diff --git a/backend/open_webui/socket/main.py b/backend/open_webui/socket/main.py
index d88fd827f1..be0fc30dba 100644
--- a/backend/open_webui/socket/main.py
+++ b/backend/open_webui/socket/main.py
@@ -34,7 +34,7 @@ from open_webui.models.chats import Chats
 from open_webui.models.folders import Folders
 from open_webui.models.notes import Notes, NoteUpdateForm
 from open_webui.models.users import UserNameResponse, Users
-from open_webui.socket.utils import RedisDict, RedisLock, YdocManager
+from open_webui.socket.utils import RedisDict, RedisLock, YdocManager, build_prosemirror_update
 from open_webui.tasks import create_task, stop_item_tasks
 from open_webui.utils.access_control import has_permission
 from open_webui.utils.auth import get_verified_user_by_token
@@ -625,6 +625,7 @@ async def ydoc_document_join(sid, data):
     try:
         document_id = normalize_document_id(data['document_id'])
 
+        note = None
         if document_id.startswith('note:'):
             note_id = document_id.split(':')[1]
             note = await Notes.get_note_by_id(note_id)
@@ -658,8 +659,20 @@ async def ydoc_document_join(sid, data):
         active_session_ids = get_session_ids_from_room(f'doc_{document_id}')
 
         # Get the Yjs document state
-        ydoc = Y.Doc()
         updates = await YDOC_MANAGER.get_updates(document_id)
+
+        # Without this a note written outside the editor opens empty, and its first save wins.
+        if not updates and note:
+            try:
+                content = (note.data or {}).get('content') or {}
+                seed_update = build_prosemirror_update(content.get('json'))
+                if seed_update:
+                    await YDOC_MANAGER.append_to_updates(document_id=document_id, update=seed_update)
+                    updates = [seed_update]
+            except Exception:
+                log.exception('Failed to seed document %s from stored note content', document_id)
+
+        ydoc = Y.Doc()
         for update in updates:
             ydoc.apply_update(bytes(update))
 
diff --git a/backend/open_webui/socket/utils.py b/backend/open_webui/socket/utils.py
index 00f8424aae..5e89484bb3 100644
--- a/backend/open_webui/socket/utils.py
+++ b/backend/open_webui/socket/utils.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import hashlib
+import json
 import uuid
 
 import pycrdt as Y
@@ -165,6 +166,52 @@ class RedisDict:
         return self[key]
 
 
+def _append_prosemirror_nodes(parent, nodes) -> None:
+    # Children are appended before being written to: pycrdt only accepts writes once integrated.
+    text_run = None  # a run of text nodes shares one XmlText, as y-prosemirror lays them out
+
+    for node in nodes or []:
+        if not isinstance(node, dict) or not isinstance(node.get('type'), str):
+            continue
+
+        if node['type'] == 'text':
+            if not isinstance(node.get('text'), str) or not node['text']:
+                continue
+            if text_run is None:
+                text_run = Y.XmlText()
+                parent.children.append(text_run)
+            marks = {
+                mark['type']: mark.get('attrs') or {}
+                for mark in node.get('marks') or []
+                if isinstance(mark, dict) and mark.get('type')
+            }
+            text_run.insert(len(text_run), node['text'], marks)
+            continue
+
+        text_run = None
+        element = Y.XmlElement(node['type'])
+        parent.children.append(element)
+        for key, value in (node.get('attrs') or {}).items():
+            if value is not None:
+                element.attributes[key] = value
+        _append_prosemirror_nodes(element, node.get('content'))
+
+
+def build_prosemirror_update(content_json) -> bytes | None:
+    """Encode a ProseMirror document as a Yjs update in the shape y-prosemirror reads back."""
+    if not isinstance(content_json, dict) or content_json.get('type') != 'doc' or not content_json.get('content'):
+        return None
+
+    # A content-derived client id makes a concurrent seed of the same content a no-op.
+    canonical = json.dumps(content_json, sort_keys=True, separators=(',', ':'))
+    content_digest = hashlib.sha256(canonical.encode()).digest()
+    doc = Y.Doc(client_id=int.from_bytes(content_digest[:4], 'big'))
+    fragment = Y.XmlFragment()
+    doc['prosemirror'] = fragment
+    _append_prosemirror_nodes(fragment, content_json['content'])
+    return doc.get_update()
+
+
 class YdocManager:
     COMPACTION_THRESHOLD = 500
 
diff --git a/src/lib/components/common/RichTextInput/Collaboration.ts b/src/lib/components/common/RichTextInput/Collaboration.ts
index e261af01a1..1d7147b2bb 100644
--- a/src/lib/components/common/RichTextInput/Collaboration.ts
+++ b/src/lib/components/common/RichTextInput/Collaboration.ts
@@ -130,7 +130,9 @@ export class SocketIOCollaborationProvider {
 
 							const isEmptyEditor = !this.editor?.getText().trim();
 							if (isEmptyEditor && this.editor) {
-								if (this.initialContent && (data?.sessions ?? ['']).length === 1) {
+								// The lowest joined session seeds, so viewers don't each insert the content
+								const seedingSession = data.sessions?.sort()[0];
+								if (this.initialContent && seedingSession === this.socket.id) {
 									// Check if initialContent is HTML (string) or JSON (object)
 									if (typeof this.initialContent === 'string') {
 										// HTML content - let the editor parse it, then sync to Yjs