feat(supervisor): push agent completion notifications to the spawning context

The spawned-agent task now pushes an agent_completed/agent_failed event
into the spawning context's notification queue before returning, so a
parent that keeps working learns mid-turn that a child finished instead
of discovering it only at the turn-end guardrail. Cancelled or
already-collected agents are suppressed by the existing drain-time
registration filter. This delivery applies regardless of whether
background jobs are enabled.

src/function/mod.rs

@@ -2553,7 +2553,7 @@ mod tests {
     };
     use crate::config::{Agent, AgentConfig, AppConfig, AppState, WorkingMode};
     use crate::supervisor::escalation::{EscalationQueue, EscalationRequest};
-    use crate::supervisor::notification::job_notification;
+    use crate::supervisor::notification::{agent_notification, job_notification};
     use base64::Engine;
     use base64::engine::general_purpose::STANDARD;
     use rmcp::model::{CallToolResult, ContentBlock};
@@ -2779,6 +2779,68 @@ mod tests {
         assert!(drain_live_notifications(&ctx).is_empty());
     }
 
+    fn ctx_with_registered_agent(id: &str) -> RequestContext {
+        let rt = tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()
+            .unwrap();
+        let agent_id = id.to_string();
+        let join_handle = rt.spawn(async move {
+            Ok(crate::supervisor::AgentResult {
+                id: agent_id,
+                agent_name: "explore".into(),
+                output: String::new(),
+                exit_status: crate::supervisor::AgentExitStatus::Completed,
+            })
+        });
+        std::mem::forget(rt);
+        let handle = crate::supervisor::AgentHandle {
+            id: id.to_string(),
+            agent_name: "explore".to_string(),
+            depth: 1,
+            inbox: Arc::new(crate::supervisor::mailbox::Inbox::new()),
+            abort_signal: crate::utils::create_abort_signal(),
+            join_handle,
+            child_supervisor: None,
+        };
+        let mut sup = crate::supervisor::Supervisor::new(4, 3);
+        sup.register(handle).unwrap();
+        let mut ctx = RequestContext::new(Arc::new(AppState::test_default()), WorkingMode::Cmd);
+        ctx.supervisor = Some(Arc::new(parking_lot::RwLock::new(sup)));
+        ctx
+    }
+
+    #[test]
+    fn drain_live_notifications_keeps_registered_agent_events() {
+        let ctx = ctx_with_registered_agent("agent_explore_1");
+        ctx.notification_queue
+            .push(agent_notification("agent_explore_1", "explore", true));
+
+        let live = drain_live_notifications(&ctx);
+
+        assert_eq!(live.len(), 1);
+        assert_eq!(live[0]["event"], "agent_completed");
+        assert_eq!(
+            live[0]["next_action"],
+            "agent__collect --id agent_explore_1 for output"
+        );
+    }
+
+    #[test]
+    fn drain_live_notifications_drops_collected_agent_events() {
+        let ctx = ctx_with_registered_agent("agent_explore_1");
+        ctx.supervisor
+            .as_ref()
+            .unwrap()
+            .write()
+            .take("agent_explore_1")
+            .unwrap();
+        ctx.notification_queue
+            .push(agent_notification("agent_explore_1", "explore", true));
+
+        assert!(drain_live_notifications(&ctx).is_empty());
+    }
+
     #[test]
     fn eval_tool_calls_merges_notifications_at_depth_without_escalations() {
         let mut ctx = ctx_with_registered_job("job_n1");

src/function/supervisor.rs

@@ -5,6 +5,7 @@ use crate::config::{
     jobs_enabled, list_agents_with_descriptions,
 };
 use crate::supervisor::mailbox::{Envelope, EnvelopePayload, Inbox};
+use crate::supervisor::notification::agent_notification;
 use crate::supervisor::{AgentExitStatus, AgentHandle, AgentResult, Supervisor, TaskKind};
 use crate::utils::{AbortSignal, create_abort_signal, wait_abort_signal};
 
@@ -866,25 +867,33 @@ async fn handle_spawn(ctx: &mut RequestContext, args: &Value) -> Result<Value> {
     let spawn_agent_id = agent_id.clone();
     let spawn_agent_name = agent_name.clone();
     let spawn_abort = child_abort.clone();
+    let spawn_notifications = Arc::clone(&ctx.notification_queue);
     let child_supervisor = child_ctx.supervisor.clone();
 
     let join_handle = tokio::spawn(async move {
         let result = run_child_agent(child_ctx, input, spawn_abort).await;
 
-        match result {
-            Ok(output) => Ok(AgentResult {
+        let agent_result = match result {
+            Ok(output) => AgentResult {
                 id: spawn_agent_id,
                 agent_name: spawn_agent_name,
                 output,
                 exit_status: AgentExitStatus::Completed,
-            }),
-            Err(e) => Ok(AgentResult {
+            },
+            Err(e) => AgentResult {
                 id: spawn_agent_id,
                 agent_name: spawn_agent_name,
                 output: String::new(),
                 exit_status: AgentExitStatus::Failed(e.to_string()),
-            }),
-        }
+            },
+        };
+        let success = agent_result.exit_status == AgentExitStatus::Completed;
+        spawn_notifications.push(agent_notification(
+            &agent_result.id,
+            &agent_result.agent_name,
+            success,
+        ));
+        Ok(agent_result)
     });
 
     let handle = AgentHandle {