## Summary
Fixes cross-user cache contamination for AI chat threads in multi-user
workspaces.
`agentChatThread` is the only user-scoped (`userWorkspaceId`-filtered)
entry in `METADATA_NAME_TO_ENTITY_KEY`, but its create/update events
were going through `WorkspaceEventBroadcaster`, which fans out to every
active SSE stream in the workspace. Every client therefore received
other users' threads into their local `agentChatThreads` metadata store
(which is persisted to localStorage). On a subsequent session,
`AgentChatThreadInitializationEffect` would pick the
most-recently-updated thread — potentially another user's — and fire
`GetChatMessages` against it; the server's `userWorkspaceId` filter
didn't match, producing "Thread not found" errors (now 404 thanks to
twentyhq/twenty#19831).
### The fix mirrors the RLS pattern already used for object records
`ObjectRecordEventPublisher` already reads
`streamData.authContext.userWorkspaceId` to filter per subscriber.
Metadata events had no equivalent. This PR closes that gap with a
minimal, opt-in change:
- Add optional `recipientUserWorkspaceIds?: string[]` to
`WorkspaceBroadcastEvent`. Omit → workspace-wide (unchanged for views,
objects, fields, etc.). Set → delivered only to streams whose
`authContext.userWorkspaceId` is in the list.
- `WorkspaceEventBroadcaster.broadcast` builds the payload per stream
and skips events whose recipient doesn't match.
- Both `agentChatThread` broadcast call sites in `AgentChatService` now
pass `recipientUserWorkspaceIds: [userWorkspaceId]`.
### Scope
3 files, +40/-11 LOC:
-
`subscriptions/workspace-event-broadcaster/types/workspace-broadcast-event.type.ts`
-
`subscriptions/workspace-event-broadcaster/workspace-event-broadcaster.service.ts`
- `metadata-modules/ai/ai-chat/services/agent-chat.service.ts`
### Stale cache note
Existing clients still carry poisoned localStorage from before this
lands. They self-heal on sign-out/in because
`clearAllSessionLocalStorageKeys` already drops `agentChatThreads`. If
we want to actively flush on deploy, a frontend cache-version bump can
follow in a separate PR.
### Related
- twentyhq/twenty#19831 turns the resulting "Thread not found" from 500
to 404. This PR addresses the root cause; #19831 stops the Sentry noise.
## Test plan
- [x] `npx nx typecheck twenty-server`
- [x] `npx oxlint --type-aware` on all 3 files (0 warnings/errors)
- [x] `npx prettier --check` on all 3 files
- [ ] Manual: two users in the same workspace, user A creates/sends a
chat thread — confirm user B's session does not receive the event and
their `chatThreads` sidebar is unaffected
- [ ] CI
## 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