chore: import upstream snapshot with attribution

apps/sim/stores/presence/store.ts

@@ -0,0 +1,24 @@
+import { create } from 'zustand'
+import { devtools } from 'zustand/middleware'
+import type { PresenceState } from '@/stores/presence/types'
+
+/**
+ * Live collaborator presence for the active workflow room.
+ *
+ * Presence is high-frequency (cursor frames arrive many times per second), so it
+ * lives in its own store rather than the broad socket context. Only presence
+ * consumers (`<Cursors>`, `<Avatars>`) subscribe to it, so cursor frames no
+ * longer re-render emitter-only `useSocket()` consumers such as `WorkflowContent`.
+ */
+export const usePresenceStore = create<PresenceState>()(
+  devtools(
+    (set) => ({
+      presenceUsers: [],
+      setPresenceUsers: (users) => set({ presenceUsers: users }),
+      updatePresenceUsers: (updater) =>
+        set((state) => ({ presenceUsers: updater(state.presenceUsers) })),
+      clearPresenceUsers: () => set({ presenceUsers: [] }),
+    }),
+    { name: 'presence-store' }
+  )
+)

apps/sim/stores/presence/types.ts

@@ -0,0 +1,23 @@
+/**
+ * A collaborator present in the active workflow room. Mirrors the presence
+ * payload broadcast by the realtime server (`presence-update`, cursor/selection
+ * deltas, and `join-workflow-success`).
+ */
+export interface PresenceUser {
+  socketId: string
+  userId: string
+  userName: string
+  avatarUrl?: string | null
+  cursor?: { x: number; y: number } | null
+  selection?: { type: 'block' | 'edge' | 'none'; id?: string }
+}
+
+export interface PresenceState {
+  presenceUsers: PresenceUser[]
+  /** Replace the full presence list (join success, presence-update). */
+  setPresenceUsers: (users: PresenceUser[]) => void
+  /** Apply a functional update to the presence list (cursor/selection deltas). */
+  updatePresenceUsers: (updater: (prev: PresenceUser[]) => PresenceUser[]) => void
+  /** Clear presence when leaving or losing the workflow room. */
+  clearPresenceUsers: () => void
+}