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+---
+epic: 9
+story: 9.6
+title: "Collaborative Editing"
+status: draft
+---
+
+## Epic 9 — Web App (React + WASM)
+**Goal:** Zero-install web experience with real-time collaboration.
+
+### Story 9.6: Collaborative Editing
+
+As a team member,
+I want to edit a CalcPad sheet simultaneously with others,
+So that we can build and review calculations together in real time.
+
+**Acceptance Criteria:**
+
+**Given** a sheet owner enables "Edit" sharing on a sheet
+**When** they share the link with collaborators
+**Then** each collaborator can open the sheet and make live edits
+
+**Given** multiple users have the same sheet open for editing
+**When** one user types or modifies a line
+**Then** the change appears on all other users' screens within 500ms
+**And** each user's cursor is visible with a distinct color and name label
+
+**Given** two users edit the same line simultaneously
+**When** both changes arrive at the server
+**Then** conflicts are resolved automatically via CRDT (Yjs or Automerge)
+**And** no data is lost from either user's input
+
+**Given** a user is on the Free plan
+**When** they share a sheet for collaborative editing
+**Then** up to 5 simultaneous editors are allowed
+**And** additional users beyond 5 see a "sheet is full" message with an upgrade prompt
+
+**Given** a user is on the Pro plan
+**When** they share a sheet for collaborative editing
+**Then** up to 25 simultaneous editors are allowed