## Summary
Refactored AI chat state management to use component family states
instead of global atoms. This change enables proper state isolation per
chat thread, preventing state leakage between different chat instances.
## Key Changes
- **Converted global atoms to component family states:**
- `agentChatErrorState` → `agentChatErrorComponentFamilyState`
- `agentChatIsStreamingState` →
`agentChatIsStreamingComponentFamilyState`
- `agentChatFirstLiveSeqState` →
`agentChatFirstLiveSeqComponentFamilyState`
- `agentChatHandleEventCallbackState` →
`agentChatHandleEventCallbackComponentFamilyState`
- `agentChatUsageState` → `agentChatUsageComponentFamilyState`
- `currentAIChatThreadTitleState` →
`currentAIChatThreadTitleComponentFamilyState`
- **Updated state access patterns:**
- Introduced `useAtomComponentFamilyStateCallbackState` hook to get
family state callbacks
- Changed from direct atom access to family key-based access using `{
threadId }` as the family key
- Updated all components and hooks to use the new family state patterns
- **Removed instance ID dependency:**
- Eliminated `AGENT_CHAT_INSTANCE_ID` constant usage
- Simplified state access by using thread ID directly as the family key
- **Updated affected components and hooks:**
- `useAgentChatSubscription`: Now creates family state atoms per thread
- `AgentChatMessagesFetchEffect`: Uses family state callbacks for event
handling
- `AgentChatThreadInitializationEffect`: Sets family state values per
thread
- `useAIChatThreadClick`: Updates family states when switching threads
- `AIChatErrorUnderMessageList`, `AIChatLastMessageWithStreamingState`,
`AIChatEmptyState`, `AIChatStandaloneError`, `SendMessageButton`,
`AIChatContextUsageButton`, `SidePanelAskAIInfo`: Updated to use family
state values with thread ID
## Implementation Details
- All new component family states use
`AgentChatComponentInstanceContext` for proper component-level isolation
- Family key structure: `{ threadId: string | null }`
- Removed `disposed` flag logic as it's no longer needed with proper
state isolation
- Updated dependency arrays in hooks to include family callback
functions
https://claude.ai/code/session_01D8syiJtCXu5bEHSr5KYkCt
---------
Co-authored-by: Claude <noreply@anthropic.com>
## Summary
- **Queue messages while streaming**: Messages sent during active AI
streaming are queued server-side and auto-flushed when the current
stream completes. Frontend renders queued messages optimistically in a
dedicated queue UI.
- **Drop `@ai-sdk/react` + `resumable-stream`**: Replace the dual HTTP
SSE + AI SDK client architecture with a single GraphQL SSE subscription
per thread. All events (token chunks, message persistence, queue
updates, errors) flow through Redis PubSub → GraphQL subscription.
- **Server-driven architecture**: The server decides whether to queue or
stream (via `POST /:threadId/message`). The frontend mirrors this
decision for optimistic rendering but defers to the server response.
- **Reuse AI SDK accumulation logic**: `readUIMessageStream` from the
`ai` package handles chunk-to-message accumulation on the frontend,
avoiding a custom 780-line accumulator.
## Key files
**Backend:**
- `agent-chat-event-publisher.service.ts` — publishes events to Redis
PubSub
- `agent-chat-subscription.resolver.ts` — GraphQL subscription resolver
- `stream-agent-chat.job.ts` — publishes chunks via PubSub instead of
resumable-stream
- `agent-chat.controller.ts` — unified `POST /:threadId/message`
endpoint
**Frontend:**
- `useAgentChatSubscription.ts` — subscribes to `onAgentChatEvent`,
bridges to `readUIMessageStream`
- `useAgentChat.ts` — send/stop/optimistic rendering (no more AI SDK)
- `AgentChatStreamSubscriptionEffect.tsx` — replaces
`AgentChatAiSdkStreamEffect.tsx`
## Test plan
- [ ] Send message on new thread → optimistic render, streaming response
appears
- [ ] Send message while streaming → queued instantly (no flash in main
thread)
- [ ] Queued message auto-flushes after current stream completes
- [ ] Remove queued message via queue UI
- [ ] Stop streaming mid-response
- [ ] Leave chat idle for several minutes → streaming still works after
(SSE client recycling)
- [ ] Token refresh during session → requests succeed (authenticated
fetch)
- [ ] Switch threads while streaming → clean subscription handoff
Made with [Cursor](https://cursor.com)
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Félix Malfait