fix(harness): correlate subagent lifecycle events

Author: mikemikimike

agentscope-harness/src/main/java/io/agentscope/harness/agent/tool/AgentSpawnTool.java

@@ -780,19 +780,20 @@ private Mono<Msg> execLocalSync(
                     if (emitterOpt.isPresent()) {
                         AgentEventEmitter parentEmitter = emitterOpt.get();
                         String sourcePath = buildSourcePath(spawned, parentCtx);
+                        String replyId = UUID.randomUUID().toString().replace("-", "");
                         AgentEventEmitter taggedEmitter =
                                 event -> parentEmitter.emit(event.withSource(sourcePath));
 
                         parentEmitter.emit(
-                                new AgentStartEvent(spawned.sessionId(), null, spawned.agentId())
+                                new AgentStartEvent(spawned.sessionId(), replyId, spawned.agentId())
                                         .withSource(sourcePath));
 
                         AtomicBoolean endEmitted = new AtomicBoolean();
                         Runnable emitEnd =
                                 () -> {
                                     if (endEmitted.compareAndSet(false, true)) {
                                         parentEmitter.emit(
-                                                new AgentEndEvent(null).withSource(sourcePath));
+                                                new AgentEndEvent(replyId).withSource(sourcePath));
                                     }
                                 };
 

agentscope-harness/src/test/java/io/agentscope/harness/agent/tool/AgentSpawnToolCancelEndEventTest.java

@@ -16,6 +16,7 @@
 package io.agentscope.harness.agent.tool;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 
@@ -74,6 +75,14 @@ public void emit(AgentEvent event) {
         long count(Class<? extends AgentEvent> type) {
             return events.stream().filter(type::isInstance).count();
         }
+
+        <T extends AgentEvent> T first(Class<T> type) {
+            return events.stream()
+                    .filter(type::isInstance)
+                    .map(type::cast)
+                    .findFirst()
+                    .orElseThrow();
+        }
     }
 
     @Test
@@ -125,6 +134,7 @@ void parentCancel_emitsAgentEndEvent() throws Exception {
                 "parent cancel must still close the child's event stream — an AgentStartEvent"
                         + " without a matching AgentEndEvent leaves consumers rendering the"
                         + " subagent as running forever (doOnTerminate does not fire on cancel)");
+        assertReplyIdPair(emitter);
     }
 
     @Test
@@ -153,6 +163,14 @@ void normalCompletion_emitsPairedEvents() throws Exception {
 
         assertEquals(1, emitter.count(AgentStartEvent.class), "expected one start event");
         assertEquals(1, emitter.count(AgentEndEvent.class), "expected one end event");
+        assertReplyIdPair(emitter);
+    }
+
+    private static void assertReplyIdPair(RecordingEmitter emitter) {
+        AgentStartEvent start = emitter.first(AgentStartEvent.class);
+        AgentEndEvent end = emitter.first(AgentEndEvent.class);
+        assertNotNull(start.getReplyId(), "subagent start event should have a replyId");
+        assertEquals(start.getReplyId(), end.getReplyId());
     }
 
     private static final class NoopTaskRepository implements TaskRepository {