Replace the legacy monolithic ChatInterface.jsx implementation with a modular TypeScript architecture centered around a small orchestration component (ChatInterface.tsx).
Core architecture changes:
- Remove src/components/ChatInterface.jsx and add src/components/ChatInterface.tsx as a thin coordinator that wires provider state, session state, realtime WebSocket handlers, and composer behavior via dedicated hooks.
- Update src/components/MainContent.tsx to use typed ChatInterface directly (remove AnyChatInterface cast).
State ownership and hook extraction:
- Add src/hooks/chat/useChatProviderState.ts to centralize provider/model/permission-mode state, provider/session synchronization, cursor model bootstrap from backend config, and pending permission request scoping.
- Add src/hooks/chat/useChatSessionState.ts to own chat/session lifecycle state: session loading, cursor/claude/codex history loading, pagination, scroll restoration, visible-window slicing, token budget loading, persisted chat hydration, and processing-state restoration.
- Add src/hooks/chat/useChatRealtimeHandlers.ts to isolate WebSocket event processing for Claude/Cursor/Codex, including session filtering, streaming chunk buffering, session-created/pending-session transitions, permission request queueing/cancellation, completion/error handling, and session status updates.
- Add src/hooks/chat/useChatComposerState.ts to own composer-local state and interactions: input/draft persistence, textarea sizing and keyboard behavior, slash command execution, file mentions, image attachment/drop/paste workflow, submit/abort flows, permission decision responses, and transcript insertion.
UI modularization under src/components/chat:
- Add view/ChatMessagesPane.tsx for message list rendering, loading/empty states, pagination affordances, and thinking indicator.
- Add view/ChatComposer.tsx for composer shell layout and input area composition.
- Add view/ChatInputControls.tsx for mode toggles, token display, command launcher, clear-input, and scroll-to-bottom controls.
- Add view/PermissionRequestsBanner.tsx for explicit tool-permission review actions (allow once / allow & remember / deny).
- Add view/ProviderSelectionEmptyState.tsx for provider and model selection UX plus task starter integration.
- Add messages/MessageComponent.tsx and markdown/Markdown.tsx to isolate message rendering concerns, markdown/code rendering, and rich tool-output presentation.
- Add input/ImageAttachment.tsx for attachment previews/removal/progress/error overlay rendering.
Shared chat typing and utilities:
- Add src/components/chat/types.ts with shared types for providers, permission mode, message/tool payloads, pending permission requests, and ChatInterfaceProps.
- Add src/components/chat/utils/chatFormatting.ts for html decoding, code fence normalization, regex escaping, math-safe unescaping, and usage-limit text formatting.
- Add src/components/chat/utils/chatPermissions.ts for permission rule derivation, suggestion generation, and grant flow.
- Add src/components/chat/utils/chatStorage.ts for resilient localStorage access, quota handling, and normalized Claude settings retrieval.
- Add src/components/chat/utils/messageTransforms.ts for session message normalization (Claude/Codex/Cursor) and cached diff computation utilities.
Command/file input ergonomics:
- Add src/hooks/chat/useSlashCommands.ts for slash command fetching, usage-based ranking, fuzzy filtering, keyboard navigation, and command history persistence.
- Add src/hooks/chat/useFileMentions.tsx for project file flattening, @mention suggestions, mention highlighting, and keyboard/file insertion behavior.
TypeScript support additions:
- Add src/types/react-syntax-highlighter.d.ts module declarations to type-check markdown code highlighting imports.
Behavioral intent:
- Preserve existing chat behavior and provider flows while improving readability, separation of concerns, and future refactorability.
- Move state closer to the components/hooks that own it, reducing cross-cutting concerns in the top-level chat component.
