fix(realtime): check for online users before clearing note

The disconnect handler for the realtime connection checks whether the
disconnecting socket was the last user for that note. If that's the
case and the note had unsaved changes, it persists them to the database
which is an async progress. In the callback of this async progress, the
note and all its pending changes (should be empty) are deleted.
However, when the user reconnects quickly because of a flaky
connection, it could happen that they create new pending changes before
the database saving finished. As there was no additional "no-users"
check before clearing the note, this could lead to content loss.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

lib/realtime.js

@@ -1,4 +1,5 @@
 'use strict'
+const util = require('util')
 // realtime
 // external modules
 const cookie = require('cookie')
@@ -569,16 +570,13 @@ function disconnect (socket) {
       if (note.server.isDirty) {
         updateNote(note, function (err, _note) {
           if (err) return logger.error('disconnect note failed: ' + err)
+          // Check again for online users before clear, because users could reconnect during the async updateNote
+          if (Object.keys(note.users).length <= 0) {
             // clear server before delete to avoid memory leaks
             note.server.document = ''
             note.server.operations = []
             delete note.server
             delete notes[noteId]
-          if (config.debug) {
-            logger.debug(notes)
-            getStatus(function (data) {
-              logger.debug(JSON.stringify(data))
-            })
           }
         })
       } else {
@@ -596,7 +594,7 @@ function disconnect (socket) {
   if (disconnectSocketQueue.length > 0) { disconnect(disconnectSocketQueue[0]) }
 
   if (config.debug) {
-    logger.debug(notes)
+    logger.debug(util.inspect(notes))
     getStatus(function (data) {
       logger.debug(JSON.stringify(data))
     })

public/docs/release-notes.md

@@ -9,6 +9,7 @@
 ### Bugfixes
 
 - All links will be opened in new tabs instead of the same tab as the note. This was changed when the external link warning was implemented and now the old behavior is restored.
+- Fixed a bug in the realtime disconnect handler that could lead to data-loss of users with a flaky connection
 
 ## <i class="fa fa-tag"></i> 1.11.1 <i class="fa fa-calendar-o"></i> 2026-07-24