add subagent done notifications

AGENTS.md

@@ -37,3 +37,5 @@
       reads the `action` field from the input and dispatches to the right sub-component)
     - `loop/predictable.go` (the "tool smorgasbord" demo response)
     - See `ui/src/components/AGENTS.md` for more detail.
+
+16. Prefer `wait: false` for subagents doing background research. Use `wait: true` only when you need the result to continue, and keep timeouts short (30s max). Never block the conversation for minutes.

server/convo.go

@@ -73,6 +73,10 @@ type ConversationManager struct {
 	// onStateChange is called when the conversation state changes.
 	// This allows the server to broadcast state changes to all subscribers.
 	onStateChange func(state ConversationState)
+
+	// onDone is called when the agent finishes working (transitions to not working).
+	// Used by subagents to notify their parent conversation.
+	onDone func()
 }
 
 // NewConversationManager constructs a manager with dependencies but defers hydration until needed.
@@ -134,6 +138,7 @@ func (cm *ConversationManager) SetAgentWorking(working bool) {
 	}
 	cm.agentWorking = working
 	onStateChange := cm.onStateChange
+	onDone := cm.onDone
 	convID := cm.conversationID
 	modelID := cm.modelID
 	cm.mu.Unlock()
@@ -149,6 +154,9 @@ func (cm *ConversationManager) SetAgentWorking(working bool) {
 			Model:          modelID,
 		})
 	}
+	if !working && onDone != nil {
+		onDone()
+	}
 }
 
 // IsAgentWorking returns the current agent working state.

server/server.go

@@ -837,6 +837,11 @@ func (s *Server) getOrCreateSubagentConversationManager(ctx context.Context, con
 			existing.Touch()
 			return existing, nil
 		}
+		// Wire up done notification: when this subagent finishes, notify the parent.
+		manager.onDone = func() {
+			go s.notifyParentSubagentDone(conversationID)
+		}
+
 		s.activeConversations[conversationID] = manager
 		s.mu.Unlock()
 		return manager, nil
@@ -847,6 +852,66 @@ func (s *Server) getOrCreateSubagentConversationManager(ctx context.Context, con
 	return manager, nil
 }
 
+// notifyParentSubagentDone injects a message into the parent conversation's loop
+// when a subagent finishes, so the parent agent knows to check results.
+func (s *Server) notifyParentSubagentDone(subagentConversationID string) {
+	ctx := context.Background()
+
+	// Look up the subagent's parent conversation ID and slug
+	var conv generated.Conversation
+	err := s.db.Queries(ctx, func(q *generated.Queries) error {
+		var err error
+		conv, err = q.GetConversation(ctx, subagentConversationID)
+		return err
+	})
+	if err != nil || conv.ParentConversationID == nil {
+		return
+	}
+
+	parentID := *conv.ParentConversationID
+	slug := "unknown"
+	if conv.Slug != nil {
+		slug = *conv.Slug
+	}
+
+	// Find the parent's loop and inject a notification
+	s.mu.Lock()
+	parentManager, ok := s.activeConversations[parentID]
+	s.mu.Unlock()
+	if !ok {
+		return
+	}
+
+	parentManager.mu.Lock()
+	loopInstance := parentManager.loop
+	parentManager.mu.Unlock()
+	if loopInstance == nil {
+		return
+	}
+
+	// Get the subagent's last response for the notification
+	runner := NewSubagentRunner(s)
+	response, err := runner.getLastAssistantResponse(ctx, subagentConversationID)
+	if err != nil || response == "" {
+		response = "(completed, use subagent tool to read results)"
+	}
+	// Truncate long responses
+	if len(response) > 500 {
+		response = response[:500] + "..."
+	}
+
+	notification := llm.Message{
+		Role: llm.MessageRoleUser,
+		Content: []llm.Content{{
+			Type: llm.ContentTypeText,
+			Text: fmt.Sprintf("[Subagent '%s' finished]\n%s", slug, response),
+		}},
+	}
+
+	loopInstance.QueueUserMessage(notification)
+	s.logger.Info("Notified parent of subagent completion", "subagent", slug, "parent", parentID)
+}
+
 // ExtractDisplayData extracts display data from message content for storage
 func ExtractDisplayData(message llm.Message) interface{} {
 	// Build a map of tool_use_id to tool_name for lookups