Newly accepted chat on desktop does not link to the correct chat on Android

Guidelines

• I have searched open and closed issues for duplicates
• I am submitting a bug report for existing functionality that does not work as intended
• This isn't a feature request or a discussion topic

Bug description

Hi,

I have encountered a strange and somewhat concerning bug on the Android app.

For a while (like two weeks), I had the Android app disabled, i.e. it could not even run in the background, because I did not want to receive any messages so that the sender could see that I did not receive them. I still used Signal desktop from time to time. On there, I accepted a new chat from a person who had previously not been in my contacts. I will call them A in the following. That worked fine on desktop, just the person's name was not synchronised (obviously because the app on my phone was disabled).

Today, I re-activated the app because I wanted to synchronise the contacts. Firstly, Signal warned me that my device might not correctly receive messages (which makes sense), and then the synchronisation kicked in. Most of that went through quite well; however, the chat with A was not correctly synchronised. Firstly, the name shown for this chat was not A, but a completely unrelated name which I had never heard/seen before and do not have in my contacts. I will refer to this name by B in the following. As profile picture was also missing. Secondly, the first message in the chat (sent by A) was missing on my mobile, the other two messages in this chat were available and correct. Thirdly, I had to accept the chat on my mobile again, which I found weird. Nonetheless, I accepted it. On my laptop, the name of A was correctly substituted with the name from my contacts.

Then, I checked the security number of this chat and noticed, that the security number on my laptop was different from the one displayed on my mobile. I went to the contacts menu on Signal, searched for A to see what would happen when I want to send a message to them from the contacts menu; it opened the chat that I described above which has the name of B but with (a part of the messages) that I had exchanged with A. Then, I searched for B in my Signal contacts, which was there too and opened this chat too. I then deleted B from my Signal contacts. After that, opening a chat with A from the contacts list in the Signal app opened an empty chat with A. I then sent a message to A through this empty chat to see what would happen; this message was correctly sent to A and also turned up in the chat with A on the Signal desktop instance. Then, I went back to the chat titled B and sent a message in there. Then, on my Signal desktop instance, a new chat with name B popped up, actually even showing a profile picture of a person that I've never seen before. So apparently, I've sent a message to a random stranger, and I do not know how I got their contact data. Both Signal desktop and the Signal app tell me that I do not have any groups in common with this person; however, it could be the case that I once was in a group with them as I was part of a few rather big groups.

So, to summarise: Signal Android has put some messages from a chat with A in a new chat with B. However, I do not know B, have thus not started a chat with them, but somehow now have a chat with them.

Screenshots

I have removed some sensitive information on the screenshots like the real names of the people involved.

Chat with A on Desktop:

Chat with A on Android:

Chat with B (which I do not know) on Desktop:

Chat with B on Android (containing some of the messages which belong into the chat with A):

Device

Google Pixel 9a

Android version

Android 16, Graphene OS build number 2026060101, with Google Play Services

Signal version

8.13.2

Link to debug log

https://debuglogs.org/android/8.13.2/2fed541008d51a0f26f929f5bf3fbfff08cedcba965d939ebe2375fb9dc488e4

Start with the linked debug log for Signal Android 8.13.2 and trace the desktop-to-Android synchronization described in the report. Reproduce the accepted chat after Android has been disabled, then verify that the contact, messages, profile picture, and security number remain associated with A rather than B.