- MobileChatView: full-screen mobile chat using 100dvh, back button, safe-area input
- ChatPanel: conditionally renders MobileChatView on mobile via useMediaQuery
- ChatConversationList: wraps ScrollArea in PullToRefresh for mobile
- ChatInput: pb-[env(safe-area-inset-bottom)] padding + 44px Send button touch target
- ChatConversationItem: min-h-[48px] touch target per UI-SPEC
- Add scrollToMessageId/setScrollToMessageId to ChatPanelContext
- Add "Search chat messages" item to CommandPalette (dispatches nexus:open-chat-search)
- Integrate ChatSearchDialog, ChatBranchSelector, ChatBookmarkList into ChatPanel
- Add export buttons (Markdown) and bookmarks panel toggle in header
- Wire branch-on-edit: branchConversation called when editing message with subsequent replies
- Add scroll-to-message support in ChatMessageList via virtualizer.scrollToIndex
- Show GitBranch icon for branch conversations in ChatConversationList
- Add Search/X icons and Input to ChatConversationList with 300ms debounce
- Listen for nexus:focus-chat-search event to focus search input
- Add onSearch handler to useKeyboardShortcuts (fires before input guard)
- Wire Layout Cmd+K to open chat panel and dispatch focus event
- Add ChatConversationItem with DropdownMenu actions (Rename, Pin/Unpin, Archive, Delete) and active highlight
- Add ChatConversationList with IntersectionObserver infinite scroll, loading skeletons, delete confirmation dialog, and CRUD handlers
- Add ChatMessageList with auto-scroll-to-bottom on new messages and empty state
- Update ChatPanel to render ChatConversationList (left column) and ChatMessageList (right column); handleSend uses two paths: direct chatApi for new conversations, hook mutation for existing ones
