fix: use live worker observation snapshots

crates/worker-runtime/src/execution.rs

@@ -393,6 +393,11 @@ pub trait WorkerExecutionBackend: Send + Sync + 'static {
             "execution backend does not support cancelling workers",
         )
     }
+
+    #[cfg(feature = "ws-server")]
+    fn worker_snapshot(&self, _handle: &WorkerExecutionHandle) -> Option<protocol::Event> {
+        None
+    }
 }
 
 #[derive(Clone)]
@@ -472,6 +477,14 @@ impl WorkerExecutionBackendRef {
     pub(crate) fn cancel_worker(&self, handle: &WorkerExecutionHandle) -> WorkerExecutionResult {
         self.backend.cancel_worker(handle)
     }
+
+    #[cfg(feature = "ws-server")]
+    pub(crate) fn worker_snapshot(
+        &self,
+        handle: &WorkerExecutionHandle,
+    ) -> Option<protocol::Event> {
+        self.backend.worker_snapshot(handle)
+    }
 }
 
 impl fmt::Debug for WorkerExecutionBackendRef {

crates/worker-runtime/src/runtime.rs

@@ -783,8 +783,19 @@ impl Runtime {
         &self,
         worker_ref: &WorkerRef,
     ) -> Result<protocol::Event, RuntimeError> {
-        let state = self.lock()?;
-        let _worker = state.worker(worker_ref)?;
+        let (backend, handle) = {
+            let state = self.lock()?;
+            let worker = state.worker(worker_ref)?;
+            (
+                state.execution_backend.clone(),
+                worker.execution_handle.clone(),
+            )
+        };
+        if let (Some(backend), Some(handle)) = (backend, handle) {
+            if let Some(snapshot) = backend.worker_snapshot(&handle) {
+                return Ok(snapshot);
+            }
+        }
         Ok(protocol::Event::Snapshot {
             entries: Vec::new(),
             greeting: protocol::Greeting {
@@ -1826,6 +1837,8 @@ mod tests {
         restore_result: Mutex<Option<WorkerExecutionSpawnResult>>,
         restore_count: Mutex<u64>,
         contexts: Mutex<BTreeMap<WorkerId, WorkerExecutionContext>>,
+        #[cfg(feature = "ws-server")]
+        snapshots: Mutex<BTreeMap<WorkerId, protocol::Event>>,
     }
 
     impl TestExecutionBackend {
@@ -1833,6 +1846,14 @@ mod tests {
             *self.dispatch_result.lock().unwrap() = Some(result);
         }
 
+        #[cfg(feature = "ws-server")]
+        fn set_worker_snapshot(&self, worker_ref: &WorkerRef, snapshot: protocol::Event) {
+            self.snapshots
+                .lock()
+                .unwrap()
+                .insert(worker_ref.worker_id.clone(), snapshot);
+        }
+
         #[cfg(feature = "ws-server")]
         fn publish_text_delta(
             &self,
@@ -1917,6 +1938,15 @@ mod tests {
                 WorkerExecutionRunState::Stopped,
             )
         }
+
+        #[cfg(feature = "ws-server")]
+        fn worker_snapshot(&self, handle: &WorkerExecutionHandle) -> Option<protocol::Event> {
+            self.snapshots
+                .lock()
+                .unwrap()
+                .get(&handle.worker_ref().worker_id)
+                .cloned()
+        }
     }
 
     fn runtime_with_backend() -> Runtime {
@@ -2123,6 +2153,51 @@ mod tests {
         ));
     }
 
+    #[cfg(feature = "ws-server")]
+    #[test]
+    fn observation_snapshot_prefers_live_backend_snapshot() {
+        let (runtime, backend) = runtime_and_backend();
+        let detail = runtime
+            .create_worker(task_request("observe snapshot"))
+            .unwrap();
+        let expected_entry = serde_json::json!({"kind": "restored-log-entry"});
+        backend.set_worker_snapshot(
+            &detail.worker_ref,
+            protocol::Event::Snapshot {
+                entries: vec![expected_entry.clone()],
+                greeting: protocol::Greeting {
+                    worker_name: "live-worker".to_string(),
+                    cwd: "/tmp/live".to_string(),
+                    provider: "test-provider".to_string(),
+                    model: "test-model".to_string(),
+                    scope_summary: "live snapshot".to_string(),
+                    tools: Vec::new(),
+                    context_window: 128,
+                    context_tokens: 64,
+                },
+                status: protocol::WorkerStatus::Running,
+                in_flight: protocol::InFlightSnapshot { blocks: Vec::new() },
+            },
+        );
+
+        let snapshot = runtime
+            .worker_observation_snapshot(&detail.worker_ref)
+            .unwrap();
+        match snapshot {
+            protocol::Event::Snapshot {
+                entries,
+                greeting,
+                status,
+                ..
+            } => {
+                assert_eq!(entries, vec![expected_entry]);
+                assert_eq!(greeting.worker_name, "live-worker");
+                assert_eq!(status, protocol::WorkerStatus::Running);
+            }
+            other => panic!("expected snapshot, got {other:?}"),
+        }
+    }
+
     struct InputOnlyBackend;
 
     impl WorkerExecutionBackend for InputOnlyBackend {

crates/worker-runtime/src/worker_backend.rs

@@ -1082,6 +1082,17 @@ where
             WorkerExecutionRunState::Idle,
         )
     }
+
+    #[cfg(feature = "ws-server")]
+    fn worker_snapshot(&self, handle: &WorkerExecutionHandle) -> Option<protocol::Event> {
+        if handle.backend_id() != self.backend_id() {
+            return None;
+        }
+        let workers = self.workers.lock().ok()?;
+        workers
+            .get(handle.worker_ref())
+            .map(|execution| execution.handle.snapshot_event())
+    }
 }
 
 #[cfg(test)]

crates/worker/src/controller.rs

@@ -5,8 +5,8 @@ use std::sync::atomic::Ordering;
 use llm_engine::EngineError;
 use llm_engine::llm_client::client::LlmClient;
 use manifest::TicketFeatureAccessConfig;
-use session_store::Store;
 use session_store::WorkerMetadataStore;
+use session_store::{LogEntry, Store};
 use ticket::LocalTicketBackend;
 use ticket::config::TicketConfig;
 use tokio::sync::{broadcast, mpsc, oneshot};
@@ -16,7 +16,7 @@ use crate::discovery::{
     WorkerDiscovery, list_workers_tool, restore_worker_tool, send_to_peer_worker_tool,
 };
 use crate::feature::FeatureRegistryBuilder;
-use crate::in_flight::InFlightEvents;
+use crate::in_flight::{InFlightEvents, snapshot_from_guard};
 use crate::ipc::alerter::Alerter;
 use crate::ipc::notify_buffer::NotifyBuffer;
 use crate::ipc::server::SocketServer;
@@ -66,6 +66,31 @@ impl WorkerHandle {
         self.event_tx.subscribe()
     }
 
+    pub fn snapshot_event(&self) -> Event {
+        self.snapshot_event_with_entry_subscription().0
+    }
+
+    pub(crate) fn snapshot_event_with_entry_subscription(
+        &self,
+    ) -> (Event, broadcast::Receiver<LogEntry>) {
+        let (entries, entry_rx, in_flight) = {
+            let in_flight_guard = self.in_flight.snapshot_guard();
+            let (entries, entry_rx) = self.sink.subscribe_with_snapshot();
+            let in_flight = snapshot_from_guard(&in_flight_guard);
+            (entries, entry_rx, in_flight)
+        };
+        let event = Event::Snapshot {
+            entries: entries
+                .into_iter()
+                .map(|entry| serde_json::to_value(entry).expect("log entry serializes"))
+                .collect(),
+            greeting: self.shared_state.greeting.clone(),
+            status: self.shared_state.get_status(),
+            in_flight,
+        };
+        (event, entry_rx)
+    }
+
     /// Broadcast an event to all listeners (including socket clients).
     pub fn send_event(&self, event: Event) -> Result<usize, broadcast::error::SendError<Event>> {
         self.event_tx.send(event)

crates/worker/src/ipc/server.rs

@@ -7,7 +7,6 @@ use tokio::net::UnixListener;
 use tokio::task::JoinHandle;
 
 use crate::controller::WorkerHandle;
-use crate::in_flight::snapshot_from_guard;
 use protocol::{Event, Method};
 
 /// Unix socket server for Worker Protocol.
@@ -111,16 +110,10 @@ async fn handle_connection(stream: tokio::net::UnixStream, handle: WorkerHandle)
     // committed entry or as the still-present in-flight block. This lock
     // order matches `append_entry` (in-flight clear before sink publish) and
     // keeps the snapshot/live boundary gap-free.
-    let (entries_snapshot, mut entry_rx, alert_snapshot, mut rx, in_flight) = {
-        let in_flight_guard = handle.in_flight.snapshot_guard();
-        let (entries_snapshot, entry_rx) = handle.sink.subscribe_with_snapshot();
-
-        // Atomically subscribe and snapshot buffered alerts so that warnings
-        // emitted before this client connected are replayed exactly once.
-        let (alert_snapshot, rx) = handle.alerter.subscribe_with_snapshot();
-        let in_flight = snapshot_from_guard(&in_flight_guard);
-        (entries_snapshot, entry_rx, alert_snapshot, rx, in_flight)
-    };
+    let (snapshot_event, mut entry_rx) = handle.snapshot_event_with_entry_subscription();
+    // Atomically subscribe and snapshot buffered alerts so that warnings
+    // emitted before this client connected are replayed exactly once.
+    let (alert_snapshot, mut rx) = handle.alerter.subscribe_with_snapshot();
     for alert in alert_snapshot {
         if writer.write(&Event::Alert(alert)).await.is_err() {
             return;
@@ -129,15 +122,6 @@ async fn handle_connection(stream: tokio::net::UnixStream, handle: WorkerHandle)
 
     // Send the typed snapshot up front so late attachers can
     // reconstruct view state without an extra round trip.
-    let snapshot_event = Event::Snapshot {
-        entries: entries_snapshot
-            .into_iter()
-            .map(|e| serde_json::to_value(&e).expect("LogEntry is Serialize"))
-            .collect(),
-        greeting: handle.shared_state.greeting.clone(),
-        status: handle.shared_state.get_status(),
-        in_flight,
-    };
     if writer.write(&snapshot_event).await.is_err() {
         return;
     }