Agent response to a handoff doc

0.md

Thanks for sharing this comprehensive handoff document! I've read through it carefully and understand the Phase 3 changes from the React team.

Summary of Changes Impacting Session Controls

The React hooks (useChat and useToolNotifications) now automatically handle:

1. Message Updates: Messages can receive tool_calls metadata after initial render
2. Notification Clearing: Tool notifications automatically clear on session switches and interaction ends

This opens up great UX opportunities for showing tool activity in the session list!

My Implementation Plan

🎯 Priority Decisions

Let me propose answers to the key questions from the handoff:

Q1: Notification Clearing Timing

My Recommendation: Clear DURING session switch animation (concurrent approach)

• Rationale: Provides smoothest UX, no waiting for sequential operations
• Implementation: Use CSS exit animations + Promise.all for concurrent operations

Q2: Tool Activity Display

My Recommendation: Start with Option C (both active count and last tool used), iterate based on feedback

• Phase 1: Badge showing active tool count (global, since no sessionId yet)
• Phase 2: Last tool used in preview text
• Phase 3: Future enhancement for per-session tracking when sessionId available

Q3: Session Metadata Storage

My Recommendation: Client-side calculation with memoization for now

• Rationale: Simpler, no server coordination required, works immediately
• Future: Can migrate to server-side if performance becomes an issue with 1000+ sessions

📋 Implementation Phases

Phase 1: P0 - Core Coordination (Today)

• Review current session switching logic in ChatSessionList.tsx
• Add transition state management for smooth clearing
• Implement CSS exit animations for notification clearing
• Test rapid session switching for race conditions
• Ensure no visual glitches during transitions

Phase 2: P1 - Tool Activity Indicators (Next)

• Add global active tool count badge to session list
• Calculate tool usage from message history (memoized)
• Show last tool used in session preview text
• Add tool activity to session item hover states
• Update session item types to include tool metadata

Phase 3: P2 - Enhanced Features (Future)

• Add tool usage to session search/filter
• Display tool usage timeline in session details
• Show historical tool stats per session
• Coordinate with backend for sessionId in notifications

🔍 Components I'll Modify

1. ChatSessionList.tsx

   • Add transition state for session switches
   • Integrate global tool notification count
   • Calculate and display tool activity per session

2. SessionItem.tsx (or equivalent internal component)

   • Add tool activity badge
   • Show last tool used in preview
   • Add tool-related hover states

3. ChatSidebar.tsx

   • Coordinate notification clearing with sidebar state
   • Ensure smooth transitions during session switches

📊 Type Additions

I'll create new types for tool activity tracking:

interface SessionToolActivity {
  sessionId: string;
  activeToolCount: number;        // From global notifications
  lastToolUsed?: string;          // From message tool_calls
  lastToolTimestamp?: string;
  totalHistoricalCalls: number;
  toolsUsed: string[];
}

Questions Before I Start

1. Design System: Are there existing Censuite badge components for tool activity indicators, or should I create new ones following the design system?

2. Animation Timing: What's the standard transition duration for session switches? Should I match that for notification clearing (300ms suggested in doc)?

3. Coordination Point: Should I reach out to the UI Chat Controls specialist about consistent tool call rendering patterns before implementing, or proceed with session list implementation first?

4. Testing Scope: Should I coordinate with my test partner NOW before implementing, or implement P0/P1 first and then hand off for testing?

Let me know if my approach looks good, and I'll start with Phase 1 (P0 coordination work)! 🚀

1.handoff.md

React Team Handoff - Phase 3: React Hook Updates

Dev-to-Test Handoff: Tool Call Fix Phase 3

From: Eve (Event Stream Development Specialist)
To: React Development Team
Date: October 4, 2025
Work Unit: Update React hooks to handle new tool call events from Phase 1 & 2

---

🎯 Objective

Update React hooks to handle new events from the core package so that:

1. Messages can be updated after initial render (backward tool attachment)
2. Tool notifications can be cleared by session or globally
3. Event signatures match the updated core package API

---

📋 Context: What Phase 1 & 2 Accomplished

Phase 1: Session-Aware Tracking & Backward Attachment ✅

• Implemented session-aware tool tracking (composite keys: ${sessionId}:${toolId})
• Added backward attachment logic (attach tools to previous message)
• Added proper cleanup when interaction ends
• Created safety net cleanup on user turn start
• Added new events that React hooks need to handle

Phase 2: Resumed Session Tool Display ✅

• Fixed tool call display in resumed sessions
• Tool calls from saved messages now attach to message metadata
• Consistent structure between live and resumed sessions

Phase 3 (This Work): React Hook Updates 🔨

• Handle new events in React hooks
• Update message state when backward attachment occurs
• Clear notifications when requested by core
• Match API signature changes

---

🔥 New Events from Core Package

Event 1: message-updated (NEW)

Purpose: Notify React layer that a message was updated with backward-attached tool calls

Signature:

'message-updated': {
  sessionId: string;
  messageIndex: number;
  message: Message;  // Updated message with tool calls in metadata
}

When Emitted:

• In EventStreamProcessor.handleCompletion() when tool calls are backward-attached to a previous message
• Happens when an interaction ends and tools need to be attached to the last message

Example:

// Core emits this after backward attachment
sessionManager.emit('message-updated', {
  sessionId: 'session-123',
  messageIndex: 5,
  message: {
    role: 'assistant',
    content: 'I will help you with that.',
    metadata: {
      toolCalls: [
        { id: 'toolu_abc', type: 'tool_use', name: 'workspace_read', input: {...} }
      ],
      toolResults: [
        { type: 'tool_result', tool_use_id: 'toolu_abc', content: '...' }
      ]
    }
  }
});

---

Event 2: tool-notifications-cleared (NEW)

Purpose: Clear tool notifications for a specific session or globally

Signature:

'tool-notifications-cleared': {
  sessionId?: string;  // If undefined, clear ALL sessions
  reason: 'interaction_ended' | 'user_turn_start';
}

When Emitted:

1. With sessionId - When InteractionEndEvent with started: false is received

   • Clears tools for specific session
   • Reason: 'interaction_ended'

2. Without sessionId - When user_turn_start event is received (safety net)

   • Clears ALL active notifications globally
   • Reason: 'user_turn_start'

Examples:

// Clear tools for specific session (proper cleanup)
sessionManager.emit('tool-notifications-cleared', {
  sessionId: 'session-123',
  reason: 'interaction_ended'
});

// Clear all tools globally (safety net)
sessionManager.emit('tool-notifications-cleared', {
  sessionId: undefined,
  reason: 'user_turn_start'
});

---

Event 3: tool-notification-removed (SIGNATURE CHANGED)

Purpose: Remove a specific tool notification (unchanged purpose, new signature)

OLD Signature:

'tool-notification-removed': string  // Just the toolId

NEW Signature:

'tool-notification-removed': {
  sessionId: string;
  toolId: string;
}

Why Changed: Session-aware tracking requires both IDs to identify the correct tool

Impact:

• ✅ Already updated in Phase 1: useToolNotifications.ts line 89
• No further changes needed, but documented here for completeness

---

📁 Files That Need Updates

File 1: packages/react/src/hooks/useMessages.ts 🔨 PRIMARY

Current State: Listens to messages event to receive new messages from core

Change Needed: Add listener for message-updated event to update existing messages in state

Location: Line ~57 (in useEffect where event listeners are set up)

---

File 2: packages/react/src/hooks/useToolNotifications.ts 🔨 PRIMARY

Current State:

• Listens to tool-notification event to add notifications
• Listens to tool-notification-removed event to remove individual notifications
• Has local clearNotifications() method but no listener for global clear

Change Needed: Add listener for tool-notifications-cleared event

Location: Line ~66 (in useEffect where event listeners are set up)

---

🔨 Implementation Details

Implementation 1: Handle message-updated in useMessages.ts

Current Code Structure (Lines ~30-80)

useEffect(() => {
  if (!client) return;

  const handleMessages = (newMessages: Message[]) => {
    // Adds new messages to state
    setMessages(prev => [...prev, ...newMessages]);
  };

  client.on('messages', handleMessages);

  return () => {
    client.off('messages', handleMessages);
  };
}, [client]);

Required Changes

Add New Handler:

const handleMessageUpdated = useCallback((data: { 
  sessionId: string; 
  messageIndex: number; 
  message: Message;
}) => {
  setMessages(prev => {
    // Create a new array to trigger React re-render
    const updated = [...prev];
    
    // Replace the message at the specified index
    if (data.messageIndex >= 0 && data.messageIndex < updated.length) {
      updated[data.messageIndex] = data.message;
    }
    
    return updated;
  });
}, []);

Register Event Listener:

useEffect(() => {
  if (!client) return;

  const handleMessages = (newMessages: Message[]) => {
    setMessages(prev => [...prev, ...newMessages]);
  };

  // NEW: Add message-updated listener
  const handleMessageUpdated = (data: { 
    sessionId: string; 
    messageIndex: number; 
    message: Message;
  }) => {
    setMessages(prev => {
      const updated = [...prev];
      if (data.messageIndex >= 0 && data.messageIndex < updated.length) {
        updated[data.messageIndex] = data.message;
      }
      return updated;
    });
  };

  client.on('messages', handleMessages);
  client.on('message-updated', handleMessageUpdated);  // NEW

  return () => {
    client.off('messages', handleMessages);
    client.off('message-updated', handleMessageUpdated);  // NEW
  };
}, [client]);

Edge Cases to Consider

1. Invalid Index: Check bounds before updating

   • If messageIndex is out of bounds, log warning and skip update

2. Session Mismatch: Should we validate sessionId?

   • Current implementation doesn't track session per message
   • For now, trust the core package (it only emits for current session)
   • Future: Consider validating if session tracking added to hook

3. Message Already Has Metadata:

   • This is valid - backward attachment adds metadata to existing message
   • Replace entire message (don't merge) as core sends complete updated message

4. Empty Messages Array:

   • Bounds check handles this (messageIndex >= messages.length returns false)

---

Implementation 2: Handle tool-notifications-cleared in useToolNotifications.ts

Current Code Structure (Lines ~30-100)

useEffect(() => {
  if (!client) return;

  const handleToolNotification = (notification: ToolNotification) => {
    setNotifications(prev => {
      // Add or update notification
      const existing = prev.find(n => n.id === notification.id);
      if (existing) {
        return prev.map(n => n.id === notification.id ? notification : n);
      }
      return [...prev, notification];
    });
  };

  const handleToolNotificationRemoved = (data: { sessionId: string; toolId: string }) => {
    setNotifications(prev => prev.filter(n => n.id !== data.toolId));
  };

  client.on('tool-notification', handleToolNotification);
  client.on('tool-notification-removed', handleToolNotificationRemoved);

  return () => {
    client.off('tool-notification', handleToolNotification);
    client.off('tool-notification-removed', handleToolNotificationRemoved);
  };
}, [client]);

Required Changes

Add New Handler:

const handleToolNotificationsCleared = useCallback((data: { 
  sessionId?: string; 
  reason: 'interaction_ended' | 'user_turn_start';
}) => {
  if (data.sessionId) {
    // Clear notifications for specific session
    setNotifications(prev => 
      prev.filter(n => n.sessionId !== data.sessionId)
    );
  } else {
    // Clear ALL notifications
    setNotifications([]);
  }
}, []);

Register Event Listener:

useEffect(() => {
  if (!client) return;

  const handleToolNotification = (notification: ToolNotification) => {
    setNotifications(prev => {
      const existing = prev.find(n => n.id === notification.id);
      if (existing) {
        return prev.map(n => n.id === notification.id ? notification : n);
      }
      return [...prev, notification];
    });
  };