_auth,
-                    spec.name
+            );
-                ),
-            });
         }
 
         let producer_call = Arc::clone(&self.producer_leg.call);
@@ -227,6 +237,76 @@ impl ChannelRelay {
             )
             .map_err(|e| RelayError::Registration { message: e })
     }
+
+    /// Register a from_call-imported **marked `Pub`** spec as a relay
+    /// openable — the put-forwarding translation (ADR-047 amendment 4
+    /// §4.7). The consumer leg runs the full marked-pub wrapper (adopt
+    /// → establish → pub handler awaited inline); this side's compose:
+    ///
+    /// - the establisher allocates the hub's connect-side id on the
+    ///   producer leg (`open_channel` — an odd id, disjoint from the
+    ///   spoke's even allocations), sends the open op **in the
+    ///   background** (the spoke's put response cannot exist before
+    ///   its byte stream completes; an establisher that awaited it
+    ///   deadlocks the leg), and plans the spoke-leg streams + the
+    ///   response's oneshot; the plan's Drop guard reclaims the
+    ///   producer-leg entry on every handler path, as ADR-051 §6 pins.
+    /// - the handler pumps the consumer-leg bytes → the spoke leg
+    ///   (one direction, pub), EOFs the spoke side on consumer EOF,
+    ///   then awaits the spoke's single response, strips the
+    ///   producer's reserved reply key (the consumer reply carries the
+    ///   hub-allocated consumer-leg id; a spoke `channel_id` merged
+    ///   through would shadow it — the same reserved-key class the
+    ///   wrapper refuses), and returns the remainder — the consumer-leg
+    ///   wrapper merges it with the pinned order (ack fields are none
+    ///   here; the put acks in the spoke's result, §4.5).
+    ///
+    /// A spoke open-time establishment failure surfaces verbatim in
+    /// the final response (put-acks-in-result; the spoke's mapped
+    /// `channel:open_failed` rides the response, not the establisher).
+    fn register_relay_pub_openable(
+        &self,
+        consumer_core: &ChannelCore,
+        consumer_registry: &OperationRegistry,
+        spec: OperationSpec,
+        consumer_auth: AuthContext,
+    ) -> Result<(), RelayError> {
+        let producer_call = Arc::clone(&self.producer_leg.call);
+        let producer_manager = self.producer_leg.manager.clone();
+        let op_name = spec.name.clone();
+
+        let establisher: OpenEstablisher = Arc::new(move |input, per_call_auth| {
+            let producer_call = Arc::clone(&producer_call);
+            let producer_manager = producer_manager.clone();
+            let op_name = op_name.clone();
+            Box::pin(async move {
+                open_pub_on_producer_leg(
+                    &producer_call,
+                    &producer_manager,
+                    &op_name,
+                    input,
+                    &per_call_auth,
+                )
+                .await
+            })
+        });
+
+        let pub_open_handler: PubOpenHandler =
+            Arc::new(move |_input, plan, channel_conn, _auth| {
+                Box::pin(async move { pub_relay_forward(channel_conn, plan).await })
+            });
+
+        consumer_core
+            .register_pub_openable(
+                spec,
+                Some(establisher),
+                pub_open_handler,
+                consumer_registry,
+                consumer_auth,
+                None,
+            )
+            .map_err(|e| RelayError::Registration { message: e })
+    }
 }
 
 /// The translate hop (ADR-051 §1 layer 1, §2): call the producer leg's
@@ -288,6 +368,7 @@ async fn open_on_producer_leg(
         producer_manager: producer_manager.clone(),
         spoke_send: Some(spoke_send),
         spoke_recv: Some(spoke_recv),
+        pub_reply: None,
     }) as super::operations::ChannelPlan);
     Ok(if reply_fields.is_empty() {
         establishment
@@ -334,6 +415,123 @@ fn map_spoke_error(spoke_error: &CallError) -> EstablishmentError {
     }
 }
 
+/// The put path's translate hop (ADR-047 amendment 4 §4.7): allocate
+/// the hub's connect-side channel id on the producer leg, send the
+/// spoke's open op **in the background** with the reserved input key
+/// set, and plan the spoke-leg streams + the response oneshot. The
+/// establisher returns promptly; the spoke's response arrives when the
+/// spoke's put completes (or fails) — put-acks-in-result.
+async fn open_pub_on_producer_leg(
+    producer_call: &Arc<CallConnection>,
+    producer_manager: &ChannelManager,
+    op_name: &str,
+    input: Value,
+    per_call_auth: &AuthContext,
+) -> Result<Establishment, EstablishmentError> {
+    let (spoke_id, spoke_send, spoke_recv) = producer_manager
+        .open_channel(
+            "alk/relay",
+            // The opener ledger is inert on the hub's connect side
+            // (the connect side does not enforce the per-identity cap,
+            // ADR-041) — the record is observability only.
+            "hub-relay",
+            None,
+        )
+        .await
+        .map_err(|e| EstablishmentError::ResourceShortage {
+            message: format!("producer leg: channel allocation failed: {e}"),
+        })?;
+
+    let mut hop_input = input.clone();
+    if let Some(obj) = hop_input.as_object_mut() {
+        obj.insert(
+            crate::registry::spec::RESERVED_OPEN_INPUT_KEY.to_string(),
+            serde_json::json!(spoke_id),
+        );
+    }
+    let payload = build_relay_payload(op_name, hop_input, per_call_auth);
+
+    let (reply_tx, reply_rx) = tokio::sync::oneshot::channel();
+    let producer_call_task = Arc::clone(producer_call);
+    tokio::spawn(async move {
+        let _ = reply_tx.send(producer_call_task.call_with_payload(payload).await);
+    });
+
+    Ok(Establishment::new(Arc::new(RelayPlan {
+        spoke_id,
+        producer_manager: producer_manager.clone(),
+        spoke_send: Some(spoke_send),
+        spoke_recv: Some(spoke_recv),
+        pub_reply: Some(reply_rx),
+    }) as ChannelPlan))
+}
+
+/// The relay pub handler (ADR-047 amendment 4 §4.7): pump the
+/// consumer-leg bytes → the spoke leg (one direction, pub — the
+/// shutdown-on-completion contract, ADR-050's), then await the spoke's
+/// single response and strip its reserved reply key. The plan's Drop
+/// guard reclaims the producer-leg entry on every path.
+async fn pub_relay_forward(
+    channel_conn: crate::core::types::Connection,
+    plan: Option<ChannelPlan>,
+) -> Result<Value, CallError> {
+    let Some(plan) = plan else {
+        return Err(CallError::internal(
+            "relay: pub establisher produced no plan",
+        ));
+    };
+    let Ok(relay_plan_arc) = plan.downcast::<RelayPlan>() else {
+        return Err(CallError::internal(
+            "relay: establisher plan of unexpected type",
+        ));
+    };
+    let Ok(mut relay_plan) = Arc::try_unwrap(relay_plan_arc) else {
+        return Err(CallError::internal(
+            "relay: establisher plan held elsewhere; skipping pump",
+        ));
+    };
+    let Some(mut spoke_send) = relay_plan.spoke_send.take() else {
+        return Err(CallError::internal(
+            "relay: pub plan missing the spoke send half",
+        ));
+    };
+    relay_plan.spoke_recv.take();
+
+    let Ok(bidi) = channel_conn.accept_bi().await else {
+        return Err(CallError::internal(
+            "relay: consumer leg data plane never opened",
+        ));
+    };
+    let (mut read_half, _write_half) = tokio::io::split(bidi);
+    // The one-direction pump: consumer bytes → spoke; shutdown on
+    // consumer EOF (the pump contract, ADR-050).
+    let _copied = tokio::io::copy(&mut read_half, &mut spoke_send)
+        .await
+        .unwrap_or(0);
+    let _ = spoke_send.shutdown().await;
+    drop(spoke_send);
+
+    match relay_plan.pub_reply.take() {
+        Some(rx) => match rx.await {
+            Ok(response) => match response.result {
+                Ok(mut out) => {
+                    if let Some(obj) = out.as_object_mut() {
+                        obj.remove(RESERVED_REPLY_KEY);
+                    }
+                    Ok(out)
+                }
+                Err(e) => Err(e),
+            },
+            Err(_) => Err(CallError::internal(
+                "relay: producer-leg open resolved without a response",
+            )),
+        },
+        None => Err(CallError::internal(
+            "relay: pub plan missing the response receiver",
+        )),
+    }
+}
+
 /// Build the `call.requested` payload for the translate hop: the hub
 /// as caller, the consumer as `forwarded_for` (ADR-026 §3, ADR-032 §3
 /// — the same shape `build_forwarded_payload` produces for the plain
@@ -357,18 +555,15 @@ fn build_relay_payload(op_name: &str, input: Value, per_call_auth: &AuthContext)
 
 /// The assembly-time errors `ChannelRelay::register_relay_openable`
 /// produces (ADR-051 §6 — the rejection postures are loud, never
-/// silent stubs).
+/// silent stubs; the `PubTypedOpen` variant was removed by ADR-047
+/// amendment 4 §4.7 — pub-typed marked specs translate now, never
+/// reject-and-strand).
 #[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
 pub enum RelayError {
     /// The spec carries no `channel_open` marker — the relay only
     /// registers marked specs.
     #[error("unmarked spec: {message}")]
     UnmarkedSpec { message: String },
-    /// A `Pub`-typed marked spec — the Pub open path is not
-    /// implemented (C-08 blocker; `channel:pub_open_not_implemented`
-    /// class).
-    #[error("pub-typed open op: {message}")]
-    PubTypedOpen { message: String },
     /// The consumer-leg registration itself failed (schema compile,
     /// handler-kind mismatch).
     #[error("registration failed: {message}")]

src/channels/relay_tests.rs

@@ -89,15 +89,21 @@ async fn unmarked_spec_is_rejected_at_registration() {
 }
 
 #[tokio::test]
-async fn pub_typed_marked_spec_is_rejected_at_registration() {
+async fn pub_typed_marked_spec_registers_through_the_relay() {
+    // ADR-047 amendment 4 §4.7: the put-forwarding translation replaced
+    // the `PubTypedOpen` rejection — a pub-typed marked spec composes
+    // through `register_pub_openable` (the full marked-pub wrapper
+    // machinery) and lands on the consumer-leg registry, discoverable.
+    let producer_manager = manager_for_test();
     let relay = ChannelRelay::new(ProducerLeg {
         call: overlay_connection(),
-        manager: manager_for_test(),
+        manager: producer_manager,
     });
-    let err = relay
+    let registry = OperationRegistry::new();
+    relay
         .register_relay_openable(
             &core_for_test(),
-            &OperationRegistry::new(),
+            &registry,
             relay_spec(
                 "channels/x/pub",
                 OperationType::Pub,
@@ -105,12 +111,10 @@ async fn pub_typed_marked_spec_is_rejected_at_registration() {
             ),
             AuthContext::anonymous(b"alk/call"),
         )
-        .expect_err("Pub-typed marked spec must be rejected");
+        .expect("the pub openable registers through the relay");
-    assert!(
+    assert!(registry.registration("channels/x/pub").is_some());
-        matches!(err, RelayError::PubTypedOpen { .. }),
+    let registration = registry.registration("channels/x/pub").expect("registered");
-        "got {err:?}"
+    assert!(registration.spec.channel_open.is_some());
-    );
-    assert!(err.to_string().contains("pub_open_not_implemented"));
 }
 
 // --- ADR-051 §3: the reason mapping --------------------------------------
@@ -228,6 +232,7 @@ async fn relay_plan_drop_reclaims_the_adopted_producer_leg_entry() {
         producer_manager: producer_manager.clone(),
         spoke_send: Some(spoke_send),
         spoke_recv: Some(spoke_recv),
+        pub_reply: None,
     };
     drop(plan);
 
@@ -256,7 +261,16 @@ fn manager_for_test() -> ChannelManager {
     tokio::spawn(async move {
         let _ = runner.run().await;
     });
-    ChannelManager::with_defaults(handle, None)
+    // The producer leg's manager belongs to the hub, which is the
+    // connect side of the hub↔spoke channels connection (ADR-051 §4 —
+    // the spoke's ids are even, the hub's odd).
+    ChannelManager::new(
+        handle,
+        crate::channels::manager::DEFAULT_MAX_CHANNELS,
+        crate::channels::reassembly::DEFAULT_BUFFER_CAP,
+        None,
+        crate::channels::manager::ChannelSide::Connect,
+    )
 }
 
 fn core_for_test() -> ChannelCore {

src/channels/resource.rs

@@ -0,0 +1,70 @@
+//! `ResourceEnumerators` — the registry behind
+//! `channel/resources/subscribe`'s live subscription (ADR-053).
+//!
+//! Each openable-ALPN crate registers one enumerator (its resource
+//! truth: which containers are running, which sessions are active);
+//! the subscribe handler aggregates them. The channels layer never
+//! interprets the payloads — they ride opaquely, merged with the
+//! producing ALPN's name (ADR-053 §1).
+
+use std::collections::HashMap;
+use std::pin::Pin;
+use std::sync::Arc;
+
+use futures::Stream;
+use parking_lot::RwLock;
+use serde_json::Value;
+
+/// A registered enumerator's item: `(alpn, payload)` — the payload is
+/// the ALPN's full current resource state (snapshot-then-changes,
+/// ADR-053 §1). The channels layer does not interpret it.
+pub type ResourceItem = (String, Value);
+
+/// A registered enumerator's merged stream.
+pub type ResourceStream = Pin<Box<dyn Stream<Item = ResourceItem> + Send>>;
+
+/// The resource enumerator contract (ADR-053 §1). The producing crate
+/// owns its change detection; the first item on the returned stream is
+/// the current snapshot, and each subsequent item is a full snapshot
+/// of the changed set.
+pub trait ResourceEnumerator: Send + Sync + 'static {
+    fn subscribe(&self) -> ResourceStream;
+}
+
+/// The registry of ALPN resource enumerators (ADR-053 §2). Shared per
+/// accepting peer (like `PerIdentityChannelPolicy` — ADR-041): one
+/// `Arc<ResourceEnumerators>` across every channels connection that
+/// peer accepts. Registered at assembly/install time; the subscribe
+/// handler scans it once at subscription start (the scan-once pin —
+/// late registrations are invisible to in-flight subscriptions;
+/// re-subscribe to see them).
+#[derive(Clone, Default)]
+pub struct ResourceEnumerators {
+    inner: Arc<RwLock<HashMap<String, Arc<dyn ResourceEnumerator>>>>,
+}
+
+impl ResourceEnumerators {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Registered at assembly/install time by the composing crate.
+    pub fn register(&self, alpn: &str, enumerator: Arc<dyn ResourceEnumerator>) {
+        self.inner.write().insert(alpn.to_string(), enumerator);
+    }
+
+    /// The registered ALPNs (observability).
+    pub fn alpns(&self) -> Vec<String> {
+        self.inner.read().keys().cloned().collect()
+    }
+
+    /// Snapshot the registered set (the subscribe handler's scan-once
+    /// read; ADR-053 §2).
+    pub(crate) fn snapshot(&self) -> Vec<(String, Arc<dyn ResourceEnumerator>)> {
+        self.inner
+            .read()
+            .iter()
+            .map(|(alpn, enumerator)| (alpn.clone(), Arc::clone(enumerator)))
+            .collect()
+    }
+}

src/client/mod.rs

@@ -13,7 +13,10 @@ pub use from_call::{from_call, FromCallConfig};
 // crate-internal surface for the `op/register` bootstrap path (review
 // 004 F-05): the forwarding-handler constructor and the spec wire
 // parser are shared with `registry::op_register`.
-pub(crate) use from_call::{make_forwarding_handler, rebuild_spec_for};
+pub(crate) use from_call::{
+    make_forwarding_handler, make_sink_forwarding_handler, make_streaming_forwarding_handler,
+    rebuild_spec_for,
+};
 
 use crate::registry::registration::HandlerRegistration;
 

src/protocol/adapter.rs

@@ -538,7 +538,7 @@ mod tests {
             None,
             Capabilities::new(),
         );
-        conn.register_imported(imported);
+        let _error = conn.register_imported(imported);
         let peer_identity = Identity {
             id: "worker-a".to_string(),
             scopes: vec![],
@@ -607,7 +607,7 @@ mod tests {
             None,
             Capabilities::new(),
         );
-        conn.register_imported(imported);
+        let _error = conn.register_imported(imported);
 
         let context =
             adapter.build_root_context("req-6".to_string(), "fs/readFile", None, None, &conn);

src/protocol/connection.rs

@@ -159,9 +159,27 @@ impl CallConnection {
         &self.pending
     }
 
-    pub fn register_imported(&self, registration: HandlerRegistration) {
+    /// Land a peer-announced/discovered bundle on the connection
+    /// overlay. Marked (`channel_open`) specs refuse here: a marked op
+    /// is unreachable by composition (`OperationEnv::invoke` is
+    /// request/response-only; ADR-046 §6) and its data plane has no
+    /// overlay path — registration-time loudness, never an advertised
+    /// dead body (ADR-047 amendment 4 §4.8; ADR-022's 2026-10-13
+    /// amendment). Relay composition
+    /// (`ChannelRelay::register_relay_openable`) is the sanctioned
+    /// marked-op import.
+    pub fn register_imported(&self, registration: HandlerRegistration) -> Result<(), String> {
+        if registration.spec.channel_open.is_some() {
+            return Err(format!(
+                "register_imported: spec `{}` carries the `channel_open` marker — marked \
+                 specs are not overlay-importable; compose `ChannelRelay` or consume via \
+                 `ChannelClient` (ADR-047 amendment 4 §4.8)",
+                registration.spec.name
+            ));
+        }
         let name = registration.spec.name.clone();
         self.imported_operations.write().insert(name, registration);
+        Ok(())
     }
 
     /// `true` when the connection overlay holds a registration for
@@ -176,11 +194,24 @@ impl CallConnection {
         self.imported_operations.read().get(name).cloned()
     }
 
-    pub fn register_imported_all(&self, registrations: Vec<HandlerRegistration>) {
+    pub fn register_imported_all(
+        &self,
+        registrations: Vec<HandlerRegistration>,
+    ) -> Result<(), String> {
         let mut overlay = self.imported_operations.write();
         for reg in registrations {
-            overlay.insert(reg.spec.name.clone(), reg);
+            if reg.spec.channel_open.is_some() {
+                return Err(format!(
+                    "register_imported_all: spec `{}` carries the `channel_open` marker — \
+                     marked specs are not overlay-importable; compose `ChannelRelay` or \
+                     consume via `ChannelClient` (ADR-047 amendment 4 §4.8)",
+                    reg.spec.name
+                ));
+            }
+            let name = reg.spec.name.clone();
+            overlay.insert(name, reg);
         }
+        Ok(())
     }
 
     pub fn overlay_env(&self) -> Arc<dyn OperationEnv + Send + Sync> {
@@ -975,7 +1006,7 @@ mod tests {
 
         assert!(!env.contains("worker/exec"));
 
-        conn.register_imported(imported_registration("worker/exec"));
+        let _error = conn.register_imported(imported_registration("worker/exec"));
 
         assert!(env.contains("worker/exec"));
         assert!(!env.contains("worker/missing"));
@@ -986,11 +1017,12 @@ mod tests {
         let conn = CallConnection::new(stub_connection());
         let env = conn.overlay_env();
 
-        conn.register_imported_all(vec![
+        let registrations_result = conn.register_imported_all(vec![
             imported_registration("worker/exec"),
             imported_registration("worker/status"),
             imported_registration("fs/readFile"),
         ]);
+        let _error = registrations_result;
 
         assert!(env.contains("worker/exec"));
         assert!(env.contains("worker/status"));
@@ -1001,7 +1033,7 @@ mod tests {
     #[tokio::test]
     async fn overlay_env_dispatches_to_imported_op() {
         let conn = CallConnection::new(stub_connection());
-        conn.register_imported(imported_registration("worker/exec"));
+        let _error = conn.register_imported(imported_registration("worker/exec"));
         let env = conn.overlay_env();
 
         let scoped = ScopedPeerEnv::new(["worker/exec"]);
@@ -1018,7 +1050,7 @@ mod tests {
     #[tokio::test]
     async fn overlay_env_contains_returns_false_for_non_imported_op() {
         let conn = CallConnection::new(stub_connection());
-        conn.register_imported(imported_registration("worker/exec"));
+        let _error = conn.register_imported(imported_registration("worker/exec"));
         let env = conn.overlay_env();
 
         assert!(!env.contains("worker/missing"));
@@ -1039,7 +1071,7 @@ mod tests {
     #[tokio::test]
     async fn overlay_env_reachability_check_returns_not_found_for_disallowed_op() {
         let conn = CallConnection::new(stub_connection());
-        conn.register_imported(imported_registration("worker/exec"));
+        let _error = conn.register_imported(imported_registration("worker/exec"));
         let env = conn.overlay_env();
 
         let scoped = ScopedPeerEnv::empty();
@@ -1069,7 +1101,7 @@ mod tests {
                 }),
             )
         });
-        conn.register_imported(HandlerRegistration::new(
+        let _error = conn.register_imported(HandlerRegistration::new(
             external_spec("worker/exec"),
             HandlerKind::Once(inspect_handler),
             OperationProvenance::FromCall,
@@ -1115,7 +1147,7 @@ mod tests {
             Arc::new(RwLock::new(HashMap::new()));
         {
             let conn = CallConnection::new(stub_connection());
-            conn.register_imported(imported_registration("worker/exec"));
+            let _error = conn.register_imported(imported_registration("worker/exec"));
             assert!(conn.overlay_env().contains("worker/exec"));
             std::mem::swap(
                 &mut *captured.write(),
@@ -1380,14 +1412,14 @@ mod tests {
         let conn = CallConnection::new_overlay_only(sample_identity("ws-peer"));
         let env = conn.overlay_env();
         assert!(!env.contains("worker/exec"));
-        conn.register_imported(imported_registration("worker/exec"));
+        let _error = conn.register_imported(imported_registration("worker/exec"));
         assert!(env.contains("worker/exec"));
     }
 
     #[tokio::test]
     async fn overlay_only_overlay_env_dispatches_imported_op() {
         let conn = CallConnection::new_overlay_only(sample_identity("ws-peer"));
-        conn.register_imported(imported_registration("worker/exec"));
+        let _error = conn.register_imported(imported_registration("worker/exec"));
         let env = conn.overlay_env();
 
         let scoped = ScopedPeerEnv::new(["worker/exec"]);
@@ -1433,7 +1465,7 @@ mod tests {
         let streaming_handler = make_streaming_handler(|input, ctx| {
             futures::stream::iter(vec![ResponseEnvelope::ok(ctx.request_id, input)])
         });
-        conn.register_imported(HandlerRegistration::new(
+        let _error = conn.register_imported(HandlerRegistration::new(
             OperationSpec::new(
                 "events/stream",
                 OperationType::Sub,

src/protocol/dispatch.rs

@@ -86,6 +86,11 @@ pub struct SinkDispatch {
     pub(crate) handler: Pin<Box<dyn Future<Output = ResponseEnvelope> + Send>>,
     pub(crate) chunk_tx: mpsc::Sender<Result<Value, CallError>>,
     pub(crate) publish_validator: Option<jsonschema::Validator>,
+    /// Marked (`channel_open`) `Pub` op (ADR-047 amendment 4 §4.1):
+    /// publish chunks never feed the handler — the first
+    /// `call.published` chunk is rejected loudly in the initiator's
+    /// direction and the rest are ignored.
+    pub(crate) reject_publish: bool,
 }
 
 /// An in-flight Pub (Sink) on the single-stream dispatch loop
@@ -100,6 +105,11 @@ struct InFlightSink {
     chunk_tx: mpsc::Sender<Result<Value, CallError>>,
     publish_validator: Option<jsonschema::Validator>,
     handler_handle: JoinHandle<()>,
+    /// Marked (`channel_open`) `Pub` op (ADR-047 amendment 4 §4.1):
+    /// the first `call.published` chunk is rejected loudly in the
+    /// initiator's direction and never fed to the handler.
+    reject_publish: bool,
+    reject_written: bool,
 }
 
 impl std::fmt::Debug for DispatchResult {
@@ -356,7 +366,7 @@ impl Dispatcher {
             .get("forwarded_for")
             .and_then(|v| serde_json::from_value::<Identity>(v.clone()).ok());
 
-        let input = payload.get("input").cloned().unwrap_or(Value::Null);
+        let mut input = payload.get("input").cloned().unwrap_or(Value::Null);
 
         let op_type = self
             .registry
@@ -391,9 +401,13 @@ impl Dispatcher {
                 context.deadline = None;
                 match self
                     .registry
-                    .resolve_sink_handler(&operation_name, &input, &context)
+                    .resolve_sink_handler(&operation_name, &mut input, &mut context)
                 {
                     Ok(sink_handler) => {
+                        let reject_publish = self
+                            .registry
+                            .registration(&operation_name)
+                            .is_some_and(|r| r.spec.channel_open.is_some());
                         let publish_validator = self.registry.publish_validator(&operation_name);
                         let (chunk_tx, chunk_rx) =
                             mpsc::channel::<Result<Value, CallError>>(PUBLISH_CHANNEL_BUFFER);
@@ -403,6 +417,7 @@ impl Dispatcher {
                             handler: Box::pin(handler),
                             chunk_tx,
                             publish_validator,
+                            reject_publish,
                         })
                     }
                     Err(envelope) => StartedDispatch::Once(Box::pin(std::future::ready(envelope))),
@@ -657,6 +672,7 @@ impl Dispatcher {
             handler,
             mut chunk_tx,
             publish_validator,
+            reject_publish,
         } = sink;
 
         let (abort_tx, mut abort_rx) = oneshot::channel::<()>();
@@ -668,6 +684,7 @@ impl Dispatcher {
         let mut handler = handler.fuse();
         let mut response: Option<ResponseEnvelope> = None;
         let mut aborted = false;
+        let mut reject_written = false;
 
         loop {
             tokio::select! {
@@ -698,6 +715,31 @@ impl Dispatcher {
                             }
                             match envelope.r#type.as_str() {
                                 EVENT_PUBLISHED => {
+                                    // Marked ops: the data plane is the adopted
+                                    // channel's `BiStream` — publish chunks are
+                                    // rejected loudly, never consumed (ADR-047
+                                    // amendment 4 §4.1). The handler continues on
+                                    // the channel plane; the initiator's pending
+                                    // call resolves with this rejection.
+                                    if reject_publish {
+                                        if !reject_written {
+                                            reject_written = true;
+                                            let rejection: EventEnvelope = ResponseEnvelope::error(
+                                                request_id.clone(),
+                                                CallError::new(
+                                                    crate::registry::spec::MARKED_PUB_CHUNKS_REJECTED,
+                                                    "the data plane of a marked pub op is the adopted \
+                                                     channel's BiStream — call.published chunks are \
+                                                     rejected (ADR-047 amendment 4 §4.1)",
+                                                    false,
+                                                ),
+                                            ).into();
+                                            if let Err(err) = writer.write_frame(&rejection).await {
+                                                warn!(error = %err, request_id = %request_id, "failed to write marked-op publish rejection");
+                                            }
+                                        }
+                                        continue;
+                                    }
                                     let chunk = envelope
                                         .payload
                                         .get("input")
@@ -923,6 +965,7 @@ impl Dispatcher {
                                 handler,
                                 chunk_tx,
                                 publish_validator,
+                                reject_publish,
                             } = sink;
                             let handle = Self::spawn_sink_response_writer(
                                 &writer,
@@ -935,6 +978,8 @@ impl Dispatcher {
                                     chunk_tx,
                                     publish_validator,
                                     handler_handle: handle,
+                                    reject_publish,
+                                    reject_written: false,
                                 },
                             );
                         }
@@ -977,6 +1022,36 @@ impl Dispatcher {
                         .unwrap_or(Value::Null);
                     let entry = in_flight_sinks.lock().remove(&request_id);
                     if let Some(mut entry) = entry {
+                        if entry.reject_publish {
+                            // Marked ops: the data plane is the adopted
+                            // channel's `BiStream` — publish chunks are
+                            // rejected loudly, never consumed (ADR-047
+                            // amendment 4 §4.1). The loud error is written
+                            // once per request; the entry stays registered
+                            // so the handler's own final response still gets
+                            // written. The handler continues on the channel
+                            // plane; the initiator's pending call resolves
+                            // with this rejection immediately.
+                            if !entry.reject_written {
+                                entry.reject_written = true;
+                                let rejection: EventEnvelope = ResponseEnvelope::error(
+                                    request_id.clone(),
+                                    CallError::new(
+                                        crate::registry::spec::MARKED_PUB_CHUNKS_REJECTED,
+                                        "the data plane of a marked pub op is the \
+                                         adopted channel's BiStream — call.published \
+                                         chunks are rejected (ADR-047 amendment 4 §4.1)",
+                                        false,
+                                    ),
+                                )
+                                .into();
+                                if let Err(err) = writer.write_frame(&rejection).await {
+                                    warn!(error = %err, request_id = %request_id, "failed to write marked-op publish rejection");
+                                }
+                            }
+                            in_flight_sinks.lock().insert(request_id, entry);
+                            continue;
+                        }
                         let validated = match &entry.publish_validator {
                             Some(validator) => {
                                 if validator.is_valid(&chunk) {
@@ -1146,6 +1221,7 @@ impl Dispatcher {
                                 handler,
                                 chunk_tx,
                                 publish_validator,
+                                reject_publish,
                             } = sink;
                             let handle = Self::spawn_sink_response_writer(
                                 &writer,
@@ -1158,6 +1234,8 @@ impl Dispatcher {
                                     chunk_tx,
                                     publish_validator,
                                     handler_handle: handle,
+                                    reject_publish,
+                                    reject_written: false,
                                 },
                             );
                         }
@@ -1200,6 +1278,36 @@ impl Dispatcher {
                         .unwrap_or(Value::Null);
                     let entry = in_flight_sinks.lock().remove(&request_id);
                     if let Some(mut entry) = entry {
+                        if entry.reject_publish {
+                            // Marked ops: the data plane is the adopted
+                            // channel's `BiStream` — publish chunks are
+                            // rejected loudly, never consumed (ADR-047
+                            // amendment 4 §4.1). The loud error is written
+                            // once per request; the entry stays registered
+                            // so the handler's own final response still gets
+                            // written. The handler continues on the channel
+                            // plane; the initiator's pending call resolves
+                            // with this rejection immediately.
+                            if !entry.reject_written {
+                                entry.reject_written = true;
+                                let rejection: EventEnvelope = ResponseEnvelope::error(
+                                    request_id.clone(),
+                                    CallError::new(
+                                        crate::registry::spec::MARKED_PUB_CHUNKS_REJECTED,
+                                        "the data plane of a marked pub op is the \
+                                         adopted channel's BiStream — call.published \
+                                         chunks are rejected (ADR-047 amendment 4 §4.1)",
+                                        false,
+                                    ),
+                                )
+                                .into();
+                                if let Err(err) = writer.write_frame(&rejection).await {
+                                    warn!(error = %err, request_id = %request_id, "failed to write marked-op publish rejection");
+                                }
+                            }
+                            in_flight_sinks.lock().insert(request_id, entry);
+                            continue;
+                        }
                         let validated = match &entry.publish_validator {
                             Some(validator) => {
                                 if validator.is_valid(&chunk) {

src/registry/op_register.rs

@@ -178,16 +178,37 @@ pub fn op_register_handler(
             }
 
             let mut spec = request.spec;
+            if spec.channel_open.is_some() {
+                return ResponseEnvelope::error(
+                    context.request_id,
+                    CallError::new(
+                        "MARKED_SPEC_UNSUPPORTED",
+                        format!(
+                            "op/register: `{}` carries the `channel_open` marker — marked ops \
+                             are channel-machinery ops (the data plane is the allocated \
+                             channel's `BiStream`, ADR-047 amendment 4); forward them with \
+                             `ChannelRelay::register_relay_openable` (a relaying hub) or \
+                             consume them directly (`ChannelClient`), never as an \
+                             announcement",
+                            spec.name
+                        ),
+                        false,
+                    ),
+                );
+            }
             spec.visibility = Visibility::Internal;
             let remote_name = spec.name.clone();
 
-            let handler = forwarding_stub_for_announced_op(
+            let handler = forwarding_kind_for_announced_op(
                 Arc::clone(&connection),
                 remote_name,
                 spec.op_type,
             );
 
-            connection.register_imported(HandlerRegistration::new(
+            // The marked-refusal arm is unreachable here (marked
+            // announcements were refused above); an invariant break
+            // maps to the wire rather than a panic.
+            let registered = connection.register_imported(HandlerRegistration::new(
                 spec.clone(),
                 handler,
                 OperationProvenance::FromCall,
@@ -195,6 +216,12 @@ pub fn op_register_handler(
                 None,
                 Capabilities::new(),
             ));
+            if let Err(e) = registered {
+                return ResponseEnvelope::error(
+                    context.request_id,
+                    CallError::internal(format!("op/register: overlay landing refused: {e}")),
+                );
+            }
 
             ResponseEnvelope::ok(
                 context.request_id,
@@ -204,15 +231,14 @@ pub fn op_register_handler(
     })
 }
 
-/// The forwarding stub for a peer-announced op. Query/Mutation ops get
+/// The forwarding handler kind for a peer-announced op. Query/Mutation
-/// the `from_call` forwarding shape (nested `call.requested` back over
+/// get the `from_call` forwarding shape (nested `call.requested` back
-/// channel 0, `forwarded_for` populated per ADR-032 §3). Announced
+/// over channel 0, `forwarded_for` populated per ADR-032 §3); unmarked
-/// Sub/Pub ops are registered as stubs that return
+/// `Sub`/`Pub` get the real streaming/sink forwarding shapes (review
-/// `INVALID_OPERATION_TYPE` on invocation — nested composition is
+/// 010 S-04's remedy: never accept-then-fail — the handler actually
-/// request/response-only (`OverlayOperationEnv`'s contract); the
+/// forwards). Marked specs refuse at this boundary (ADR-047 amendment
-/// streaming/sink forwarding shapes ride on the `from_call` import
+/// 4 — checked before this function is reached).
-/// path, which the announcing side can use in the other direction.
+fn forwarding_kind_for_announced_op(
-fn forwarding_stub_for_announced_op(
     connection: Arc<CallConnection>,
     remote_name: String,
     op_type: OperationType,
@@ -221,17 +247,13 @@ fn forwarding_stub_for_announced_op(
         OperationType::Query | OperationType::Mutation => HandlerKind::Once(
             crate::client::make_forwarding_handler(connection, remote_name),
         ),
-        OperationType::Sub | OperationType::Pub => {
+        OperationType::Sub => HandlerKind::Stream(
-            HandlerKind::Once(make_handler(|_input, context| async move {
+            crate::client::make_streaming_forwarding_handler(connection, remote_name),
-                ResponseEnvelope::error(
+        ),
-                    context.request_id,
+        OperationType::Pub => HandlerKind::Sink(crate::client::make_sink_forwarding_handler(
-                    CallError::invalid_operation_type(
+            connection,
-                        "peer-announced Sub/Pub ops are not invocable over nested \
+            remote_name,
-                         composition (request/response only)",
+        )),
-                    ),
-                )
-            }))
-        }
     }
 }
 
@@ -757,4 +779,111 @@ mod tests {
             .expect("marker survives the announce");
         assert_eq!(marker.alpn, "alk/tunnel");
     }
+
+    // --- review 010 S-04's remedy (ADR-022, 2026-10-13 amendment) --------
+
+    /// Forward-through: an announced unmarked `Sub` op registers the
+    /// real streaming forwarding shape, not an always-failing stub.
+    #[tokio::test]
+    async fn announced_unmarked_sub_registers_real_streaming_forward() {
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+        let handler = op_register_handler(Arc::clone(&conn), Arc::new(OperationRegistry::new()));
+
+        let input = OpRegisterRequest {
+            spec: OperationSpec::new(
+                "worker/events",
+                OperationType::Sub,
+                Visibility::External,
+                json!({}),
+                json!({}),
+                vec![],
+                AccessControl::default(),
+                None,
+            ),
+            replace: false,
+        }
+        .to_json();
+        let response = handler(input, test_context("req-s04-1")).await;
+        assert!(response.result.is_ok(), "got {:?}", response.result);
+
+        let registration = conn
+            .overlay_registration("worker/events")
+            .expect("registered");
+        assert!(
+            matches!(registration.handler, HandlerKind::Stream(_)),
+            "the announced sub op is a real forwarding handler, not a stub"
+        );
+    }
+
+    /// Forward-through: an announced unmarked `Pub` op registers the
+    /// real sink forwarding shape.
+    #[tokio::test]
+    async fn announced_unmarked_pub_registers_real_sink_forward() {
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+        let handler = op_register_handler(Arc::clone(&conn), Arc::new(OperationRegistry::new()));
+
+        let input = OpRegisterRequest {
+            spec: OperationSpec::new(
+                "worker/ingest",
+                OperationType::Pub,
+                Visibility::External,
+                json!({}),
+                json!({}),
+                vec![],
+                AccessControl::default(),
+                None,
+            ),
+            replace: false,
+        }
+        .to_json();
+        let response = handler(input, test_context("req-s04-2")).await;
+        assert!(response.result.is_ok(), "got {:?}", response.result);
+
+        let registration = conn
+            .overlay_registration("worker/ingest")
+            .expect("registered");
+        assert!(
+            matches!(registration.handler, HandlerKind::Sink(_)),
+            "the announced pub op is a real forwarding handler, not a stub"
+        );
+    }
+
+    /// Marked-spec refusal (ADR-047 amendment 4 §4.8's wire side): a
+    /// marked announcement is rejected with the typed code, no overlay
+    /// entry, and the message names the sanctioned compositions.
+    #[tokio::test]
+    async fn announced_marked_spec_is_refused() {
+        use crate::registry::spec::ChannelOpenSpec;
+
+        let conn = Arc::new(CallConnection::new(stub_connection()));
+        let handler = op_register_handler(Arc::clone(&conn), Arc::new(OperationRegistry::new()));
+
+        let input = OpRegisterRequest {
+            spec: OperationSpec::new(
+                "channels/tunnel/direct",
+                OperationType::Sub,
+                Visibility::External,
+                json!({}),
+                json!({}),
+                vec![],
+                AccessControl::default(),
+                None,
+            )
+            .with_channel_open(ChannelOpenSpec::new("alk/tunnel")),
+            replace: false,
+        }
+        .to_json();
+        let response = handler(input, test_context("req-s04-3")).await;
+        let e = response.result.expect_err("marked announcement refused");
+        assert_eq!(e.code, "MARKED_SPEC_UNSUPPORTED");
+        assert!(
+            e.message.contains("ChannelRelay"),
+            "the refusal names the sanctioned composition: {}",
+            e.message
+        );
+        assert!(
+            !conn.overlay_contains("channels/tunnel/direct"),
+            "the refused announcement lands nowhere"
+        );
+    }
 }

src/registry/registration.rs

@@ -84,6 +84,12 @@ pub struct HandlerRegistration {
     pub composition_authority: Option<CompositionAuthority>,
     pub scoped_env: Option<ScopedPeerEnv>,
     pub capabilities: Capabilities,
+    /// Set only by the channels-layer wrapper builders — a marked
+    /// (`channel_open`) spec is registered only through the
+    /// channel-machinery seam (`register_openable*`, `register_pub_openable`,
+    /// the relay). Generic registrations of marked specs are refused
+    /// (ADR-047 amendment 4 §4.8 — the registered-but-incapable class).
+    pub(crate) channel_wrapper: bool,
 }
 
 impl HandlerRegistration {
@@ -102,8 +108,17 @@ impl HandlerRegistration {
             composition_authority,
             scoped_env,
             capabilities,
+            channel_wrapper: false,
         }
     }
+
+    /// The channel-machinery wrapper family's constructor seam
+    /// (crate-internal — the only sanctioned registrations of marked
+    /// specs).
+    pub(crate) fn with_channel_wrapper(mut self) -> Self {
+        self.channel_wrapper = true;
+        self
+    }
 }
 
 pub struct OperationRegistry {
@@ -215,6 +230,23 @@ impl OperationRegistry {
                 registration.spec.op_type, expected, actual
             ));
         }
+        if registration.spec.channel_open.is_some() && !registration.channel_wrapper {
+            return Err(format!(
+                "spec `{}` carries the `channel_open` marker — marked ops are registered \
+                 only through the channel-machinery seam (`ChannelCore::register_openable*`, \
+                 `ChannelCore::register_pub_openable`, `ChannelRelay::register_relay_openable`); \
+                 a generic registration cannot serve the marker's data plane (ADR-047 amendment 4 §4.8)",
+                registration.spec.name
+            ));
+        }
+        if registration.spec.channel_open.is_some() && registration.spec.publish_schema.is_some() {
+            return Err(format!(
+                "spec `{}` carries both the `channel_open` marker and a `publish_schema` — \
+                 publish chunks never exist on a marked op (the data plane is the adopted \
+                 channel's `BiStream`); the field is dead machinery here (ADR-047 amendment 4 §4.2)",
+                registration.spec.name
+            ));
+        }
         Self::validate_and_cache_publish_schema(&mut self.validators.write(), &registration.spec)?;
         Self::validate_and_cache_input_schema(
             &mut self.input_validators.write(),
@@ -436,12 +468,21 @@ impl OperationRegistry {
     /// dispatch path (`Dispatcher::dispatch` Pub branch) call it, so the
     /// two paths cannot diverge (P-08: the `invoke_sink` path IS the
     /// wire path).
+    ///
+    /// Marked `Pub` ops (ADR-047 amendment 4 §4.3): the
+    /// wrapper-reserved input key ([`crate::registry::spec::
+    /// RESERVED_OPEN_INPUT_KEY`]) is stripped **before**
+    /// `input_schema` validation — the producing crate's schema never
+    /// contains it — and the initiator-allocated channel id is handed
+    /// to the wrapper via `context.metadata`. A marked pub op whose
+    /// input lacks the reserved key is rejected here (`INVALID_INPUT`)
+    /// — the id is mandatory, not optional plumbing.
     #[allow(clippy::result_large_err)]
     pub(crate) fn resolve_sink_handler(
         &self,
         name: &str,
-        input: &Value,
+        input: &mut Value,
-        context: &OperationContext,
+        context: &mut OperationContext,
     ) -> Result<SinkHandler, ResponseEnvelope> {
         let request_id = context.request_id.clone();
         let registration = match self.registration(name) {
@@ -477,6 +518,43 @@ impl OperationRegistry {
             return Err(ResponseEnvelope::forbidden(request_id, message));
         }
 
+        if registration.spec.channel_open.is_some()
+            && registration.spec.op_type == OperationType::Pub
+        {
+            let reserved_id = match input
+                .as_object_mut()
+                .and_then(|obj| obj.remove(crate::registry::spec::RESERVED_OPEN_INPUT_KEY))
+            {
+                Some(value) => match value.as_u64() {
+                    Some(id) if id <= u32::MAX as u64 => id as u32,
+                    _ => {
+                        return Err(ResponseEnvelope::error(
+                            request_id,
+                            CallError::invalid_input(format!(
+                                "marked pub open op: the reserved `{}` key must be a u32 \
+                                 channel id (the initiator-allocated id; ADR-047 amendment 4 §4.3)",
+                                crate::registry::spec::RESERVED_OPEN_INPUT_KEY
+                            )),
+                        ));
+                    }
+                },
+                None => {
+                    return Err(ResponseEnvelope::error(
+                        request_id,
+                        CallError::invalid_input(format!(
+                            "marked pub open op input missing the reserved `{}` key \
+                             (the initiator-allocated channel id; ADR-047 amendment 4 §4.3)",
+                            crate::registry::spec::RESERVED_OPEN_INPUT_KEY
+                        )),
+                    ));
+                }
+            };
+            context.metadata.insert(
+                crate::registry::spec::RESERVED_OPEN_METADATA_KEY.to_string(),
+                serde_json::json!(reserved_id),
+            );
+        }
+
         self.check_input_schema(&registration, input, &request_id)?;
 
         match &registration.handler {
@@ -505,14 +583,16 @@ impl OperationRegistry {
     pub async fn invoke_sink(
         &self,
         name: &str,
-        input: Value,
+        mut input: Value,
         publish_stream: PublishStream,
-        context: OperationContext,
+        mut context: OperationContext,
     ) -> ResponseEnvelope {
-        match self.resolve_sink_handler(name, &input, &context) {
+        let publish_stream_resolved =
-            Err(envelope) => envelope,
+            match self.resolve_sink_handler(name, &mut input, &mut context) {
-            Ok(sink_handler) => sink_handler(input, context, publish_stream).await,
+                Err(envelope) => return envelope,
-        }
+                Ok(sink_handler) => sink_handler,
+            };
+        publish_stream_resolved(input, context, publish_stream).await
     }
 }
 
@@ -2942,3 +3022,85 @@ mod tests {
         assert_eq!(err.code, "INVALID_INPUT");
     }
 }
+
+#[cfg(test)]
+mod marked_spec_gates {
+    use super::*;
+
+    fn marked_spec(name: &str, op_type: OperationType) -> OperationSpec {
+        OperationSpec::new(
+            name,
+            op_type,
+            crate::registry::spec::Visibility::External,
+            serde_json::json!({}),
+            serde_json::json!({}),
+            vec![],
+            crate::registry::spec::AccessControl::default(),
+            None,
+        )
+        .with_channel_open(crate::registry::spec::ChannelOpenSpec::new("alk/x"))
+    }
+
+    /// ADR-047 amendment 4 §4.2 gate: `publish_schema` on a marked
+    /// spec refuses at registration — publish chunks never exist on a
+    /// marked op. (Registered through the sanctioned wrapper seam, so
+    /// the §4.8 invariant is satisfied and this refusal is the one
+    /// that fires.)
+    #[test]
+    fn marked_spec_with_publish_schema_refused() {
+        let registry = OperationRegistry::new();
+        let spec = marked_spec("channels/x/pub", OperationType::Pub)
+            .with_publish_schema(serde_json::json!({ "type": "object" }));
+        let registration = HandlerRegistration::new(
+            spec,
+            HandlerKind::Sink(make_sink_handler(|_input, _ctx, _stream| async {
+                ResponseEnvelope::ok("r", serde_json::json!({}))
+            })),
+            OperationProvenance::Local,
+            None,
+            None,
+            crate::core::types::Capabilities::new(),
+        )
+        .with_channel_wrapper();
+        let e = registry.register(registration).expect_err("refused");
+        assert!(e.contains("publish_schema"), "got: {e}");
+    }
+
+    /// ADR-047 amendment 4 §4.8 gate: a marked spec through the
+    /// generic registration path is refused — the registered-but-
+    /// incapable class review 010 outlaws; the sanctioned seam is the
+    /// channel wrapper family.
+    #[test]
+    fn marked_spec_refused_outside_the_wrapper_seam() {
+        let registry = OperationRegistry::new();
+        let spec = marked_spec("channels/x/pub", OperationType::Pub);
+        let registration = HandlerRegistration::new(
+            spec,
+            HandlerKind::Sink(make_sink_handler(|_input, _ctx, _stream| async {
+                ResponseEnvelope::ok("r", serde_json::json!({}))
+            })),
+            OperationProvenance::Local,
+            None,
+            None,
+            crate::core::types::Capabilities::new(),
+        );
+        let e = registry.register(registration).expect_err("refused");
+        assert!(e.contains("channel-machinery seam"), "got: {e}");
+
+        // A marked `Sub` spec — the same class.
+        let registry2 = OperationRegistry::new();
+        let spec2 = marked_spec("channels/x/sub", OperationType::Sub);
+        let registration2 = HandlerRegistration::new(
+            spec2,
+            HandlerKind::Stream(make_streaming_handler(|_input, _ctx| {
+                Box::pin(futures::stream::empty())
+            })),
+            OperationProvenance::Local,
+            None,
+            None,
+            crate::core::types::Capabilities::new(),
+        );
+        let e2 = registry2.register(registration2).expect_err("refused");
+        assert!(e2.contains("channel-machinery seam"), "got: {e2}");
+    }
+}

src/registry/spec.rs

@@ -49,6 +49,28 @@ pub struct ChannelOpenSpec {
     pub alpn: Cow<'static, str>,
 }
 
+/// The wrapper-reserved input key on a **marked `Pub` op's** input
+/// (ADR-047 amendment 4 §4.3): the initiator-allocated `channel_id` the
+/// responder adopts. The same key the open wrapper owns on the reply
+/// side (the channels layer's `RESERVED_REPLY_KEY`); the wrapper owns
+/// `channel_id` on both sides of a marked open op. Stripped
+/// pre-validation in the sink resolve path and delivered to the
+/// wrapper via `OperationContext.metadata`
+/// ([`RESERVED_OPEN_METADATA_KEY`]).
+pub const RESERVED_OPEN_INPUT_KEY: &str = "channel_id";
+
+/// The `OperationContext.metadata` key the sink resolve path uses to
+/// hand the stripped reserved input value (the initiator-allocated
+/// channel id) to the marked-pub open wrapper (ADR-047 amendment 4
+/// §4.3).
+pub const RESERVED_OPEN_METADATA_KEY: &str = "channel_open_channel_id";
+
+/// The wire error code for a `call.published` chunk arriving on a
+/// marked (`channel_open`) `Pub` op (ADR-047 amendment 4 §4.1): the
+/// marked op's data plane is the adopted channel's `BiStream`; publish
+/// chunks are rejected loudly and never consumed.
+pub const MARKED_PUB_CHUNKS_REJECTED: &str = "channel:publish_chunks_rejected";
+
 impl ChannelOpenSpec {
     pub fn new(alpn: impl Into<Cow<'static, str>>) -> Self {
         Self { alpn: alpn.into() }

tests/stub_guard.rs

@@ -0,0 +1,49 @@
+//! The stub guard (review 010 action 3): no `*:not_implemented` path
+//! may exist in `src/`. A handler that registers successfully and
+//! returns an error of this form on every invocation is a bug, not a
+//! documented limitation — shipping one is a hard failure per the
+//! repo ruling (reviews 010/011; four stubs shipped across nine
+//! published versions before this guard existed).
+
+#[test]
+fn source_tree_has_no_not_implemented_path() {
+    let manifest = env!("CARGO_MANIFEST_DIR");
+    let src = std::path::Path::new(manifest).join("src");
+    let mut offenders = Vec::new();
+    walk(&src, &mut offenders);
+    assert!(
+        offenders.is_empty(),
+        "no `not_implemented` string may appear in src/ — a registered surface \
+         that always fails is the stub class (review 010 S-01..S-04); offended \
+         by: {offenders:?}"
+    );
+}
+
+fn walk(dir: &std::path::Path, offenders: &mut Vec<String>) {
+    let entries = match std::fs::read_dir(dir) {
+        Ok(entries) => entries,
+        Err(_) => return,
+    };
+    for entry in entries.flatten() {
+        let path = entry.path();
+        if path.is_dir() {
+            walk(&path, offenders);
+        } else if path.extension().is_some_and(|e| e == "rs") {
+            let contents = match std::fs::read_to_string(&path) {
+                Ok(c) => c,
+                Err(_) => continue,
+            };
+            for (line_no, line) in contents.lines().enumerate() {
+                if line.contains("not_implemented") {
+                    offenders.push(format!(
+                        "{}:{}",
+                        path.strip_prefix(env!("CARGO_MANIFEST_DIR"))
+                            .unwrap_or(&path)
+                            .display(),
+                        line_no + 1
+                    ));
+                }
+            }
+        }
+    }
+}