Phase 4.11 -- Messages Page

Parent: #762 | Wave 4

Scope

• Sender indicators: agent avatar + name for each message
• Timestamp grouping: group messages by time period (today, yesterday, date)
• Threading: related messages grouped visually
• Channel selection: channel list with badges showing unread counts
• Channel badges: unread message indicators
• Formatted content: message bodies with proper formatting, attachments display
• Real-time: WebSocket-driven new message arrival with scroll-to-bottom behavior

Data requirements

• GET /messages (paginated, filtered by channel)
• GET /messages/channels
• WebSocket: messages channel

Deliverables

• Messages page with all features
• Channel list with unread badges
• Message threading
• Real-time message arrival
• Unit tests

Blocked by

• feat: interaction components and animation patterns #776 (interaction components)